Transverse and Longitudinal Stress Analysis in Reinforced Welded Oil Branched Pipes

Abstract

Welding process results in the non-uniform distribution of heat. Combined with thermal strain, plastic deformation and welding-induced distortion, it causes important problems such as failure. This study models welding process in a 12×16 split tee junction using finite element. This junction is a reinforcing branch used in the hot taping of oil pipe line. The model is studied in 3D state. This zone, i.e. heat affected zone (HAZ) is of high importance due to the existence of a severe temperature gradient and stress in the vicinity of HAZ. This study analyses single pass butt welding with a cooling time of 2700 seconds. In order to apply boundary conditions to the model, the studied structure should be in Free State according to practical procedure. The main aim of this simulation is to analyse Longitudinal and transverse residual stresses originated from co-directional and opposite-directional welding. This joint is formed of two semicircles welded to each other as linear single pass welding. Two welders simultaneously welded both sides of the pipe.