Finite element simulation of mechanical stress relieving in welded pipe—flange joint

Abstract

The mechanical stress relieving (MSR) treatment is commonly employed as post-weld stress relieving process in pressure vessels. Its application to piping system is rarely reported in the literature. This article presents a three-dimensional finite-element analysis for MSR in welded pipe—flange joint of carbon—manganese steel. Sequentially coupled transient, non-linear thermo-mechanical analysis for single pass gas metal arc welding is first performed to calculate welding residual stresses. Subsequently, separate parametric studies for three different types of MSR loads including internal pressure, external pressure, and axial pull are performed on the pre-stressed model and stress-relieving behaviour is studied. The method of post-weld MSR has found an effective way for mitigation of the residual stresses in the piping systems. It is concluded that both the internal pressure and the axial pull have significant effect on the residual stresses on the inner surface of the joint.