Specimen temperature conditioning and drift before an S4 pipe fracture test

Abstract

The resistance of plastic (primarily polyethlene) pipe to rapid axial crack propagation under pressure is specified using the ISO 13477 'S4' (small scale steady state) test method. Pipe performance in this test may be very sensitive to temperature under standard test conditions. There has recently been concern that the temperature conditioning of pipe specimens required by ISO 13477 may not be sufficiently precise. In order to compensate for an over-estimated increase in surface temperature between removal from the conditioning fluid and testing, some laboratories condition specimens well below test temperature. Here, infra-red imaging data are used to calibrate a simple and conservative model for the evolution of surface temperature during this interval. The results broadly support the present specification for testing at 0°C, and provide a more secure basis for conditioning of specimens to be tested at lower temperatures.

Burst Pressures of High-Density Polyethylene Pipes Considering the Notch Effect: Testing and Prediction

“…Microscopic and macroscopic damage are inevitable during the process of manufacture and long-term application, such as defects or notches, medium abrasion, material degradation due to chemical corrosion or exposure to sun UV rays and so on. Some typical failure modes of HDPE pipes include slow crack growth produced by small defects [7,8,9], rapid crack propagation at low temperature due to ductile-fragile transition [10,11], fatigue fracture [12,13,14], burst or buckling due to mechanical loads [ 15]. Therefore, damage and life prediction are key problems for the integrity assessment of HDPE pipes in practical engineering.…”