轴向应变埋地燃气管道直流杂散电流腐蚀影响规律仿真分析

Analysis of Stray Current and Axial Strain Coupling Corrosion on Municipal Buried Gas Pipeline Based on Numerical Simulation

本文采用数值模拟方法,对直流杂散电流和应力场耦合条件下埋地燃气管道涂层破损处的腐蚀电流密度分布规律进行研究。研究发现,应变水平、杂散电流大小、涂层缺陷大小和土壤电导率对燃气管线涂层破损处局部电流密度分布存在影响。其中,应变水平引起缺陷中心应力集中区发生塑性形变时,缺陷处局部电流密度分布呈现中间高两侧低的不均匀性;缺陷中心处电流密度随杂散电流和土壤电导率变大而增大,随涂层缺陷变大而减小。埋地燃气管道涂层破损处在杂散电流和应力耦合作用下,由于阳极电流密度集中,破损处中心位置极易发生局部腐蚀穿孔。

In this paper,the coupling effect of stray current and axial strain on municipal buried gas pipeline has been investigated through numerical simulation methods.It was found that axial strain size,stray current magnitude,coating defect size and soil conductivity could influence the distribution of local current density on coating defect of gas pipeline.The distribution of local current density at coating defect was uneven because of plastic deformation at defect center caused by axial strain.The local current density increased with the growth of axial strain,stray current and soil conductivity,while decreased with the growth of coating defect size.