Numerical simulation of residual stress in circumferential weld of X80 pipeline

ABAQUS software was used to simulate the circumferential weld welding of X80 natural gas pipeline with a diameter of 1 016 mm in 1-layer-1-pass,4-layers-4-passes and 6-layers-6-passes. When the wall thickness of the pipeline was fixed,the variation trend of axial and circumferential welding residual stress on the inner and outer surfaces of the pipeline was studied with the change of the number of welding layers. Then,the post welding heat treatment of the pipeline was simulated to investigate the variation law of residual stress after heat treatment.The results showed that when the number of welding layers increased,the welding residual stress in the high stress area of circumferential weld section decreased as a whole. The circumferential stress distribution law on the inner and outer surfaces was changing from tensile stress to compressive stress as a whole. Being different from 4-layers and 6-layers welding,the axial stress on the outer surface of 1-layer welding pipe was always compressive stress. After heat treatment,the peak value of axial stress on the outer surface could be significantly reduced by 51. 5%. The peak value of circumferential stress on the inner surface could be significantly reduced by 65. 1%.