Three-dimensional thermomechanical analysis of circumferentially welded thin-walled pipes

Circumferentially welded pipes are frequently used in boiling water reactor piping systems, oil pipe transport systems and steam piping systems. When two pieces of pipe are welded together, residual stresses arise in the Vicinity of the weld owing to the circumferential welding of the pipes. Residual stresses are attributed to the elastoplastic response of the object towards the transient thermal stresses generated by the thermal cycle. They can be a major source of cracking and fracture problems in welded structures. Finite element simulation of the welding process is a highly effective means of predicting thermomechanical behavior. To enhance the accuracy of the numerical solution and bring it close to the real situation, this work presents a three-dimensional finite element model. The three-dimensional temperature and stresses in circumferential single-pass welded pipes are also analyzed using the elastic-plastic three-dimensional finite element method. Exactly how the pipe wall thickness influences the welding residual stresses is also discussed. (C) 1998 Elsevier Science Ltd. All rights reserved.