Effects of axial misalignment welding defects on the erosive wear of natural gas piping

•A three-dimensional model of natural gas elbow model with wrong-side weld defects was established.•A CFD-based flow characterization for bends containing weld wrong-side defects was analyzed.•The most eroded areas in natural gas bends containing wrong-side welds were determined.•The sensitivity of each factor affecting the erosion effect was analyzed by orthogonal test. When considering solid particles in the pipe and axial misalignment weld defects in natural gas transmission systems, changes in the flow field due to structural differences can lead to various erosion characteristics in the bends. To investigate the erosion process within the bend, the computational fluid dynamics (CFD) - discrete phase model (DPM) method to develop a bend model with axial misalignment weld seam defects was employed. The erosion distributions of a bend with an axial misalignment weld were investigated under various transport parameters, bend orientation, axial misalignment height, and particle incidence angle. The results indicated that the erosion rate of the outermost elbow increases with the increase of the height of the axial misalignment weld on the outside of the bend pipe. When the axial misalignment height ranges from 1 mm to more than 5 mm, the difference in the maximum erosion rate escalates from 7 % to approximately 30 %. When the length of the inlet straight pipe is shorter, an increased incident angle intensifies the erosion effect and vice versa. This research can provide a reference for field construction work involving defective natural gas pipe bends.