文中采用MSC·Marc软件对天然气管道在役修补焊接过程进行数值模拟. 采用的焊接方式为钨极惰性气体保护焊. 焊接过程中熔池底部未熔化材料受高温后强度降低，管道内部的压力易导致其失效. 温度场分析结果表明，当焊接电流为220 A时，管道内壁温度峰值为1 131 ℃，低于管道材料的熔点，该温度下材料的屈服强度远高于管道内压. 当焊接电流介于240~260 A范围时，容易发生焊透缺陷. 盖板周围为封闭环焊缝，其应力场相比于直焊缝较复杂，模拟结果显示其等效残余应力分布不对称，在焊缝的收弧区域出现峰值，220 A焊接电流下为212.3 MPa. 盖板沿着管道径向方向发生收缩变形，最大变形量为1.79 mm.
During the in-service welding of natural gas pipeline, large depth of molten pool can result into low strength of the un-melted material at the bottom of the molten pool. The pipeline will fail if it cannot bear the inner gas pressure. To avoid this, this work used MSC·Marc software to simulate the in-service welding of natural gas pipeline. Tungsten Inert Gas (TIG) Welding was employed. The simulation result of the temperature field showed that the peak temperature of the inner wall of the pipe was 1 131℃ under a welding current of 220 A and did not exceed the melting point of the pipe material. Under this temperature, the yield strength of the material was 19 MPa, which was higher than the gas pressure inside the pipe. Burnthrough easily appeared when the welding currents ranged from 240-260 A. The surrounding of the cover plate was a closed ring weld. The stress field was more complicated than that of the straight weld. The results showed that the residual stress distribution was asymmetrical and its peak value was 212.3 MPa under the welding current of 220 A. The maximum deformation of the cover was 1.79 mm.
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