Review of the Bureau of Reclamation's Corrosion Prevention Standards for Ductile Iron Pipe (2009)

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5 Evaluation of Other Corrosion Control Alternatives Since it did not appear that ductile iron pipe (DIP) with polyethylene encase- ment (PE) and cathodic protection (CP) would meet the necessary reliability threshold values of the Bureau of Reclamation, the committee considered other corrosion control measures with the goal of determining whether they would do so. The results of this evaluation are summarized in this chapter. BONDED DIELECTRIC COATINGS ON STEEL PIPELINES WITH CATHODIC PROTECTION Although the majority of dielectrically bonded steel pipes with CP are reported not to have a history of leaks, in a few instances corrosion resulted in leaks. This information is summarized below by the four source classifications (U.S. Depart- ment of Transportation [DOT], steel water pipe manufacturers, the Bureau of Reclamation, and others) and in Table 5-1. Department of Transportation As explained earlier in this report, the committee used a large data set published by DOT’s Office of Pipeline Safety (OPS), which categorizes all reported leaks for liquid and gas pipelines regulated under the Pipelines and Hazardous Materials 116 

E va l uat i o n of O t h e r C o r r o s i o n C o n t r o l A lt e r n at i v e s 117 TABLE 5-1  Partial List of Bonded Dielectric Coatings on Steel Water Pipelines Date of Construction Project and/or and Type of Pipe Pipe Route Notes (Any Problems or Corrosion Source Coating Diameter Length Corrosivity Activity Reported) Bureau of 1960s to Varies 320 Varies No external corrosion leaks reported Reclamation present miles through 2008. Technical Memorandum 8140-CC-2004-1a Southwest 1983-1992 Varies; 43 Severely No external corrosion leaks reported Pipeline Project, Tape assume miles corrosive through 2008. N.Dak.; Bureau 24- to below 36-inch 2,000 ohm-cm Mid-Dakota Rural 1996 to 2002 Varies; 25.4 Severely No external corrosion leaks reported Water System, assume miles corrosive through 2008. Miller, S.Dak.; 24-to Bureau 30-inch Mni Wiconi, 1993 to 2007 Varies; 100 Below No external corrosion leaks reported Pierre, S.Dak.; Polyurethane 24- to miles 2,000 through 2008. Bureau 30-inch ohm-cm Lewis and Clark, 2003 to Varies; 78.5 Below No external corrosion leaks reported Sioux Falls, present 24- to miles 2,000 through 2008. South Dakota; 54-inch ohm-cm Bureau East Bay 1920s, 65-inch 90 Varies Leaks. Stopped after adequate Municipal Utility Aqueduct riveted miles cathodic protection (CP) levels were District, Calif. No. 1 steel restored; no external corrosion leaks reported through 2008. Cheyenne, Wyo. 1964, Stage 1 26-inch 40 Portions In 1987, 23 leaks on Stage I Coal tar miles less than pipeline. After joint bonding and enamel 1,000 CP improvements were made and ohm-cm adequate CP levels were restored in 1990, no external corrosion leaks were reported between 1990 and 2008. Shoshone 1988-1990 24- to 50 Portions No external corrosion leaks reported Pipeline, Cody, Tape 36-inch miles less than through 2008. Wyo. 1,000 ohm-cm aBureau of Reclamation, U.S. Department of the Interior, Technical Memorandum 8140-CC-2004-1, “Corrosion Considerations for Buried Metallic Water Pipe,” Washington, D.C., July 2004. 

118 Corrosion Prevention Standards for Ductile Iron Pipe Safety Administration (PHMSA). This data set provides a basis for determin- ing a documented failure rate for steel pipelines with bonded dielectric coatings and CP. Theoretically, with the incorporation of CP on buried metallic pipelines and its ability to mitigate corrosion to acceptable levels, the incidence of corrosion failure should be near zero. In fact, however, the OPS data present a history of external-corrosion-related failures (leaks) on steel pipelines with CP. Although CP is extremely effective in the mitigation of corrosion, it is not perfect. The external corrosion leaks reported by OPS can be categorized as being caused by one or more of the following: • Disbonded coating, • Interference or stray currents, • Improper levels of CP at or near the leak area, and/or • CP system failure. To reduce the number of leaks, the regulations and PHMSA require liquid and gas pipeline operators to implement an Integrity Management Program (IMP), which incorporates a proactive system of evaluation protocols in an attempt to provide corrosion monitoring and assessment methodologies to further reduce the leak rates. At a minimum, for regulatory compliance the following are required: • Bimonthly rectifier and critical bond monitoring and • Annual surveys of the CP levels at test locations. In addition, IMP includes expanded monitoring such as the following: • Detailed, close-interval surveys, • Direct assessment of the pipeline in suspect areas, • Intelligent pigging of pipeline segments, and • Direct current voltage gradient or alternating current voltage gradient. PHMSA has shown that with the incorporation of IMP, many of the pipeline segments experiencing corrosion due to the causes listed above can be located and mitigated before a leak occurs. The overall number of reported leaks has significantly decreased since PHSMA implemented IMP as part of the regulations in 2002. Typically, installation of CP on an existing steel pipeline will reduce the cumu- lative number of leaks as long as the CP system is designed, adjusted, and main-  Pipeline and Hazardous Materials Safety Administration, Code of Federal Regulations, Title 49, Parts 192 and 195. 

E va l uat i o n of O t h e r C o r r o s i o n C o n t r o l A lt e r n at i v e s 119 tained correctly. A classic example of the ability of CP to reduce corrosion leaks is shown for the East Bay Municipal Utility District for its Aqueduct No. 1. This line is a 90-mile, 65-inch (1,650-mm)-diameter riveted steel transmission pipeline installed near Oakland, California, in the early 1920s. Corrosion leaks occurred until the line was put under adequate CP, at which time all leaks stopped. A chart of cumulative leaks versus time for almost 70 years of service clearly shows the benefit of CP in extending the service life of this water transmission pipeline. In the paper containing the chart of leaks versus time, the author discusses the positive experience that Canadian cities have had with hot-spot protection of existing ductile iron and cast iron mains in reducing the number of leaks and presents corresponding cumulative leak charts versus time of CP installation. Similarly, a paper on “Protecting Ductile Iron Water Mains” describes a number of examples of the effectiveness of CP in minimizing corrosion leaks on corroding or new pipelines. Another example of how CP can reduce corrosion is demonstrated by the city of Cheyenne, Wyoming, which had a high-pressure 1964 steel water line in which some sections had inadequate CP levels. That pipeline experienced a high number of leaks (23 in the first half of 1987) due to a localized failure of the CP system caused by highly resistant or broken joint bonds. After the steel pipeline’s electrical continuity was restored by conducting joint bond repairs, the existing CP system was upgraded in 1990, providing enhanced potential levels to the entire pipeline. This 650-psi water pipeline has not had a corrosion leak since then. Steel Water Pipeline Manufacturers Based on information that the committee received from U.S. steel pipe manu- facturers, more than 500 miles of bonded dielectric coated steel pipe are manufac- tured and installed each year for water transmission pipelines. Bureau of Reclamation The Bureau of Reclamation reports that, since the 1960s, approximately 320 miles of bonded dielectric coated steel pipe on Reclamation projects have been designed and installed. The bureau has stated that, to date, it is unaware of any cor-  R.A. Gummow, “Corrosion Control of Iron and Steel Water Piping—A Historical Perspective,” NACE International Northern Area Eastern Conference, Quebec City, Canada, August 26-27, 2007.  B. Rajani and Y. Kleiner, “Protecting Ductile Iron Water Mains: What Protection Method Works Best for What Soil Condition,” Journal of the American Water Works Association 95(11):110-125 (2003).  Bureau of Reclamation, U.S. Department of the Interior, Technical Memorandum 8140-CC-2004- 1, “Corrosion Considerations for Buried Metallic Water Pipe,” Washington, D.C., July 2004. 

120 Corrosion Prevention Standards for Ductile Iron Pipe rosion failures for bonded dielectric coated steel pipeline with CP on Reclamation- designed projects. A partial list of bonded, dielectric coated steel pipeline projects is listed in Table 5-1. BONDED DIELECTRIC-COATED DUCTILE IRON PIPELINES WITH CATHODIC PROTECTION Bonded dielectric coatings for use on DIP have been provided since the mid- 1970s. According to Horton, external coatings for DIP that historically have been used “include, but are not limited to: polyurethane, coal tar epoxy, coal tar enamel, tapewrap, extruded polyethylene, metallic zinc, zinc/epoxy/polyurethane, and fusion bonded epoxy.” Information provided by the Ductile Iron Pipe Research Association (DIPRA) for a 5-year period indicates that less than 1 percent of DIP produced has been provided with bonded, dielectric coatings. Most of the dielectric bonded coatings require some type of surface prepara- tion of the DIP prior to application of the coating; this may include abrasive blast- ing and removal of the epidermal layer or simply cleaning the pipe and applying the coating directly to the epidermal layer, depending on the type of coating. Most bonded dielectric coatings applied in the United States have been added by third- party applicators, although one U.S. DIP manufacturer did apply them for a short period of time. By contrast, international DIP manufacturers primarily apply the bonded dielectric coatings in-house. Bonded dielectric coatings for DIP have not been used widely in the United States for the past 5 or 6 years. New bonded dielectric coated DIP installations have been curtailed because of the refusal by the U.S manufacturers of DIP to provide  D. Lieu and M. Szeliga, “Protecting Underground Assets with State-of-the-Art Corrosion Control,” Materials Performance 41(7):24 (2002); Shiwei Guan, “Corrosion Protection by Coatings for Water and Wastewater Pipelines,” paper presented at Appalachian Underground Corrosion Short Course, Water and Wastewater Program, Morgantown, W.Va., 2001; Rajani and Kleiner, “Protecting Ductile Iron Water Mains”; J.R. Pimentel, “Bonded Thermoplastic Coating for Ductile Iron Pipe,” Materials Performance 40(7):36 (2001); William Spickelmire, “Corrosion Control Considerations for Ductile Iron Pipe—A Consultant’s Perspective,” Materials Performance 41(7):16 (2002); Sasan Hosein, “Duc- tile Iron Pipes—Inorganic Zinc Application Project Review,” Corrpro Companies, Conyers, Ga.  A.M. Horton, “Special Protective Coatings and Linings for Ductile Iron Pipe,” pp. 745-756 in Advances in Underground Pipeline Engineering II, Bellevue, Wash.: American Society of Civil Engi- neers (1995).  Information provided by DIPRA to NACE International TG 14 Committee on Corrosion and Corrosion Control for Buried Cast- and Ductile-Iron Pipe.  CorroNews: A Newsletter of Protective Coating Information from Madison Chemical, Vol. 9 (Sum- mer 1997). 

E va l uat i o n of O t h e r C o r r o s i o n C o n t r o l A lt e r n at i v e s 121 pipe for the application of bonded dielectric coatings. As described earlier in this report, the U.S.-based DIP manufacturers cite problems with surface preparation and coating application as the reasons for not providing bonded dielectric coatings when requested.10 Based on a literature search performed by the committee as well as on dis- cussions with and correspondence from coating manufacturers, applicators, and European DIP manufacturers, it appears that most major coating manufacturers believe that they have developed standard surface preparation and coating applica- tion techniques and specifications for ductile iron or cast iron that allow successful bonded dielectric coating for DIP.11 A number of U.S. applicators indicated that they also believe that they have successfully resolved the technical issues of surface preparation and applying bonded coatings to DIP.12 One polyurethane manufac- turer stated that as far as applying coating to DIP, “for a knowledgeable applicator it is really no more difficult than coating steel.” As to the difficulty in coating of joints, the manufacturer stated that “the coating thickness needs to be decreased in close tolerance areas and there is a very simple method for doing so. This method was developed about 20 years ago and worked well throughout the period that DIP manufacturers were willing to use bonded coatings.”13 As noted earlier in this report, a wider variety of bonded dielectric coatings are still used and being developed on the international DIP market. According to one  Jose Villalobos, “Assessing DIPRA’s New Corrosion Standards,” V&A Newsletter, Infrastructure Protection News (June 2003). 10 DIPRA, “Surface Preparation of Ductile Iron Pipe to Receive Special Coatings,” DIPRA Ductile Iron Pipe News (Fall/Winter 1993); Gregg Horn, “Product Advisory: Tape Coat,” DIPRA Ductile Iron Pipe News (Fall/Winter 1992); Troy Stroud and James Voget, “Corrosion Control Measures for Ductile Iron Pipe,” 46th Annual Appalachian Underground Corrosion Short Course (Morgantown, W.Va.: West Virginia University, 2001). 11 Polyken Pipe Coatings Technical Reports, Technical Review of Bonded Tape Coatings on Ductile Iron Pipe (Gardena, Calif.); Madison Chemical Industries, Inc., Long Form Specification Polyurethane Coatings for the Internal Lining and External Coating of Ductile Iron Pipe and Fittings, Specification No. SP-LF 1997-03, Milton, Ontario, Canada; Berry Plastics Corporation Corrosion Protection Group, Polyken YGIII System for Ductile Iron Pipe Application Specifications, Franklin, Mass.; Tek-Rap Inc., DI-4 Ductile Iron Coating System Specification, Houston, Tex.; Polyken Bonded Tape Coating Proce- dures for Small Diameter Bare Steel or Ductile Pipe (when plant applied application is not possible), Specification 2003, Chase Construction Products Tapecoat/Royston: Evanston, Ill. 12 Don Barder, Liberty Coating Company, LLC, Morrisville, Pa., communication with the commit- tee, 2008; Dick Brunst, Western Pipe Coaters and Engineers, Orem, Utah, communication with the committee, 2008; Delor Baumann, Baumann Coatings, Inc., Bessemer, Ala., communication with the committee, 2008; Ross Mitchell, Madison Chemical Industries, Inc., Milton, Ontario, Canada, communication with the committee, 2008; Jim Havey, Mobile Pipe Wrappers and Coatings, Inc., Adelanto, Calif., communication with the committee, 2008. 13 Mitchell, communication with the committee, September 2008. 

122 Corrosion Prevention Standards for Ductile Iron Pipe coating manufacturer, more than 3,000 miles of the polyurethane-type coatings have been applied to DIP in the Asian market alone.14 For pipe-surface preparation in Europe, the standard as-cast external surface (with or without the zinc or zinc/aluminum) forms the basis for additional top coatings, with the exception of polyurethane, which requires an abrasive blast. Joints are normally coated with a thin (six-thousandths of an inch) epoxy coating. In more aggressive soils, the joints are protected by epoxy coatings, or by rubber boots, petrolatum tape, or heat shrink sleeves.15 DIP, fittings, accessories, and their joints for water or gas applications are covered in ISO 2531, under Paragraph 4.4,16 “Coatings and Linings for Pipes,” which states: Pipes shall normally be delivered internally and externally coated. External coatings depending on the external conditions and taking into account existing national standards, the following coatings may be supplied: • metallic zinc with finishing layer, in accordance with ISO 8179-1; • zinc rich paint with finishing layer, in accordance with ISO 8179-2; • thicker metallic zinc with finishing layer; • polyethylene sleeving, in accordance with ISO 8180; • polyurethane; • polyethylene; • fibre cement mortar; • adhesive tapes; • bituminous paint; • epoxy. When ISO standards do not exist, these coatings shall comply with national standards, or with an agreed technical specification. Within Europe there is a general consensus with respect to pipe protection, which is described in British Standard (BS) EN 545,17 the specification for DIP, which states that specific coatings may be used in soil conditions with different ratings. External coatings and standards in the United Kingdom are reported to include extruded polyethylene (BS EN 14628),18 polyurethane (BS EN 15189),19 14 Shiwei Guan, Brederow Shaw, communication and correspondence with the committee, Sep- tember 24, 2008. 15 Trevor Padley, Saint Gobain Pipelines plc, Derbyshire, England, communication with the com- mittee, 2008. 16 International Organization for Standardization, “Ductile Iron Pipes, Fittings, Accessories and Their Joints for Water or Gas Applications” (2004). 17 British Standards Institute, BS EN 545, “Ductile Iron Pipes, Fittings, Accessories and Their Joints for Water Pipelines. Requirements and Test Methods” (2006). 18 British Standards Institute, BS EN 14628, “Ductile Iron Pipes, Fittings and Accessories. External Polyethylene Coating for Pipes. Requirements and Test Methods” (2005). 19 British Standards Institute, BS EN 15189 “Ductile Iron Pipes, Fittings and Accessories. External Polyurethane Coating for Pipes. Requirements and Test Methods” (2006). 

E va l uat i o n of O t h e r C o r r o s i o n C o n t r o l A lt e r n at i v e s 123 and fiber cement coating (BS EN 15542)20 or adhesive tapes. Pipes with these more robust types of external coatings (extruded polyethylene, polyurethane, fiber cement or adhesive tapes) are allowed to be buried in soils of all levels of corrosivity according to the BS EN 545 standards. According to a DIP manufacturer in England, the standard approach is to coat DIP with a zinc or zinc/aluminum plus epoxy or bitumen top coats.21 In more aggressive soils, options include (1) the zinc coating with an epoxy or bitumen-type finish coat augmented with PE or tape or (2) the zinc/aluminum coating with an epoxy top coat. PE is only used for larger-diameter DIP (>800 diameter nominal). The zinc/aluminum epoxy option is now being recommended more and more by the pipe manufacturers for these types of applications, except for larger-diameter pipe. For highly aggressive soils, pipes are protected with thick, adherent barrier coatings, such as extruded polyethylene, polyurethane, or fiber cement, mortar. Another approximately 3 to 5 percent of the DIP produced annually is coated with either extruded polyethylene or polyurethane-type bonded dielectric coatings.22 Fiber cement mortar is reported to be used mainly in Germany where the soil is extremely rocky or for directional drill and direct-pipe-insertion-type instal- lations. The other countries in Europe have reportedly used bonded dielectric polymeric-barrier-type coatings since the 1980s.23 Zinc coatings have been used in France since the early 1950s. Although the majority of North American DIP is covered with PE, there are examples of bonded, dielectric coated ductile iron pipelines with CP. The com- mittee collected information on more than 225 bonded dielectric coated DIP projects from tape and coating manufacturers, applicators, owners, and corrosion and engineering firms, and obtained information on DIP lines with different types of coatings, some of which are exemplified in the subsections that follow.24 The projects described are primarily projects for which contact information was known and the corrosion performance of the coated DIP with CP could be confirmed. Various North American projects are summarized in Table 5-2. 20 British Standards Institute, BS EN 15542, “Ductile Iron Pipes, Fittings and Accessories. External Cement Mortar Coating for Pipes. Requirements and Test Methods” (2008). 21 Padley, communication with the committee, 2008. 22 Padley, communication with the committee, 2008. 23 Padley, communication with the committee, 2008. 24 Rod Jackson and Jerry Duppong, CH2M Hill, communication with the committee, 2008; Bob Hayes and Galloway, communication with the committee, 2008; Ross Mitchell, communication with the committee, 2008; Tek Rap, Inc., fax to customers on D.I. Cold Applied System List, November 1998; Corrpro fax to customers on List of Ductile Iron Pipe with Bonded Coatings, June 1998; Scott Smith, CANUSA, communication with the committee, September 2008; Richard Newell, Washington Suburban Sanitary Commission, communication with the committee, 2008; Jeff Mattson, Corrosion Control Technologies, communication with the committee, 2008; Les Nelson, Seattle Public Utilities, communication with the committee, 2008. 

124 Corrosion Prevention Standards for Ductile Iron Pipe Reclamation’s records indicate that it has been specifying dielectric bonded coatings for iron pipe since 1954.25 The bureau has used dielectric bonded, tape- coated DIP on the Mni Wiconi Regional Water System Water Treatment Plant (Pierre, South Dakota) since the mid-1990s. Polyurethane coated, 6-inch fire hydrant DIP stubs were also provided until 2003-2004 when the U.S. DIP manu- facturers’ moratorium on the use of bonded dielectric coating was instituted. A review of the data that the committee was able to gather indicates that even for a partial list there is actually more bonded dielectric coated DIP with CP in North America (877 miles) than there is DIP with PE and CP (369 miles). In 1999, there were no reported failures or leaks on 860.4 miles of coated DIP. Of the 860.4 miles of coated DIP, the committee confirmed that 525.9 miles had experienced no failures or leaks up to the writing of this report. For the remaining 334.5 miles, the com- mittee was not able to obtain updated information. It should also be noted that the coated pipe in Canada was 33 years old, almost 10 years older than the previously referenced DIP with PE and CP projects in North and South Dakota. This partial list of projects with coated DIP does not include the bonded, dielectric coated pipe used internationally, which may amount to thousands of additional miles. Calgary, Alberta, Canada The city of Calgary was facing an alarming increase in the number of corro- sion leaks on its bare and polyethylene-encased iron pipelines in the 1970s.26 The city started an aggressive campaign of pipe replacement and the use of a bonded d ­ ielectric coating on its DIP, working with a local coating applicator to develop a process to apply an extruded polyethylene coating (yellow jacket) on its DIP. In the early 1970s Calgary experimented with several different types of DIP external coat- ings, including taped urethane, yellow-jacket urethane, and yellow-jacket extruded polyethylene. In 1975, the city started to aggressively coat its DIP with extruded polyethylene. In a paper in 2001, it was reported that the largest portion of Calgary’s DIP (373 miles [600 km]) was coated with yellow jacket. The city stated that its y ­ ellow-jacketed ductile iron (YDI) “is especially well protected against corrosion, both with coating and cathodic protection.” The city went on to note that it still uses YDI where DIP is used and that it had no corrosion problems with its YDI pipe. The city verified in 2008 that it has had no corrosion leaks in its coated DIP and was beginning a program to replace the CP galvanic anodes on the YDI pipelines.27 25 Technical Memorandum 8140-CC-2004-1, “Corrosion Considerations for Buried Metallic Water Pipe.” 26 Roy Brander, “Water Pipe Materials in Calgary, 1970-2000,” 2001 Infrastructure Conference, Orlando, Fla. 27 Jim Buker, The City of Calgary Project, communication with the committee, 2008. 

E va l uat i o n of O t h e r C o r r o s i o n C o n t r o l A lt e r n at i v e s 125 TABLE 5-2  Partial List of Bonded Dielectric Coated Ductile Iron Pipelines Project and/or Date of Construction Pipe Route Known Source and Type of Coating Pipe Diameter Length Corrosivity Failures Mni Wiconi, Tape on water treatment Varies Est. less Less than No external Pierre, S.Dak.; plant piping and than 1 2,000 corrosion Bureau polyurethane coating on mile ohm-cm leaks reported 6-inch fire hydrant stubs through 2008. Calgary, Alberta, Begun in 1975; extruded Varies 373 Very No external Canada polyethylene miles corrosive, corrosion (600 typically leaks reported km) previous leak through 2008. locations Washington Begun in 1982; coal tar Varies; 6- to 27 miles Varies, very No external Suburban Sanitary epoxy and tape; would 60-inch corrosive corrosion Commission, like to use extruded and/or stray leaks reported Washington, D.C. polyurethane current through 2008. locations City of Tape and extruded 8- to 12-inch 18 miles Unknown No reported Philadelphia polyurethane failures based on Corrpro fax in 1999.a Philadelphia Varies 8- to 10-inch 1.5 miles Unknown No reported Suburban Water failures based Company on Corrpro fax in 1999.a Russell Corrosion, Late 1970s, small- 6- to 48-inch Est. 30 Varies; very No external various locations diameter, and 1990s, miles corrosive corrosion larger-diameter; fusion leaks reported bonded epoxy, liquid through 2008. epoxy, tape, extruded polyethylene Seattle, Wash. Varies; tape and Varies 31 miles Varies, very No external thermoplastic corrosive corrosion leaks reported through 2008. Price, Utah 2003; tape with taped 24-inch 11 miles Very No external joints corrosive corrosion leaks reported through 2008. San Diego, Calif. 1995; polyurethane and Varies, 10- to 50 miles Very No external coal tar epoxyb 36-inch, some corrosive corrosion high-pressure leaks reported (450 psi) through 2008. sewage lines continues 

126 Corrosion Prevention Standards for Ductile Iron Pipe TABLE 5-2  Continued Project and/or Date of Construction Pipe Route Known Source and Type of Coating Pipe Diameter Length Corrosivity Failures San Jose, Calif. Varies;c tape 315 Unknown No external miles corrosion leaks reported through 1999. Santa Rosa, Calif. Unknown 24-inch water 15.5 500 ohm-cm Unknown reuse pipeline miles with high chlorides City of Renton, 1994; tape coating, wax 8- to 16- 0.4 mile Stray current No external Wash. tape joints and galvanic inch water corrosion anodes transmission leaks reported main through 2008. Puget Sound, 1994; 100% solid 14-inch water 0.5 mile <10,000 No external Wash. Private polyurethane and transmission with pockets corrosion manufacturing galvanic anodes main of lower- leaks reported facility resistivity through 2008. soils Puget Sound ca. 1983; coal tar epoxy 18-inch 0.23 <1,000 Unknown Municipality, and galvanic anodes underwater mile (crossing Wash. wastewater under force mains saltwater inlet) Puget Sound ca. 1983; coal tar epoxy 8- to 12-inch Est. 1 <1,000 Unknown Municipality, and galvanic anodes wastewater mile plus (saltwater Wash. force mains beach) City of Vancouver, ca. 1986; galvanic 10-inch to Unknown <1,000 (wet/ Unknown B.C., Canada anodes 12-inch water heavy clays) distribution mains City of Aurora, Estimated 15 to 20 16-inch 2 miles Corrosive No external Colo. years; tape coated water supply corrosion to military leaks reported facility through 2008. aCorrprofax on List of Ductile Iron Pipe with Bonded Coatings, June 1998. bApproximately46 miles polyurethane and 4 miles coal tar epoxy. cWere doing approximately 15 miles a year in 1999. Washington Suburban Sanitary Commission, Washington, D.C. In discussions with the committee, corrosion control experts within the Wash- ington Suburban Sanitary Commission (WSSC) in Washington, D.C., indicated that the WSSC had historically used coal tar epoxy and tape coating systems. In its decision tree with respect to installing bare DIP, DIP with PE, or coated DIP 

E va l uat i o n of O t h e r C o r r o s i o n C o n t r o l A lt e r n at i v e s 127 for larger-diameter pipelines, the WSSC employs a risk assessment procedure that evaluates soil corrosivity, size of pipe, and presence of groundwater or interfer- ence. The WSSC claims that it was able to obtain holiday-free coating applications by doing two or more coats of the epoxy coating or by using the multilayer tape systems. The commission completed more than 50 projects from 1987 to 2002, at which time U.S. DIP manufacturers ceased applying bonded dielectric coating to its product. Since the corrosion control project managers at WSSC at present cannot obtain DIP with bonded dielectric coating, they have installed several thousand feet of bare DIP with CP; they do not use DIP with PE and CP for fear of electri- cal shielding.28 San Diego, California Based on its historical problems with pipelines with PE, the city of San Diego now requires bonded dielectric coatings (polyurethane) and CP on its DIP lines.29 The city also reported good success with the use of petrolatum wax tape for wrap- ping valves and fittings since beginning its use in 1989.30 San Diego reports that it has had good success with bonded dielectric coatings on pipelines and has done a number of bonded dielectric coatings on DIP with polyurethane and on one pipeline with coal tar epoxy. San Diego continues to coat DIP with fusion-bonded epoxy coatings and linings for pump stations and small piping.31 San Diego’s pres- ent corrosion consultant stated that the city’s high-pressure (above 400 psi) poly- urethane-coated ductile iron force main, which is both buried in highly corrosive soils and exposed above grade on a bridge, demonstrates that one can successfully coat and line DIP.32 Price, Utah An example of a tape-coated DIP project is the 11-mile, 24-inch pipeline for Price, Utah, that was completed in 2003. Adhesion pull tests were completed on the tape-coated DIP throughout the project and were well above the acceptable range. The pipeline joints were coated with a field-applied joint wrap tape that conformed 28 Richard Newell and Mike Woodcock, Washington Suburban Sanitary Commission, communica- tion with the committee, 2008. 29 Martin Fogata, City of San Diego Water Department, communication with the committee, 2008. 30 Fogata, communication with the committee, 2008. 31 Ernesto Fernandez, City of San Diego Water Department, communication with the committee, 2008. 32 Jose Villalobos, V&A Consulting Engineers, communication with the committee, 2008. 

128 Corrosion Prevention Standards for Ductile Iron Pipe to the changing size of the ductile iron bell.33 The tape applicator reported that the DIP tape coating project was very successful, with just a few problems with overblasting (slivers, scars, pockets, and so on), even with the DIP in the abrasive blaster for up to 5 minutes in order to obtain a near-white blast on the DIP. The tape applicator also added that there had been few problems with tape coating of the bells and that the adhesion values were very good on the entire project.34 The corrosion engineer confirmed that they were pleased, that there was little problem with the coated DIP, and that a second phase with coated DIP had been planned, but the DIP manufacturers would not provide pipe to be coated so the second phase of the project used plastic pipe instead.35 Cairo, Egypt Another approach to applying a dielectric bonded coating to DIP is to tape coat the pipe without abrasive blasting of the DIP surfaces. On a large-diameter DIP pipeline installed in Cairo, Egypt, the U.S.-made DIP was primed with the standard asphaltic primer before being shipped. When it arrived in Egypt, the DIP was cleaned and refreshed with a tape primer that was compatible with the DIP plant-applied asphaltic primer to provide a 100 percent primed surface. The pipe was then inserted in a rack- or lathe-type system that spun the pipe, and the three-coat tape system was applied with tensioned tape spindles. The tape-coated DIP was holiday tested and installed with copper strap bonds, and the joints were provided with mastic filler and a hot-melt adhesive, heat-shrink sleeve. The techni- cal representative of this tape-coating process stated that there had been minimal- to-no problems with the tape application and that there were good bonds to the pipe and bell. He also stated that joint coating with the mastic bar and the hot-melt adhesive, heat-shrink sleeve performed well, with no voids or problems observed at the joints.36 The corrosion engineer and tape manufacturer also reported that the DIP tape-coating project went very well.37 Seattle, Washington Since the early 1980s, Seattle, Washington, has required bonded dielectric coat- ings on DIP in soils below 2,500 ohm-cm; in less-corrosive soils, DIP with PE is 33 Berry Plastics, “Job Site Report Polyken Tape 24″ Ductile Iron Transmission–Main” (Norwood, Mass.: Tyco Adhesives). 34 Dick Brunst, Western Pipe Coaters, communication with the committee, 2008. 35 Jeff Mattson, Corrosion Control Technologies, communication with the committee, 2008. 36 Don Hoff, John Hoff Co., Inc., communication with the committee, September 2008. 37 Rod Jackson, CH2M Hill, communication with the committee, 2008; Tek-Rap Inc., Houston, Tex., previous communication and correspondence with committee member. 

E va l uat i o n of O t h e r C o r r o s i o n C o n t r o l A lt e r n at i v e s 129 allowed. The city estimated that it has more tape-coated DIP (26.5 miles) than DIP with PE (14.9 miles).38 Because of some problems with tape coatings on uneven appurtenances at valve bodies, tees, bends and joints, damage due to soil stresses, and the fact that the tape will degrade over time if exposed to sunlight, the city investigated and tried a thermoplastic coating39 that had been used with positive results internationally. In 1998, the city engineers visited the water utility in Gothenburg, Sweden, to evaluate that city’s 15 years of experience with the thermoplastic-type coating and excavated and examined a section of DIP that had been buried for 12 years. Based on this evaluation and on the advantages of this type of coating with good adhesion, good impact and ultraviolet resistance, ease of repair, and the ability to coat the entire pipe and appurtenances including the bell-and-spigot-type joints, Seattle elected to try this coating on DIP. The city first conducted testing of the coating on four small projects (1,500 feet or less) to make sure that there were no unforeseen problems in the use of this type of coating in the United States. Based on the success of this trial project, the city added the thermoplastic-type coating to the types of coating options that it would consider, and used it on a 4.5-mile project in the late 1990s in the Port of Seattle area. The city reports that it experi- enced minor to little difficulty in surface preparation and application of the ther- moplastic coating and was very satisfied with the installation of the coated DIP. Because of the advantages of thermoplastic coating—including but not limited to the ability to coat the entire bell-and-spigot assembly including the bell face, and the physical properties and characteristics of the coating—it was selected as the standard DIP coating system.40 However, since Seattle can no longer obtain DIP on which to apply this type of dielectric coating and because of its concerns with electrical shielding with PE, it has installed approximately 40,000 feet of bare DIP with CP. The city is still investigating other types of coatings that may be applied over unblasted ductile iron.41 OTHER CORROSION MITIGATION METHODS The committee considered other corrosion mitigation methods that might have potential for providing the needed level of reliability for DIP (some of these are discussed in greater detail in Appendix D). The simple system of protecting bare DIP with CP alone has the advantage of likely providing a very high level of 38 Les Nelson, Seattle Public Utilities, Seattle, Wash., communication with the committee, September 2008. 39 Pimentel, “Bonded Thermoplastic Coating for Ductile Iron Pipe.” 40 Pimentel, “Bonded Thermoplastic Coating for Ductile Iron Pipe.” 41 Nelson, communication with the committee. 

130 Corrosion Prevention Standards for Ductile Iron Pipe corrosion protection without the concerns of shielding, provided the CP system remains reliable. That method is frequently not practical because of the high level of CP current required, particularly in highly corrosive soils, and may be best suited for short lengths of pipe. It may be possible to improve on this method by using controlled low strength material (CLSM) bedding and backfill, although some concerns have been reported on its use in areas where the ground freezes.42 The use of CLSM will likely reduce the currents needed, but this is a very untested method and cannot be endorsed by the committee as a reliable method. However, it is deserving of additional study and evaluation. The use of perforated PE is one of the current research directions of which the committee is aware. In this case, the polyethylene is intentionally perforated on a grid that has the potential to minimize shielding of the CP currents. Like the PE currently being used, this method has the potential of being easy and inexpensive to install, but there is insufficient information available about the needed current levels and the degree of corrosion protection provided to endorse it at this time. In principle, PE or perforated PE could be used in conjunction with CLSM bed- ding and backfill for additional protection, but again, these methods are only in the conceptual stage. The committee believes that these methods are worthy of additional study. Galvanized zinc coatings with various top coats have been used for DIP in Europe. There are ISO (International Organization for Standardization) standards for both metal coatings and high-zinc-content paint coatings, but the committee is not aware of how reliable these may be for the applications at hand. Based on their long-term use and acceptance in Europe, however, these coatings may show some promise that should be investigated further. Finally, the committee considered the possibility of manufacturing DIP with excess wall thickness to extend the time to failure from external corrosion. The committee decided that this is not a viable solution because it would impose costs with no real assurance of protection—corrosion could still lead to local failure despite the higher wall thickness. Some of these options are discussed in more detail in Appendix D. 42 K. Sepehr and L.E. Goodrich, “Frost Protection of Buried PVC Water Mains in Western Canada,” Canadian Geotechnical Journal 31:491-501 (1994).