This thesis deals with the pursuit of simple and efficient models for the prediction of welding residual deformation and stress, in particular ways to reduce the computational effort spent on the analysis. In the first part of the thesis, finite element models which reduce the number of degrees of freedom and thereby the execution time are presented. Using the model developed, a more complicated constitutive behaviour of the material can be described. A simplified method for the determination of deformation due to the welding of a flange onto a pipe is developed. The method is intended to aid the designer when designing such weld joints, by providing estimates of the radial displacement and twisting angle of the flange caused by each weldpass, thus the influence of the welding sequence on the residual deformation state can be judged. This method is then further refined.