地下管线服役期内发生穿孔失效将会造成严重的安全事故及巨大的经济损失。某厂X60钢管线埋地一年后, 7.1 mm厚的管身出现蚀孔漏气现象。通过现场调研及SEM、XRD取样分析, 研究了管壁穿孔失效的腐蚀机制。结果表明: 蚀孔全部呈直线状分布于管底, 蚀孔附近的腐蚀产物表面含有大量硫、氯元素; EDS及XRD分析确认腐蚀产物为硫铁化合物; 钢管内壁基体侧氧化铁皮中含有大量FeO(OH)腐蚀产物。综合现场腐蚀环境、腐蚀形貌及腐蚀产物的详细分析, 明确了蚀孔产生的原因为硫酸盐还原菌造成的微生物腐蚀, 结合腐蚀特点及现场情况提出了改进措施。

Pitting in the body of underground pipelines and the failure during their service period will result in serious security incidents and huge economic loss. There appeared pitting in the body of X60 pipeline with the thickness of 7.1mm after 13 months of service, which resulted in air leakage. The corrosion mechanism of the pipeline body pitting was researched through site investigation and sample analysis by SEM and XRD. The results showed that all corrosion holes were located in the bottom of the pipeline in a straight line shape, plenty of S and Cl elements were found in the corrosion product around the holes, which was confirmed as FexSy through EDS and XRD analyses. A plenty of FeO(OH)were found in the scales beside the pipeline body. The cause of the corrosion holes was confirmed with the combination analyses of site environment, corrosion morphology and corrosion products to be microbiological corrosion due to SRB. Improvement measures were proposed according to the corrosion characteristic and site condition.