In this paper, a finite element simulation, based on abaqus software is presented for analyzing the temperature history and the residual stress states in multipass welds in stainless steel pipe. The uncoupled thermal–mechanical a three-dimensional (3D) model and a two-dimensional (2D) model are developed. The volumetric heat source with double ellipsoidal distribution for front and rear heat source, proposed by Goldak and Akhlaghi, has also been used. Furthermore, a moving heat source has been modeled by abaqus subroutine DFLUX. A user subroutine FILM has also been used to simulate the combined thermal boundary conditions. The results of both a 3D model and a 2D axisymmetric model which are compared with the available experimental measurements show good agreements. Predictions show that the axial and hoop residual stresses in a 3D model and a 2D axisymmetric model have the same distributions in all locations except the starting point of welding. The effects of welding sequences on the thermal and structural analysis are also investigated. Four types of welding sequences for circular welds of pipe have been used and thermal history and axial and hoop residual stresses are compared. Predictions show that for other locations (except the starting point of welding) there are no important differences of axial and hoop residual stresses for welding sequences and they have the same distribution along axial direction.
