Performance of corrosion inhibitors used in underground petroleum product pipeline under microbial influenced corrosion risk

摘要

Injection of corrosion inhibitor is one of the acceptable methods to combat internal corrosion of underground petroleum product pipelines. The most preferred method to assess the efficacy of the pipeline corrosion inhibitors is NACE TM 0172 test guidelines. This method simulates pipeline corrosivity situations in a petroleum product environment with addition of water during the testing using a rotational stirrer. Although, this method predicts corrosivity in short duration, however, it does not address the effects of presence of corrosive microorganisms on the pipeline internal surface. The present study was designed to examine the performance of corrosion inhibitors used in underground petroleum product pipeline under risk to microbiologically influenced corrosion (MIC). In the study, the metallic coupons were exposed to simulated corrosive environment of pipeline under dynamic condition in corrosion wheel test and corrosion rates were measured by gravimetric method with and without inhibitor in presence of MIC causing microbial consortium. It was observed that the corrosion inhibitors used in the study rendered acceptable performance at 4ppm, 6ppm and 8ppm dosage as per NACE TM 0172 and in corrosion wheel test. But in the presence of corrosive microorganisms the corrosion protection efficacy of the corrosion inhibitor was significantly reduced. The finding of the study adds a new dimension for selection of a suitable pipeline corrosion inhibitor.