Effect of vibratory weld conditioning on the residual stresses and distortion in multipass girth-butt welded pipes

Abstract

For a fully welded body valve, the last procedure is welding, so it is important to control the residual stress and distortion in order to assure spool rotation, valve watertightness, stress corrosion resistance and non-deformability in active service. In this study, the effects of vibratory weld conditioning (VWC) on the residual stress and distortion were studied in multipass girth-butt welded pipes through comparison between VWC and normal submerged arc welding. The results show that VWC can reduce the residual hoop stresses at the outer surface and the radial distortion significantly; but VWC has only a slight effect on the residual axial stresses at the outer surface and axial distortion. Moreover, the residual stresses decrease and are lower than the yield strength using VWC, which decreases the susceptibility of a weld to fatigue damage, stress corrosion cracking and fracture, and improves the safety of welded structures.