芳烃装置户外钢结构腐蚀与防护对策

文章通过对中国石化上海石油化工股份有限公司4号芳烃装置户外钢结构腐蚀情况及腐蚀原因进行调研,对钢结构失效的涂层进行了取样分析,分析结果表明,钢结构涂层失效的主要腐蚀原因为在氯化物及硫化物强腐蚀环境下涂层设计选材不合理所致。根据分析结果提出了不同表面处理要求的3套户外钢结构的防腐蚀方案,并对3套防腐蚀方案进行加速腐蚀盐雾试验和SO2腐蚀试验,试验结果显示只要防腐蚀涂层的表面处理质量达到要求,厚度达到250μm以上,并分底、中、面3层进行刷涂,同时严格控制每层刷涂的间隔时间,均能达到良好的防腐蚀效果。根据试验结果确定了两套钢结构防腐蚀措施,并根据现场情况选择了其中一套方案对钢结构进行防腐蚀施工,钢结构涂层至今使用4 a仍完好,涂层使用寿命得到了提高。

Corrosion of Steel Structure of Aromatic Unit and Protection Measures

The coating of outdoor steel structure of No. 4 aromatic unit failed after 2 years＇ operation. The investigation of corrosion and corrosion causes and sampling analysis of failed coating of outdoor steel structure showed that the main corrosion factors of coating failure were chlorides, sulfides and improper selection of coating materials for strongly corrosive services. Three corrosion protection schemes of different surface treatments were proposed for three outdoor steel structures based upon the analysis results. The salt spray tests for accelerated corrosion and SO2 corrosion tests were conducted for three corrosion protection schemes. The results demonstrated that good corrosion protection could be achieved when the surface treatment met the coating requirements, the coating thickness was over 250 ixm, primer, intermediate and surface coatings were applied and the interval between coating applications was strictly controlled. Two corrosion protection measures for steel structures were determined and one of them was applied for the corrosion protection construction. The coating of steel structure is still in good conditions after 4 years＇ operation. The service life of the coating is greatlv extended.