由于储罐接管常年处于腐蚀环境中,容易形成腐蚀缺陷,腐蚀缺陷不易检测,且不断向纵深扩展,导致接管泄漏事故发生,因而具有很大的潜在风险.该文主要采用数值模拟的方法研究了储罐接管表面腐蚀缺陷对接管阴极保护效果的影响.通过测试极化曲线得到模拟所需要的电位和电流密度等边界条件.采用ABAQUSCAE有限元分析软件模拟接管表面不同腐蚀缺陷处的局部电流密度和电位变化情况.结果表明:接管腐蚀缺陷内的阴极保护效果与腐蚀缺陷部位的形状、大小及深度有关.在腐蚀缺陷部位,阴极保护电位和电流密度分布不均匀,使得接管上有腐蚀缺陷的部位不能得到完全有效的保护.阴极保护电流在腐蚀缺陷处被部分屏蔽,尤其是在缺陷底部.随着缺陷深度的增加或宽度的减小,缺陷底部阴极保护电位变正,电流密度增加,缺陷对阴极保护的屏蔽作用增强,使阴极保护效果变差.更负的阴极保护电位有助于提高接管腐蚀缺陷部位的阴极保护效果.试验所得结果可以为储罐接管的阴极保护效果评价提供参考.
Tank connections were constantly exposed to corrosive environments,which can easily lead to the formation of corro-sion defects.Corrosion defects were difficult to detect and continued to expand in depth,resulting in pipe leakage accidents,thus posing significant potential risks.The influence of surface corrosion defects on the cathodic protection effect for tank connections was studied by numerical simulation.The boundary conditions such as potential and current density required for simulation were obtained by measuring the polarization curve.Then,local current density and potential changes at different corrosion defects on the surface of connections were simulated by ABAQUSCAE.The results displayed the impact of cathodic protection inside the corrosion defect was related to the shape,size,and depth of the defect.The uneven distribution of cathodic protection potential and current density made it impossible to provide complete and effective protection for areas with corrosion defects at the connec-tions.The cathodic protection current was partially shielded at the corrosion defect,especially at the bottom of the defect.With the increase of defect depth or the decrease of defect width,the cathodic protection potential at the bottom of the defect became positive,the current density intensified,and the shielding effect of the defect on cathodic protection was enhanced,leading to a poorer cathodic protection result.A more negative cathodic protection potential helped to improve the cathodic protection effect of the corrosion defect area at connections.The results can provide reference for the evaluation of cathodic protection effect of tank connections.