天然气管道在役焊接熔池流动行为及成形研究

Study on Flow Behavior and Forming of Welding Molten Pool of Natural Gas Pipeline In Service

为解决天然气管道在役焊接安全性评价中焊缝几何形状不易控制的问题,探明工艺参数对焊缝参数的影响规律,基于Fluent软件建立了天然气管道在役焊接过程中焊缝熔滴下落、与熔池混合、焊缝温度场-流场动态演变过程的三维动态模型,分析了焊接电流、管壁散热系数对熔池温度场、流场及焊缝几何参数的影响。结果表明,随着焊接电流的增加,焊缝宽度、熔池深度逐渐增加,焊缝高度逐渐降低;与焊接电流110A相比,焊接电流为170A时焊缝宽度、熔池深度分别增加了4.92%和28.39%,焊缝高度降低了16.77%;而随着散热系数的增加,焊缝宽度、熔池深度逐渐减小,焊缝高度逐渐增加;与散热系数620W/(m^(2)·℃)相比,散热系数为2320W/(m^(2)·℃)时焊缝宽度、熔池深度分别降低了3.39%和9.28%,焊缝高度则增加了5.27%;散热系数对焊缝参数的影响程度由大到小依次是熔池深度、焊缝高度、焊缝宽度。研究结果可为在役管道现场焊接应用提供理论参考。

In order to solve the problem that the weld geometry is not easy to obtain in the in service welding safety evaluation of natural gas pipeline,and to find out the law of the influence of process parameters on weld parameters,a three-dimensional dynamic model was established based on Fluent software for the dynamic evolution process of the temperature field and flow field of the weld drop,mixing with the weld pool and forming the weld.The influences of welding current and heat dissipation coefficient on temperature field,flow field and weld geometry parameters were analyzed.The results show that with the increase of welding current,the width of weld and the depth of molten pool increase gradually,and the height of weld decreases gradually.Compared with 110 A,the weld width and pool depth increased by 4.92%and 28.39%respectively when the welding current is 170 A,and the weld height decreases by 16.77%.With the increase of heat dissipation coefficient,the width of weld and the depth of weld pool gradually decrease,and the height of weld gradually increases.Compared with 620 W/(m^(2)·℃),when the heat dissipation coefficient is 2320 W/(m^(2)·℃),the weld width and pool depth are reduced by 3.39%and 9.28%respectively,and the weld height is increased by 5.27%.The influence degree of heat dissipation coefficient on weld parameters in descending order is the depth of weld pool,the height of weld seam and the width of weld seam.The research results can provide theoretical reference for the application of in service pipeline welding process engineering.