Numerical Simulation of Multi-pass Discontinuous Welding of T-joint
XUE Xiao-long 1,SANG Zhi-fu 1,ZHU Jia-gui 2 (1 College of Mechanical and Power Engineering, Nanjing University of Technology, Nanjing 210009,China 2 Yangzi Petrochemical Maintenance and Installation Co.,Ltd., Nanjing 210048,China)
In-service welding is an important operation of hot tapping. There is no need to stop transportation. However, the properties of medium such as pressure and temperature etc. will affect the safety of operation. The localized high temperature is the major factor that causes burn-through. In this paper, a technique of discontinuous welding was used for in-service welding. The temperature and stress field were simulated by FEM. It can be concluded that the elevated temperatures could be reduced effectively by discontinuous welding. The values of residual stresses are close to those of continuous welding. However, due to frequent arc starting, the quality is difficult to guarantee.