Assessing the integrity of in service polyethylene pipes

The service life of Polyethylene (PE) pipes is influenced by many factors including type of PE resin used, time in service as well as service location. Assessing the integrity of PE pipes which have been in service using standard test methods is complicated by the requirement that samples should be sectioned directly from the used pipe wall. In this current study, a new fatigue test method, termed the Cyclic PENT (CPENT), is described that allows direct testing of unaltered material sectioned from the pipe wall. The CPENT was combined with oxidation induction time measurements to provide information on the relative ranking of pipes which have been in service for a time period of 20-40 years from 3 different service locations. It was found that both service location and in-service time are important factors when assessing the remaining life of PE pipes.