Premature Failure of Submarine Well Fluid Lines: A Case Study

This paper deals with premature failure of two well fluid lines of an offshore asset. The well fluid lines leaked due to internal corrosion. In the internal surface of the failed pipes, longitudinal groove and holes were observed at the 6 o’clock position. The superficial liquid velocity of both the lines was significantly low which resulted in settling, deposition and accumulation of suspended solids, and biomass as a result of proliferation of bacterial colonies. These conditions made the site prone to microbial-induced corrosion and under deposit corrosion. Apart from low velocity, lack of required cleaning pigging, inadequate dosing of corrosion inhibitor and bactericide caused premature failure of the pipes. The details of tests carried out with their results and suitable recommendations have been provided in this paper.