Numerical assessment of welding sequences in single-pass pipe welding for minimizing residual stresses

Abstract

This research aims to investigate the impact of different welding sequences in the circumferential direction on the welding process of 304 stainless steel pipes. A fully coupled transient thermo-mechanical simulation technique used to numerically replicate welding behaviour on a single-pass butt-welded cylinder joint with a nominal diameter of 300 mm and a thickness of 8.38 mm. Five distinct welding sequences are considered, and temperature profiles are measured at four circumferential positions. The findings reveal that the residual stresses within and near the weld deposit are indeed influenced by the chosen welding sequence. In case 1, the value of maximum temperature reached 1840 Degree K at point T4, achieving equilibrium between the flux input and heat losses during welding. In case 3, the maximum temperature value (1530 Degree K) is lower than all other cases due to better heat distribution. Respective to the temperature distribution the maximum stress values in case-1 to 5 are 211, 201, 138, 146, and 147 Mpa. Based on a comprehensive analysis of these factors, case 3 emerges as the preferable welding sequences for pipes falling in the NPS 10 to NPS 24 size category.