Microbiologically Influenced Corrosion (MIC) may be a factor in 15–30% of failures due to corrosion in all industries. Chemical treatments for mitigating and controlling MIC processes represent significant cost and environmental liability. Because regulatory pressure on the use of toxic biocides is increasing, more environmentally acceptable control measures must be developed, To that end, laboratory experimental test-loops (TLs) were used to test more environmentally acceptable treatment chemicals. Produced waters from natural gas production and storage fields were recirculated through TLs under anaerobic conditions. Carbon steel coupons exposed to TL fluids were quickly colonized by microorganisms. Coupons continuously exposed to a quaternary amine (QA) in TL fluids had very low surface colonization and lower corrosion rates than did control coupons. The biocidal effect of QA in TL fluids appeared to be minimal. Coupons dipped in QA solutions and then exposed to control TL fluids also showed lower colonization and corrosion rates than did control coupons. These results suggest that QA may prevent MIC by mechanisms other than killing bacteria and that treatments preventing surface colonization may persist longer than most biocides.
Keywords: microbiologically influenced corrosion, MIC, inhibitors, biocides, pitting.