油气管道焊接动火作业中杂散电流的防范

Prevention of stray current during welding and hot work operation for oil and gas pipeline

油气管道焊接动火作业产生的电流较大,防护或操作不当极易引发火灾、爆炸事故。建立了油气管道电焊动火中管内杂散电流分布的理论模型,将管道划分为N个单元,利用节点电压法给出关于各节点电压的N阶三对角方程组,利用追赶法求解管/地电压分布和管内杂散电流值,并验证计算结果对所取空间步长的收敛性。利用该模型研究了油气管道电焊动火作业中管内杂散电流的主要影响因素,包括绝缘盲板的安装位置、管/地过渡电阻、焊接主回路接触电阻、管道接地保护的设置以及相连容器的位置等,并基于研究结论提出防范措施,可为油气管道焊接动火作业中杂散电流的防范提供指导。

Large current occurs during the welding and hot work operation for oil and gas pipelines.Improper protection or wrong operation may cause fi re and explosion accidents.The theoretical model was established for stray current distribution of pipeline during welding and hot work operation.The pipeline was meshed to N elements,the N-order tri-diagonal equations for each node was set up by utilizing nodal voltage method,with the catch-up method calculating the pipe-ground voltage distribution and stray current values in pipe.The convergences with respect to different spatial calculating steps were verifi ed.With the model,the main factors affecting the stray current during welding and hot work operation were investigated,including the installation position of insulation blind plate,ground-pipe resistance,contact resistance of main welding circuit,ground protection settings of pipe and locations of connected containers.The corresponding prevention measures were brought to provide an instruction to the prevention of stray current during welding and hot work operation oil and gas pipelines.