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Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide (2004)

Chapter: Thermally Sprayed Metal Coating Guide

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Page 61
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
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Page 62
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 63
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 64
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 65
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
Page 65
Page 66
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 67
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 68
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 69
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 70
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 71
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 72
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 73
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 74
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 75
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 76
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 77
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
Page 77
Page 78
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 79
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 80
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 81
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 82
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 83
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
Page 83
Page 84
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
Page 84
Page 85
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
Page 85
Page 86
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
Page 86
Page 87
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 88
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 89
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 90
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
Page 90
Page 91
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
Page 91
Page 92
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
Page 92
Page 93
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 94
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 95
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 96
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 97
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 98
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 99
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 100
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 101
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 102
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 103
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 104
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 105
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 106
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 107
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 108
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 109
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 110
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 111
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 112
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 113
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 114
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 124
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 125
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 126
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 127
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 134
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 135
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 136
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 137
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 138
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Page 139
Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
×
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Suggested Citation:"Thermally Sprayed Metal Coating Guide." National Academies of Sciences, Engineering, and Medicine. 2004. Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide. Washington, DC: The National Academies Press. doi: 10.17226/13766.
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THERMALLY SPRAYED METAL COATING GUIDE CONTENTS 2 SECTION 1 Introduction 3 SECTION 2 Safety and Environmental 12 SECTION 3 Coating Materials and Selection 23 SECTION 4 Surface Preparation 31 SECTION 5 TSMC Application 45 SECTION 6 Sealer Selection and Application 51 SECTION 7 Repair and Maintenance 56 SECTION 8 Quality Control and Inspection 68 SECTION 9 Qualifications 74 SECTION 10 Referenced Documents 89 SECTION 11 Generic Sealer Specification 94 GLOSSARY

21 INTRODUCTION The U.S. Army Corps of Engineers and a consortium of three technical societies (AWS [American Welding Society], NACE [National Association of Corrosion Engineers] International, and SSPC [The Society for Protective Coatings]) have developed metallizing guides. They are Thermal Spraying: New Construction and Maintenance (U.S. Army Corps of Engineers, Washington, D.C., January 29, 1999) and “Guide for the Application of Thermal Spray Coatings (Metallizing) of Aluminum, Zinc, and Their Alloys and Composites for the Corrosion Protection of Steel” (ANSI/AWS C2.18A-XX, SSPC CS 23.00A-XX, and NACE International TPX #XA), which is currently under development. These guides provide detailed information about metallizing in general. The objective of this guide is to compile existing information about metallizing into a form directed toward steel piling designers and users. The guide is intended to focus on the specialized needs of steel pilings: • The presence of edges and crevices, • Geometric shapes, • Different exposure zones and interactions between zones, • Abrasion/erosion factors, and • The effect of mechanical damage to coating. This guide covers the procedures for the application and use of thermally sprayed metal coatings (TSMCs) for corrosion control applications on piles used in highway construction. Surface preparation, materials selection, test methods, and field repair are also discussed. The guide provides the information necessary for a user to select, specify, and apply a metallized coating for steel piles in freshwater, brackish water, or seawater environments. This guide contains • Information needed to successfully apply thermally sprayed metal technology to the corrosion protection of steel piles used in highway construction. • A brief description of metallizing and the various methods of applying metallic coatings to steel, emphasizing the most appropriate means of both shop and field application of metallic coatings to steel piles. This guide discusses only wire-arc and wire-flame spray techniques because these are the most effective techniques for coating steel piles. • Descriptions of appropriate TSMCs, their life expectancies under various exposure conditions, methods of application, and any specific advantages and disadvantages. • A discussion of coating selection. • A listing of specifications and existing documents useful in the selection and application of TSMCs. • Applicator, equipment, and inspector qualifications and certifications. • Surface preparation methods and equipment. • Application methods, equipment, and tolerances. • A review of sealer coatings and a generic specification. • Inspection and quality control (QC) requirements. • A review of the effects of mechanical damage and maintenance and repair methods. • Safety and environmental considerations. • Glossary/definitions of terms and abbreviations.

32 SAFETY AND ENVIRONMENTAL 2.1 Introduction Surface preparation, thermal spraying, and sealing and painting operations expose workers to numerous potential health and safety hazards. Common health and safety hazards associated with the industry include (a) electric shock; (b) flammable and explosive solvents, gases, and fine particulate dusts and fumes; (c) confined space entry; (d) fall hazards; (e) exposure to high- intensity noise, ultraviolet light, and toxic materials; and (f) high-velocity particle impingement. While this guide does not purport to address all of the safety issues regarding TSMCs and their application, some of the more important safety concerns associated with the process are discussed below. It is recommended that all personnel involved with the thermal spray process be familiar with safe working practices and safety regulations in current standards and guides. These standards and guides include, but are not limited to, documents from the American National Standards Institute (ANSI), the American Welding Society (AWS), the Coast Guard Academy (CGA), the military, the National Association of Corrosion Engineers (NACE), the National Fire Protection Association (NFPA), the Occupational Safety and Health Administration (OSHA), and the Society for Protective Coatings (SSPC). Also refer to the U.S. Army Corps of Engineers’s Manual, Safety—Safety and Health Requirements, EM 385-1-1, Washington, D.C., November 3, 2003. Some of these standards are listed in Section 10 of this guide. 2.2 Blast Cleaning 2.2.1 Equipment Maintenance and Use Maintain abrasive blast machines and equipment in accordance with the manufacturers’ recommendations. Tag and remove from service worn or damaged components pending replacement or repair. 2.2.1.1 Hose connections. Use hoses and hose connections that do not allow electrostatic discharge. Use hose couplings and nozzles designed to prevent accidental disconnection. Use a “deadman” control device that automatically shuts off the flow of air and abrasive when the hose is dropped. Inspect hoses and fittings used for abrasive blasting frequently to ensure the timely replacement of worn parts and equipment. 2.2.1.2 Hose use. Blast hoses shall be kept as straight as possible. Use a large radius of curvature for any bends so as to avoid excessive friction and wear. Store hoses in cool dry areas to avoid accelerated degradation. Never point the blast nozzle at the body parts of any person. Relieve air pressure in the blast tank and system before working on the system. Use a “tag- out” labeling system during system maintenance. 2.2.1.3 Ventilation. Provide mechanical ventilation in blasting operations that are not performed in the open or in a properly designed and ventilated room.

42.2.2 Personal Protective Equipment Wear respiratory protective devices—helmets, hand shields, eye protection (face shields or goggles), and appropriate protective clothing—during all blasting operations. For blasting in the open, use a mechanical filter respirator in conjunction with face shields and dust hoods. Alternatively, an air-line respirator may be used. For blasting in confined or enclosed spaces, a continuous flow air-line respirator, a full-face piece or helmet, and dust hood are required. 2.2.2.1 Respirators. The guidelines listed below should be followed when using respirators. • Compressed air should meet at least the requirements of the specification for Type 1, Grade D breathing air as described in CGA G 7.1 “Commodity Specification for Air.” • Respiratory protection shall be in accordance with ANSI Z88.2. • All respiratory devices shall comply with the U.S. Bureau of Mines and the National Institute for Occupational Safety and Health (NIOSH). Respirators selected from those currently approved and certified by NIOSH/Mine Safety and Health Administration (MSHA) Section 134 should be used. • Use NIOSH-certified Type CE respirator and Type CE hood (air-line-supplied air hood with faceplate and devices to protect the wearer’s eyes, face, chin, neck, shoulders, and upper body from rebounding abrasive blasting media). • Note: Personnel using/wearing respirators require “fit-testing” before they can legally work under these conditions. Also, beards can affect the efficacy of respirators. 2.2.2.2 Eye and body protection. The guidelines listed below should be followed when using eye and body protection. • Head protection shall be in accordance with ANSI Z89.1. Face shields or helmets shall be equipped with dust hoods to protect the eyes, face, chin, and neck. • Personnel in or near blasting operations should wear helmets, handshields, faceshields, or goggles conforming to ANSI Z87.1 and eye protection conforming to ANSI Z89.1. • Appropriate protective clothing shall be worn during spray operations. Clothing should be strapped tightly around wrists and ankles to prevent contact with abrasive dust. Open shirt collars and unbuttoned pocket flaps are unacceptable. High-top shoes should be worn and cuff-less trousers should cover the tops. • Blasting operators should wear heavy canvas or leather gloves and an apron or coveralls. Approved safety shoes should be worn to protect against foot injury. 2.2.2.3 Hearing protection. Noise levels generated during blasting and thermal spray operations can cause temporary or permanent hearing loss, damage, and fatigue. • Wear approved earmuffs and properly fitted approved earplugs when thermal spray operators and personnel are in the immediate vicinity of thermal spray operations to reduce the high-intensity noise levels to acceptable conditions. • All personnel in the vicinity of blasting operations shall be provided with hearing protection if the noise exposure exceeds the limitations established by OSHA in paragraph 1910.95, “Occupational Noise Exposure”.

52.2.3 Cleaning with Compressed Air Cleaning with compressed air should be restricted to systems where the air pressure has been reduced to 204 kPa (30 psi) or less. Cleaning operators should wear safety goggles or a face shield, hearing protection, and appropriate body covering. Compressed air or pressurized gas nozzles should never be pointed at other personnel or at exposed skin. 2.2.4 Cleaning with Solvents The guidelines listed below should be followed when cleaning with solvents. • The material safety data sheet (MSDS) for each solvent used must be readily available and should be consulted for specific solvent information, handling, and storage and disposal procedures, in addition to those listed here. • Flammable liquids with a closed-cup test flash point below 100°F (38°C) should not be used for cleaning purposes. • Sources of ignition should not be permitted in the vicinity of solvent cleaning if there is any indication of combustible gas or vapor present. • Measurements should be made to ensure that solvent vapors are not present during thermal spray operations, especially in confined spaces. Representative air samples should be collected from the breathing zone of workers involved in the cleaning process to determine the specific solvent vapor concentrations. • Worker exposures should be controlled to levels below the Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit, as indicated in CFR 29 Part 1910, Section 1000. 2.3 Thermal Spraying 2.3.1 Safety Issues Airborne metal dusts and fumes, finely divided solids, or other particulate accumulations should be treated as explosive materials. Proper ventilation, good housekeeping, and safe working practices should be maintained to prevent the possibility of fire and explosion. Thermal spray equipment should never be pointed at personnel or flammable materials. Thermal spraying should not be performed in areas where paper, wood, oily rags, or cleaning solvents are present. Electrically conductive safety shoes should be worn in any work area where an explosion is a concern. During thermal spray operations, including the preparation and finishing processes, employees should wear approved protective coveralls or aprons, hand protection, eye protection, ear protection, and respiratory protection. SAFETY PRECAUTION: The fine aluminum and zinc particulates (metal dust and fume) produced during thermal spraying may be an extreme explosion hazard. Special precaution should be taken during wire-arc spraying due to the higher amounts of metal dust and fume produced that accompany higher spray rates, especially if multiple wire-arc spray units are being used in the same work area. Do not use water to extinguish aluminum or zinc fires. Use dry sand or a Class D extinguisher.

62.3.2 Personal Protective Equipment The general requirements for the protection of personnel involved with thermal spraying are the same as those specified for welders in ANSI/AWS Z49.1, “Safety in Welding and Cutting.” Helmets, hand shields, eye protection (face shields or goggles), hearing protection, respirators, and appropriate protective clothing shall be worn during all spraying operations. 2.3.2.1 Eye and skin protection. All thermal spray processes introduce particulates and fumes into the air that may irritate and damage the eyes or skin. The processes also emit hazardous ultraviolet (UV), infrared (IR) and intense visible light radiation. • Eye and face protection must be worn to protect against particulate impingement. Hoods or face shields conforming to ANSI Z87.1 and ANSI Z89.1 with filter lenses should be worn to protect the face and eyes. Various shades of lens filters are recommended based on the type of thermal spray process being used: – For wire-flame spray, use lens shades 2 to 4. – For wire-arc spray, use lens shades 9 to12. – Shades 3 to 6 can be used for wire-arc spray if the gun is equipped with an arc shield. The shield encloses the arc and reduces the operator’s exposure to the high-intensity light radiation. • Other workers in the vicinity of the thermal spray applicator should also use proper eye protection. • Flame-resistant clothing should be worn to protect the skin. Clothing should be strapped tightly around the wrists and ankles to prevent contact with sprayed materials. Open shirt collars and unbuttoned pocket flaps are unacceptable. High-top shoes should be worn, and cuff-less trousers should cover the shoe tops. Protection against radiation from the spray process is detailed in ANSI/AWS Z49.1. • Aluminized clothing may be used with the following precautions: – IR and UV radiation are not to be reflected onto unprotected skin. – Provide suitable protection against electric shock. 2.3.2.2 Hearing protection. Thermal spray produces very high noise levels (up to 130 dBA) that can rapidly cause permanent hearing loss. • Thermal spray operators and other workers in the vicinity of the thermal spray operation should wear approved hearing protection at all times. • Protection against the effects of noise exposure should be provided in accordance with the requirements of EM 385-1-1, Section 5, “Personal Protective and Safety Equipment,” Subsection 05.C, “Hearing Protection and Noise Control,” and CFR 29 Part 1910, Section 95. • Insert earplugs should be used during wire or powder flame spray. Insert earplugs should be worn as a minimum protection during wire-arc spraying. Insert earplugs and approved earmuffs are recommended for use with wire-arc, plasma, and high-velocity oxygen fuel

(HVOF) spray. Table 1 lists the minimum recommended hearing protection devices for various thermal spray application methods. 2.3.2.3 Respiratory protection. Thermal spray generates toxic dusts and fumes. Thermal spray operators and personnel in the general vicinity of the spraying operation should wear appropriate approved respirators. Overexposure to zinc fume is known to produce flu-like symptoms, often called “metal fume fever.” • An approved mechanical filter type respirator shall be used when spraying nontoxic materials with dust and metal-fume exposure. When spraying in confined spaces, an air- line respirator shall be used. When spraying highly toxic materials, the air-line respirator shall be equipped with an emergency auxiliary cylinder of respirable air. Respiratory protection shall be in accordance with ANSI Z88.2. • All respiratory devices used shall comply with the U.S. Bureau of Mines and the National Institute for Occupational Safety and Health (NIOSH). 2.3.3 Wire-Arc Spray 2.3.3.1 Electrical shock prevention. High DC voltages and amperages (currents) inherent to the wire-arc spray process pose severe electrical hazards. The operator shall be thoroughly trained in the safe operation of the wire-arc spray equipment prior to its use. • The manufacturer’s safe operating procedures should always be followed. • Ground protection for equipment and cords should be present, in good condition, and tested regularly for correct operation. • Electrical outlets should have ground fault circuit interrupters (GFCIs) in addition to appropriate over-current protection (e.g., fuses and circuit breakers). Electrical circuit grounds and GFCIs should be tested before work begins and tagged, reported, and not used if found to be faulty. • Switches and receptacles should have proper covers. • Buttons, lights, plugs, and cables shall be in compliance with ANSI/NFPA 70, “National Electrical Code.” Periodic inspections of cables, insulation, and hoses shall be performed. Damaged components shall be tagged, removed from service, and immediately repaired or replaced. • Cords should be approved for outdoor or wet or damp locations. The cords should be hard usage or extra hard usage as specified in ANSI/NFPA 70 “National Electrical Code.” Cords should not be spliced. • Arc guns and power supplies should be cleaned frequently, as per the manufacturer’s recommendations, to remove build-ups of metallic dusts, which may cause short circuits. 7 Thermal Spray Process Noise Level, dB(A) Minimum Recommended Protection Wire-flame spraying 114 Earplugs Wire-arc 111–116 Earplugs and earmuffs TABLE 1 Typical noise levels and hearing protection requirements

2.3.4 Flame Spray 2.3.4.1 Gas cylinder safety. To ensure gas cylinder safety, the guidelines listed below should be followed. • Compressed gas cylinders should be handled in accordance with ANSI Z49.1 and with CGA P-1. • Only special oxidation-resistant lubricants should be used with oxygen equipment; grease or oil should not be used. • Manifolds, pressure-reducing regulators, flow meters, hoses, and hose connections should be installed in accordance with ANSI Z49.1. • A protective shield should be used to shield glass tube flowmeters from the spray gun. • Pressure connecting nuts should be tight, but not overly tight. Fittings that cannot be sealed without excessive force should be tagged and replaced. • Compressed air for thermal spraying or blasting operations should only be used at pressures recommended by the equipment manufacturers. The air-line should be free from oil and moisture. • Compressed air, oxygen, or fuel gas should never be used to clean clothing. • Cylinders should be handled, stored, and secured in accordance with established regulations and safe working practices. • Hoses used with flammable gases shall be fitted with approved “flash-back” arrestors to prevent any flame burning back along the hoses from reaching the cylinders. 2.3.4.2 Flame spray safety. To ensure flame spray safety, the guidelines listed below should be followed. • Flame spray equipment should always be maintained and operated according to the manufacturer’s instructions. Thermal spray operators should be trained and familiar with their equipment before starting an operation. • Valves should be properly sealed and lubricated. • Friction lighters, pilot lights, or arc ignition methods of lighting flame spray guns should be used. • If the flame spray gun backfires, it should be extinguished immediately. Re-ignition of a gun that has backfired or blown out should not be attempted until the cause of the trouble has been determined and remedied. • Flame spray guns or hoses should not be hung on regulators or cylinder valves. Gas pressure should be released from the hoses after the equipment is shut down or when equipment will be left unattended. • Lubricating oil should not be allowed to enter the gas mixing chambers when cleaning flame spray guns. • Do not light wire-flame and rod guns without wire or rod in the nozzle as flames may burn back into the gun, causing operator injury and equipment damage. 2.3.5 Ventilation Thermal spraying should only be performed by operators using appropriate respiratory protection and in locations with adequate ventilation. 8

• Local exhaust or general ventilation systems should be used to control toxic fumes, gases, or dusts in any operations not performed in the open. Thermal spraying in an enclosed space should be performed with general mechanical ventilation, air-line respirators, or local exhaust ventilation sufficient to reduce the fumes to safe limits specified by ACGIH-02. • Personnel exposures should be controlled to the safe levels recommended by ACGIH-02 or prescribed by CFR 29 Part 1910, whichever is the more stringent. • Air sampling should be performed before entry of personnel into a confined space, during confined-space entry that involves contaminant-generating operations such as flame spraying, and in areas where ventilation is inadequate to ensure that air contaminants will not accumulate. • Engineering controls (enclosures and/or hoods with ducted, mechanical ventilation of sufficient volume to remove contaminants from the work space) are the most desired methods of preventing job-related illness resulting from breathing air contaminated with harmful dusts, mists, fumes, vapors, and/or gases. • Treat airborne metal dusts, finely divided solids, or their accumulations, as explosives. Use adequate ventilation in the thermal spray work area and collect overspray to minimize the danger of dust explosions and fires. In shop environments, wet, bag, and dry filter-cartridge type collectors may be used to collect the fine overspray particles, thus minimizing the explosion and fire hazard and release of controlled and/or hazardous materials. Keep bag- and filter-cartridge collector units at least 50 ft (15 m) away from the spraying area to preclude ignition from the flame or heat of the thermal spray process. • Thermally sprayed aluminum and zinc powders, nominally 40 to 110 µm (0.0016 to 0.0044 in.) in diameter, are not a combustion or explosive hazard when handled and used in accordance with a powder manufacturer’s instructions. Refer to the Aluminum Association’s recommendations for the safe storage and handling of aluminum powders. • All fans, pipes, dust arrestors, and motors should be properly grounded. Ground to piping that carries fuel gases or oxygen should not be used. Ventilating fans should be kept running when cleaning out spray booths, pipes, etc., to prevent the accumulation of dust or fumes in the system. Aluminum and magnesium dusts present an explosive hazard that requires special attention. Adequate wet collector systems should be used with either of these metals. Care should be exercised, since these metallic dusts may generate hydrogen gas on contact with water. These systems should be designed to prevent hydrogen accumulation. Frequent, scheduled, cleanout operations should be performed to reduce residues. Residues should be handled and disposed of in accordance with OSHA and EPA regulations. 2.4 Housekeeping 2.4.1 Thermal Spraying Area Remove paper, wood, oily rags, cleaning solvents, sealers, and paints from the thermal spraying area. 2.4.2 Shop and Field Work Areas Good housekeeping in the shop and field work areas should always be maintained to ensure proper storage of hazardous materials and to avoid accumulation of combustible or 9

potentially explosive materials and metal dusts, and particular attention should be given to inspecting for dust build-ups on beams, rafters, booth tops, and in floor cracks. 2.5 Sealers and Topcoats 2.5.1 Solvents Solvents used for cleaning or to apply sealers or topcoats (e.g., acetone, xylene, or alcohol) emit vapors that are harmful and can be fatal. • Use only with adequate ventilation or proper respiratory protection and other protective clothing as needed. • Avoid breathing solvent vapors and skin contact with solvents. • Most solvents are also flammable liquids. All solvent tanks must have lids and be covered when not in use. Take proper safety precautions. • Keep all solvents and flammable materials at least 50 ft (15.2 m) away from welding, oxyfuel cutting and heating, and thermal spraying operations. 2.5.2 Spray Application Sealers and paint coats are typically applied by spray application. Spray application is a high- production rate process that may rapidly introduce very large quantities of toxic solvents and vapors into the air. • Airless spray systems operate at very high pressures. Very high fluid pressures can result in penetration of the skin on contact with exposed flesh. • Tip guards and trigger locks should be used on all airless spray guns. The operator should never point the spray gun at any part of the body. • Pressure remains in the system even after the pump is turned off and can only be relieved by discharging or “blow-down” through the gun. 2.6 Material Safety Data Sheets (MSDSs) The contractor should maintain current MSDSs for all materials used on the job. These materials include cleaning solvents, compressed gases, thermal spray wires or powders, sealers, thinners, and paints or any other materials required to have an MSDS as specified in CFR 29 Part 1910, Section 1200. The MSDSs should be readily available to all personnel on the job site in a clearly labeled folder. 2.7 Environmental 2.7.1 Regulations Federal, state, and local regulations may be applicable with regard to containment, storage, and disposal of blasting debris and metallizing emissions. This may include partial or complete containment of the work site for surface preparation and thermal spraying and the collection and safe disposal of used blasting media and thermal spray overspray. Ensure compliance 10

with the purchaser’s requirements and all pertinent government agency requirements and regulations for air-quality and hazardous-materials control. 2.7.2 Handling Debris The applicator and the purchaser should coordinate the specific requirements, responsibilities, and actions for the containment, storage, collection, removal, and disposal of the debris produced by the TSMC operations. 2.7.3 Lead in Coating The removal of old coating containing lead requires special treatment. Further information is available in Chapter 11 of the U.S. Army Corps of Engineers Engineering and Design Manual, Painting: New Construction and Maintenance, EM 1110-2-3400, Washington, D.C., April 30, 1995. 11

3 COATING MATERIALS AND SELECTION 3.1 Alloy Selection TSMCs are used for the protection of the exposed surfaces of iron and steel components used in various corrosive environments. Long-term protection in excess of 20 years in both industrial and marine exposures has been documented. Zinc, aluminum, and zinc/aluminum alloy coatings provide sacrificial corrosion protection to a steel substrate, even when areas of the substrate are exposed to the corrosive environment. The relatively low corrosion rates of these coatings, in combination with the sacrificial corrosion protection that they offer, make them suitable for use in such harsh environments. Zinc has a higher electrochemical activity than aluminum has and thereby provides a higher level of cathodic protection to a steel substrate than does aluminum. Aluminum, with its lower electrochemical activity and adherent oxide film formation, provides a lower level of cathodic protection to a steel substrate. Electrical conductivity and pH contribute to the corrosivity in immersion environments. Due to the relatively high electrical conductivity of natural seawater, aluminum is the recommended thermal spray coating material for this environment. The higher galvanic interaction of zinc with the steel corresponds to a higher consumption rate in seawater immersion. In a freshwater environment, where the electrical conductivity is lower, zinc or 8515 weight percent (wt%) zinc/aluminum alloy coating will provide a better balance between cathodic protection and barrier protection and is the recommended thermal spray coating material. 3.1.1 Types of Exposure and Suitable Alloys Foreknowledge of the environmental stresses to which the protective coating system will be exposed is critical for the proper selection of the coating system. This is true of both paint and thermally sprayed coating systems. Exposure environments typically encompass one or more of the following environmental stresses: extremes of temperature, high levels of humidity, complete or partial or intermittent immersion, extremes of pH, solvent exposure, wet/dry cycling, thermal cycling, ultraviolet exposure, impact and abrasion, cavitation/erosion, and special exposures. The service environment is the single most important consideration in the selection of a coating system. Table 2 provides a summary of thermal spray metal coatings selection recommendations. Table 2 lists several environmental categories. It should be recognized that, particularly in atmospheric environments, a single category might not represent a particular environment. Moisture, wind direction, solar radiation, and local pollution effects (e.g., groundwater runoff discharge pipes and industrial drainage) can create microclimates that will affect the performance of materials and coatings. These conditions must be recognized in the selection of the proper coating. 3.1.1.1 Atmospheric high humidity. High humidity is often accompanied by condensation, which is considered to approximate the severity of freshwater immersion. An 8515 wt% zinc/ aluminum wire-arc spray coating to a thickness of 12 mils (305 µm) is the recommended thermal spray system for high-humidity environments. Typically, high-performance paint 12

systems, such as the epoxy and vinyl systems, are specified for high-humidity applications. Because paint systems are generally less costly to apply, they are more likely to be used for these types of exposures. However, the 8515 wt% zinc/aluminum thermal spray system should have a longer service life than paint coatings for this application. 3.1.1.2 Wet/dry cycling. A zone of alternating wet and dry is generally the most corrosive zone due to macrocell corrosion. This type of exposure is found in splash zones and tidal zones. Most TSMC systems will provide adequate protection under such conditions. Sealing and topcoating of the TSMC is generally recommended for such exposures. 3.1.1.3 Immersion. Immersion exposures range from immersion in deionized water to immersion in natural waters, including freshwater and seawater. Ionic content and pH contribute to the corrosivity of immersion environments. Typical sealers and topcoats are vinyl paints and coal tar epoxy coatings. Several epoxy and vinyl systems are appropriate for various immersion exposures depending on whether the water is fresh or salt and the degree of impact and abrasion. Epoxy systems are preferred for saltwater exposures, whereas the vinyl systems are generally preferred for freshwater exposures, especially where the level of impact and abrasion is significant. • Seawater. Wire-arc sprayed aluminum to a coating thickness of 10 mils (250 µm) is recommended for seawater immersion. Aluminum thermal spray has been used extensively by the offshore oil industry to protect immersed and splash zone platform components from corrosion. Aluminum thermal spray is thought to perform better in seawater immersion without an organic sealer and paint topcoat, and some specifications, such as U.S. Army COE CEGS-09971, recommend not using a sealer in seawater immersion. Wire-arc sprayed aluminum is the recommended thermal spray system for this application. 13 Environment Coating Thickness mils [µm] Sealer* Atmospheric Rural Zinc or zinc-aluminum 6–8 [150–200] No Industrial Zinc or zinc-aluminum 12–15 [305–380] Yes Marine Aluminum or zinc- aluminum 12–15 [305–380] No Immersion Freshwater Zinc-aluminum 12–15 [305–380] Yes Brackish Water Aluminum 12–15 [305–380] No Seawater Aluminum 12–15 [305–380] No Alternate Wet-Dry Freshwater Zinc-aluminum 10–12 [250–305] Yes Seawater Aluminum 12–15 [305–380] Yes Abrasion Zinc-aluminum 14–16 [355–405] Yes Condensation Zinc or zinc-aluminum 10–12 [250–305] Yes * See Section 6, “Sealer Selection and Application,” for further information. TABLE 2 Thermally sprayed metal coating selection guide for 20- to 40-year life

• Freshwater. Wire-arc sprayed 8515 wt% zinc/aluminum to a coating thickness of 12 mils (300 µm) is recommended for freshwater immersion. These systems can be used either with or without sealers and topcoats. The 8515 wt% zinc/aluminum system combines the superior corrosion resistance of zinc and the improved impact and abrasion resistance of aluminum. Seal coats and paint topcoats may be used to add a further degree of protection to the TSMC systems used in freshwater immersion, but their use is not considered an absolute necessity. 3.1.1.4 Ultraviolet exposure. Resistance to ultraviolet (UV) radiation–induced degradation is an important aspect of coating performance. All thermally sprayed coatings are essentially unaffected by UV radiation. Organic sealers and topcoats used over TSMCs will be affected the same way as any other paint materials of the same type. Organic paint coatings are affected by UV radiation to varying degrees. Depending on the coating resin and pigmentation types, UV degradation may result in loss of gloss, color fading, film embrittlement, and chalking. Certain paints, including silicone and aliphatic polyurethane coatings, may exhibit superior UV resistance. Some coatings, including most epoxies and alkyds, have fairly poor UV resistance. The properties of a specific coating must be considered when selecting a coating that must have UV light resistance. 3.1.1.5 Impact and abrasion. Impact and abrasion are significant environmental stresses for any coating system. Abrasion is primarily a wear-induced failure caused by contact of a solid material with the coating. Examples include foot and vehicular traffic on floor coatings, ropes attached to mooring bitts, sand particles suspended in water, and floating ice. When objects of significant mass and velocity move in a direction normal to the surface as opposed to parallel, as in the case of abrasion, the stress is considered to be an impact. Abrasion damage occurs over a period of time, whereas impact damage is typically immediate and discrete. Many coating properties are important to the resistance of impact and abrasion including adhesion to the substrate, cohesion within the coating layers, toughness, ductility, and hardness. Thermally sprayed coatings of zinc, aluminum, and their alloys are very impact resistant. Zinc metallizing has only fair abrasion resistance in immersion applications because the coating forms a weakly adherent layer of zinc oxide. This layer is readily abraded, which exposes more zinc, which in turn oxidizes and is abraded; 8515 wt% zinc/aluminum is more impact/abrasion resistant than pure zinc or pure aluminum. 3.2 Concerns Related to Performance of the TSMC 3.2.1 Limits on Surface Preparation Coating selection may be limited by the degree or type of surface preparation that can be achieved on a particular structure or structural component. Because of physical configuration or proximity to other sensitive equipment or machinery, it may not always be possible to abrasive blast a steel substrate. In such cases, other types of surface preparation, such as hand tool or power tool cleaning, may be necessary, which, in turn, may place limits on the type of coatings that may be used. In some cases, it may be necessary to remove the old coating by means other than abrasive blasting, such as power tools, high-pressure water jetting, or chemical strippers. These surface preparation methods do not impart the surface profile that is needed for some types of coatings to perform well. In the case of thermally sprayed 14

coatings, a high degree of surface preparation is essential. This kind of preparation can only be achieved by abrasive blasting using a good-quality, properly sized angular blast media. Thermal spraying should never be selected for applications in which it is not possible to provide the highest quality surface preparation. 3.2.2 Ease of Application Coating selection may also be limited by the ability of the applicator to access the surfaces to be coated. This is usually the result of the physical configuration or design of the structure. Items of limited access such as back-to-back angles, cavities, blind holes, and crevices may be difficult, if not impossible, to coat. Most items that can be coated by paint spray application may also be coated by thermal spray. Both methods require about the same amount of access area for hoses, maneuvering, and standoff distance. As a rule of thumb, if access to the surface allows proper blast cleaning, then thermal spray application is feasible. TSMCs perform best when sprayed in a direction normal (i.e., 90 degrees) to the surface and within a particular range of standoff distances from the substrate. Application at angles of less than 45 degrees to the vertical is not recommended. Maximum and minimum standoff distances depend on the material being applied, the manufacturer, and the type of thermal spray equipment used. If the standoff distance and spray angle cannot be maintained within the specified range, hand application of a paint coating may be necessary. 3.2.3 Regulatory Requirements The use of paint coatings is regulated in terms of the types and amounts of solvents or volatile organic compounds (VOCs) they contain. Certain types of solvents, such as water and acetone, are exempt from these regulations because they do not contribute to the formation of photochemical pollution or smog in the lower atmosphere. Regulations vary by geographic location and by industry. Different rules apply for architectural and industrial maintenance painting, marine painting, and miscellaneous metal parts painting. The specifier should consult with local and state officials to determine which rules, if any, affect the proposed coating work. There are no VOC emissions associated with the use of TSMCs, and their use is not regulated by any such rule. TSMCs offer an excellent VOC-compliant alternative to paint coatings for many applications. However, the sealers and topcoats recommended for thermal spray systems are not exempt from VOC-type regulations. The thermal spray coatings will often perform just as well without the sealers and topcoats, which can therefore be omitted for reasons of compliance with air pollution regulations. It should also be noted that there are typically low-VOC paint coating alternatives for most applications. The relative merits of these products should be weighed against those of the zero-VOC TSMC systems. Thermal spraying of metals produces airborne metal dusts and fumes. Finely divided solids or other particulate accumulations are an explosion hazard. Fine metal particles might damage some types of equipment, such as electronics and bearings. Metal fumes can pose a health hazard (e.g., “metal fume fever”). Proper containment and ventilation may be required in order to reduce these risks. See Section 2 for a discussion of appropriate safety and environmental concerns. 15

3.2.4 Field Conditions The conditions under which the coating work will be performed are another important consideration in coating selection. Certain atmospheric conditions, including high levels of humidity and condensation, precipitation, high winds, and extreme cold or heat, place severe limitations on any type of coating work. 3.2.4.1 Moisture. Moisture on the surface should always be avoided to the greatest extent possible. Certain types of paint are more tolerant of small amounts of water on the surface than others and should be specified for work where such conditions cannot be avoided. Thermally sprayed coatings should never be applied if moisture is present on the surface. 3.2.4.2 High winds. High winds may affect the types of surface preparation and coating application methods that are practical for a given job. High winds will tend to carry surface preparation debris and paint overspray over longer distances. This problem can be avoided by using methods other than open abrasive blasting and spray application of paints. 3.2.4.3 High atmospheric temperatures. For sealers and finish coats, the pot life of multi-component catalyzed coatings such as epoxies can be greatly reduced by high atmospheric temperatures. High ambient air and surface temperatures can also adversely affect paint application and the subsequent performance of the coating; for example, vinyl paints are prone to dry spray at high temperatures. Most paints should not be applied below a certain minimum temperature because they will not cure or dry. Most epoxy paints should not be applied when the ambient and substrate temperatures are below 50°F (10°C); however, there are some specialized epoxy coatings that can be applied at temperatures as low as 20°F (−7°C). Latex coatings should never be applied when temperatures are expected to fall below 50°F (10°C) during application and drying. Vinyl paints can be applied at quite low temperatures compared with most paints. Vinyl application at 32°F (0°C) can be performed with relative ease. There are generally no upper or lower ambient or surface temperature limits on the application of TSMCs, although there are practical limits at which personnel can properly perform their tasks. 3.2.5 Maintainability The future maintainability of a coating system should be considered by the specifier. Some protective coatings are easier to maintain than others. The specifier should also be cognizant of how maintenance painting is normally achieved, whether by contractor or with in-house labor. In-house labor is usually sufficient for low-technology processes requiring minimal training and equipment. For example, “touch-up” painting with brushes or rollers of paints exposed to the atmosphere is readily accomplished with in-house labor. More sophisticated, dedicated, in-house paint crews can carry out more complicated work including abrasive blasting and spray application of paints for immersion service. TSMC and maintenance, because of their specialized nature and relatively high equipment costs, are ordinarily best accomplished by outside contractors. TSMCs are more difficult to repair than are most paint coatings. The ease of spot repair of TSMCs approximates that of the vinyl paint systems. As with the vinyls, special care must be taken to properly feather the edges of the blast-repaired areas without causing the adjacent coating to disbond or lift from the surface. Because of the difficulty of effecting appropriate repairs, TSMC systems, like the vinyls, are generally kept in service until total recoating is needed. 16

3.3 Cost 3.3.1 Cost Considerations Coating systems are cost-effective only to the extent that they provide the requisite corrosion protection. Cost should be considered only after the identification of coating materials that will perform in the exposure environment. Given that a number of alternative coating systems may perform in a given application, the next consideration is the cost of the coating job. Ideally, protective coating systems will be selected based on life-cycle cost rather than simple installed cost. However, given the realities of budgets, this approach is not always practical. Therefore, coating systems are sometimes selected on the basis of first or installed cost. Because TSMC systems are almost always more expensive to install than paint systems for a given application, they are often passed over, when, in fact, they can have significantly lower life-cycle costs than paint systems. Additional information on the cost of TSMCs and how to perform cost calculations is provided below. 3.3.2 Cost Analysis 3.3.2.1 Cost of materials and application. The cost of a TSMC system in terms of materials and application is higher than the cost of conventional liquid-applied coatings; however, the major cost of a coatings project is not the materials and application. The dominant factor in coating rework is not material and application cost, but rather it is the cost of taking the facility out of service, contractor mobilization, environmental constraints (e.g., containment and disposal), and monitoring. In most complex coating rework, the actual cost of materials and application is less than 20 percent of the total process. Thus, if one is able to gain a three- fold life extension by using TSMC, the process can pay for itself. 3.3.2.2 Life-cycle cost. Whenever possible, coating selection should be based on life-cycle cost. In reality, the engineer must balance competing needs and may not always be able to specify the least expensive coating on a life-cycle cost basis. Because of their somewhat higher first cost, TSMCs are often overlooked. To calculate life-cycle costs, the installed cost of the coating system and its expected service life must be known. Life-cycle costs for coating systems are readily compared by calculating the average equivalent annual cost (AEAC) or present worth (PW) for each system under consideration. The present worth can be calculated using the following relationship: where F = cost of initial coating system, M = cost of maintenance in year Pn, r = interest rate, r1 = inflation rate, n = number of maintenance actions required to achieve life of structure, P1 = number of years to first maintenance, PW F M r r M r r M r r P P P P P P n n = + + + + + + + + + + ( ) ( ) ( ) ( ) ( ) ( ) 1 1 1 1 1 1 1 1 1 1 1 2 2 L 17

P2 = number of years to second maintenance, and Pn = number of years to last maintenance. (For more information, refer to E. L. Grant, W. G. Irerson, and R. S. Leavenworth, Principles of Engineering Economy, 7th ed., John Wiley & Sons, New York, 1982 and ASM Handbook, Volume 13—Corrosion, 9th ed., ASM International, Materials Park, OH, 1987, pp. 369–374). 3.3.2.3 Installed cost. The basic installed cost of a TSMC system is calculated by adding the costs of surface preparation, materials, consumables, and thermal spray application. The cost of surface preparation is well known. The cost of time, materials, and consumables may be calculated using the elements: (1) Surface area to be coated (SA). SA = length × width (2) Volume (V) of coating material needed to coat the area. V = SA × coating thickness (3) Weight of the material to be deposited (Wd). The density (D) of the applied coating will be less than that of the feedstock material. A good assumption is that the applied coating will be about 90 percent of the density of the feedstock material. Densities are as follows: aluminum—0.10 lb/in.3 (2.70 g/cm3), zinc—26 lb/in.3 (7.13 g/cm3), and 8515 wt% zinc/aluminum wire—0.207 lb/in.3 (5.87 g/cm3). Wd = V × 0.9D (4) Weight (W) of material used. Deposition efficiencies (DE) of zinc, aluminum, and 8515 wt% zinc/aluminum, applied by wire-arc spray, are estimated to be 60 to 65 percent, 70 to 75 percent, and 70 to 75 percent, respectively. W = Wd /DE (5) Spray time (T). Spray rates (SRs) for wire-arc sprayed materials vary depending on wire diameter and current settings. Table 5 (in Section 5) provides typical spray rates for materials and wire sizes. T = W/SR (6) Electricity or oxygen and fuel gas consumption (C). Typical consumption rates (CRs) for electricity, fuel gas, and oxygen are available from equipment manufacturers. C = CR x T (7) Cost of materials (CM). CM = W × cost per unit weight 18

(8) Cost of application (CA). CA = T × unit labor cost (9) Cost of consumables (CC). CC = T × unit cost of consumable (10) Total cost (TC) of the TSMC. TC = CM + CA + CC. 3.3.2.4 Factors that increase cost. Factors that increase the cost of thermal spray and other coating jobs include the cost of containment, inspection, rigging, mobilization, waste storage and disposal, and worker health and safety. These can have a significant effect on coating cost and might be independent of the type of coating system being considered. They should be considered when comparing annual cost or PW of different systems. 3.3.2.5 Cost-effectiveness of TSMCs. In 1997, the Federal Highway Administration (FHWA) compared the performance of a number of coating systems, including paints and thermal spray. Coating life expectancies were estimated based on their performance in an aggressive marine atmospheric exposure and a mildly corrosive environment. Installed and life-cycle costs were calculated for each coating system for each exposure. Average equivalent annual costs were calculated based on a 60-year structure life. For the more severe marine atmospheric exposure, TSMCs of aluminum, zinc, and 8515 wt% zinc/ aluminum alloy were the most cost-effective coatings. For the less severe mildly corrosive atmospheric exposure, thermal spray was no more or less cost-effective than other coating options. Report FHWA-RD-96-058 provides the details of the study. For example, the costs used were the following: 19 Costs per square foot Item Zinc/Aluminum Epoxy Annual @ 6 mils Mastic/ EscalationPolyurethane Rate, % Surface preparation (labor + material), $ 1.25 $ 0.60 3.94 SSPC-SP 10 Coating application (labor) $ 2.50 $ 0.30 4.00 Coating material $ 1.50 $ 0.42 1.91 Containment and air filtration system $ 2.00 $ 2.00 3.00 Rigging $ 0.50 $ 0.50 3.00 Mobilization $ 0.50 $ 0.50 3.00 Hazardous waste storage and disposal $ 2.50 $ 2.50 6.00 Worker health and safety $ 2.00 $ 2.00 4.00

While the surface preparation, coating material, and application costs were initially higher for the zinc/aluminum TSMC, the savings came in the number of times the coating must be applied. The TSMC requires two applications within the 60-year life of the structure (one initial coat and one maintenance recoat), whereas the epoxy/polyurethane requires eight coats within the 60-year life of the structure (one initial coat and seven maintenance recoats). This worked out to a total present value for the epoxy mastic/polyurethane system of $21.37/ft2 ($1.99/m2) compared with $18.38/ft2 ($1.71/m2) for the zinc/aluminum TSMC. 3.4 Design Proper design can improve the performance of coatings by removing some features that tax the coatings’ ability to protect the structure. NACE International Recommended Practice RP0178, “Fabrication Details, Surface Finish Requirements, and Proper Design Considerations for Tanks and Vessels To Be Lined for Immersion Service,” while it addresses tanks, has some pertinent recommendations that are applicable to piles. These include the following: • Avoid dissimilar metals in direct contact with each other. Examples to be avoided are aluminum or stainless steel fasteners connected directly to steel without dielectric bushings and washers and aluminum conduit and straps connected directly to steel without dielectric insulation. • Where welding is used, use a continuous weld bead. Remove weld spatter and weld metal irregularities that could interfere with obtaining an adequate coating film thickness. • Edges should be beveled or rounded to break up sharp corners. Optimally, edges should have a minimum radius of 1/8 in. (3 mm) and preferably 1/4 in. (6 mm). • Allow drainage in the case of horizontal members by installing drain holes or orienting the member such that it does not hold water. Make the drain hole large enough to reduce the likelihood of becoming clogged. • Avoid lap joints (faying surfaces) where possible because these do not permit coating of the surfaces within the joint. If unavoidable, seal weld lap joints. • Avoid pockets where the abrasive blast equipment cannot effectively clean and thermal spray cannot effectively coat the surface. • Avoid back-to-back angles because the interior facing surfaces cannot be cleaned and protected. Alternately use a T-section or other shape that allows open access to all surfaces. Seal weld back-to-back angles if they must be used. • Ensure that all corrosion-prone surfaces are accessible for applying TSMCs both during initial fabrication and during the lifetime of the structure. 3.5 Areas Requiring Special Treatment 3.5.1 Portions Below the Mudline The TSMCs discussed in this guide are generally applicable to areas above the water, in tidal and splash zones, and below the waterline. Figure 1 shows typical corrosion losses with low- alloy and carbon steel. Significant corrosion occurs in the splash, tidal, and immersion zones and in the zone a few feet below the mudline, with relatively little corrosion deeper into the mud. This is because there is little oxygen below the mudline to support aggressive 20

corrosion. The application of a TSMC below the mudline is not necessary; however, coating a few feet below the mudline will allow for changes in bottom elevation with time and situations in which the piles are not driven to their intended depth. However, if this is considered, it should be kept in mind that macrocell galvanic corrosion reactions occur below the waterline and mudline. These might result in reduced TSMC life below the water line. Consideration should be given to applying TSMC on the whole pile to eliminate this galvanic corrosion. 3.5.2 Faying Surfaces Faying surfaces are surfaces that are in contact with each other and joined by bolting or other means. Faying surfaces should be seal welded, or the TSMC should be applied to the faying surfaces before joining. TSMCs can be applied to slip critical surfaces. 3.5.3 Sheet Pile Interlock Joints Figure 2 illustrates a typical sheet pile interlock joint. The surfaces within the joint are of relatively close tolerance and if coated with the full thickness of the TSMC, the combined thickness of both joints might prevent the piles from being joined together. The coating must be applied to a lesser thickness within the joint. The coating thickness should be no more than 3 to 5 mils (76 to127 µm) unless experience indicates that a thicker coating will work. In some cases, sections of sheet pile might be already joined, and it will not be possible to put any coating on the inside of the joint. In this case, the coating should be as evenly applied as possible across the joint interface. 21 Figure 1. Corrosion of sheeting piling at various locations (Source: AASHTO Highway Structures Design Book, Vol. 1, 1986, p. 10.49).

3.6 Effect of Steel Composition Small variations in steel hardness caused by alloy content will have little effect on the adhesion or performance of TSMCs; however, it is important to ensure that the appropriate surface profile is achieved prior to applying the TSMC. Hardened areas, such as the heat- affected zones of welds, might require special care to ensure an adequate surface profile. Flame-cut areas will require special care to ensure that an adequate profile is achieved. 3.7 Effect of Holidays on Protective Ability of Coating Coating holidays will affect the ability of the metallic coating to protect the steel substrate. Small holidays, such as pinholes and narrow scratches, will be protected by the galvanic action of the coating. Large holidays, those exceeding 1/2 in. (1.3 cm), in immersed areas should be protected by galvanic interaction with the coating. Large holidays in the atmospheric, splash, and tidal zones will not be fully protected by the coating. All holidays will eventually result in deterioration of the TSMC, leading to corrosion of the steel. The consequence of the corrosion (e.g., small hole leading to seepage through the piling, a large corroded area resulting in structural weakening of the pile, or aesthetic requirements) should be taken into consideration when determining whether to repair the coating on existing structures. All visible holidays on new structures should be repaired using appropriate materials prior to the pile being placed in service. 3.8 Thermally Sprayed Metal Wire Storage Temperature, humidity, and dew point cause problems if thermal spray feedstock is not properly stored. All of the active metal wires will oxidize if exposed to moisture. The oxide film can cause feed problems in both flame and arc equipment. Extreme temperature changes may also cause zinc and zinc/aluminum alloy wire to recrystallize and become brittle. Thermal spray wires should be securely sealed and protected from moisture intrusion to prevent oxidation of the material until they are to be used. 22 Figure 2. Schematic of an interlock joint.

4 SURFACE PREPARATION 4.1 Introduction TSMCs require a very clean, rough surface that is free of oil, grease, dirt, scale, and soluble salts. Surface contaminants must be removed with solvents prior to removal of mill scale, corrosion products, and old paint by abrasive blasting. 4.1.1 Role of Surface Preparation Surface preparation is the single most important factor in determining the success of a corrosion-protective TSMC system. Abrasive blasting or abrasive blasting combined with other surface preparation techniques is used to create the necessary degree of surface cleanliness and roughness. 4.1.2 Objective of Surface Preparation The principal objective of surface preparation is to provide proper adhesion of the TSMC to the substrate being coated. Adhesion is the key to the success of the TSMC. 4.1.3 Purpose of Surface Preparation The purpose of surface preparation is to roughen the surface, creating angular asperities and increased surface area for mechanical bonding of the TSMC to the steel substrate. The roughening is typically referred to as the anchor pattern or profile. The profile is a pattern of peaks and valleys that are cut into the substrate surface when high-velocity abrasive grit blast particles impact on the surface. 4.1.4 Surface Cleanliness Surface cleanliness is essential for proper adhesion of the TSMC to the substrate. TSMCs applied over rust, dirt, grease, or oil will have poor adhesion. Premature failure of the TSMC may result from coating application to contaminated substrates. 4.2 Solvent Cleaning (SSPC-SP-1) Solvent cleaning (SSPC-SP-1) is a procedure for removing surface contaminants, including oil, grease, dirt, drawing and cutting compounds, and soluble salts, from steel surfaces by means of solvents, water, detergents, emulsifying agents, and steam. Solvent cleaning is not designed to remove mill scale, rust, or old coatings and precedes the use of abrasive blast cleaning. Ineffective use of the solvent cleaning technique may spread or incompletely remove surface contaminants. Three common methods of solvent cleaning are water washing, steam cleaning, and cleaning with hydrocarbon (organic) solvents. 23

4.2.1 Hydrocarbon Solvent Cleaning Hydrocarbon solvents used to remove grease and oil are typically petroleum-based distillates, as described by ASTM D235, “Standard Specification for Mineral Spirits (Petroleum Spirits) (Hydrocarbon Dry Cleaning Solvent).” Type I—Regular (Stoddard Solvent) with a minimum flash point of 100°F (38°C) can be used when ambient temperatures are below 95°F (35°C). Type II—High Flash Point mineral spirits with a minimum flash point of 140°F (60°C) should be used when ambient temperatures exceed 95°F (35°C). Aromatic solvents such as xylene and high flash aromatic naphtha 100 or 150 (ASTM D 3734 Types I and II) are sometimes used when a stronger solvent is needed. The use of aromatic hydrocarbons (e.g., benzene) should be limited because of their generally greater toxicity. Solvent cleaning using hydrocarbon solvents is typically accomplished by wiping the surface with solvent- soaked rags. Rags should be changed frequently to afford better removal and to prevent spreading and depositing a thin layer of grease or oil on the surface. 4.2.2 Water Washing Low-pressure water cleaning, up to 5,000 psi (34 MPa), and high-pressure water cleaning from 5,000 to 10,000 psi (34 MPa to 70 MPa) are effective means of removing dirt and soluble salt contamination. When used with a detergent or emulsifying agent, the method can also be used to remove organic contaminants such as grease and oil. Thorough rinsing with clean water is necessary to ensure complete removal of the cleaning agent. If an alkaline cleaner is used, the pH of the cleaned surface should be checked after the final rinse to ensure that the cleaning agent has been completely removed. 4.2.3 Steam Cleaning Steam cleaning is an effective means of removing dirt, salt, oil, and grease from both coated and uncoated substrates. The method employs a combination of detergent action and high- pressure heated water (280°F [138°C] to 300°F [149°C] at 3 to 5 gpm [11.3 to 18.9 l/min]). Thorough rinsing with steam or water should be used to remove any deposited detergent. 4.3 Abrasive Blast Cleaning Abrasive blasting is performed in preparation for thermal spray after the removal of surface contaminants by solvent cleaning. Abrasive blasting is conducted to remove mill scale, rust, and old coatings, as well as to provide the surface roughness profile necessary to ensure good adhesion of the thermally sprayed coating to the substrate. Conventional abrasive blast cleaning is accomplished through the high-velocity (450 mph [724 km/h]) propulsion of a blasting media in a stream of compressed air (90 to 100 psi [620 to 698 kPa]) against the substrate. The particle mass and high velocity combine to produce kinetic energy sufficient to remove rust, mill scale, and old coatings from the substrate while simultaneously producing a roughened surface. The Society for Protective Coatings (SSPC) and NACE International have published standards for surface cleanliness. These standards and an SSPC supplemental pictorial guide provide guidelines for various degrees of surface cleanliness. Only the highest degree of 24

cleanliness, SSPC-SP-5 “White Metal Blast Cleaning,” or NACE #1, is considered acceptable for TSMCs. SSPC and NACE have developed blast-cleaning standards and specifications for steel surfaces. SSPC-SP-5 and NACE #1 describe the condition of the blast-cleaned surface when viewed without magnification as free of all visible oil, grease, dust, dirt, mill scale, rust, coating, oxides, corrosion products, and other foreign matter. SSPC-SP-VIS 1-89 supplements the written blast standards with a series of photographs depicting the appearance of four grades of blast cleaning over four initial grades of mill scale and rust. The last two pages of the standard depict a white metal blast-cleaned substrate achieved using three different types of metallic abrasives and three types of nonmetallic abrasives. The resulting surfaces have slight color and hue differences caused by the type of media used. Abrasive blast cleaning may be broadly categorized into centrifugal blast cleaning and air abrasive blast cleaning. Air abrasive blast cleaning may be further subdivided to include open nozzle, water blast with abrasive injection, open nozzle with a water collar, automated blast cleaning, and vacuum (suction) blast cleaning. Open nozzle blasting is the method most applicable to preparation for TSMC. 4.3.1 Equipment An open nozzle abrasive blast-cleaning apparatus consists of an air compressor, air hose, moisture and oil separators/air coolers and dryers, blast pot, blast hose, nozzle, and associated safety equipment. 4.3.1.1 Air compressor. The air compressor supplies air to the system to carry the abrasive. Production rate depends on the volume of air that the compressor can deliver. A larger compressor can supply more air and can therefore sustain operation of more blast nozzles or larger blast nozzle diameters. 4.3.1.2 Air hose. The air hose supplies air from the compressor to the blast pot. The air hose should be as short as possible, with as few couplings and as large a diameter as possible to optimize efficiency. The minimum inside diameter (ID) should be 1.25 in. (31.75 mm) with measurements of 2 to 4 in. (50.8 to 101.6 mm) ID being common. 4.3.1.3 Moisture and oil separators/air coolers and dryers. If not removed, moisture from the air and oil mists from the compressor lubricants may contaminate the abrasive in the blast pot and, subsequently, the surface being cleaned. Oil/moisture separators are used to alleviate this problem. The devices should be placed at the end of the air hose as close to the blast pot as possible. Separators are typically of the cyclone type with expansion air chambers and micron air filters. Air coolers/dryers are commonly used to treat the air produced by the compressor. 4.3.1.4 Blast pot. Most blast pots used for large blasting projects are of the gravity-flow type. These machines maintain equal pressure on top of and beneath the abrasive. The typical blast pot consists of air inlet and outlet regulator valves, a filling head, a metering valve for regulating the abrasive flow, and a hand hole for removing foreign objects from the pot chamber. For large jobs, the pot should hold enough media to blast for 30 to 40 minutes. For continuous production, a two-pot unit can be used, allowing one pot to be filled while the other operates. 25

4.3.1.5 Blast hose. The blast hose carries the air-media mixture from the blast pot to the nozzle. A rugged multi-ply hose with a minimum 1.25-in. (31.75-mm) ID is common. A lighter, more flexible length of hose called a whip is sometimes used for added mobility at the nozzle end of the blast hose. Maximum blast efficiency is attained with the shortest, straightest blast hoses. Blast hoses should be coupled with external quick-connect couplings. 4.3.1.6 Blast nozzle. Blast nozzles are characterized by their diameter, material, length, and shape. Nozzle sizes are designated by the inside diameter of the orifice and are measured in sixteenths of an inch. A 3/16-in. diameter orifice is designated as a No. 3 nozzle. The nozzle diameter must be properly sized to match the volume of air available. Too large an orifice will cause pressure to drop and productivity to decrease. Too small an orifice will not fully utilize the available air volume. The nozzle size should be as large as possible while still maintaining an air pressure of 90 to 100 psi (620 to 689 kPa) at the nozzle. Blast nozzles may be lined with a variety of different materials distinguished by their relative hardness and resistance to wear. Ceramic- and cast iron–lined nozzles have the shortest life. Tungsten and boron carbide are long-lived nozzles. Nozzles may be either straight bore or of the venturi type. The venturi nozzle is tapered in the middle, resulting in much higher particle velocities. Venturi nozzles have production rates 30 to 50 percent higher than straight bore nozzles. Long nozzles, 5 to 8 in. (127 to 203 mm), will more readily remove tightly adherent rust and mill scale and increase production rates. Worn nozzles can greatly decrease productivity and should be replaced as soon as they increase by one size (1/16 in. [1.6 mm]). 4.3.2 Blast-Cleaning Techniques A proper blasting technique is important in order to accomplish the work efficiently with a high degree of quality. The blast operator must maintain the optimal standoff distance, nozzle angle, and abrasive flow rate. The best combination of these parameters is determined by an experienced blaster on a job-to-job basis. 4.3.2.1 Balance of abrasive and air flows. The blaster should balance the abrasive and air flows to produce a “bluish” colored abrasive airstream at the nozzle, which signals the optimum mix. Blasters often use too much abrasive in the mix, which results in reduced efficiency. The mix is adjusted using the valve at the base of the blast pot. 4.3.2.2 Nozzle-to-surface angle. The nozzle-to-surface angle should be varied to achieve the optimal blast performance for the given conditions. Rust and mill scale are best removed by maintaining a nozzle-to-surface angle of 80 to 90 degrees. A slight downward angle will direct dust away from the operator and improve visibility. The best nozzle-to-surface angles for removing old paint are 45 to 70 degrees. The final blast profile should always be achieved with a nozzle-to-surface angle of 80 to 90 degrees. Inside corners—for example, the inside flange surface of a narrow H-pile—require special attention to achieve angles as close to the optimum angles as possible. 4.3.2.3 Standoff. Standoff, or nozzle-to-surface distance, will also affect the quality and speed of blast cleaning. The lower the standoff distance, the smaller the blast pattern will be, and the longer it will take to cover a given area. However, close standoff distances allow more 26

kinetic energy to be imparted to the surface, allowing for the removal of more tenacious deposits, such as mill scale. A standoff distance of as little as 6 in. (153 mm) may be necessary for the removal of tight mill scale and heavy rust deposits. Greater standoff distances, on the order of 18 in. (457 mm), are more efficient for the removal of old, loosely adherent coatings. 4.3.3 Abrasive Media The selection of the proper abrasive blast media type and size is critical to the performance of the TSMC. Blast media that produce very dense and angular blast profiles of the appropriate depth must be used. 4.3.3.1 Mix. Steel shot and slag abrasives composed of all rounded or mixed angular, irregular, and rounded particles should never be used to profile steel surfaces for thermal spraying. Mixed abrasives and lower-cost abrasives (e.g., mineral slag and garnet) may be used to initially clean the surface, but the final profile must be obtained with completely angular abrasives. 4.3.3.2 Type/size. New steel grit should conform to the requirements of SSPC-AB-3, “Newly Manufactured or Re-Manufactured Steel Abrasives.” Various hardnesses of steel grit are available, but generally grit with Rockwell C hardness in the range of 50 to 60 is used. Harder steel grit (Rockwell C 60 to 66) may also be used, provided that the proper surface profile is obtained. Table 3 shows the recommended blast media types as a function of the thermal spray process and coating material. 4.3.3.3 Angularity. An angular blast media must always be used. Rounded media such as steel shot, or mixtures of round and angular media, will not produce the appropriate degree of angularity and roughness in the blast profile. The adhesion of TSMCs can vary by an order of magnitude as a function of surface roughness profile shape and depth. TSMCs adhere poorly to substrates prepared with rounded media and may fail in service by spontaneous delamination. Hard, dense, angular blast media such as aluminum oxide, silicon carbide, iron oxide, and angular steel grit are needed to achieve the depth and shape of blast profile necessary for good TSMC adhesion. Steel grit should be manufactured from crushed steel shot conforming to SAE J827. Steel grit media composed of irregularly shaped particles or mixtures of irregular and angular particles should never be used. Steel grit having a classification of “very angular,” “angular,” or “subangular,” as classified by the American Geological Institute, should be used (also found in J. D. Hansink, “Maintenance Tips,” Journal of Protective Coatings and Linings, Vol. 11, No. 3, March 1994, p. 66). 27 Thermal Spray Material Spray Process Blasting Media Aluminum, zinc, 85:15 zinc-aluminum Wire flame spray Aluminum oxide Angular steel grit Aluminum, zinc, 85:15 zinc-aluminum Arc spray Aluminum oxide Angular steel grit Angular iron oxide TABLE 3 Recommended blast media for thermal spray surface preparation

4.3.4 Blast Profile TSMCs are generally more highly stressed than paint coatings and as such require a deeper blast profile to dissipate the tensile forces within the coating. In general, the greater the thickness of TSMC being applied, the deeper the blast profile that is required. The minimum recommended blast profile for the thinnest coatings of zinc and 8515 wt% zinc/aluminum (0.004 to 0.006 in. [100 to 150 µm]) is 0.002 in. (50 µm). Thicker coatings of zinc and 8515 wt% zinc/aluminum, 0.010 in. (250 µm) or greater, require a minimum 0.003-in. (75-µm) profile. A 0.005-in. (125-µm) aluminum coating requires a minimum surface profile of 0.002 in. (50 µm), and a 0.010-in. (250-µm) aluminum coating requires a minimum 0.0025-in. (62.5-µm) profile. The specifier should specify the maximum and minimum surface profile required for the TSMC. The maximum profile for thicker TSMCs should not exceed approximately a third of the total average coating thickness. As a general rule, the maximum blast profile should be 0.001 in. (25 µm) greater than the specified minimum profile depth. Table 4 shows average profiles for various abrasive sizes. 4.3.5 Centrifugal Blast Cleaning Centrifugal blast cleaning is commonly used in fabrication shops. The method is generally faster and more economical than open abrasive blasting. The method involves conveying the steel through a blast cabinet or enclosure where high-speed rotating wheels fitted with blades propel abrasive particles at the steel. The blasting debris falls to the bottom of the chamber, where it is reclaimed, cleaned, and then recycled. The degree of cleanliness achieved is determined by the abrasive velocity and the conveyor speed. Steel shot is usually used in centrifugal blast machines. For TSMCs, a subsequent profiling blast using angular media is required to achieve the desired blast profile depth and angularity. Centrifugal blast-cleaning machines are now available for fieldwork as well, but their use is not widespread. 4.3.6 Cleaning After Blasting Cleanliness after abrasive blasting is important. Any remaining traces of spent abrasive or other debris must be blown, swept, or vacuumed from the surface prior to thermal spray application. A hard-to-see layer of abrasive dust may adhere to the substrate by static electric charge and must be removed. The thermal spray applicator may accomplish this by triggering just the compressed air from the flame or arc gun. Scaffolding, staging, or support steel above the thermal spray coating area must also be cleaned prior to application to prevent debris from falling onto the surfaces to be coated. Blasting and thermal spraying should not occur simultaneously unless the two operations can be adequately isolated to prevent contamination of the thermal spray surfaces. 28 Abrasive Size Profile, mils (µm) Steel grit G40 2.4 ± 0.5 (61 ± 12.7) Steel grit G25 3.1 ± 0.7 (79 ± 17.8) Steel grit GL16 4.0 + (102) Steel grit G14 5.1 ± 0.9 (130 ± 22.8) Aluminum oxide 16 4.0 + (102) TABLE 4 Average surface profiles for selected abrasive sizes

4.3.7 Time Between Blasting and Thermal Spraying After completion and inspection of the final profiling blast, the steel substrate should be coated as soon as possible. The TSMC should be applied within the same work shift in which the final surface preparation is completed. A maximum holding period of 6 hours should be allowed to elapse between the completion of blast cleaning and thermal spraying. Shorter holding periods should be used under humid or damp conditions or when it is clear that the quality of the blast or coating is degraded. This period should allow adequate time for the changeover from blasting to thermal spraying. Thermal spray should commence prior to the appearance of any visible rust bloom on the surface. Foreign matter such as paint overspray, dust and debris, and precipitation should not be allowed to contact the prepared surfaces prior to thermal spraying. Under no circumstances should the application of thermal spray be allowed on re-rusted or contaminated surfaces. In some cases, it may be possible to apply only a single spray pass or some other fraction of the total thermal spray system within 6 (maximum) hours of blasting. This single layer must cover the peaks of the surface profile. The partial coating is intended to temporarily preserve the surface preparation. Before applying additional sprayed metal to the specified thickness, the first layer of coating should be visually inspected to verify that the coating surface has not been contaminated. Any contamination between coats should be removed before any additional material is applied. The remaining coating should be sprayed to achieve the specified thickness as soon as possible. In some cases, it may be possible to hold the surface preparation for extended periods using specially designed dehumidification (DH) systems. These systems supply dry air to a blast enclosure or other contained air space. The dry air prevents the reappearance of rust for extended periods of time and allows for thermal spray jobs to be staged in a different fashion. Dehumidification systems may be particularly useful for jobs in very humid environments, which are typical of many locations during the spring through fall maintenance season. These areas typically have dense morning fog and hot humid afternoons. Holding the quality of blast needed for TSMCs would be difficult under such conditions without the use of dehumidification. 4.3.8 Pitted Steel Heavily corroded, deeply pitted surfaces are difficult to prepare for TSMC. Wide, shallow pits do not pose any particular problem, but deep and irregularly shaped pits can pose a problem. Pits with an aspect ratio of greater than unity (i.e., as deep as they are wide) should be ground with an abrasive disk or other tool prior to blasting. Pits with sharp edges, undercut pits, and pits with an irregular horizontal or vertical orientation must be ground smooth prior to abrasive blasting. Grinding does not need to level or blend the pit with the surrounding steel, but it should smooth all the rough and irregular surfaces to the extent necessary to allow the entire surface of the pit to be blasted and coated. Nozzle-to-surface angles of 80 to 90 degrees are optimal for cleaning pits. Heavily pitted steel on bridges or in other environments where soluble salt contamination is likely should be cleaned with high- pressure water after grinding to ensure that salt contaminants are removed from the pits. 29

4.3.9 Edges and Welds 4.3.9.1 Sharp edges. These present problems in achieving adequate surface preparation and coating. As a general rule, all sharp edges should be ground prior to blasting to a uniform minimum radius of 1/8 in. (3 mm). A radius of 1/4 in. (6 mm) is preferred. 4.3.9.2 Flame-cut edges. Flame cutting results in localized hardening of the steel on the cut edge. This will degrade the ability of abrasive blasting to provide an adequate surface profile in these areas because the hardened steel can be harder than the abrasive. The result will be poor coating adhesion on the hardened edge. The hardened edge must be removed either with a grinder or belt-driven abrasive, followed by abrasive blasting. Abrasive that is harder than the flame-hardened edge, such as alumina, can also be used. 4.3.9.3 Welded areas. Rough welds shall be ground to remove sharp edges, undercuts, pinholes, and other irregularities. Remove weld spatter. Welds can also result in locally hardened areas on the steel in the heat-affected zone, on which it could be difficult to achieve an adequate surface profile compared with the unaffected steel surface. Particular care should be taken in these areas to ensure that adequate surface profile is achieved. Surface profile testing should be conducted in weld heat-affected zones to develop the correct blasting procedure for that piece. 4.4 Water Jetting High-pressure water jetting from 10,000 to 25,000 psi (70 MPa to 170 MPa) and ultra-high- pressure jetting above 25,000 psi (170 MPa) are used to prepare a surface for recoating. These methods will not produce a surface profile on the metal that is sufficient for the adhesion of TSMCs unless that profile already exists on the metal surface from prior abrasive blasting. Water jetting will also not remove mill scale. The flash rusting that can occur on a water-jetted surface can interfere with the adhesion of TSMCs. However, water jetting can be used to remove existing coatings as a preliminary step in preparing the surface prior to abrasive blasting. The use of high-pressure water jetting can result in savings in abrasive volume and reduced costs in disposal of wastes. More information is available in the joint NACE International/SSPC Standard, NACE #5/SSPC-SP-12, “Surface Preparation and Cleaning of Steel and Other Hard Materials by High- and Ultrahigh-Pressure Water Jetting Prior to Recoating.” 4.5 Surface Contamination Surface contamination from chlorides (deicing salts and sea salts) prior to applying the TSMC can lead to loss of coating adhesion, particularly with aluminum TSMC. Surface contamination can be removed by detergent washing, power washing, water jetting, or wet abrasive blasting. 30

5 TSMC APPLICATION 5.1 Equipment 5.1.1 Thermally Sprayed Metal Processes Metals can be applied by thermal spray in a variety of ways that can be categorized as either combustion or electric processes. Combustion processes include flame spraying, high-velocity oxygen fuel (HVOF) spraying, and detonation-gun spraying. Electric processes include wire-arc spraying and plasma spraying. This guide will address the flame and electric arc processes for wire. 5.1.1.1 Flame process. The flame spray process can be used to apply a wide variety of feedstock materials including metal wires, ceramic rods, and metallic and nonmetallic powders. In flame spraying, the feedstock material is fed continuously into the tip of the spray gun or torch, where it is then heated and melted in a fuel gas/oxygen flame and accelerated toward the substrate being coated in a stream of atomizing gas. Common fuel gases used include acetylene, propane, and methyl acetylene-propadiene (MAPP). Oxyacetylene flames are used extensively for wire-flame spraying because of the degree of control and the higher temperatures attainable with these gases. The lower-temperature oxygen/propane flame can be used for melting metals such as aluminum and zinc, as well as polymer feedstock. The basic components of a flame spray system include the flame spray gun or torch, the feedstock material and a feeding mechanism, oxygen and fuel gases with flowmeters and pressure regulators, and an air compressor and regulator. With wire-flame spraying, the wire-flame spray gun or torch consists of a drive unit with motor and drive rollers for feeding the wire and a gas head with valves, gas nozzle, and an air cap that controls the flame and atomization air. Compared with wire-arc spraying, wire- flame spraying is generally slower and more costly because of the relatively high cost of the oxygen-fuel gas mixture compared with the cost of electricity. However, flame spraying systems are generally simpler and less expensive than wire-arc spraying systems. Both flame spraying and wire-arc spraying systems are field portable and may be used to apply quality metal coatings for corrosion protection. 5.1.1.2 Wire-arc process. Due to its high deposition rates, excellent adhesion, and cost-effectiveness, wire-arc spray is the preferred process for applying TSMCs to steel pilings. With the wire- arc spray process, two consumable wire electrodes of the metal being sprayed are fed into a gun such that they meet at a point located within an atomizing air (or other gas) stream. An applied DC potential difference between the wires establishes an electric arc between the wires that melts their tips. The atomizing air flow subsequently shears and atomizes the molten droplets to generate a spray pattern of molten metal directed toward the substrate being coated. Wire-arc spray is the only thermal spray process that directly heats the material being sprayed, a factor contributing to its high energy efficiency. 31

The wire-arc spray system consists of a wire-arc spray gun or torch, atomizing gas, flowmeter or pressure gauge, a compressed air supply, DC power supply, wire guides/hoses, and a wire feed control unit. Operation of this equipment must be in strict compliance with the manufacturers’ instructions and guidelines. 5.1.2 Thermal Spray Guns (Wire-Arc and Flame) Figure 3 illustrates a typical wire-arc spray gun or torch and Figure 4 illustrates a typical flame spray gun. 5.1.3 Air Compressors (Arc and Flame) Compressed air should be free of oil and water. Accurate air regulation is necessary to achieve uniform atomization. Under continuous use conditions, the actual atomization air 32 Shroud Gas Atomization Zone Shroud Cap Electric Arc Atomizing Gas Arc Shield Wire Feed Figure 3. Schematic of a typical wire-arc spray gun. Figure 4. Schematic of a typical flame-wire spray gun.

pressure and volumetric flow rate should remain nearly constant and, ordinarily, should not deviate from the set value by more than 5 percent. 5.1.4 Atomizing Gas Supply (Wire-Arc and Flame Spray) Provisions shall be made to monitor and control, read clearly, and adjust (by means of instruments), any deviations of the atomizing gas pressure and volumetric flow rates from the set values during the spraying process. These values shall be recorded during acceptance inspection. For the wire-arc spray process, the atomizing gas supply and control system shall be designed and constructed to allow continuous operation at selected pressures and flow rates. 5.1.5 Air Dryers (Wire-Arc and Flame Spray) An air dryer is necessary to provide clean, dry air (as per ASTM D4285) for surface preparation and thermal spraying. Air dryers shall be inspected and tested regularly and replaced as necessary to maintain the desired moisture content in the process air streams. 5.1.6 Oxygen and Fuel Gas (Flame Spray) The use of oxygen and fuel gas flowmeters allows for the best control of the flame and thus higher spray rates. Under continuous use conditions, the actual oxygen and fuel gas flow rates and pressures should remain nearly constant and, ordinarily, should not deviate from the set values by more than 5 percent. Flame spraying equipment shall permit spraying with the combustible gases, atomizing gas (if any), and powder carrier gas (if any) for which it was designed. 5.1.7 Gases for Flame Spraying Gaseous oxygen equal or equivalent to Federal Specification BB-O-925 should be used for thermal spraying. Acetylene equal or equivalent to Federal Specification BB-A 106 should be used for thermal spraying. Other fuel gases (e.g., methyl acetylene-propadiene [MAPP] stabilized, propane, or propylene) as specified by the thermal spray equipment manufacturer may also be used. 5.1.8 Power Supply (Wire-Arc Spray) In general, the higher the power output of the direct current (DC) power supply used, the greater the possible production spray rate of the unit. Under continuous use conditions, the actual current output should remain nearly constant and, ordinarily, should not deviate from the set value by more than 5 percent. Power supplies that are adequately sealed may be operated in dusty atmospheres and do not need to be located at a remote distance from the thermal spray operation. DC power supplies rated up to 600 A are common. A lightweight power supply mounted on pneumatic tires will have added portability. There is typically an optimum amperage for each coating material that may further depend on wire diameter and the particular equipment model. The open-circuit voltage should be adjustable to accommodate different wire materials. The voltage should be set slightly above the lowest level consistent with good arc stability. This 33

will provide smooth dense coatings with superior deposition efficiency. Higher voltages tend to increase droplet sizes, resulting in rougher coatings with lower densities. Under continuous use conditions, the actual arc voltage should remain nearly constant and, ordinarily, should not deviate from the set value by more than 5 percent. 5.1.9 Wire Feed Control (Wire-Arc and Flame Spray) The wire feed and guide mechanisms should be designed to provide automatic alignment. Manual alignment of the wires is both time consuming and inexact. The wire feed mechanism must be capable of delivering wire to the arc tips at a rate commensurate with the power generated in the arc. Under continuous use conditions, the actual wire feed rate should remain nearly constant and, ordinarily, should not deviate from the set value by more than 5 percent. For flame spray equipment, the spraying material feed unit shall comply with the following conditions: • The unit shall permit uniform and consistent processing of the consumables for which it was designed. • It shall enable adjustment of the feedstock material feed rate. • The set-point values shall be constant and reproducible; a precondition of this is adequate and constant gas pressures and flow rates, atomizing air pressures (where used), and supply of electrical power, as appropriate. 5.1.10 Air Cap Selection (Wire-Arc Spray) A range of different air caps is usually available for use with wire-arc spray equipment. Air caps used in wire-arc spraying include fan (elliptical) and circular spray patterns. Some air caps are adjustable. The nozzle system (contact tubes and air nozzle) shall permit a continuous and stable arc to be maintained and provide atomization of the feedstock materials without causing a buildup of deposits that may degrade gun operation. 5.1.11 Cable Length (Wire-Arc Spray) Most manufacturers offer optional cable packages that allow operation of the spray gun or torch up to 100 ft (30 m) from the power supply. Longer cables provide added flexibility when thermal spraying in the field. 5.1.12 Arc-Shorting Control (Wire-Arc Spray) Arc shorting is a phenomenon wherein the wires are fused or welded together, creating a short circuit and cessation of melting and spraying. Shorting sometimes requires that the wire ends be manually clipped before the arc can be restruck. This operation can be very time consuming and must only be conducted with the power supply de-energized and by appropriately trained personnel. Occasionally during arc shorting, lumps of unmelted wire are shorn off and deposited on the substrate, resulting in poor coating quality. An added feature available on some wire-arc spray equipment can control arc shorting. 34

5.1.13 Wire Tips (Wire-Arc Spray) Wire guide tips that hold and align the wires as they enter the arc zone are subject to wear. Wear rate depends on the properties of the material being sprayed and the level of current used, since these tips are also part of the means by which electrical current is transferred to the wires. Properly designed equipment will allow cooler operating temperatures that will prolong tip life and reduce maintenance time. Easy-to-change contact tips are also beneficial. 5.1.14 Nozzles (Flame Spray) Processing of the feedstock materials shall be possible without any degrading deposit buildup on the gun, air nozzle, or both. 5.2 Thermal Spray Equipment Setup and Validation • The thermal spray equipment should be set up, calibrated, and operated as per the manufacturer’s instructions and technical manuals. • Spray parameters should be set for spraying the specified feedstock material and, at a minimum, be validated using the bend test. • Validation of the TSMC procedure includes (1) successful surface preparation, (2) correct application procedures for the specified TSMC, (3) achievement of the required thickness, and (4) successful bend testing of at least one bend coupon at the beginning of each work shift. • If the bend test fails, the problem shall be identified and fixed before spraying continues. • Results of all validation tests shall be clearly identified and documented. 5.2.1 Procedures for Acceptance Inspection 5.2.1.1 Electrical power and wire feed unit (wire-arc spray). Compliance with the requirements specified for electrical power for continuous operation wire feed units shall be met by (1) Spraying 8515 wt% zinc/aluminum wire at maximum capacity for 20 minutes (alternate feedstock—for example, aluminum or zinc wire—may be specified by the purchaser). (2) Measuring ≤ 5 percent deviations of the adjusted electrical values or other disturbances. 5.2.1.2 Atomizing gas (wire-arc spray). The equipment shall be deemed to comply with the requirements if the atomizing gas supply gauge pressure does not deviate by more than ± 5 percent from the set value over a 20-minute period of spraying. 5.2.1.3 Nozzle system (wire-arc and flame spray). The nozzle system shall be deemed to comply with the requirements if, after 20 minutes of spraying 8515 wt% zinc/aluminum wire at the maximum spray rate, there are no degrading deposits of feedstock material visible on or inside the nozzle. 5.2.1.4 Monitoring (wire-arc spray). The limits of error of the measuring instruments shall not exceed ±5 percent for all set values and shall correspond to at least Class 2.5 instruments. 35

5.2.1.5 Gases (flame spray). Flame spray equipment shall be deemed to comply with the requirements if the values of supply gas pressure and gas flow volume meet the class deviations of the following from the set values over a 10-minute period of spraying. Class Deviations for Supply Gas Pressure and Flow Volume Class A Class B ≤2% ≤5% 5.2.1.6 Validity of inspection report. The inspection report shall be deemed valid for as long as all specifications of this guide are in compliance. 5.2.1.7 Retests. The guidelines listed below should be followed for retests. (1) If the values obtained during acceptance inspection of a thermal spraying system are altered by modification or repair work, retesting of the properties affected shall be carried out. (2) Retests shall be carried out in the same way as the initial tests described in this guide. 5.3 Coating Application 5.3.1 Thickness Table 2 provides recommended thickness values for various coatings and environments. 5.4 Application and Feed Rates 5.4.1 Feed Rates and Spray Rates Table 5 provides information on typical feed rates for flame spray and arc spray. Table 6 provides information on spray rates for flame spray and arc spray for different wire diameters. 36 Flame Spray Wire-Arc Spray Feedstock Material (wire) Deposit Efficiency (%) Material Required kg/m2/µm lb/ft2/mil Deposition Efficiency (%) Material Required kg/m2/µm lb/ft2/mil Aluminum (Al) 80–85 0.0027 0.014 70–75 0.0029 0.017 Zinc (Zn) 65–70 0.0098 0.050 60–65 0.011 0.054 85:15 Zn/Al 85–90 0.0070 0.036 70–75 0.0093 0.049 1 mil = 0.001 in. TABLE 5 Nominal feedstock required per unit area/unit thickness (deposition efficiency on a flat plate)

The values in these tables should be taken as approximate only. The wire feed rate should be adjusted to properly optimize the dwell time in the flame. Excessive feed rates may result in inadequate or partial heating and melting of the feedstock and may result in very rough deposited coatings. Too slow a feed rate may cause the wire to be over-oxidized, resulting in poor-quality coatings containing excessive levels of oxides and poor cohesion. Under continuous use conditions, the actual wire feed rate should remain virtually constant and, ordinarily, should not deviate from the set value by more than 5 percent. 5.4.2 Holding Period 5.4.2.1 Correct surface cleanliness and profile. TSMCs should always be applied to “white” metal (SSPC-SP-5/NACE # 1). It is common practice in fieldwork to apply the TSMC during the same work shift in which the final blast cleaning is performed. The logical end point of the holding period is when the surface cleanliness degrades or a change on performance (as per bend or tensile test) occurs. If the holding period is exceeded, the surface must be re-blasted to establish the correct surface cleanliness and profile. 5.4.2.2 Duration of the holding period. Thermal spraying should be started as soon as possible after the final anchor-tooth or brush blasting and completed within 6 hours for steel substrates subject to the temperature to dew point and holding-period variations. In high-humidity and damp environments, shorter holding periods should be used. 5.4.2.3 Extending the holding period—temperature/humidity. In low-humidity environments or in controlled environments with enclosed structures using industrial dehumidification equipment, it may be possible to retard the oxidation of the steel and hold the near-white- metal finish for more than 6 hours. With the concurrence of the purchaser, a holding period of greater than 6 hours can be validated by determining the acceptable temperature-humidity envelope for the work enclosure by spraying and analyzing bend test coupons or tensile adhesion coupons, or both. Should the sample fail the bend test, the work must be re-blasted and re-tested. 37 Flame Spray (by wire diameter) Wire-Arc Spray (per 100 amps) 2.4 mm 3.2 mm 4.8 mm 3/32 in. 1/8 in. 3/16 in. Spray Rate (Coverage) Spray Rate (Coverage) Feedstock Material Spray Rate, kg/hr (Coverage, m2/hr/100µm) Spray Rate, lb/hr (Coverage, ft2/hr/mil) kg/hr (m2/hr/100µm) lb/hr (ft2/hr/mil) Aluminum 2.5 (8.73) 5.4 (18.9) 7.3 (25.3) 5.5 (370) 12 (800) 16 (1,070) 2.7 (8.26) 6 (350) Zinc 9.1 (9.44) 20 (21.2) 30 (30.7) 20 (400) 45 (900) 65 (1,300) 18 (11.0) 25 (465) 85:15 Zn/Al 8.2 (11.8) 18 (26.2) 26 (38.0) 18 (500) 40 (1,110) 58 (1,610) 16 (9.68) 20 (410) 1 mil = 0.001 in. TABLE 6 Nominal wire feedstock spray rates and coverage

5.4.2.4 Extending the holding period—application of flash coat. When specified by the purchasing contract, a flash coat of TSMC equal to or greater than 1 mil (25 µm) may be applied within 6 hours of completing the surface preparation in order to extend the holding period for up to 4 hours beyond the application of the flash coat. The final TSMC thickness, however, should be sprayed within 4 hours of the application of the flash coat. This procedure should be validated using a tensile adhesion test or bend test, or both, by spraying a flash coat and waiting through the delay period before applying the final coating thickness. 5.4.2.5 Small and moveable parts. For small and movable parts, if more than 15 minutes is expected to elapse between surface preparation and the start of thermal spraying or if the part is moved to another location, the prepared surface should be protected from moisture, contamination, and finger/hand marks. Wrapping with clean print-free paper is normally adequate. 5.4.2.6 Rust bloom, blistering, or coating degradation. If rust bloom, blistering, or a degraded coating appears at any time during the application of the TSMC, the following procedure should be performed: (1) Stop spraying. (2) Mark off the satisfactorily sprayed area. (3) Repair the unsatisfactory coating (i.e., remove the degraded coating and re-establish the minimum “white metal” finish and anchor-tooth profile depth as per the maintenance and repair procedure). (4) Record the actions taken to resume the job in the job documentation. (5) Call the coating inspector to observe and report the remedial action to the purchaser. 5.5 Overspray 5.5.1 Examples of Overspray • TSMC material that is applied outside the authorized parameters, primarily the gun-to- substrate standoff distance and spray angle (perpendicular ± 30 degrees). • TSMC material that misses the target or bounces off of the substrate. 5.5.1.1 Foreign matter. Foreign matter such as paint overspray, dust and debris, and precipitation should not be allowed to contact prepared surfaces prior to thermal spraying. 5.5.1.2 Masking. Cleaning, thermal spray application, and sealing should be scheduled so that dust, overspray, and other contaminants from these operations are not deposited on surfaces readied for TSMC or sealing. Surfaces that will not be thermally sprayed should be protected from the effects of blast cleaning and thermal spray application through the use of removable masking materials or other means. Mask all fit and function surfaces and surfaces and areas specified by the purchaser not to be abrasive blasted or to be thermally sprayed. Mask on complex geometries (e.g., pipe flanges, intersections of structural beams, and valve manifolds) to eliminate or minimize overspray. Ensure that the covers and masking are securely attached and will survive the blasting and thermal spraying operations. Masking should also be designed to avoid “bridging,” which can lead to debonding or edge lifting. 38

5.5.1.3 Overspray-control area. For complex geometries where overspray cannot be eliminated, an overspray-control area should be established. Clean, metal masks or clean, removable masking materials should be used to prevent overspray from depositing on surfaces not already sprayed to the specified thickness. 5.5.1.4 Dust, fumes, and particles. Special care should be taken to prevent the entry of abrasive and thermally sprayed metal dusts and fumes into sensitive machinery and electrical equipment. Painted surfaces adjacent to surfaces receiving TSMCs should be adequately protected from damage by molten thermally sprayed metal particles. 5.5.1.5 High winds. High winds may affect the types of surface preparation and coating application methods that are practical for a given job. High winds will tend to carry surface preparation debris and paint overspray longer distances. This problem can be avoided by using methods other than open abrasive blasting and spray application of paints. 5.6 Temperature 5.6.1 Ambient Temperature Although there are no high or low temperature limitations when applying thermally sprayed metal, it is often advisable to preheat the surface to 250°F (120°C) when first beginning to flame spray to prevent water vapor in the flame from condensing on the substrate. Preheat the initial 1- to 2-ft (0.1- to 0.2-m2) starting-spray area. 5.6.2 Metal Surface Temperature The steel surface temperature must be at least 5°F (3°C) above the dew point in order to prevent condensation on the surface that will adversely affect coating adhesion. 5.6.3 Low Ambient Temperature Thermal spraying in low-temperature environments, below 40oF (5oC), must (1) Meet the substrate surface temperature and cleanliness (Section 5.4.2.1) and holding period (Section 5.4.2.2). Moisture condensation on the surface is not permissible during thermal spraying. (2) Be qualified using a bend test or a portable tensile-bond test, or both. (3) Meet the substrate surface temperature (Section 5.4.2.3). Substrate heating may be required to improve the TSMC tensile adhesion to the substrate and reduce internal (residual) stresses because the TSMCs are mechanically bonded to the substrate. 5.7 Coating Thickness Build 5.7.1 Achieving Specified Coating Thickness Manually applied TSMCs should be applied in a block pattern measuring approximately 24 in. (60 cm) on a side. Each spray pass should be applied parallel to and overlapping the 39

previous pass by approximately 50 percent. Successive spray coats should be applied at right angles to the previous coat until the desired coating thickness is achieved. Approximately 0.002 to 0.003 in. (50 to 75 µm) of coating should be applied per spray pass. In no case should less than two spray coats applied at right angles be used to achieve the specified coating thickness. Laying down an excessively thick spray pass increases the internal stresses in the TSMC and will decrease the ultimate tensile-bond strength of the TSMC. 5.7.1.1 Minimizing thin spots—manual spraying. During manual spraying, use crossing passes to minimize the thin spots in the coating. 5.7.1.2 Minimizing thin spots—robotic spraying. During robotic spraying, program overlapping and crossing passes to eliminate thin spots and stay within the coating thickness specification. Validate the automated spraying parameters and spraying program using tensile-bond or metallographic analysis, or both. 5.7.1.3 Equipment. Use approved spray gun extensions, compressed-air deflectors, or similar devices to reach into recessed spaces and areas. 5.7.2 Spray Angle, Width, and Standoff Distance 5.7.2.1 Gun-to-surface angle. The gun-to-surface angle is very important because of the generally greater distances that the sprayed particles travel prior to striking the substrate, producing a porous and oxidized coating with reduced cohesion and adhesion for similar reasons as those described in Section 5.7.2.2. Porosity, oxide content, and adhesion are strongly affected by spray angle. In some cases, it may be necessary for the applicator to spray at less than 90 degrees because of limited access to the surface. In no case should the applicator spray at an angle of less than 45 degrees. Some degradation in performance might result even at the 45-degree angle. Spray gun extensions are available from some equipment manufacturers that allow better access to difficult-to-spray areas. A good spray technique consists of the applicator maintaining the spray gun perpendicular (at 90 degrees) or near perpendicular (90 ± 5 degrees) to the substrate at all times. Maintain the gun as close to perpendicular as possible and within ± 30 degrees from perpendicular to the substrate. 5.7.2.2 Standoff distance. Standoff distance depends on the type and source of thermal spray equipment used. Excessive standoff distance will result in porous and oxidized coatings with reduced cohesion and adhesion. The higher porosity may be attributed to the greater degree of cooling and the lower velocity that the thermal spray particles or droplets experience prior to impact. Adhesion is directly proportional to the kinetic energy of the spray particles, and the kinetic energy varies as the square of the particle velocity. Cooler, more slowly impacting particles will not adhere as well to each other or to the substrate, resulting in weaker, less adherent coatings. Excessive standoffs may occur because the applicator is not sufficiently familiar with the requirements of the equipment or because of fatigue or carelessness. Increased standoffs may also result from the applicator’s arm or wrist arcing during application. It is very important that the applicator’s arm move parallel to the substrate in order to maintain a consistent standoff distance. Holding the thermal spray gun too close to the surface may result in poor coverage and variations in coating thickness because of the reduced size of the spray pattern. Some degradation in performance might result at the higher standoff distance. 40

Use the manufacturer’s recommended standoff distance for the air cap installed. Table 7 lists nominal standoff and spray pass width values. 5.7.3 Supplemental Surface Preparation Surfaces that have become contaminated or that have exceeded the holding period must be recleaned to establish the required degree of cleanliness and profile. Small areas that have been damaged and require coating repair should be treated according to Section 7, “Repair and Maintenance.” 5.8 Inspection and Quality Control 5.8.1 Quality Control (QC) Equipment Quality control (QC) equipment for thermal spray application should include the following: • Substrate Temperature—Contact thermocouple or infrared pyrometer to measure substrate temperatures. • Air Temperature, Dew Point, and Humidity—Psychrometer or an equivalent digital humidity measurement instrument. • TSMC Thickness—Magnetic pull-off or electronic thickness gauge with secondary thickness standards per SSPC-PA-2. • TSMC Ductility—2 in. × 4 to 8 in. × 0.050 in. (50 mm × 100 to 200 mm × 13 mm) (ANSI- SAE 10xx sheet) for bend test coupons and a mandrel of a diameter suitable for the specified TSMC thickness. • Bend Coupon, Companion Coupon, and Sample Collection—Sealable plastic bags to encase bend coupons and other QC samples collected during the job. 5.8.2 Coating Thickness The thickness of the TSMC should be evaluated for compliance with the specification. Magnetic film thickness gauges such as those used to measure paint film thickness should be used. Gauges should always be calibrated prior to use. Thickness readings should be made either in a straight line with individual readings taken at 1-in. (25-mm) intervals or spaced randomly within a 2-in.- (50-mm-) diameter area. Line measurements should be used on large flat areas, and area measurements should be used on complex surface geometry and surface transitions such as corners. The average of five readings constitutes 41 Spray Pass Width, in. [mm] Air Cap Thermal Spray Method Perpendicular Standoff in. [mm] Regular Fan Wire-flame 5–7 [130–180] 0.75 [20] Not Available Wire-arc 6–8 [150–200] 1.5 [40] 3–6 [75–150] TABLE 7 Nominal flame-spray and arc-spray standoff distances and spray widths

one thickness measurement. A given number of measurements per unit area (e.g., five per 100 ft2 [9 m2]) should be specified in the contract documents. Areas of deficient coating thickness should be corrected before sealing begins. 5.8.3 Adhesion 5.8.3.1 Bend test. Each day, or every time the thermal spray equipment is used, the inspector should record and confirm that the operating parameters are the same as those used to prepare the job reference standard (Section 8.3.3). The thermal spray applicator should then apply the coating to prepared test panels and conduct a bend test. The bend test is a qualitative test used to confirm that the equipment is in proper working condition. The test consists of bending coated steel panels around a cylindrical mandrel and examining the coating for cracking. Details of the test are described in Section 8. If the bend test fails, corrective actions must be taken prior to the application of the TSMC. The results of the bend test should be recorded, and the test panels should be labeled and saved. Test panels should be examined visually without magnification. The bend test is acceptable if the coating shows no cracks or exhibits only minor cracking with no lifting of the coating from the substrate. If the coating cracks and lifts from the substrate, the results of the bend test are unacceptable. TSMCs should not be applied if the bend test fails, and corrective measures must be taken. Figure 5 depicts representative bend test results. Bend test samples can also be used for metallographic evaluations of porosity, oxide content, and interface contamination. 5.8.4 Appearance 5.8.4.1 Inspecting the coating. The applied TSMC should be inspected for obvious defects related to poor thermal spray applicator technique and/or equipment problems. The coating should 42 Figure 5. 180-degree bend test illustrating pass and fail appearance.

be inspected for the presence of blisters, cracks, chips or loosely adherent particles, oil, pits exposing the substrate, and nodules. A very rough coating may indicate that the coating was not applied with the gun perpendicular to the surface or that the coating was applied at too high of a standoff distance. Coatings that appear oxidized or powdery should be evaluated by light scraping. If scraping fails to produce a silvery metallic appearance, the coating is defective. 5.8.4.2 Coating appearance. The appearance of the coating should match that of the job reference standard. 5.9 Handling, Storage, and Transportation of Thermally Sprayed Metal Coated Piles 5.9.1 Aluminum, Zinc, and Zinc-Aluminum Coatings Thermally sprayed metal surfaces are tough and are ready to be handled immediately after the application of the coating. However, aluminum, zinc, and zinc-aluminum coatings are softer than the steel substrate and are subject to scratching, gouging, and impact damage. 5.9.2 Handling Coated Piles Coated piles should at all times be handled with equipment such as stout, wide belt slings and wide padded skids designed to prevent damage to the coating. Bare cables, chains, hooks, metal bars, or narrow skids shall not be permitted to come in contact with the coating. All handling and hauling equipment should be approved before use. 5.9.3 Loading Piles for Shipping by Rail When shipped by rail, all piles should be carefully loaded on properly padded saddles or bolsters. All bearing surfaces and loading stakes shall be properly padded with approved padding materials. Pile surfaces should be separated so that they do not bear against one another, and the whole load must be securely fastened together to prevent movement in transit. 5.9.4 Loading Piles for Shipping by Truck When shipped by truck, the piles should be supported in wide cradles of suitably padded timbers hollowed out on the supporting surface to fit the curvature of pipe, and all chains, cables, or other equipment used for fastening the load should be carefully padded. 5.9.5 Storing Piles Stored piles should be supported on wooden timbers above the ground. 43

5.9.6 Hoisting Piles Piles should be hoisted using wide belt slings. Chains, cables, tongs, or other equipment, no matter how well padded, are likely to cause damage to the coating and should not be permitted. Dragging or skidding the pile should not be permitted. 5.9.7 Repairing Damaged Coating Damaged coating should be repaired in accordance with Section 7 of this guide. 44

6 SEALER SELECTION AND APPLICATION 6.1 Purpose All TSMCs contain porosity that can range up to 15 percent. Many thermally sprayed coatings (e.g., aluminum, zinc, and their alloys) tend to be self-sealing. Over time, natural corrosion products fill the pores in the coating. This oxidation consumes a relatively small amount of the metal coating material. Interconnected or through-porosity may extend from the coating surface to the substrate. Through-porosity may impair the barrier performance of the TSMC. Aluminum coatings can “blush” or exhibit pinpoint rusting after several years. Aluminum coatings less than 0.006 in. (150 µm) thick and zinc coatings less than 0.009 in. (225 µm) thick should be sealed for this reason. Sealers are intended to fill porosity and improve the overall service life of the thermal spray system. Sealers are not intended to completely isolate the metal coating from the environment and are not intended to function as barrier coatings. Topcoats having higher film build properties are needed to perform the function of a barrier coating. Compared with unsealed TSMCs, sealed TSMCs generally have a longer service life, are easier to clean and maintain, and tend to improve the performance of externally applied cathodic protection somewhat by reducing the area of metal that must be protected. In some cases, sealing is performed to improve the appearance and “cleanability” of the thermally sprayed metal coated surface. Sealers reduce the retention of dirt and other contaminants by the TSMC. In particular, the sealer may prevent the accumulation of corrosive salts, rain-borne corrosives, and bird droppings. Thermally sprayed coatings on a steel substrate should be sealed or sealed and topcoated under any of the following conditions: • When the environment is very acidic or very alkaline (the normal useful pH range for pure zinc is 6 to 12 and for pure aluminum is 4 to 11). • When the metallic coating is subject to direct attack by specific chemicals. • When a particular decorative finish is required. • When additional abrasion resistance is required. • Under conditions of frequent saltwater spray, splashing, or immersion service. • Under conditions of frequent freshwater spray, splashing, or immersion service. 6.2 Characteristics 6.2.1 Characteristics of Sealers Sealers must exhibit the following characteristics: • They must be low-viscosity products in order to infiltrate the pores of the TSMC. The pigment particle size for colored sealers must be small enough to flow easily into the pores of the TSMC, as per ASTM D1210. 45

• They must be low-build products that may be applied at low film thickness, generally 0.003 in. (75 µm) or less. • The resin chemistry of the sealer must be compatible with the thermally sprayed coating material. Some oleoresinous sealers may saponify if applied over zinc metal surfaces because of the alkalinity of zinc. This will cause the sealer to dissolve at the metal interface, resulting in disbondment of the coating. • The selected sealer material must also be compatible with the intermediate coats and topcoats of paint, if used. • Sealers must be suitable for the intended service environment. • Sealers and topcoats should meet the local regulations on volatile organic compound (VOC) content. They should be applied in accordance with the manufacturer’s instructions or as specified by the purchaser. • As applied to TSMCs on a steel substrate, sealer must meet a minimum drop weight impact requirement of 188 ft-lbs (254 n-M) when tested in accordance with ASTM D2794 (Modified). 6.2.2 Characteristics of Topcoats Topcoats must exhibit the following characteristics: • The topcoat is used for additional chemical resistance and must be compatible with the service environment. • The topcoat should be compatible with the sealer and the TSMC. • The topcoat should be applied to relatively low film thickness, generally not exceeding 0.005 in. (125 µm). • Full topcoats will greatly reduce or entirely diminish the cathodic protection effects of the TSMC in immersion or underground service. • A conventional paint should not be applied over an unsealed TSMC. • Topcoats should have gloss and color retention where appearance is a concern. 6.3 Types Descriptions and specifications for sealers and topcoat paints may be found in • The Steel Structures Painting Council’s Steel Structures Painting Manual, Volume 2. • Table 4C, Part 2, Product Section CP, “Pretreatment and Sealers for Sprayed-Metal Coatings,” of BS 5493, Code for Practice for Protective Coating of Iron and Steel Structures Against Corrosion (1977). • The U.S. Army Corps of Engineers Engineering and Design Manual, Thermal Spraying: New Construction and Maintenance, EM 1110-2-3401, Washington, D.C., January 29, 1999. • The U.S. Army Corps of Engineers Guide Specification for Construction, Painting: Hydraulic Structures, CEGS-09965. Many types of sealers are appropriate for use on steel pilings. These include vinyl, epoxy, and oleoresinous coatings. Of concern in the selection of a sealer is the volatile organic compound (VOC) content. Some sealers or thinned sealers might exceed VOC content regulations. 46

6.3.1 Vinyls Vinyl-type coatings are well suited to sealing TSMCs. They are compatible with most service environments, including saltwater and freshwater immersion and marine, industrial, and rural atmospheres. Vinyls are compatible with zinc, aluminum, and 8515 wt% zinc/aluminum coatings. They are very-low-viscosity materials with low film build characteristics. Vinyl sealers should be applied to a dry film thickness of about 0.0015 in. (37.5 µm). Vinyl sealers are readily topcoated with vinyl paint. Subsequent coats of vinyl should be applied to a dry film thickness of 0.002 in. (50 µm) per coat. The vinyl sealer should be thinned 25 percent by volume with the specified thinner. The approximate viscosity of the sealer should be 20 to 30 sec measured with a No. 4 Ford Cup Viscometer in accordance with ASTM D1200, “Test Method for Viscosity by Ford Cup Viscometer.” 6.3.2 Epoxies Three types of epoxy sealers are commonly used: coal tar epoxy, aluminum epoxy mastic, and epoxy sealer–urethane topcoat systems. 6.3.2.1 Coal tar epoxy. Coal tar epoxy may be applied as a relatively thick film single-coat sealer for use over zinc, aluminum, and 8515 wt% zinc/aluminum thermal spray coatings. The coal tar epoxy sealer should be thinned approximately 20 percent by volume and applied in a single coat to a dry film thickness of 0.004 to 0.006 in. (100 to 150 µm). The sealer is applied at a thickness suitable for covering the roughness of the TSMC, providing a smooth surface that minimizes hydraulic friction. 6.3.2.2 Aluminum epoxy mastic. Aluminum epoxy mastic sealers are suitable for one-coat use over zinc, aluminum, and 8515 wt% zinc/aluminum thermally sprayed coatings for use in marine, industrial, and rural atmospheres as well as for use over aluminum and 90-10 aluminum- aluminum oxide in nonskid applications. The aluminum epoxy mastic should be thinned to the maximum extent recommended in the manufacturer’s written directions and applied to a dry film thickness of 0.003 to 0.005 in. (75 to 125 µm). This sealer provides an aluminum finish. 6.3.2.3 Epoxy sealer–urethane topcoat systems. Epoxy sealer–urethane topcoat systems are suitable for use over zinc, aluminum, and 8515 wt% zinc/aluminum coatings exposed in marine, industrial, and rural atmospheres as well as for use on nonskid aluminum and 90-10 aluminum-aluminum oxide coatings. The epoxy sealer coat should be thinned to the maximum extent recommended in the manufacturer’s written directions and applied to a dry film thickness of 0.003 to 0.004 in. (75 to 100 µm). The polyurethane topcoat should be applied to a maximum dry film thickness of 0.003 in. (75 µm). The polyurethane topcoat may be procured in a variety of colors. 6.3.3 Oleoresinous Two types of oleoresinous sealers are used: tung-oil phenolic aluminum and vinyl-butyral wash primer/alkyd (SSPC Paint No. 27). 47

6.3.3.1 Tung-oil phenolic aluminum (TT-P-38). This phenolic aluminum sealer is suitable for use over zinc, aluminum, and 8515 wt% zinc/aluminum thermally sprayed coatings exposed in marine, industrial, and rural atmospheres. The sealer should be thinned 15 percent by volume and applied to a dry film thickness of 0.0015 in. (37.5 µm). A second coat of the phenolic aluminum should be applied to the dried sealer to a dry film thickness of approximately 0.002 in. (50 µm). This sealer system produces an aluminum finish. 6.3.3.2 Vinyl-butyral wash primer/alkyd (SSPC Paint No. 27). This wash primer/alkyd sealer system is suitable for use over zinc, aluminum, and 8515 wt% zinc/aluminum thermally sprayed coatings exposed in marine, industrial, and rural atmospheres. The wash primer coat sealer should be thinned according to the manufacturer’s instructions and applied to an approximate dry film thickness of 0.0005 in. (12.5 µm). Commercial alkyd sealer coatings should be applied over the dried wash primer coat to a dry film thickness of 0.002 to 0.003 in. (50 to 75 µm). Other topcoats can be applied per manufacturer’s recommendations. 6.3.4 Low Surface Energy, High-Solids Epoxy Low surface energy, high-solids sealers are deep-penetrating primers that penetrate the pores of the TSMC. They have a high solids content—up to 100 percent—but have a very low viscosity that permits them to penetrate through pores and cracks. The sealer is applied to a thickness of 1.0 to 2.0 mils (25 to 50 µm) per coat. They are two-part systems. They are designed for use with a topcoat and can be topcoated with acrylics, alkyds, epoxies, or polyurethanes. 6.3.5 Low-Viscosity Penetrating Urethane These are single-component, micaceous-iron-oxide-pigmented, moisture-cured polyurethane coatings. 6.3.6 Other Sealers Other sealers can be considered as long as they comply with the characteristics listed. 6.4 Application 6.4.1 Application Work Period In general, surface preparation, thermal spray application, and sealing of a given area should be accomplished in one continuous work period of not longer than 16 hours, and preferably within 8 hours of the thermal spray coating step. Subsequent paint coats should be applied in accordance with the requirements of the painting schedule. 6.4.2 Preparation for Sealing Surfaces to be sealed should first be blown down using clean, dry, compressed air to remove dust. If the sealer cannot be applied within 8 hours or if there is an indication of contamination, verify by visual (10x) inspection that the sprayed metal coating has not been contaminated 48

and is dust free (ISO 8502-3 clear cellophane tape test) before applying the sealer. The thermally sprayed surfaces should be sealed before visible oxidation of the TSMC occurs. 6.4.3 Presence of Moisture If moisture is present or suspected in the TSMC pores, the steel may be heated to 120°F (50°C) to remove the moisture prior to the seal coat application. When possible, the steel from the reverse side of the TSMC should be heated to minimize oxidation and contamination of the TSMC prior to sealing. 6.4.4 Application Techniques Sealers should be applied by conventional or airless spraying, except that vinyl-type sealers must only be applied using conventional spray techniques. Spray application provides the level of control necessary to achieve thin, uniformly thick coatings. Thin sealer-topcoat systems are preferred to thicker films that may retain moisture and reduce the overall coating system life. 6.4.5 Regulations and Recommendations for Application All paint sealer and topcoating should be applied according to SSPC-PA-1, “Shop, Field and Maintenance Painting,” and the paint manufacturer’s recommendations for use of the product with a TSMC system. 6.4.6 Thinning Sealers may need to be suitably thinned to effectively penetrate the TSMC. 6.4.7 Dry Film Thickness Typically the sealer coating is applied at a spreading rate resulting in a theoretical 1.5-mil (38-µm) dry film thickness. 6.4.8 Topcoat A topcoat is essentially a full coat of paint and may be applied over a seal coat. Topcoats should normally be applied as soon as the sealer is dry and preferably within 24 hours. 6.5 Quality Control 6.5.1 Confirm Complete Coverage of Seal Coat During application of the seal coat, visually confirm complete coverage. The seal coat should be thin enough when applied to penetrate into the body of the TSMC and seal the porosity. Added thickness to a porous TSC might not be measurable. 6.5.2 Confirm Complete Coverage of Topcoat During application of the topcoat, visually validate complete coverage. 49

6.5.3 Measuring Thickness of the Topcoat If required by the contract, measure the thickness of the topcoat per SSPC-PA-2 using a Type 2 fixed-probe gauge. The measurement may be made on either a companion coupon or the sealed TSMC if the TSMC thickness has been previously measured. Alternately, the thickness can be measured destructively using ASTM D4138, Test Method A. This method has the advantage of being able to observe all the layers; however, this type of measurement should be minimized since the areas tested must be repaired in order to maintain the coating integrity. 6.5.4 Correcting Areas of Deficient Thickness Areas of deficient thickness should be noted and corrected, if practicable, by adding sealer or paint. Additional testing may be necessary to determine the extent of the area with deficient sealer or paint thickness. The sealer thickness should be checked prior to the application of paint coats, if practical, and the measurement procedure should be repeated for the sealer and paint. 6.5.5 Methods to Determine Sealer Coverage The thickness of sealers is difficult to quantify because of the thin coats applied and the absorption of the sealer into the pores. A high film build of sealer over the thermally sprayed metal is not desired. In fact, sealer thickness is of value only in determining whether it has been uniformly applied to the surface. Two methods that can be used to determine sealer coverage include the following: • Dry film thickness measurement. (This is probably the least reliable because of the very thin thickness of the sealer and the absorption of the sealer into the thermally sprayed coating. Dry film thickness measurements are best used as statistical comparisons between unsealed areas and sealed areas. A coupon that has been prepared with a known thickness of unknown thermally sprayed metal using the same techniques used to coat the structure [equipment, operator, number of passes, and deposition rate] can be used.) • Tinting the sealer. 6.6 Generic Sealer Specification Section 11 presents a generic sealer specification. 50

7 REPAIR AND MAINTENANCE 7.1 Introduction Deterioration and damage to the TSMC can occur under several circumstances, including damage during installation, impact by foreign objects, abrasion, and corrosion. Damage that occurs during installation should be identified by the inspector and repaired according to the specifications. Repair to installation damage can vary from complete replacement of the coating to minor touch-up depending on the extent of the damage. This section can be used for minor repairs as defined by the specification or agreement between the owner and applicator. Damage that occurs during service requires periodic inspection to identify the need to repair TSMC systems. 7.2 Assessment The first step in the repair of TSMCs is an assessment of the type of thermal spray coating system under evaluation and the nature of the damage or wear. Steps in assessing the need to repair a thermal spray coating system are listed below. 7.2.1 Identification of the Type of Thermal Spray and Sealer Material Originally Applied Historic records should be reviewed for information on the type of TSMC and sealer used as well as any previous repairs. Chemical analyses may also be used. The experienced observer may also be able to distinguish between the various types of thermally sprayed materials. 7.2.2 Identification and Documentation of the Type and Extent of Deterioration 7.2.2.1 Test methods for quantifying coating deterioration. The following test methods have visual standards for quantifying coating deterioration: • ASTM F1130, “Standard Practice for Inspecting the Coating of a Ship” (useful for standardizing the method of reporting the extent of corrosion and coating deterioration). • ASTM D610, “Test Method for Evaluating Degree of Rusting on Painted Steel Surfaces” (provides standard charts for quantifying the amount of rusting on a steel surface). • ASTM D3359, “Test Method for Measuring Adhesion by Tape Test.” • ASTM D714, “Test Method for Evaluating Degree of Blistering of Paints.” • ASTM D4214, “Test Method for Evaluating Degree of Chalking of Exterior Paint Films.” • ASTM D660, “Test Method for Evaluating Degree of Checking of Exterior Paints.” • ASTM D661, “Test Method for Evaluating Degree of Cracking of Exterior Paints.” • ASTM D662, “Test Method for Evaluating Degree of Erosion of Exterior Paints” (a standardized reporting form should be developed and kept on file for the structure for future reference). 7.2.2.2 Identification of sealer defects. Sealer defects are difficult to identify unless a topcoat has been used. Sealer and topcoat defects include disbondment from the substrate, cracking, 51

checking, and mechanical damage. These will expose the thermally sprayed metal to the environment, which can reduce its service life. Lesser defects include discoloration and chalking, which do not necessarily indicate that the substrate is exposed, but do indicate eventual exposure of the substrate. 7.2.2.3 Identification of defects in thermally sprayed metal. Defects in the thermally sprayed metal include worn coating (indicated by general or localized thickness reductions); coating oxidation (evident by the presence of a powdery residue on the coating surface); the presence of rust and bare steel; and cracked, blistered, and delaminated areas. 7.3 Determination of Repair and Recoat Intervals 7.3.1 TSMC The need to repair or replace the metal coating depends on how much corrosion the structure can tolerate, the type of corrosion that can be tolerated, and the corrosion rate of the structure in the environment. For example, pitting on a pile often can be tolerated because it does not affect the structural integrity of the structure. On the other hand, a pit in a sheet pile might not be acceptable since a perforation would affect the ability of the structure to hold back water. In that case, even small pits must be repaired quickly. The corrosion rate of the structure should be monitored at defects in the coating and repairs scheduled when it is determined that the amount of corrosion is threatening to reach the critical thickness. In a corrosive environment (e.g., seawater), repairs to the coating will have to be more frequent than in a less corrosive environment (e.g., freshwater). 7.3.2 Sealer and Topcoat One approach to determining the time to repair and recoat detailed in G. H. Brevoort, M F. Melampy, and K. R. Shields, “Updated Protective Coating Costs, Products, and Service Life,” Materials Performance, February 1997, pp. 39–51: Maintenance painting can take the following sequence: Action % Breakdown Occurrence Original coating Initially Spot touch-up and repair 5–10* 33% of expected life Maintenance repaint (spot prime and full coat) 5–10* 50% of expected life Full recoat 5–10* 100% of expected life * before active rusting of substrate 7.4 Repair Methods 7.4.1 Standards for Repair and Maintenance The American National Standards Institute (ANSI) and the American Welding Society (AWS) have published a standard for the repair and maintenance of TSMCs. The TSMC 52

repair procedures used depend on the type and extent of degradation and the presence or absence of sealer and paint topcoats. ANSI/AWS C2.18-93, “Guide for the Protection of Steel with Thermal Sprayed Coatings of Aluminum and Zinc and Their Alloys and Composites,” addresses the maintenance and repair of TSMCs. This section summarizes the types of repairs that might be encountered and the procedures available. 7.4.2 Repair Procedures 7.4.2.1 Increasing TSMC thickness. Unsealed TSMCs that are worn thin or that were applied to less than the specified thickness may be repaired by repreparing the surface and applying more metal. If the coating was recently applied, it may be possible to simply apply additional coating directly onto the original coating. If the coating is oxidized, the abrasive brush blast procedure should be used prior to application of additional TSMC material. 7.4.2.2 Repair of small (<1 ft2 [<0.1 m2]) damaged areas with steel substrate not exposed. Repair by solvent cleaning, scraping with a flexible blade tool, wire brushing, edge feathering, lightly sanding to abrade the cleaned areas, and sealing and painting. 7.4.2.3 Repair of large (>1 ft2 [>0.1 m2]) damaged areas with steel substrate not exposed. Repair by solvent cleaning, abrasive brush blasting, edge feathering, and sealing and painting. 7.4.2.4 Repair of TSMCs with steel substrate exposed. Either of two procedures may be used to repair TSMCs damaged to the extent that the steel substrate is exposed. One method uses a rapid “paint only” repair procedure that is useful in emergency situations, and the other utilizes a TSMC plus sealer and paint coats procedure that is far more durable. The emergency repair procedure should always be followed by the more permanent repair when conditions permit. 7.4.2.4.1 The rapid “paint only” repair procedure. The rapid “paint only” repair procedure includes solvent cleaning, scraping with a hard blade tool, power tool cleaning, edge feathering, sealing, and topcoating. 7.4.2.4.2 The thermal spray repair procedure. The thermal spray repair procedure includes solvent cleaning, scraping with a hard blade tool, abrasive blast cleaning to near white metal, edge feathering, TSMC application, sealing, and topcoating. 7.4.3 Description of Repair Procedure 7.4.3.1 Solvent cleaning. Grease and oil should be removed by solvent cleaning. The solvent may be applied by wiping, brushing, or spraying. The following cleaning solvents may be used: Super Hi-Flash Naphtha, Type I (ASTM D3734) and n-Butyl Alcohol (ASTM D304). Precautions should be taken to protect any parts that may be affected by the solvents, and all appropriate safety precautions must be taken. 7.4.3.2 Flexible-blade scrape to bonded TSMC. Use a 1-in. (25-mm) flexible-blade paint scraper to remove loose paint and TSMC around damaged or worn areas until the tightly adherent paint and TSMC is reached. Care should be taken not to gouge or further damage the TSMC. 53

7.4.3.3 Hard-blade scrape to bonded TSMC. Use a hard-blade paint scraper to push the blade underneath the loose TSMC, and push and scrape away all loosely adherent paint and TSMC until reaching a well-bonded area. 7.4.3.4 Hand brush clean. Use a stiff hand-held stainless-steel or bristle brush to vigorously brush away loose debris. Power tools should not be used as they will polish the thermally sprayed coating and may wear through the thermally sprayed coating to the substrate. 7.4.3.5 Abrasive brush blast. Clean abrasive blasting media, such as fine mesh (30–60) angular iron oxide grit or aluminum oxide, may be used to abrasive brush blast away loose paint. Use low enough blasting pressures to minimize abrasion and removal of thermal spray coating, but high enough pressure for reasonable paint and loose TSMC removal and the development of a sufficient anchor-tooth pattern for sealers and topcoat paints. 7.4.3.6 Power-tool cleaning per SSPC-SP-3. For power-tool cleaning, hand-held power cleaning tools (e.g., disc sander with 80-mesh abrasive paper and stainless steel rotary brushes) should be used, using light pressure to clean and roughen the surface for painting. Do not polish the surface smooth. 7.4.3.7 Abrasive blast to near-white-metal finish and ≥ 2.5-mil (63-µm) profile. The surface should be abrasively (or mechanically) blasted to a near-white-metal finish with a ≥ 2.5-mil (63-µm) profile. The blasting nozzle should be kept perpendicular ± 10 degrees to the work surface; angle blasting into the TSMC/steel bond line may debond the bonded TSMC from the substrate. 7.4.3.8 Feathering. A 2- to 3-in. (50- to 80-mm) border should be feathered into the undamaged paint and TSMC area. Feathering is the operation of tapering off the edge of a coating. 7.4.3.9 Light abrasion. The prepared surface and the feathered area around the exposed TSMC should be lightly abraded with sand/grit paper to provide a mechanical bonding surface for the sealer or sealer and topcoat. 7.4.3.10 TSMC application. The thermal spray repair metal should be the same as that originally applied. Flame sprayed coatings should be repaired only by the flame spray technique. Wire- arc spray has a greater energy (particle impact velocity and temperature) and may delaminate marginal flame sprayed coatings. Wire-arc sprayed coatings may be repaired using either wire-arc or flame spray. 7.4.3.11 Sealers and topcoats. Apply the sealer and/or topcoat using proper application techniques. 7.5 Quality Control Quality control provisions apply to the various repair procedures as detailed in the corresponding sections of the guide regarding • Ambient air conditions, • Surface temperature, 54

• Surface cleanliness, • Surface profile, • Adhesion, • TSMC thickness, • Sealer thickness, and • Topcoat thickness. 55

8 QUALITY CONTROL AND INSPECTION 8.1 Introduction Owners should make provisions to ensure the quality of the coating by providing detailed specifications and competent inspection. Wire manufacturers need to have quality control systems in place to ensure that the wire can be applied and will perform as intended. Applicators must ensure that they have the correct experience and equipment and competent applicators to prepare the structure and apply the coating. Inspection is one of the most important aspects of coating. It provides a written record of the details of the coating application, ensures that the coating specifications are met, and finds and ensures the correction of inadequate coating areas before they become failure locations in the future requiring costly correction. Particular attention must be directed toward difficult-to-coat areas, such as the inside surfaces of H-shapes and the interlock knuckles of sheet piling, because these are areas where optimum nozzle/gun angles and distances will be difficult to attain. 8.2 Quality Assurance Functions for Owners 8.2.1 Informed Selection An informed selection should be made of TSMCs taking into account planned use of the coatings and the environment in which they are to be used. 8.2.2 Provide Definitive Specifications Specifications should include, as a minimum and as an addition to contractual provisions, the following: • Scope of work, to include the structure to be coated and portions not to be coated; • All applicable references; • Provisions for payment; • Definitions; • A list of required submittals; • Safety provisions; • Requirements for delivery, storage, and handling of materials and supplies; • Chemical composition, finish, coil weight, and preparation of metallizing wire; • Requirements for sampling and testing thermally sprayed materials and the applied sealer; • A job reference standard with a description of appearance and adhesion requirements; • Requirements for surface preparation; • Metallizing application; • Workmanship; • Atmospheric and surface conditions; 56

• Sequence of operations; • Approved methods of metallizing; • Coverage and metallizing thickness; • Progress of metallizing work; • Sealing and painting instructions; • Metallizing schedule; and • Quality control requirements. 8.2.3 Coating Inspector Provide a qualified coating inspector to provide full-time inspection services. This should be a third-party inspector with the power and ability to work out problems with the applicator to achieve the desired coating quality. Section 9.3 lists the necessary qualifications of an inspector. 8.3 Quality Control 8.3.1 Documentation The documentation of inspection activities provides a permanent record of the thermal spray job. Thorough documentation provides a written record of the job in the event of a contract dispute or litigation. Inspection records may also be used to help diagnose a premature coating failure. Future maintenance activities may also be simplified by the existence of complete inspection records. As a minimum, at least one full-time inspector should be used on all thermal spray jobs to ensure adequate inspection and documentation. A qualified third- party inspector from a reputable firm should perform the inspection. As a minimum, the inspector should perform and document the inspection procedures described in this section. Sample documentation forms for industrial coating activities are available through NACE International and the Society for Protective Coatings. The inspector should record the production and quality control information required by the purchaser or the purchasing contract. Among the items that should be recorded are • Information about the contractor and purchaser; • Surface preparation and abrasive blasting media requirements; • Flame or wire-arc spray equipment used; • Spraying procedure and parameters used; • TSMC requirements; • Safety precautions followed; • Environmental precautions; • Test data taken, including – Nature of the test, – When conducted, – Where conducted, 57

– Results, and – Abnormalities and resolution; and • Problems and resolution. The inspector should keep records for the time period required for regulatory compliance and required by the purchasing contract. 8.3.2 Testing Frequency The required frequency of inspection procedures should be documented in the specification. Inspection can be expensive, and care should be taken not to overspecify inspection procedures. Conversely, inspection has an intrinsic value that is sometimes intangible. It is difficult to measure the value added by inspection resulting from the conscientious performance of the contract. Thermal spray can be quite sensitive to the quality of surface preparation, thermal spray equipment setup, and application technique. Therefore, it is important to specify an appropriate level of inspection. Table 8 presents recommended frequencies for various inspection procedures. 8.3.3 Job Reference Standard and Material Samples 8.3.3.1 Material samples. Reference samples of each material used on a thermal spray job should be collected, including clean, unused abrasive blast media; thermal spray wire; sealer; and paint. Samples may be used to evaluate the conformance of materials to any applicable specifications. • A 2.2-lb (1-kg) sample of blast media should be collected at the start of the job. The sample may be used to verify the cleanliness, media type, and particle size distribution of the virgin blast media. A 12-in. (30-cm) sample of each lot of thermal spray wire should be collected. • The wire sample may be used to confirm that the manufactured wire conforms to the size and compositional requirements of the contract. • One-quart (1-liter) samples of all sealers and paints should be collected for compliance testing. 58 Inspection Procedure Recommended Frequency per Unit Area Surface profile 3 per 500 ft2 (45 m2) or less Thermal spray coating thickness 5 per 100 ft2 (9 m2) or less Thermal spray adhesion 2 per 500 ft2 (45 m2) or less Sealer thickness 2 per 500 ft2 (45 m2) or less Paint thickness 2 per 500 ft2 (45 m2) or less Soluble salts 1 per 1,000 ft2 (90 m2) or less TABLE 8 Recommended inspection frequencies for selected procedures

8.3.3.2 Job reference standard. A thermal spray job reference standard (JRS) should be prepared. The JRS may be used at the initiation of a thermal spray contract to qualify the surface preparation, thermal spray application, and sealing processes. The JRS and the measured values may be used as a visual reference or job standard for surface preparation, thermal spray coating, sealing, and painting, in case of dispute. 8.3.3.3 Preparing the JRS. The JRS should be prepared prior to the onset of production work. To prepare the JRS, a steel plate of the same alloy and thickness to be coated, measuring 2 × 2 ft (60 × 60 cm) should be solvent and abrasive blast cleaned in accordance with the requirements of the contract. The abrasive blast equipment and media used for the JRS should be the same as those that will be used on the job. One-quarter of the JRS plate should be masked using sheet metal, and the TSMC should be applied to the unmasked portion of the plate. The TSMC should be applied using the same equipment and spray parameters proposed for use on the job. The gun should be operated in a manner substantially the same as the manner in which it will be used on the job. The approximate traverse speed and standoff distance during spraying should be measured and recorded. Two-thirds of the thermal spray–coated portion of the JRS should be sealed in accordance with the requirements of the contract. One-half of the sealed area should be painted in accordance with the contract if applicable. The sealer and paint should be applied using the same paint spray equipment that will be used for production. The prepared JRS should be preserved and protected in such a manner that it remains dry and free of contaminants for the duration of the contract. The preserved JRS should then be archived for future reference in the event of a dispute or premature coating failure. Once the JRS is qualified, the operating parameters should not be altered by the contractor, except as necessitated by the requirements of the job. Figure 6 depicts a representative JRS. 59 Figure 6. Job reference standard configuration (1 in. = 2.54 cm, 1 ft = 30.48 cm).

8.3.3.4 Evaluating the JRS. The surface cleanliness; blast profile shape and depth; thermal spray appearance, thickness, and adhesion; and sealer and paint thickness should be determined in accordance with the contract requirements and recorded. 8.3.4 Testing Prior to Surface Preparation 8.3.4.1 Ambient conditions measurement. An assessment of the local atmospheric conditions should be made before surface preparation and thermal spray application begins. Measurement of ambient conditions includes substrate temperature, air temperature, dew point, and relative humidity. • A contact thermocouple or infrared pyrometer should be used to measure the substrate temperature. • Air temperature should be measured using a sling psychrometer, thermometer, or digital measurement instrument. • Dew point should be calculated using the appropriate psychrometric charts. • Humidity should be determined in accordance with ASTM E337, “Test Method for Measuring Humidity with a Psychrometer (The Measurement of Wet-Bulb and Dry-Bulb Temperatures).” 8.3.4.2 Inspection preceding surface preparation. Prior to abrasive blasting, inspect the substrate for the presence of contaminants including grease and oil, weld flux and spatter, heat-affected zones, flame-cut edges, pitting, sharp edges, and soluble salts. • Grease and oil. Painted surfaces and newly fabricated steel should be visibly inspected for the presence of organic contaminants such as grease and oil, as required by the project specification. Continue degreasing until all visual signs of contamination are removed. Conduct the UV light test, qualitative solvent evaporation test, or the heat test to detect the presence of grease and oil. – Use a UV lamp to confirm the absence of oil or grease contamination. – The solvent evaporation test should be made by applying several drops or a small splash of a residual-less solvent, such as trichloromethane, on the areas suspected of oil and grease retention (e.g., pitting and crevice corrosion areas and depressed areas, especially those collecting contamination, etc.). An evaporation ring will form if oil or grease contamination is present. – The heat test should be made by using a torch to heat the degreased metal to about 225oF (110oC). Residual oil/grease contamination should be drawn to the metal surface and is visually apparent. • Weld flux and spatter. A visual inspection for the presence of weld flux and spatter should be performed, as required by the project specification. Weld flux should be removed prior to abrasive blast cleaning using a suitable SSPC-SP 1 “Solvent Cleaning” method. Weld spatter may be removed either before or after abrasive blasting using suitable impact or grinding tools. Areas that are power-tool cleaned of weld spatter should be abrasive blast cleaned. 60

• Heat-affected zones caused by welding. Heat-affected zones should be identified and marked prior to abrasive blasting as required by the specification. Extra care during surface preparation and extra attention to profile inspection should be given to these areas. • Flame-cut edges. Flame-cut edges should be identified and marked prior to abrasive blasting as required by the specification. The demarcated areas should be ground using power tools prior to abrasive blast cleaning. • Pitting. Deep pits or pitted areas should be identified and marked prior to abrasive blast cleaning as required by the specification. The demarcated areas should be ground using power tools prior to abrasive blast cleaning. • Sharp edges. Sharp edges should be identified and marked prior to abrasive blasting as required by the specification. The demarcated edges should be prepared by grinding to a minimum radius of 1/8 in. (3 mm) prior to blast cleaning. • Soluble salts. When soluble salt contamination is suspected, the contract documents should specify a method of retrieving and measuring the salt levels as well as acceptable levels of cleanliness. Salt contamination is prevalent on structures exposed in marine environments and on structures such as parking decks and bridges exposed to deicing salts. Structures that are likely to have soluble salt contamination, including those in marine or severe industrial atmospheres, bridges or other structures exposed to deicing salts, and seawater immersed structures, should be tested. Soluble salt levels should be rechecked for compliance with the specification after solvent cleaning and abrasive blasting have been completed. Common methods for retrieving soluble salts from the substrate include cell retrieval methods and swabbing or washing methods. Various methods are available for assessing the quantity of salts retrieved, including conductivity, commercially available colorimetric kits, and titration. The rate of salt retrieval is dependent on the retrieval method. The retrieval and quantitative methods should be agreed upon in advance. The recommended testing procedure employs the Bresle cell (ISO 8502-6) to extract soluble salts from the substrate. Chloride ion concentration is readily measured in the field using titration strips available from Quantab. The test strip analyzes the collected sample and measures chloride ion concentration in parts per million. The unit area concentration of chloride ions is calculated in micro-grams per centimeter. The lower detection limit for the Bresle/Quantab method is about 2 µm/cm2. SSPC-SP-12/NACE #5 describes levels of soluble salt contamination. It is recommended that surfaces cleaned to an SC-2 condition be used for TSMCs. An SC-2 condition is described as having less than 7 µm/cm2 of chloride contaminants, less than 10 µm/cm2 of soluble ferrous ions, and less than 17 µm/cm2 of sulfate contaminants. The number of tests per unit area (e.g., 1 per 1,000 ft2 [90 m2]) should be specified in the contract documents. Also refer to “SSPC Technology Update: Field Methods for Retrieval and Analysis of Soluble Salts on Substrates,” and SSPC-91-07. 8.3.5 Testing During Surface Preparation 8.3.5.1 Abrasive cleanliness. Abrasive blast media must be free of oil and salt to prevent contamination of the substrate. Recycled steel grit abrasive should comply with requirements of SSPC-AB-2, “Specification for Cleanliness of Recycled Ferrous Metallic Abrasives.” • Evaluating for salt in abrasives. Most abrasives used to prepare steel substrates for thermal spraying are unlikely to contain appreciable amounts of soluble salts. However, 61

slag abrasives used for strip blasting may sometimes contain measurable quantities of salts. Slag abrasives should be evaluated in accordance with ASTM D4940, “Test Method for Conductimetric Analysis of Water Soluble Ionic Contamination of Blasting Abrasives.” • Testing for oil in abrasives. To test for oil in abrasives, a clear glass container should be half filled with unused abrasive, and then distilled or deionized water should be added to fill the container. The resulting slurry mixture should be stirred or shaken and allowed to settle. The water should then be examined for the presence of an oil sheen. If a sheen is present, the media should not be used, and the source of contamination should be identified and corrected. 8.3.5.2 Air cleanliness. The following guidelines apply to air cleanliness. • The compressed air used for abrasive blasting, thermal spraying, sealing, and painting should be clean and dry. Oil or water in the blasting air supply may contaminate or corrode the surface being cleaned. Oil or water in the thermal spray, sealing, or painting air supply may result in poor coating quality or reduced adhesion. Compressed air cleanliness should be checked in accordance with ASTM D4285, “Method for Indicating Water or Oil in Compressed Air.” The air compressor should be allowed to warm up, and air should be discharged under normal operating conditions to allow accumulated moisture to be purged. An absorbent clean white cloth should be held in the stream of compressed air not more than 24 in. (60 cm) from the point of discharge for a minimum of 1 minute. The air should be checked as near as possible to the point of use and always after the position of the in-line oil and water separators. The cloth should then be inspected for moisture or staining. • If moisture or contamination is detected, the deficiency should be corrected before going further. 8.3.5.3 Blast air pressure. The contractor should periodically measure and record the air pressure at the blast nozzle. The measurement should be performed at least once per shift and should be performed on each blast nozzle. Measurements should be repeated whenever work conditions are altered such that the pressure may change. Pressures should be checked concurrently with the operation of all blast nozzles. The method employs a hypodermic needle attached to a pressure gauge. The needle is inserted into the blast hose at a 45-degree angle toward and as close to the nozzle as possible. The blast pressure is read directly from the gauge. 8.3.5.4 Blast nozzle orifice. The contractor should visually inspect the blast nozzle periodically for wear or other damage. Gauges are available that insert into the end of the nozzle and measure the orifice diameter. Nozzles with visible damage or nozzles that have increased one size should be replaced. Worn nozzles are inefficient and may not produce the desired blast profile. Damaged nozzles may be dangerous. 8.3.5.5 Surface cleanliness. The following applies to surface cleanliness. • Blast Cleanliness. The final appearance of the abrasive cleaned surface should be inspected for conformance with the requirements of SSPC-SP-5. An SP-5 surface is defined as free of all visible oil, grease, dirt, dust, mill scale, rust, paint, oxides, corrosion products, and 62

other foreign matter. The appearance of SP-5 surfaces is dependent on the initial condition of the steel being cleaned. SSPC-VIS-1 may be used to interpret the cleanliness of various blast-cleaned substrates based on the initial condition of the steel and the type of abrasive used. Initial conditions depicted include the following: – Rust Grade A—a steel surface completely covered with adherent mill scale with little or no rust visible; – Rust Grade B—a steel surface covered with both mill scale and rust; – Rust Grade C—a steel surface completely covered with rust with little or no pitting; and – Rust Grade D—a steel surface completely covered with rust with visible pitting. The inspector should determine the initial substrate condition or conditions. The final appearance of the surfaces should then be compared with the appropriate photograph. No stains should remain on the SP-5 surface. However, the appearance of the surface may also vary somewhat, depending on the type of steel, presence of roller or other fabrication marks, annealing, welds, and other differences in the original condition of the steel. The job reference standard should be used as the basis for judging the surface cleanliness. • Dust. Abrasive blasting and overspray from painting or metallizing can leave a deposit of dust on a cleaned substrate. The dust may interfere with the adhesion of the TSMC. Residual dust may be detected by applying a strip of clear tape to the substrate. The tape is removed and examined for adherent particles. Alternatively, a clean white cloth may be wrapped around a finger and wiped across the surface. The cloth and substrate are then examined for signs of dust. The preferred method of removing residual dust is by vacuuming. Alternatively, the surface may be blown down with clean, dry compressed air. 8.3.5.6 Surface profile. The following applies to surface profile. • ASTM D4417, “Test Methods for Field Measurements of Surface Profile on Blast Cleaned Steel,” provides test methods for surface profile measurement. Methods A and B use either a needle depth micrometer to measure the depth of the valleys in the steel or comparator charts. Method C is the recommended method for measuring the surface profile depth. Methods A and B may provide unreliable measures of the blast profile. • Method C employs replica tape and a spring gauge micrometer to measure the surface profile. With the wax paper backing removed, the replica tape is placed face down against the substrate, and a burnishing tool is used to rub the circular cutout until a uniform gray appearance develops. The replica tape thickness (compressible foam plus plastic backing) is then measured using the spring micrometer. The profile is determined by subtracting the thickness of the plastic backing material, 0.002 in. (50 µm), from the measured value. Three readings should be taken within a 16-in.2 (100-cm2) area, and the surface profile at that location should be reported as the mean value of the readings. The number of measurements per unit area (e.g., 3 per 500 ft2 [45 m2]) should be specified in the contract document. Two types of replica tape are available, coarse (0.0008 to 0.002 in. [20 to 50 µm]) and X-coarse (0.0015 to 0.0045 in. [37.5 to 112.5 µm]). In most cases, the X-coarse tape will be used to measure profile. It may be possible to measure profiles as high as 0.006 in. (150 µm) using the X-coarse tape. 63

8.3.6 Testing During and After Coating Application 8.3.6.1 Coating thickness. The following applies to coating thickness. • Coating thickness is measured in accordance with SSPC-PA-2 using a Type 2 gauge. • Calibrate the instrument using a calibration wedge that is close to the contract-specified thickness placed over a representative sample of the contract-specified abrasive-blasted steel or a prepared bend coupon, or both. • Thickness readings should be made either in a straight line with individual readings taken at 1-in. (2.5-cm) intervals or spaced randomly within a 2-in. (5-cm) diameter area. Line measurements should be used for large flat areas, and area measurements should be used on complex surface geometry and surface transitions such as corners. The average of five readings constitutes one thickness measurement. A given number of measurements per unit area (e.g., five per 100 ft2 [9 m2]) should be specified in the contract documents. Figure 7 illustrates this method. • Measure thickness according to ASTM D4138, “Test Methods for Measurement of Dry Film Thickness of Protective Coating Systems by Destructive Means,” Test Method A. This method uses a tungsten carbide-tipped instrument to scribe through the sealer and paint, leaving a V-shaped cut. A heavy dark-colored marking pen is first used to mark the coated surface. The scribing instrument is then drawn across the mark. This process sharply delineates the edges of the scribe. A reticle-equipped microscope is used to read the film thickness. A total of three thickness readings should be performed in a 16-in.2 (100-cm2) area, with the average of the three tests reported as a single measurement. The number of measurements per unit area (e.g., 1 per 500 ft2 [45 m2]) should be specified in the contract documents. Thickness testing using this method should be minimized because the test method destroys the sealer and paint. Areas damaged by adhesion testing must be repaired by 64 The inspector must be aware that TSMCs create safety and health risks in the form of hot surfaces, fumes, ultraviolet light, and noise. Precautions must be taken to avoid these hazards—refer to Section 2. 5 in line at about 1 in. [2.5 cm] 5 in a spot of about 2 in. dia (5 cm) Figure 7. Methods of taking coating thickness measurements.

touch-up with sealer or paint using a brush or spray gun. Thickness testing should be performed in a small area (16 in.2 [100 cm2]) to limit the area that must be repaired. 8.3.6.2 Adhesion tests. The following applies to adhesion tests. • Bend Test. The bend test (180-degree bend on a mandrel) is used as a qualitative test for verifying proper surface preparation, equipment setup, and spray parameters. The bend test puts the TSMC in tension. The mandrel diameter for the threshold of cracking depends on substrate thickness and coating thickness. Table 9 summarizes a very limited bend-test cracking threshold for arc-sprayed zinc TSMC thickness versus mandrel diameter for steel coupons 0.050 in. (13 mm) thick. – Test panels—the test panels should be a cold-rolled steel measuring 3 × 6 × 0.05 in. (7.5 × 15 × 1.25 cm). The panels should be cleaned and blasted in the same fashion in which the panels will be cleaned and blasted for the job. – Application of thermal spray—the TSMC should be applied to five test panels using the identical spray parameters and average specified thickness that will be used on the job. The coating should be applied in a cross-hatch pattern using the same number of overlapping spray passes as used to prepare the job reference standard. The coating thickness should be measured to confirm that it is within the specified range. – Conduct bend test—test panels should be bent 180 degrees around a steel mandrel of a specified diameter, as shown in Figure 5. Pneumatic and manual mechanical bend test apparatus may be used to bend the test panels. – Examine bend test panels—test panels should be examined visually without magnification. The bend test is acceptable if the coating shows no cracks or exhibits only minor cracking with no lifting of the coating from the substrate. If the coating cracks and lifts from the substrate, the results of the bend test are unacceptable. TSMCs should not be applied if the bend test fails, and corrective measures must be taken. Figure 5 depicts representative bend test results. A knife blade can be used to facilitate the evaluation. Apply moderate pressure to the knife blade and if the coating cannot be dislodged, the adhesion can be considered satisfactory. • Tensile Adhesion. – Field Measurement—Evaluate the adhesion of the TSMC with the specification in accordance with ASTM D4541, “Test Method for Pull-Off Strength of Coatings Using Portable Adhesion Testers.” A self-aligning Type IV tester, described in Annex A4 of ASTM D4541, should be used. A total of three adhesion tests should be performed in a 16-in2 (100-cm2) area, and the average of the three tests should be 65 TSMC Thickness (mils) ≥ 10 (254 µm) ≥ 15 (381 µm) ≥ 25 (635 µm) Mandrel Diameter 1/2 in. (1.27 cm) 5/8 in. (1.59 cm) <1 in. (2.54 cm) TABLE 9 Bend-test mandrel diameter versus zinc thermal spray coating thickness (for steel coupons 0.050 in. [13 mm] thick)

reported as a single measurement. Portable instruments with large-diameter test specimens, for instance, 2-in. versus 1-in. (50-mm versus 25-mm) diameter, produce better statistical results. The number of measurements per unit area (e.g., 1 per 500 ft2 [45 m2]) should be specified in the contract documents. Areas of deficient adhesion should be abrasive blasted, and the coating should be reapplied. Additional testing will probably be necessary to determine the extent of the area exhibiting poor adhesion. Adhesion testing should be minimized because the test method destroys the coating. Areas damaged by adhesion testing must be repaired by abrasive blasting and reapplication of the metallic coating. Adhesion testing is performed in a small area (16 in2 [100 cm2]) to limit the area that must be repaired. As an alternative to testing adhesion to the failure point, the tests can be interrupted when the minimum specified adhesion value is achieved. This method precludes the need to repair coatings damaged by the test. The adherent pull stubs can then be removed by heating to soften the glue or by firmly striking the side of the stub. Table 10 lists the recommended adhesion requirements for field- or shop-applied thermal spray coatings of zinc, aluminum, and 8515 wt% zinc/aluminum. As a caution in performing this type of test, the inspector must be aware that since the coating does contain some porosity, a low-viscosity adhesive might penetrate the coating and reach the substrate. If this occurs, the measured adhesion value will be influenced by the adhesion between the glue and the substrate. It is best to avoid low- viscosity liquid adhesives in favor of high-viscosity pastes. If there is any doubt, comparison tests should be performed to select the appropriate adhesive. – Laboratory Measurement—Tensile-bond test specimens should be carbon steel, 1 in. (2.54 cm) in diameter and 1 in. (2.54 cm) in length, threaded per ASTM C 633, “Adhesion or Cohesive Strength of Flame-Sprayed Coatings.” • Cut Test. The thermal spray coating cut test consists of a single cut, 1.5 in. [40 mm] long, through the coating to the substrate without severely cutting into the substrate. All cuts should be made using sharp-edge tools. The chisel cut should be made at a shallow angle. The bond should be considered unsatisfactory if any part of the TSMC along the cut lifts 66 Thermal Spray Material Tensile Adhesion psi [MPa] Zinc 500 [3.45] Aluminum 1,000 [6.89] 85/15 Zinc-Aluminum 700 [4.83] 90/10 Aluminum Oxide 1,000 [6.89] TABLE 10 Typical adhesion of field- and shop-applied thermally sprayed metal coatings measured by pull-off testing

from the substrate. The cutting tool used (knife, hammer and chisel, or other tool) should be specified in the contract. Perform an adhesion test every 100 ft2 (9.3 m2). The tested area and coated surfaces that have been rejected for poor adhesion shall be blast cleaned and recoated. 8.3.7 Appearance The coating should be free of blisters, cracks, chips or loosely adhering particles, oil, pits exposing the substrate, and nodules. A very rough coating might indicate that the coating was applied with the gun at too great an angle or too far from the surface. Evaluate coatings that appear powdery or oxidized by scraping. If scraping does not produce a silvery metallic appearance, the coating is defective and must be replaced. 8.3.8 Coating Morphology Metallographic examination may be used for qualifying spraying parameters, but it is not normally used for process control for corrosion control applications. Parameters included in this examination include percent porosity, percent unmelted particles, percent oxides, and the presence and amount of interface contamination. 67

9 QUALIFICATIONS 9.1 Equipment 9.1.1 Qualification Each type and source of thermal spray equipment should be qualified prior to use. The equipment should conform to the following requirements related to uniformity of operation, coating appearance, and coating adhesion. Equipment should be qualified using the type and size of wire to be used on the job. The operating parameters should be those selected by the contractor for use on the job. Equipment manufacturers may also qualify their equipment for use with specific feedstocks and operating parameters. Such qualified equipment should be accepted as prequalified, assuming the contractor proposes to operate the equipment in the same manner used for the qualification tests. 9.1.2 Wire-Flame Spray Equipment 9.1.2.1 Gases. Flame-spraying equipment shall permit spraying with the combustible gases, atomizing gas (if any), and carrier gas (if any) for which it was designed. 9.1.2.2 Oxygen and fuel gas flow rates. Under conditions of continuous use, the actual oxygen and fuel gas flow rates and pressures should remain nearly constant and should not deviate from the set values by more than 5 percent during a 15-minute period. 9.1.2.3 Atomization air pressure. Compressed air should be free of oil and water. Under conditions of continuous use, the actual atomization air pressure and flow volume should remain nearly constant and should not deviate from the set value by more than 5 percent during a 15-minute period. 9.1.2.4 Wire feed rate. It shall be possible to adjust the spraying material feed rate. Under conditions of continuous use, the actual wire feed rate should remain nearly constant and should not deviate from the set value by more than 5 percent during a 15-minute period. • The set values shall be constant and reproducible; preconditions of this are adequate and constant gas pressures, atomizing air pressures, and supply of electrical power as appropriate. • With regard to continuous operation, the equipment should not sputter, pop, or stop operating when operated continuously for 15 minutes. 9.1.2.5 Control unit and monitoring. It shall be possible to monitor and control, read clearly and correct, by means of instruments, any deviations from the set values of atomizing gas pressure and gas volume flow rate during the spraying process. These values shall be recorded during acceptance inspection. The limits of error of the measuring instruments shall not exceed ± 5 percent for all set values and shall correspond to at least Class 2.5 instruments. The reproducibility of the setting shall be proved. 68

9.1.2.6 Nozzle system. The nozzle system shall be considered acceptable if, after 20 minutes of spraying 8515 wt% zinc/aluminum wire at the maximum spray rate, there are no degrading deposits of spraying material on or in the nozzle. Nozzles shall be acceptable if, after 20 minutes of spraying nozzle-compatible materials at the maximum spray rate, there are no degrading deposits of spraying material on or in the nozzle. 9.1.3 Wire-Arc Spray Equipment 9.1.3.1 Power. Under conditions of continuous use, the actual current output should remain nearly constant and should not deviate from the set value by more than 5 percent during a 15-minute period. 9.1.3.2 Voltage. Under conditions of continuous use, the actual voltage should remain nearly constant and should not deviate from the set value by more than 5 percent during a 15-minute period. 9.1.3.3 Wire feed mechanism. The wire feed mechanism should be designed for automatic alignment. Under conditions of continuous use, the actual wire feed rate should remain nearly constant and should not deviate from the set value by more than 5 percent during a 15-minute period. 9.1.3.4 Atomization air pressure. Under conditions of continuous use, the actual atomization air pressure and flow volume should remain nearly constant and should not deviate from the set value by more than 5 percent during a 15-minute period. 9.1.3.5 Continuous operation. When operated continuously for 15 minutes, the equipment should not sputter, pop, or stop operating. 9.1.3.6 On/off operation. The equipment should be capable of continuous start and stop operation for a minimum of 15 cycles consisting of 10 seconds on and 5 seconds off without fusing, sputtering, or deposition of nodules. 9.1.3.7 Nozzle system (contact tubes and air nozzle). The nozzle system shall permit a constant arc to be maintained and provide atomization without causing a buildup of deposits that will degrade gun operation. The nozzle system shall be acceptable if, after 20 minutes of spraying 8515 wt% zinc/aluminum wire at the maximum spray rate, there are no degrading deposits of spraying material on or in the nozzle. 9.1.3.8 Coating appearance. The applied coating should be uniform and free of blisters, cracks, loosely adherent particles, nodules, and powdery deposits. 9.1.3.9 Coating adhesion. A 12- × 12- × 0.5-in. (30- × 30- × 1.25-cm) flat steel plate should be cleaned and prepared in accordance with SSPC-SP-1 and SSPC-SP-5. No. 36 aluminum oxide grit should be used to produce an angular blast profile of 0.003 ± 0.0002 in. (75 ± 5µm). The blast profile should be measured and recorded using replica tape in accordance with ASTM D4417. The coating of 8515 wt% zinc/aluminum alloy (0.016 ± 0.002 in. [400 ± 50 µm]), zinc (0.016 ± 0.002 in. [400 ± 50 µm]), or aluminum (0.010 ± 0.002 in. [250 ± 50 µm]) should be applied in not less than two half-lapped passes applied at right angles to each other. 69

The adhesion should be tested in accordance with ASTM D4541 using a self-aligning Type IV adhesion tester as described in this guide. Scarified aluminum pull stubs should be attached to the TSMC using a two-component epoxy adhesive. The adhesive strength of the coating should be measured and recorded at five randomly selected locations. The average adhesion should not be less than 1,000 psi (6,895 kPa), 1,600 psi (11,032 kPa), and 750 psi (5,171 kPa) for 8515 wt% zinc/aluminum alloy, aluminum, and zinc coatings, respectively. If the test fails, it should be repeated using a new test plate. If the adhesion fails on the second plate, the equipment should be deemed unacceptable. 9.1.4 Retests If the values obtained during acceptance inspection of a thermal spraying system are altered by modification or repair work, retesting of the properties affected shall be carried out. Retests shall be carried out in the same way as the initial tests described in this standard. 9.2 Applicator 9.2.1 General Requirements 9.2.1.1 Terminology. When the term “certified thermal sprayer” is used, it should denote “thermal spray operator or technician.” 9.2.1.2 Required skills. A thermal sprayer must have adequate instruction and training and shop and field experience to safely and proficiently apply thermal spray coatings of aluminum, zinc, and their alloys on steel. The thermal sprayer should demonstrate the ability to set up, operate (including field troubleshooting and repair), and secure thermal spray equipment. The sprayer should be knowledgeable in cleaning and preparing the steel. The sprayer should be skilled in spraying the TSMCs using the intended thermal spray equipment in accordance with the equipment manufacturer’s instructions/technical manual and the purchaser’s contract specifications. The thermal sprayer should be able to recognize proper masking and surface preparation. The thermal sprayer must be able to recognize unsatisfactory surface preparation and call for corrective action, or stop the job until deficiencies are corrected. 9.2.1.3 Standards and references for certification. The thermal sprayer knowledge and skill requirements do not supersede an employer’s or contractor’s ability to continue to certify thermal sprayers in accordance with the following other standards and references: • ASTM D4228, “Practice for Qualification of Coating Applicators for Application of Coatings to Steel Surfaces.” • MIL-STD-1687A (SH), “Thermal Spray Processes for Naval Ship Machinery Applications,” 2/11/87. • Various original equipment manufacturers (OEMs) or after-market repair, or both. Thermal spray process and spray parameter specifications from the OEM or after-market repair facility. • Material safety data sheets (MSDSs) for abrasive blasting and thermal spray feedstock materials. • EN 657, Thermal spraying—Terminology, classification, April 1994. 70

9.2.1.4 Basic skills. Thermal sprayers must have basic knowledge and skills in safe assembly, setting up, operating, and closing down procedures for equipment; personal protection; fire hazards; dust explosions; electrical hazards; flash backs; leak detection; UV radiation; and noise. 9.2.2 Demonstration of Applicator Skills 9.2.2.1 Equipment setup and operation. The TSMC applicator should be qualified to SSPC-QP-1 in regards to field application of TSMC work on complex structures or as otherwise specified by the purchasing contract. The thermal spray operator must have normal or corrected 20/20 vision. The qualified applicator should be able to demonstrate a working knowledge of the application equipment to be used on the job by proper setup and operation of the equipment. The applicator should prepare a 12- × 12- × 0.5-in. (30- × 30- × 1.25-cm) flat steel plate cleaned in accordance with SSPC-SP-1 and SSPC-SP-5. Aluminum oxide or steel grit should be used to produce an angular blast profile of 3.0 ± 0.2 mils (76 ± 5 µm). The blast profile should be measured and recorded using replica tape in accordance with ASTM D4417. The applicator should apply the coating of 8515 wt% zinc/aluminum alloy (16 ± 2 mils [400 ± 50 µm]), zinc (16 ± 2 mils [406 ± 50 µm]), or aluminum (10 ± 2 mils [250 ± 50 µm]) using the proper spray technique. 9.2.2.2 Coating appearance. The qualified applicator will have applied a coating that is uniform and free of blisters, cracks, loosely adherent particles, nodules, or powdery deposits. 9.2.2.3 Coating adhesion. The qualified applicator should be able to apply a firmly adherent coating that meets the adhesion requirements of the contract. The TSMC adhesion should be tested in accordance with ASTM D4541 using a self-aligning Type IV adhesion tester as described in Annex A4 of the method. Scarified aluminum pull stubs should be attached to the TSMC using a two-component epoxy adhesive. The adhesive strength of the coating should be measured and recorded at five randomly selected locations. The average adhesion should not be less than 1,000 psi (6,895 kPa), 1,600 psi (11,032 kPa), and 750 psi (5,171 kPa) for 8515 wt% zinc/aluminum alloy, aluminum, and zinc coatings, respectively. 9.3 Inspector 9.3.1 Description of Inspector’s Role The TSMC inspector is a person who is knowledgeable in the concepts and principles of this guide and skilled in observing and measuring conformance to them. Ideally, a third disinterested party will employ the inspector. Specific qualifications of an inspector are listed below. 9.3.1.1 Vision requirements. The inspector must have normal or corrected 20/20 vision. 9.3.1.2 ASTM D3276. An inspector must have the knowledge and ability to meet the guidelines specified in ASTM D3276, “Standard Guide for Painting Inspectors (Metal Substrates).” 71

9.3.1.3 Training program. Completion of a formal training program, such as the one offered by NACE International, and certification as a NACE International Certified Coating Inspector are recommended. 9.3.1.4 Basic knowledge requirements. The inspector should meet the basic knowledge requirements of a qualified thermal spray operator with respect to the following: • The inspector should be qualified to SSPC-QP-1 in regards to field application of TSMC work on complex structures or as otherwise specified by the purchasing contract. • The inspector should have a working knowledge of the methods of TSMC application, particularly the method to be used at the job site. • The inspector should be able to demonstrate a working knowledge of the application equipment to be used on the job by proper setup and operation of the equipment. 9.3.1.5 Observation and evaluation skills. The inspector should be skilled in observing and evaluating conformance of the application process to the contract specifications. 9.3.1.6 Job reference standard. The inspector should be skilled in setting up a job reference standard as described in Section 8. 9.3.1.7 Knowledge and skills in use of inspection equipment. The inspector should be knowledgeable and skilled in the use of inspection equipment to measure and validate the coating applicator’s conformance to the purchasing contract. Specifically (further details are provided in Section 8 and in referenced test methods), the inspector should be • Skilled in measuring surface temperature, dew point, and ambient air temperature and in calculating the dew point. Specific skills include the use of a surface temperature gauge, sling psychrometer, psychrometric charts, and digital measuring equipment. • Skilled in the use of water break, UV light, solvent evaporation, and heat tests to detect grease and oil. • Skilled in the use of conductivity, commercially available colorimetric kits, and titration kits for the measurement of soluble salts and skilled in the use of a Bresle kit for soluble salt measurement. • Knowledgeable about SSPC-AB-2, “Specification for Cleanliness of Recycled Ferrous Metallic Abrasives,” and ASTM D4940, “Test Method for Conductimetric Analysis of Water Soluble Ionic Contamination of Blasting Abrasives,” for the detection of salt in abrasives. • Skilled in the detection of oil in abrasives. • Knowledgeable about ASTM D4285, “Method for Indicating Water or Oil in Compressed Air.” • Skilled in measuring blast air pressure and nozzle orifice condition. • Knowledgeable about SSPC surface preparation standards, specifically SSPC-SP-5 and SSPC-VIS-1. • Skilled in testing surface profile using ASTM D4417, Method C. • Skilled in measuring coating thickness per SSPC-PA-2 using a Type 2 gauge, in accordance with ASTM D4138, “Test Methods for Measurement of Dry Film Thickness of Protective Coating Systems by Destructive Means.” 72

• Skilled in conducting adhesion tests, including the bend test, tensile adhesion test (ASTM D4541, “Test Method for Pull-Off Strength of Coatings Using Portable Adhesion Testers,” using a self-aligning Type IV tester, described in Annex A4 of ASTM D4541), and cut test as described in Section 8. • Knowledgeable about the ASTM test methods available to quantify coating defects. 9.3.1.8 Communications and conflict-resolution skills. The inspector should be skilled in communications and conflict resolution so that when application errors are found, they may be corrected without significant disruption to the schedule. 9.3.1.9 Reports. The inspector should submit timely oral and written reports to the purchaser. 73

74 10 REFERENCED DOCUMENTS Reference Title Address Comments American Geological Institute 4220 King St. Alexandria, VA 22302-1502 www.agiweb.org Provides classification of mineral angularity. ANSI/AWS C2.18-93 Guide for the Protection of Steel with Thermal Sprayed Coatings of Aluminum and Zinc & Their Alloys and Composites American National Standards Institute 1819 L Street, NW Washington, DC 20036 www.ansi.org Provides guidelines for the selection, surface preparation, application, and inspection of thermal spray metal coatings. TO BE SUPERCEDED BY ANSI/AWS C2.18A-XX ANSI/AWS C2.18A-XX SSPC CS 23.00A-XX NACE TPC #XA Guide for the Application of Thermal Spray Coatings (Metallizing) of Aluminum, Zinc & Their Alloys & Composites for the Corrosion Protection of Steel (in preparation) SSPC: The Society for Protective Coatings 40 24th Street, 6th Floor Pittsburgh, PA 15222-4656 www.sspc.org Will provide guidelines for the selection, surface preparation, application, and inspection of thermal spray metal coatings when completed. ANSI/AWS C2.23-XX SSPC CS 23.00B-XX NACE TPC #XB Specification for the Application of Thermal Spray Coatings (Metallizing) of Aluminum, Zinc & Their Alloys for the Corrosion Protection of Steel (in preparation) NACE International 1440 South Creek Dr. Houston, TX 77084-4906 www.nace.org ANSI/AWS C2.16A Guide for Thermal Spray Operator Qualification ANSI/AWS Provides procedures and documents for operator and equipment qualification.

75 Reference Title Address Comments ANSI Z49.1 Safety in Welding and Cutting American National Standards Institute 1819 L Street NW Washington, D.C. 20036 www.ansi.org ANSI Z87.1 Standard Practices for Occupational and Educational Eye and Face Protection ANSI Z89.1 Safety Requirements for Industrial Head Protection ANSI Z88.2 Standard Practices for Respiratory Protection ANSI/NFPA 51B Standard for Fire Prevention in Use of Cutting and Welding Processes ANSI/NFPA 70 National Electrical Code ASTM B833 Standard Specification for Zinc and Zinc Alloy Wire for Thermal Spraying (Metallizing) ASTM International 100 Barr Harbor Drive W. Conshohocken, PA 19428- 2959 www.astm.org

76 Reference Title Address Comments ASTM C633 Standard Test Method for Adhesion or Cohesive Strength of Flame-Sprayed Coatings ASTM International 100 Barr Harbor Drive W. Conshohocken, PA 19428- 2959 www.astm.org Laboratory testing of the tensile adhesion of thermal spray metal coatings. ASTM D610 Test Method for Evaluating Degree of Rusting on painted Steel Surfaces – provides standard charts for quantifying the amount of rusting on a steel surface ASTM D660 Test Method for Evaluating Degree of Checking of Exterior Paints ASTM D661 Test Method for Evaluating Degree of Cracking of Exterior Paints ASTM D662 Test Method for Evaluating Degree of Erosion of Exterior Paints ASTM D714 Test Method for Evaluating Degree of Blistering of Paints

77 Reference Title Address Comments ASTM D1186 Standard Test Methods for Nondestructive Measurement of Dry Film Thickness of Nonmagnetic Coatings Applied to a Ferrous Base ASTM D3359 Test Method for Measuring Adhesion by Tape Test ASTM D4214 Test Method for Evaluating Degree of Chalking of Exterior Paint Films ASTM D4285 Standard Test Method for Indicating Oil or Water in Compressed Air ASTM D4417 Standard Test Methods for Field Measurement of Surface Profile of Blast Cleaned Steel ASTM D4541 Standard Test Method for Pull- Off Strength of Coatings Using Portable Adhesion Testers Tensile adhesion testing of coatings using a dolly attached to the coating with an adhesive. The dolly is pulled off the surface using a hand- held device and the tensile force is indicated. Tests using different devices can yield inconsistent results.

78 Reference Title Address Comments ASTM D4940 Test Method for Conductimetric Analysis of Water-Soluble Ionic Contamination of Blasting Abrasives ASTM International 100 Barr Harbor Drive W. Conshohocken, PA 19428- 2959 www.astm.org ASTM E337 Test Method for Measuring Humidity with a Psychrometer (wet/dry bulb temperatures) ASTM F1130 Standard Practice for Inspecting the Coating of a Ship – useful for standardizing the method of reporting the extent of corrosion and coating deterioration AWS C2.1 Recommended Safe Practices for Thermal Spraying American Welding Society 550 NW LeJeune Rd. Miami, FL 33126 www.aws.org AWS TS1 Recommended Safe Practices for Thermal Spraying AWS TSM Thermal Spray Manual AWS TSS Thermal Spraying: Practice, Theory and Application

79 Reference Title Address Comments BS 5493 Code of Practice for Protective Coating of Iron and Steel Structures against Corrosion British Standards Institution 389 Chiswick High Rd. London W4 4AL United Kingdom www.bsi-global.com Provides selection and application guidance for various coatings including thermally sprayed aluminum and zinc. Current but partially replaced with EN standards. Compressed Gas Association CGA G7.1 Commodity Specification for Air Compressed Gas Association 4221 Walney Rd., 6th Floor Chantilly, VA 20151-2423 www.cganet.com EN 473 Non-destructive Testing – Qualification and Certification of Personnel European Committee for Standardization Rue de Stassart 36 B-1050 Brussels, Belgium www.cenorm.be EN 582 Thermal Spraying – Determination of the Adhesive Tensile Strength EN 657 Thermal Spraying – Terminology – Classification EN 1395 Thermal Spraying – Acceptance Testing of Thermal Spraying Equipment

80 Reference Title Address Comments EN 13214 Thermal Spraying – Thermal Spray Coordination – Tasks and Responsibilities European Committee for Standardization Rue de Stassart 36 B-1050 Brussels, Belgium www.cenorm.be prEN 13214 Thermal Spraying – Thermal Spray Coordination – Tasks and Responsibilities EN ISO 14918 Thermal Spraying – Approval Testing for Thermal Sprayers prEN ISO 14919 Thermal Spraying – Wires, Rods and Cords for Flame and Arc Spraying – Classification – Technical Supply Conditions EN 22063 Metallic and Other Inorganic Coatings – Thermal Spraying – Zinc, Aluminum and Their Alloys FHWA-RD-96-058 Environmentally Acceptable Materials for the Corrosion Protection of Steel Bridges Federal Highway Administration Turner Fairbank Highway Research Center 6300 Georgetown Pike McLean, VA 22101-2439 www.tfhrc.gov Research report on the use of environmentally friendly coatings, including thermally sprayed metal coatings.

81 Reference Title Address Comments ISO 14918 Thermal Spraying – Approval Testing of Thermal Sprayers International Organization for Standardization 1, rue de Varembe Case postale 56 CH-1211 Geneva 20, Switzerland www.iso.org Gives procedural instructions for approval testing of thermal sprayers. Defines essential requirements, ranges of approval, test conditions, acceptance requirements and certification. ISO 14922-1 Thermal Spraying – Quality Requirements of Thermally Sprayed Structures – Part 1 Guidance for Selection and Use Specifies guidelines to describe thermal spraying quality requirements suitable for application by manufacturers for coating new parts, repair and maintenance. Reference to European (EN) Standards. ISO 14922-2 Thermal Spraying – Quality Requirements of Thermally Sprayed Structures – Part 2: Comprehensive Quality Requirements Provides general guidance and reference to European (EN) Standards. ISO 14922-3 Thermal Spraying – Quality Requirements of Thermally Sprayed Structures – Part 3: Standard Quality Requirements Provides general guidance and reference to European (EN) Standards.

82 Reference Title Address Comments ISO 14922-4 Thermal Spraying – Quality Requirements of Thermally Sprayed Structures – Part 4: Elementary Quality Requirements International Organization for Standardization 1, rue de Varembe Case postale 56 CH-1211 Geneva 20, Switzerland www.iso.org Provides general guidance and reference to European (EN) Standards. ISO 2063 Metallic Coatings – Protection of Iron and Steel against Corrosion – Metal Spraying of Zinc, Aluminum and Alloys of these Materials ISO 8502 Preparation of Steel Structures Before Application of Paint and Related Products – Tests for the Assessment of Surface Cleanliness JIS H 8300 Zinc, Aluminum and their Alloys Sprayed Coatings – Quality of Sprayed Coatings Japan Standards Association 4-1-24 Akasaka Minato-ku Tokyo 107-8440 Japan www.jsa.or.ip Contains QA provisions for thermally sprayed aluminum and zinc.

83 Reference Title Address Comments MIL-80141C Metallizing Outfit, Power Gas, Guns and Accessories Commander Naval Sea Systems Command SEA 5523 Department of the Navy Washington, DC 20362-5101 http://stinet.dtic.mil MIL-M-6712C Metallizing Wire Provides specifications for chemistry, dimensions, winding and finish of wire for flame spray, including zinc and aluminum. MIL-STD-1687A(SH) Thermal Spray Processes for Naval Ship Machinery Applications Provides information for thermally spraying metal coatings onto machinery. Contains requirements for qualification of procedures and operators, use of thermal spray equipment and material, quality assurance requirements and qualification tests. MIL-STD-2138A(SH) Metal Sprayed Coatings for Corrosion Protection aboard Naval Ships (Metric) Provides specifications for surface preparation, application and testing of thermally sprayed aluminum to ships. Note that zinc is not included because of health hazards.

84 Reference Title Address Comments NACE Publication 1G194 Splash Zone Maintenance Systems for Marine Steel Structures NACE International 1440 South Creek Dr. Houston, TX 77084-4906 www.nace.org NACE Publication 6G186 Surface Preparation of Contaminated Steel Surfaces NACE Standard RP0287 Standard Recommended Practice, Field Measurement of Surface Profile of Abrasive Blast Cleaned Steel Surfaces Using a Replica Tape NACE TM0170 Visual Comparator for Surfaces of New Steel Airblast Cleaned with Sand Abrasive NACE TM0175 Visual Standard for Surfaces of New Steel Centrifugally Blast Cleaned with Steel Grit and Shot NACE Technical Report T-60-5 A Manual for Painter Safety

85 Reference Title Address Comments NIOSH Respiratory Protection – An Employer’s Manual National Institute for Occupational Safety & Health Robert A. Taft Laboratories 4676 Columbia Parkway Cincinnati, OH 45226 www.cdc.gov/niosh NIOSH Respiratory Protection – A Guide for the Employee OSHA CFR 29 Part 1910 Occupational Safety and Health Standards Occupational Safety & Health Administration 200 Constitution Ave. NW Washington, D.C. www.osha.gov SAE J827 Peening Media, General Requirements of High Carbon Cast Steel Shot Society of American Automotive Engineers 755 W. Big Beaver Suite 1600 Troy, MI 48084 www.sae.org

86 Reference Title Address Comments SS-EN 1395 Thermal Spraying – Acceptance Inspection of Thermal Spraying Equipment Swedish Standards Institute SIS Forlag AB 118 80 Stockhom, Sweden www.sis.se Provides acceptance inspection requirements for thermal spraying equipment for plasma, arc and flame spraying. SSPC SP-0/NACE No. 2 Near-White Blast Cleaning SSPC – The Society for Protective Coatings 40 24th Street, 6th Floor Pittsburgh, PA 15222-4656 www.sspc.org SSPC SP-5/NACE No. 1 White-Metal Blast Cleaning SSPC VIS-1-89 Visual Standard for Abrasive Blast Cleaned Steel SSPC AB-1 Mineral and Slag Abrasives SSPC AB-2 Specification for the Cleanliness of Recycled Ferrous Metallic Abrasives SSPC AB-3 Newly Manufactured or Re- Manufactured Steel Abrasives

87 Reference Title Address Comments SSPC CS-23.00 Guide for Thermal Spray Metallic Coating Systems SSPC – The Society for Protective Coatings 40 24th Street, 6th Floor Pittsburgh, PA 15222-4656 www.sspc.org Provides guidance for surface preparation, application and testing of aluminum, zinc-aluminum and zinc thermal spray metal coatings. IT IS TO BE REPLACED BY SSPC CS 23.00A-XX PRESENTLY IN PREPARATION. SEE ALSO ASTM AND NACE DOCUMENTS. SSPC PA-1 Shop, Field and Maintenance Painting SSPC PA-2 Measurement of Dry Paint Thickness with Magnetic Gages SSPC PA Guide 3 A Guide to Safety in Paint Application SSPC QP- Standard Procedure for Evaluating Qualifications of Painting Contractors SSPC SP-1 Solvent Cleaning Provides details for removing grease and oil contamination prior to final surface preparation.

88 Reference Title Address Comments SSPC SP-3 Power Tool Cleaning SSPC – The Society for Protective Coatings 40 24th Street, 6th Floor Pittsburgh, PA 15222-4656 www.sspc.org Provides details for removing scaling and heavy corrosion prior to final surface preparation. SSPC SP- 5/NACE 1 White Metal Blast Cleaning SSPC/NACE Provides details on proper surface preparation quality prior to thermal spray metal application. SSPC SP COM Surface Preparation Commentary Provides a discussion and information about the factors that influence surface preparation. US Army Corps of Engineers (USACE) Engineering Manual EM 1110-2-3401 Engineering and Design, Thermal Spraying: New Construction and Maintenance U.S. Army Corps of Engineers Champaign, IL http://www.usace.army.mil/inet/ usace-docs/ Provides information on thermal spray metal coatings for coating selection, surface preparation, application, testing and quality assurance. US Army Corps of Engineers (USACE) Guide Specification for Construction CEGS- 9971 Section 09971, Metallizing: Hydraulic Structures Provides specific recommendations for the selection of thermal spray metal coating systems in different environments for Corps of Engineers structures. US Army Corps of Engineers (USACE) Guide Specification for Construction CEGS- 09965 Section 09965, Painting: Hydraulic Structures Provides specific recommendations for the selection of coating systems for Corps of Engineers structures.

11 GENERIC SEALER SPECIFICATION 1. SCOPE This specification provides a general specification for sealers to be used on thermally sprayed metal coatings. A sealer is defined as a material applied to infiltrate and close the pores of a thermal spraying deposit for the purpose of improving the life expectancy of the thermally sprayed metal coating. A sealer is not intended to provide a dielectric barrier coating over the surface and is not intended to provide an aesthetic finish coat. Further intermediate or topcoats applied over the seal coat must be used for barrier coating protection and aesthetic purposes. This specification does not cover intermediate and finish coatings. Intermediate and finish coats must be compatible with the thermally sprayed metal coating and sealer. 2. APPLICABLE DOCUMENTS 2.1 AASHTO, “Thermally Sprayed Metal Coating Guide.” 2.2 U.S. Army Corps of Engineers (USACE) Guide Specification for Construction CEGS-09965, Section 09965, Painting: Hydraulic Structures. 2.3 MIL-STD-2138A (SH), “Metal Sprayed Coatings for Corrosion Protection Aboard Naval Ships.” 2.4 ASTM D1210, “Test Method for Fineness of Dispersion of Pigment-Vehicle Systems.” 2.5 ASTM D2794 (Modified), “Test Method for Resistance of Organic Coatings to the Effects of Rapid Deformation (Impact).” 2.6 ISO 8502-3, “Clear Cellophane Tape Test.” 2.7 The sealer manufacturer’s product technical data sheets. 3. SAFETY AND ENVIRONMENTAL 3.1 Safety 3.1.1 Solvents used for cleaning or to apply sealers or topcoats (e.g., acetone, xylene, or alcohol) emit vapors that are harmful and can be fatal. 3.1.1.1 Use solvents only with adequate ventilation or proper respiratory protection and other protective clothing as needed. Avoid breathing solvent vapors and skin contact with solvents. 89

3.1.1.2 Most solvents are also flammable liquids. All solvent tanks must have lids and be covered when not in use. Take proper safety precautions. 3.1.1.3 Keep all solvents and flammable materials at least 50 ft (15.2 m) away from welding, oxyfuel cutting and heating, and thermal spraying operations. 3.1.2 Sealers and paint coats are typically applied by spray application. Spray application is a high-production rate process that may rapidly introduce very large quantities of toxic solvents and vapors into the air. 3.1.2.1 Airless spray systems operate at very high pressures. Very high fluid pressures can result in penetration of the skin on contact with exposed flesh. 3.1.2.2 Tip guards and trigger locks should be used on all airless spray guns. The operator should never point the spray gun at any part of the body. 3.1.2.3 Pressure remains in the system even after the pump is turned off and can only be relieved by discharging or “blow-down” through the gun. 3.1.3 The contractor should maintain current MSDSs for all materials used on the job. These materials include cleaning solvents, compressed gases, thermal spray wires or powders, sealers, thinners, and paints or any other materials required to have an MSDS (as specified in CFR 29 Part 1910, Section 1200). The MSDSs should be readily available to all personnel on the job site in a clearly labeled folder. 3.2 Environmental 3.2.1 Ensure compliance with the purchaser’s and all pertinent government agency requirements and regulations for air-quality and hazardous-materials control. 3.2.2 The applicator and the purchaser should coordinate the specific requirements, responsibilities, and actions for the containment, storage, collection, removal, and disposal of the debris produced by the thermal spray coating operations. 3.2.3 All sealers must comply with federal, state, and local volatile organic compound (VOC) requirements for the area in which they are to be applied. 4. MATERIAL 4.1 The sealer must have the characteristics listed below. 4.1.1 The sealer must be capable of penetrating the pores of the thermally sprayed metal coating. Pigmented sealers must have a particle size nominally 5-fineness of grind (ASTM D1210). 90

91 4.1.2 The sealer must be capable of being applied to a low film thickness of 0.003 in. (76 µm) or less. 4.1.3 The sealer must be compatible with the thermally sprayed metal coating. For example, on zinc thermally sprayed coating, do not use a sealer that saponifies the zinc. 4.1.4 The sealer must be compatible with intermediate coats and topcoats. 4.1.5 The sealer must be suitable for the intended service. 4.1.6 The sealer must meet local regulations on VOC content. 4.1.7 The sealer must meet all color and other aesthetic requirements for the application. 4.2 Acceptable materials for steel pilings include those listed below. 4.2.1 Vinyl butyral wash primer (SSPC Paint 27). This is suitable for use over zinc, aluminum, and 8515 weight percent (wt%) zinc/aluminum. Thin wash primer per manufacturer’s instructions and apply to a dry film thickness of 0.0005 in. (12.7 µm). 4.2.2 U.S. Army Corps of Engineers paint specification V-766E vinyl acetate–vinyl chloride copolymer (CEGS-09965). 4.2.3 MIL-P-24441 Formula 150 polyamide epoxy thinned after the required period of induction with an equal volume amount of super hi-flash Naptha (boiling range 315°F to 353°F [157°C to 179°C]). The thinned coating shall not exceed local VOC limits (see MIL-STD-2138A [SH]). 4.2.4 Polyamide epoxy thinned 50 percent with approved solvent (or as directed by manufacturer) and applied to 1.5-mil (38.1-µm) dry film thickness. 4.2.5 High-solids low-penetrating epoxy. 4.2.6 Penetrating polyurethane. 4.2.7 Coal tar epoxy. This is suitable for use over zinc, aluminum, and 8515 wt% zinc/aluminum. Thin approximately 20 percent and apply to 0.004 to 0.006 in. (101 to 152 µm). 4.2.8 Aluminum epoxy mastic. This is suitable for use over zinc, aluminum, and 8515 wt% zinc/aluminum. Thin to the maximum extent per manufacturer’s recommended extent and apply to 0.003 to 0.004 in. (76 to 101 µm).

92 4.2.9 Tung-oil phenolic aluminum (TT-P-38). Suitable for use over zinc, aluminum, and 8515 wt% zinc/aluminum. Thin about 15 percent by volume and apply to a dry film thickness of 0.0015 in. (38 µm). 5. APPLICATION 5.1 Apply all paint sealer and topcoating according to SSPC-PA-1, “Shop, Field and Maintenance Painting,” and the paint manufacturer's recommendations for use of the product with a thermally sprayed metal coating system. The thermally sprayed metal coating before sealing shall have a uniform appearance. The coating shall not contain any of the following: blisters, cracks, chips or loosely adhering particles; oils or other internal contaminants; pits exposing the substrate; or nodules. 5.2 Surfaces that have had the thermally sprayed metal coating applied shall be inspected and approved by the inspector. The sealer shall be applied within 8 hours of the thermally sprayed metal coating application. If this is not possible, verify that the surface has not been contaminated and is dust free (cellophane tape test [ISO 8502- 3]). Visible oxidation of the thermal spray coating requires that the surface be further prepared to remove the oxidation by brush blasting. Subsequent paint coats are applied in accordance with the requirements of the painting schedule. 5.3 Blow down surfaces to be sealed using clean, dry compressed air to remove dust. 5.4 Where moisture is present or suspected in the thermal spray coating pores, heat the surface to 120°F (49°C) to remove the moisture prior to the seal coat application. When possible, the steel on the reverse side of the thermally sprayed metal coating should be heated to minimize oxidation and contamination of the thermally sprayed metal coating prior to sealing. 5.5 Apply sealers by conventional or airless spraying. Vinyl-type sealers must be applied using conventional spray techniques. 5.6 Thin sealers as recommended by the sealer manufacturer to effectively penetrate the TSMC. 5.7 Unless otherwise specified by the manufacturer or the project specifications, apply the sealer at a spreading rate resulting in a theoretical 1.5-mil (38-µm) dry film thickness. 5.8 Apply intermediate coats and topcoats as soon as the sealer is dry and preferably within 24 hours, in accordance with the coating manufacturer. 6. QUALITY CONTROL 6.1 Visually confirm complete coverage during application. Look for uniform coverage using tint and wetness of the surface as guides.

93 6.2 Measure the thickness of the topcoat per SSPC-PA-2 using a Type 2 fixed-probe gauge. The measurement may be made on either a companion coupon or the sealed thermal spray coating if the thermal spray coating thickness has been previously measured. Alternately, the thickness can be measured destructively using ASTM D4138, Test Method A. This method has the advantage of being able to observe all the layers; however, this type of measurement should be minimized because the areas tested must be repaired in order to maintain the coating integrity. 6.2.1 As an alternative, measure the thickness of the sealer as applied to a flat panel that was attached to the surface being sealed. Refer to SSPC-PA-2. 6.3 Note and correct areas with deficient sealer coverage. Correct by adding sealer. Additional testing is necessary to determine the extent of the area with deficient sealer or paint thickness. The sealer thickness must be checked prior to the application of subsequent paint coats, and the measurement procedure repeated for the sealer and paint. 6.4 As applied to thermally sprayed metal coatings on a steel substrate, sealer must meet a minimum drop weight impact requirement of 188 ft-lbs (254 N-m) when tested in accordance with ASTM D2794 (Modified).

GLOSSARY Abrasive A material used for wearing away a surface by rubbing; a fine, granulated material used for blast cleaning. Abrasive particles of controlled mesh sizes are propelled by compressed air, water, or centrifugal force to clean and roughen a surface. Blast-cleaning abrasives often are simply referred to as metallic or nonmetallic and as shot- or grit-like. Acceptance Testing The purchaser’s testing of received products to determine that the quality of manufactured products meets specified requirements. Adhesion The degree of attraction between a coating and a substrate or between two coats of paint that are held together by chemical or mechanical forces or both. Adhesion often is called the “bonding strength” of a coating. Adhesion should not be confused with “cohesion,” which is the internal force holding a single coating together. Air Contaminant Any substance of either artificial or natural origin in the ambient air, such as particulates (dust, fly ash, smoke, etc.), mists (other than water), fumes (gases), etc. Aliphatic Solvents Hydrocarbon solvents compounded primarily of paraffinic and cyclo-paraffinic (naphthenic) hydrocarbon compounds. Aromatic hydrocarbon content may range from less than 1% to about 35%. Alkyd Resins Synthetic resins formed by the condensation of polyhydric alcohols with polybasic acids. They may be regarded as complex esters. The most common polybasic alcohol used is glycerol, and the most common polybasic acid is phthalic anhydride. Alternate Immersion An exposure in which a surface is in frequent, perhaps fairly long, immersion in either freshwater or saltwater alternated with exposure to the atmosphere above the water. Ambient Air Quality Average atmospheric purity, as distinguished from discharge measurements taken at the source of pollution. The general amount of pollution present in a broad area. Anchor Pattern See Profile. Aromatic Solvents Hydrocarbon solvents composed wholly or primarily of aromatic hydrocarbon compounds. Aromatic solvents containing less than 80% aromatic compounds are frequently designated as partially aromatic solvents. 94

95 Atomization The mechanical subdivision of a bulk liquid or meltable solid, such as certain metals, to produce droplets, which vary in diameter (depending on the process) from under 10 to over 100 µm. Bend Test (Also flexibility test) Test applied to cured films to determine if they are able to elongate without fracture or debonding. Blasting Cleaning materials using a blast of air that directs small abrasive, angular particles against the surface. Blistering Formation of dome-shaped projections in coatings resulting from local loss of adhesion and lifting of the film from an underlying paint film or the base substrate. Bond Strength The force required to pull a coating free of a substrate, usually expressed in kPa (psi). Brackish Water Water with salinity between 0.5 and 17 parts per thousand. Cathodic Protection A technique to reduce the corrosion rate of a metal surface by making it a cathode of an electrochemical cell. Centrifugal Blast Cleaning Use of motor-driven bladed wheels to hurl abrasive at a surface by centrifugal force. Chalking Formation of a friable powder on the surface of a coating caused by the disintegration of the binding medium due to disruptive factors during weathering. Checking That phenomenon manifested in paint films by slight breaks in the film that do not penetrate to the underlying surface. The break is a “crack” if the underlying surface is visible. Coating System The applied and cured multilayer film or the components of a system based on non-paint type coating. Corrosion The deterioration of a metal by chemical or electrochemical reaction resulting from exposure to weathering, moisture, chemicals, or other agents in the environment in which it is placed. Cracking The splitting of a dry paint film, usually as the result of aging. Crevice Corrosion Corrosion that occurs within or adjacent to a crevice formed by contact with another piece of the same or another metal or with a nonmetallic material. Deposition Efficiency The ratio (usually expressed as a percentage) of the weight of spray deposit on the substrate to the total weight of the material sprayed.

96 Deposition Rate The weight of material deposited per unit of time. Dew Point The temperature at which water vapor present in the atmosphere is just sufficient to saturate it. When air is cooled below the dew point, the excess water vapor appears as tiny water droplets or crystals of ice, depending on the temperature of the air mass. DFT Dry film thickness. Edge Effect Loosening of the adhesive bond between a sprayed deposit and the substrate at the workpiece edges. Electrode A component for the electrical circuit through which current is conducted to the arc. Epoxy Resin Cross-linking resins based on the reactivity of the epoxide group. Flame Spray Any process whereby a material is brought to its melting point and sprayed onto a surface to produce a coating. The process includes metallizing, thermospray, and plasma flame. Flash Point The lowest temperature of a liquid at which it gives off sufficient vapor to form an ignitable mixture with the air near the surface of the liquid or within the vessel used. Flash Rusting Rusting that occurs on metal within minutes to a few hours after blast cleaning or other cleaning is completed. The speed with which flash rusting occurs may be indicative of salt contamination on the surface, high humidity, or both. Freshwater Water having salinity less than 0.5 parts per thousand. Galvanic Corrosion Accelerated corrosion of a metal because of an electrical contact with a more noble metal or nonmetallic conductor in a corrosive electrolyte. The term “dissimilar metal corrosion” is sometimes used. Galvanic Protection Reduction or elimination of corrosion of a metal achieved by making current flow to it from a solution by connecting it to a metal that is more active on the electromotive series (galvanic anode). The galvanic anode for steel would be a sacrificial metal, such as zinc, magnesium, or aluminum. Industrial Environment Environments with a large quantity of atmospheric pollutants, including sulfur-containing solids and gases that strengthen the electrolyte film. Corrosion significantly influenced by humidity, time of wetness, and wind direction.

97 Interface The contact surface between a sprayed deposit and the substrate. Marine Environment An atmospheric exposure that is frequently wetted by salt mist, but which is not in direct contact with salt spray or splashing waves. This environment contains a high concentration of chlorides. Masking Protecting a substrate surface from the effects of blasting or adhesion of a sprayed deposit. Matrix The major continuous substance of a thermally sprayed coating as opposed to inclusions or particles of materials having dissimilar characteristics. Mechanical Bond The adherence of a thermally sprayed deposit to a roughened surface by the mechanism of particle interlocking. Metallizing Spraying a coating of metal onto a surface. See also Thermal Spraying. Nozzle A device that directs a shielding media; a device that provides atomizing air in a wire-arc spray gun; the anode in a plasma gun; the gas burning jet in a rod or flame-wire spray gun. Overspray Atomized paint or sprayed coating particles that deflect from or miss the surface being sprayed; Spray particles that are not molten enough to fuse when they reach the surface being sprayed. As a result, overspray may contaminate property beyond the surface being sprayed. Oxide A chemical compound, the combination of oxygen with a metal forming a ceramic; examples include aluminum oxide and iron oxide. Parameter A measurable factor relating to several variables; loosely used to mean a spraying variable, spraying condition, spray rate, spray distance, angle, gas pressure, gas flow, etc. Particle Size The average diameter of a given powder or grit granule. Pass A single passage of the thermal spray device across the surface of a substrate. Plasma Spraying A thermal spray process in which the coating material is melted with heat from a plasma torch that generates a nontransferred arc; molten powder coating materials are propelled against the base metal by the hot, ionized gas issuing from the torch.

98 Polyurethant Coating vehicles containing a polyisocyanate monomer reacted in such a manner as to yield polymers containing a ratio, proportion, or combination of urethane linkages; active isocyanate groups; or polyisocyanate monomer. Porosity Small voids, such as in concrete, that allow fluids to penetrate an otherwise impervious material; The ratio is usually expressed as a percentage of the volume of voids in a material to the total volume of the material including the voids. Profile Surface contour of a blast-cleaned or substrate surface viewed from the edge. Psychrometer A test instrument that is used to determine humidity and dew point. Quality Control The system whereby a manufacturer ensures that materials, methods, workmanship, and the final product meet the requirements of a given standard. Replica Tape A specially constructed tape used to measure surface profile. The tape is pressed against the surface, after which the impression created by the profile is measured with a micrometer. Residual Stress Stresses remaining in a structure or member as a result of thermal or mechanical treatment, or both. Resin General term applied to a wide variety of more or less transparent and fusible products, natural or synthetic. Any polymer that is a basic material for coatings and plastics. Rural Environment An atmospheric exposure that is virtually unpolluted by smoke and sulfur gases and that is sufficiently inland to be unaffected by salt contamination or the high humidity of coastal areas. Corrosion depends on temperature, humidity, and moisture retention. Rust The reddish, brittle coating formed on iron or ferrous metals resulting from exposure to a humid atmosphere or chemical attack. Sacrificial Protection The use of a metallic coating to protect steel. In the presence of an electrolyte, such as salt water, a galvanic cell is set up and the metallic coating corrodes instead of the steel. See also Galvanic Protection. Seawater Water having salinity above 17 parts per thousand. Seal Coat Material applied to infiltrate and close the pores of a thermally sprayed deposit.

99 Silicone One of a class of compounds consisting of polymerizable, high- temperature-resistant resins; lubricant greases, and oils; organic solvent-soluble water repellants; surface tension modifiers for organic solvents; etc. Soluble Salt Contaminant Water-soluble inorganic compounds (such as chlorides and sulfates) that contaminate a product. When soluble salts are present on a prepared steel surface, they may cause premature coating failure. Soluble salt contaminants are sometimes referred to as “ionic contaminants” or “invisible contaminants.” Spalling The flaking or separation of a sprayed coating. Spraying Method of application in which the coating material is broken up into a fine mist that is directed onto the surface to be coated. Spray Angle The angle of particle impingement, measured from the surface of the substrate to the axis of the spraying nozzle. Spray Distance The distance maintained between the thermal spraying gun nozzle tip and the surface of the workpiece during spraying. Spray Rate The rate at which surfacing feedstock material passes through the gun. Substrate Basic surface on which a material (e.g., a coating) adheres. Surface Preparation Any method of treating a surface to prepare it for coating. Surface preparation methods include washing with water, detergent solution, or solvent; cleaning using hand or power tools; water washing or jetting without abrasive; or abrasive blast cleaning. Thermally Sprayed The technician or specialist who applies the thermally sprayed Coating Applicator coating. Thermally Sprayed Metal Solid coating materials that are melted (or at least softened) before Coating (TSMC) dispersion (spraying) onto a surface. Thermal Spraying Spraying finely divided particles of powder or droplets of an atomized material for overlay coating of a substrate. Topcoat The last coating material applied in a coating system, specifically formulated for aesthetic and/or environmental resistance. Also referred to as finish coat. Traverse Speed The linear velocity at which the thermal spraying gun traverses across the workpiece during the spraying operation.

100 Undercutting The penetration of a coating and the spread of delamination or corrosion from a break or pinhole in the film or from unprotected edges. Vehicle The liquid portion of paint, in which the pigment is dispersed; it is composed of binder and thinner. Vinyl Coating Coating in which the major portion of binder is from the vinyl resin family. Vinyl resins include polyvinyl acetate, polyvinyl chloride, copolymers of these, the acrylic and methacrylate resins, the polystyrene resins, etc. White Metal Blast Blast cleaning to white metal. This standard is defined in SSPC-SP-5 as a cleaned surface that, when viewed without magnification, shall be free of all visible oil, grease, dirt, dust, mill scale, rust, paint, oxides, corrosion products, and other foreign matter. Wire-Arc Spraying A thermal spray process using an electric arc discharge between two consumable wire electrodes of surfacing material. A jet of compressed gas is used to atomize and propel the surfacing material to the substrate being coated.

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Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide Get This Book
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TRB’s National Cooperative Highway Research Program (NCHRP) Report 528: Thermally Sprayed Metal Coatings to Protect Steel Pilings: Final Report and Guide investigtes thermally sprayed metal coatings (TSMCs) and offers a guide for the application of TSMCs to protect steel pilings from corrosion.

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