Analysis of Field Failures Caused by Slow Crack Growth [PE]

Since 1980, samples of field failures in polyethylene pipe for gas distribution have been collected and analyzed at Battelle in a field failure library. The majority of these failures were found to occur from slow crack growth as a result of a secondary load. Most often, the location of these failures were at points of stress concentration at socket or saddle joints in the boundary between the pipe and the fitting, although other failures have been received which occurred due to rock impingement or bending in the absence of any joints, fittings, or obvious stress concentration.
Microscopic features of representative failures will be shown and discussed, including fractures at socket joints, saddle joints, and squeeze-off locations as well as at points of rock impingement and bending.