某石化公司在2011年装置检修中发现常减压蒸馏装置7台换热器管箱内壁存在不同程度的腐蚀。经检测分析腐蚀原因有两种: 常顶油气在管箱入口法兰附近冷凝成H2S+HCl+H2O腐蚀环境而造成的局部严重腐蚀; 管箱与法兰内壁奥氏体不锈钢覆层对接环缝热影响区合金元素贫化导致的氯化物腐蚀。根据管箱腐蚀的原因, 提出了防护措施, 并进行了针对性的修复与相关检测。

Corrosion was found on the tube-case′s internal-wall of 7 heat exchangers in an atmospheric vacuum distillation unit. Failure analyses show that the corrosion reasons were divided into two types. One is serious localized corrosion on the internal-wall of tube-case′s inlet-flange which resulted from H2S+HCl+H2O corrosive environments condensed by overhead oil vapor. Another is chloride corrosion caused by alloying element depletion in internal stainless steel cladding HAZ of circular seam connecting the tube-case and flange. Corresponding prevention measures are recommended based upon the failure analysis, and related checks have been done.