Validated numerical analysis of residual stresses in safety relief valve (SRV) nozzle mock-ups: Influence of axial restraint on distortion and residual stress predictions

A simulation of the residual stress and distortion produced during the fabrication of a dissimilar metal weld (DMW) in a safety relief valve (SRV) was performed using an axi-symmetric finite element model. Traditionally, the ends of the axi-symmetric model are allowed to move freely in the axial direction, producing satisfactory predictions of residual stress; this capability has been demonstrated in previous studies [1]. However, the main limitation of the accepted axi-symmetric restraint approximation lies in the assumption of a weld bead being deposited at infinite speed, thus neglecting the constraint provided by previously deposited and already solidified weld metal. The axial constraint method presented in the current work provides a means to overcome this limitation, leading to more accurate predictions of distortion and residual stress without resorting to a computationally expensive 3D analysis.