Fracture of a saddle fusion (weld) joint in high density polyethylene (HDPE) pipe

This article documents the materials evaluation of a fractured saddle fusion weld joint on high density polyethylene (HDPE) pipe. The fusion joint failed due to inadequate surface preparation or inadvertent contamination of pipe surfaces prior to fusion that led to a joint with incomplete fusion. Failure of a defective fusion joint at the service tee allowed natural gas to leak from the gas main and, in turn, the gas migrated into a building where it ignited. Optical, stereo microscope, and scanning electron microscope (SEM) were used to evaluate the fracture faces. Exemplar fusion joints were manufactured and subjected to drop weight testing. The fracture features from fusion joints subjected to drop weight testing provided invaluable guidance for determining the origin of the fracture and direction of fracture propagation. Fracture features from the fusion joint in HDPE pipe are displayed that are not readily available from open source reports.