Comparison Between Stress Rupture Performance and Hot Water Circulation Performance Considering Actual Usage of PE Pipes for Hot Water Application

Abstract

The hydrostatic stress rupture test has conventionally been conducted as a useful method of lifetime evaluation. The hot water circulation test which is reflected to the actual operating condition is also useful method. The correlations and differences between the two tests were examined. Compared with the hydrostatic stress rupture test, it was found that the antioxidant in the resin was eluded into the circulating water and was consumed rapidly in the hot water circulation test. The lifetime of the pipe became shorter in the hot water circulation test. In addition, it was also found that when using the brass fittings, copper ions eluded from the joint accelerated degradation of a resin, a crack initiation at the pipe inner surface and a slow crack growth through the pipe thickness due to the hoop stress.