Effect of Misalignment and Weld Induced Residual Stresses on the Local Buckling Response of Pipelines

The aim of the present study is to develop numerical modeling procedures to simulate and study the effect of girth weld induced residual stresses and geometric imperfections on the behavior of conventional carbon steel oil and gas pipelines. The effect of welding residual stresses was obtained through computational simulations of the multipass girth weld process. The numerical procedures were calibrated using available pubic domain data on stainless steel. The methodology for conducting the welding simulation is presented. A parametric analysis was conducted using the finite element methods to evaluate the effects of welding residual stress due to girth welding processes, joint-to-joint misalignment associated with the girth weld, internal pressure, axial force, and diameter to wall thickness ratio on the local buckling response of pipelines. The pipeline moment-curvature response was examined to determine the influence of these parameters. For the parameters investigated, results from this study have demonstrated the significance of residual stress state due to welding processes and girth weld misalignment on the local buckling response of pipelines subjected to monotonic loading with combined stress state.