Welding residual stress measurement of an urban buried gas pipeline by X-ray diffraction method

Stress measurement and analysis were performed on the outer wall of an urban buried X65 gas pipeline to obtain the stress distribution law of the pipeline. The welding residual stresses of the axial and girth welds were measured by the X-ray diffraction method and the effect factors of the welding residual stress were analysed theoretically The results show that high welding residual stress generally occurred in the weld zone (weld seam or heat-affected zone). The maximum stress of the pipeline was in the T-shaped weld seam and was up to 250.9 MPa (0.56 sigma(s)). The axial and girth welds differed in their change rules with the welding residual stress. The influence of the extruded deformation was minimal on the pipeline and it was proven that the additional stress caused by the gravity of the suspended non-linear pipeline had a significant impact on the axial and hoop stresses of the pipeline, but this factor was not taken into consideration at the time of stress measurement.