Investigation of Creep Behavior of HDPE Pipe Butt Fusion Welded Joints Using a Stepped Isostress Method

The utilization of high-density polyethylene (HDPE) pipes is prevalent in water transportation due to their exceptional durability, resistance to corrosion, and ease of installation. Traditionally, butt fusion welding has been employed to connect HDPE pipes. In this study, scanning electron microscopy (SEM) was utilized to examine the microstructure of butt fusion welded joints of HDPE pipes, while the stepped isostress method (SSM) was employed to investigate their creep behavior at 100 °C in ambient air. SEM results revealed a significant presence of craze or lamellae in the base material, whereas minimal occurrences of craze or lamellae were observed in the melt zone. The results obtained from the SSM indicated that the creep life of butt fusion welded joints of HDPE pipes was not adversely affected by the welding bead, and their creep life was no less than that of the base material when ductile creep failure occurred.