MBR出水管线腐蚀穿孔失效分析

Failure analysis of MBR effluent pipelines

某公司炼油污水经过MBR膜生物反应器处理后,通过普通碳钢管线输送到下游用户回用。两年后回用管线出现腐蚀穿孔现象,至2011年发现漏点100余处。2012年对一段MBR回用水线进行了测厚,实测172个点,测厚数据显示管线平均腐蚀速率为0.398 mm/a,局部腐蚀速率达到了0.757 mm/a。通过水样分析、垢样分析及扫描电镜(SEM)分析等手段对MBR回用管线腐蚀穿孔原因进行了分析,结果表明MBR出水管线腐蚀穿孔主要是由溶液中的溶解氧和溶解盐引起的。

After treatment in MBR membrane bioreactor, the refinery waste water is delivered to downstream users for reutilization through carbon steel pipelines in SINOPEC Jinling Petrochemical Company. The pipelines failed by corrosion perforation after two years＇ operation, and more than 100 leaking points were found by 2011. The thickness measurements of a MBR effluent reutilization pipe line on 172 points in 2012 showed that the average corrosion rate was 0. 398 mm/a, localized corrosion rate reached 0.757 mm/a. The study of the corrosion leaking causes by water samples analysis, scale analysis, scanning electron microscopy （SEM） analysis has found that the leakage is mainly caused by the dissolved oxygen （DO） and the dissolved salt in the solution.