3-DIMENSIONAL THERMOMECHANICAL ANALYSIS OF CIRCUMFERENTIALLY WELDED THIN-WALLED PIPES

Circumferentially welded pipes are frequently used in boiling water re actor piping systems, oil pipe transport systems and steam piping syst ems. When two pieces of pipe are welded together, residual stresses ar ise in the Vicinity of the weld owing to the circumferential welding o f the pipes. Residual stresses are attributed to the elastoplastic res ponse of the object towards the transient thermal stresses generated b y the thermal cycle. They can be a major source of cracking and fractu re problems in welded structures. Finite element simulation of the wel ding process is a highly effective means of predicting thermomechanica l behavior. To enhance the accuracy of the numerical solution and brin g it close to the real situation, this work presents a three-dimension al finite element model. The three-dimensional temperature and stresse s in circumferential single-pass welded pipes are also analyzed using the elastic-plastic three-dimensional finite element method. Exactly h ow the pipe wall thickness influences the welding residual stresses is also discussed. (C) 1998 Elsevier Science Ltd. All rights reserved.