Experimental analysis of the fatigue life of threaded pipe connections under cyclic bending

Abstract

When subjected to cyclic loads, fatigue cracks can cause failure of pipe systems joined bythreaded pipe connections. In this study, the effect of contact conditions and coupling geometry isinvestigated experimentally. Fatigue tests under cyclic bending are carried out on three different threadedconnection configurations. The resulting fatigue lives are compared and fracture surfaces are investigated.The fatigue cracks are found to initiate at the last engaged thread of the pin and fatigue life can beincreased by applying PTFE tape or changing the coupling geometry.