Deformations and stresses in welded pipes : numerical and experimental investigation

Abstract: In this dissertation, deformations and stresses in welded pipes have been studied both numerically and experimentally. The aim of this work has been to investigate and verify finite element models for simulation of the fabrications of two types of pipe joints. The first joint considered is a butt-welding of thin-walled pipes where residual stresses and deformations were obtained numerically and experimentally verified. The second type of joint which has been investigated twice, is a pipeflange joint, i.e. a flange is attached to one end of a pipe by multi-pass welding. The aim of this study was to predict the distortion of the flange after completed welding. Results obtained from simulations have been compared and verified with corresponding experimental quantities. In the latter part of the pipe-flange joint study, a large amount of work has been devoted to experimental verifications of results obtained during the welding process. Furthermore, an application of additional simulations of single-pass butt-welded pipes has been performed by turning the residual fields of stresses and deformations into a finite element model for buckling analysis, investigating which of the quantities, i.e. residual stresses or residual deformations, have most influence on the reduction of the axial load carrying capacity for welded pipes.