PVC pipes exhibit length shrinkage (~0.7%) under high temperature exposure such as hot water discharge. In contrast, Polyolefin (PO) pipes show higher volume shrinkage (~3%) and may develop inward curvature at pipe ends due to uneven cooling, affecting joint integrity.
Shrinkage can cause spigot retraction in rubber ring sealed sockets, leading to leaks. In PO pipes, inward curvature at pipe ends during electro-fusion jointing may cause melt leakage. ABS pipes, with high Heat Deflection Temperature (HDT), resist these issues better.