arrangements, and valves that will permit the devices to pass. These new “smart pigs” can be used while a pipeline is in operation. They provide highly accurate location and severity information on external or internal corrosion as well as on other damage like dents or gouges. Some devices measure electrical currents traveling in pipelines, thus assessing the status of CP or stray currents from other sources. Magnetic-flux-leakage sensors can also detect coating disbondment.

  • Conducting potential measurements. Corrosion occurring under loose-bonded intact PE or disbonded bonded dielectric coatings can electrically shield active corrosion from testing techniques for surface pipeline potential made along the ground surface. These techniques will locate areas of damaged polyethylene or coating defects where contact with the soil is imminent, but they have small likelihood of detecting corrosion that may be occurring under intact polyethylene or disbonded coatings. As the Colorado Springs, Colorado, initial in-line inspection data indicated, although only 2 percent of the tested sections had major corrosion damage (with 26 to 50 percent remaining wall life), the pipeline was suffering enough corrosion leaks and damage that it could not be counted on to provide reliable service and therefore was replaced.21

  • Use of remote field technology, as described in a 2002 paper by Calgary and Hydroscope.22 This type of technology was evaluated initially under American Water Works Association Research Foundation Project No. 90601 for Nondestructive Testing of Water Mains for Physical Integrity.23 The use of these intelligent in-line inspections (smart pigging) methods, such as employed previously by Colorado Springs and Calgary in their pipeline condition assessments, are a more reliable method of determining actual pipe conditions than are just random digs.24

21

Spickelmire, “Corrosion Control Considerations for Ductile Iron Pipe—A Consultant’s Perspective.”

22

W. Hartman, K. Karlson, and R. Brander, “Waterline Restoration Based on Condition Assessment—A Case Study,” Distribution and Operations Conference, Nashville, Tenn., September 2002.

23

R. Jackson, C. Pitt, and R. Skabo, Nondestructive Testing of Water Mains for Physical Integrity (Denver, Colo.: AWWA Research Foundation, 1992).

24

Spickelmire, “Corrosion Control Considerations for Ductile Iron Pipe—A Consultant’s Perspective.”



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