Redistribution of welding residual stress following high plastic deformation in seamless pipes

This paper summarises the findings of a Joint Industry Project (JIP) led by DNV GL on the treatment of residual stress on pipes undergoing high plastic deformation. The paper presents measured residual stresses and some of the full-scale test results supported by Finite Element Analysis (FEA) for the seamless pipes before and after high plastic deformation on selected girth welds. Several FEA models of the reeling simulation have been developed including mapping an initial axial residual stress (transverse to the weld) profile onto a seamless girth-welded pipe. The initial welding residual stress distribution used for mapping was based on a number of through thickness measurement along the circumference of the girth welds. The predicted residual stresses after reeling simulation was subsequently compared with experimental measurements. It is evident that FEA models can predict welding residual stress re-distribution during the reeling process, but some differences with measurements are present through the thickness.