海底管道腐蚀产物对缓蚀剂效率的影响

目的：研究海底管道中的腐蚀产物对缓蚀剂效率的影响，对海底管道运行过程中缓蚀剂的使用提出建议。方法采用高温高压反应釜模拟现场作业条件进行CO2腐蚀实验，采用失重法测定海底管道钢试片的全面腐蚀速率，采用扫描电子显微镜观测试片微观表面形貌，实验评价已发生腐蚀试片和清除腐蚀产物试片的全面腐蚀速率和缓蚀剂效率。结果在经过CO2预腐蚀并覆盖腐蚀产物膜后，高效缓蚀剂H的缓蚀效率为75%，低于直接作用于裸钢时的缓蚀效率90%。清除腐蚀产物后，缓蚀剂H的效率为80%，比未清除前的缓蚀效率有所提高，低于常用的缓蚀剂效率设计值85%，且试片的全面腐蚀速率有所降低。结论在海底管道投产后，应避免初期缓蚀剂加注不当或不足发生的CO2腐蚀，如果通过铁离子含量检测等方法已检测发生比较严重的 CO2腐蚀，应及时采取清管和后续预膜措施，必要时应及时调整缓蚀剂加注剂量或缓蚀剂类型。

Influence of Corrosion Scales on the Corrosion Inhibitor Efficiency in Submarine Pipelines

Objective To study the influence of corrosion scales on the corrosion inhibitor efficiency in submarine pipelines, and to give suggestions for the usage of corrosion inhibitors during the operation of submarine pipelines. Methods With a high-temperature and high-pressure reaction vessel simulating the operation condition on site, the corrosion rates of submarine pipeline steel coupons were measured using weight loss method, and the micro-morphology of the test specimen was observed via scanning electron microscopy. The general corrosion rate and inhibition efficiency on both the eroded specimens and the specimens that were eroded but the corrosion scales were erased, were evaluated according to the test results. Results When the test specimen was pre-eroded by CO2 and covered by corrosion-scales, the inhibition efficiency of the high-efficiency corrosion inhibitor H was 75%, which was lower than its inhibition efficiency on the bare steel, i.e. 90%. After corrosion scales were removed, the inhibition efficiency of inhibitor H was 80%, which was higher than the inhibition efficiency on un-cleaned eroded specimen, but still lower than the inhibition efficiency on the bare steel, and also lower than the common design value of inhibition efficiency, i.e. 85%. After corrosion scales were removed, the general corrosion rate of test specimens decreased. Conclusion After submarine pipelines were applied, the CO2 corrosion caused by the incorrect or insufficient usage of corrosion inhibitors should be avoided. If significant CO2 corrosion was detected by testing iron ion content, the measures of pigging and pre-filming should be taken, and the type and amount of corrosion inhibitors should be adjusted.