AWWA JAW51670

Prestressed concrete pressure pipe (CPP) is in widespread use throughout Canada and the United States, with a total of some 19,000 mi (30,000 km) of pipe in use in North America's major water utilities. Many of these lines are more than 50 years old, and half are expected to need repair or replacement over the next 20 years. To selectively maintain these lines and avoid costs from catastrophic pipe failures, utilities needed an inspection technique that was highly sensitive, reliable, effective, and economical. An innovative electromagnetic technique, based on the remote field eddy current (RFEC) inspection technique, has been developed that allows nonintrusive inspection of prestressed CPP. Full-scale testing conducted on embedded cylinder pipes and bar-wrapped pipelines demonstrated the new RFEC technique's sensitivity to both single and multiple breaks in prestressing wire. Includes 6 references, figures.