Evaluation of stress intensity factors due to welding residual stresses for circumferential cracked pipes

To investigate the applicability of existing methods to estimate stress intensity factors due to welding residual stresses, comparisons with finite element (FE) solutions are made for two types of generic welding residual stress profiles, generated by simulating repair welds. It is found that fitting residual stresses over the crack depth using third-order polynomials gives good estimates of stress intensity factors but fitting over the entire thickness can result in inaccurate estimates even with fourth-order polynomials. Noting that welding residual stresses are often determined from FE analyses, linearization of residual stresses to estimate stress intensity factors is proposed. Comparison with FE solutions shows good agreements.

► Applicability of K estimation methods is investigated for welding residual stresses.
► Two types of generic residual stress profiles with repair welds are considered.
► Fitting residual stresses over the crack depth gives good estimates of K.
► A method to estimate K by linearising residual stress profiles is proposed.