库尔勒土壤环境中X70管线钢剥离涂层下的腐蚀特征

Corrosion characteristics of X70 pipeline steel under disbonded coatings in Kuerle soil environment

利用矩形剥离缝隙模型研究了库尔勒土壤模拟溶液中X70管线钢剥离涂层下的滞留液化学特征以及X70钢腐蚀特征.随着浸泡时间的延长,缝内滞留液的p H值逐渐下降直至稳定.Cl-在缝内滞留液中有不同程度的聚集,其中在缝隙底部的质量浓度最高.SO2-4的质量浓度在腐蚀初期表现为随距离增加而降低,到腐蚀后期表现为随距离增加而升高.HCO-3和NO-3的质量浓度从漏点至缝底有小幅降低.阳离子的质量浓度变化不明显.缝内X70钢的腐蚀形貌表现为明显的点蚀,且随距漏点距离的增加,点蚀越严重.

The chemical characteristics of trapped liquid and the corrosion features of X70 pipeline steel under a disbonded coating in a simulated solution of Kuerle soil were studied by using the rectangular stripping gap model. With the increasing of test time, the pH value of trapped solution gradually declines and finally reaches a stable level. Cl - has different degrees of gathering and its highest concentration occurs in the end of the gap. The concentration of SO2 -4 decreases at the initial stage but increases at the late stage, the concentrations of HCO -3 and NO -3 decrease slightly from the holiday to the end, and the concentration change of cations is not obvious or only a minor reduction. The corrosion morphology of X70 steel under the disbonded coating performs obvious pitting corrosion, which is much more serious with the increasing of distance from the holiday.