A fast and simple method for the determination of the residual deformation for a class of welding problems, ring-stiffened pipes, is proposed. The method can predictradial as well as angular distortion of the thin-walled pipe-ring-stiffener/flange assembly. The pipe and stiffener material is elasto-plastic. In particular, the accumulation of deformation in multipass welding is incorporated in the model. Each weld pass is treated separately. This facilitates the assessment of the influence of the sequence in which the weld passes are deposited on the residual deformation state. The method will be included in a conversational knowledge-based “expert” system for the production of a welded ring-stiffened pipe.