目的 研究西南地区某输油管道外腐蚀行为。 方法 现场检测,对土壤理化性质及腐蚀产物成分进行室内分析。 结果 开挖点 A 的土壤呈弱碱性,土壤腐蚀性弱,管道发生轻微均匀腐蚀,腐蚀产物主要为 FeO( OH) ,Fe( OH)₃ 和 Fe₃O₄ 等铁的氧化物,对应的阴极反应为吸氧反应;开挖点 B 的土壤酸性强,硫酸根离子浓度高,土壤腐蚀性强,管道发生严重坑蚀,腐蚀产物主要成分为 FeSO₄ ·7 H₂O 及少量碱式硫酸铁,对应的阴极反应以析氢反应为主。 结论 开挖点土壤的理化性质差异,导致管道的腐蚀形态、腐蚀产物和腐蚀机理显著不同。

Objective To investigate the external corrosion for two excavation points of an oil pipeline in southwest China. Methods Through the on-site testing and laboratory analysis on phys-chemical properties of soil and composition of corrosion product. Results The soil is slightly basic for the excavation point A, and its corrosivity is weak, as a result, where the pipeline suffer weakly uniform corrosion, and the corrosion products are mainly iron oxides, including FeO( OH) , Fe( OH)₃ and Fe₃ O₄ , also the cathodic reaction is reduction of dissolved oxygen. While for excavation point B, because of the strong acidity and high content of sulfate ion, the soil is highly corrosive and makes the pipeline suffer serious pitting corrosion, and corrosion products are mainly composed by FeSO₄ ·7H₂ O, also contains a small amount of basic ferric sulfate, moreover the cathodic process is mainly the reduction of hydrogen ions. Conclusion Due to the significant difference of the phys-chemical properties of soil, there are notably different on the corrosion morphology, products and mechanism of pipeline between two excavation points.