Mitigation of microbial degradation of X80 carbon steel mechanical properties using a green biocide

Abstract

Abstract Most microbiologically influenced corrosion (MIC) studies focus on the threat of pinhole leaks caused by MIC pitting. However, microbes can also lead to structural failures. Tetrakis hydroxymethyl phosphonium sulfate (THPS) biocide mitigated the microbial degradation of mechanical properties of X80 pipeline steel by Desulfovibrio ferrophilus, a very corrosive sulfate reducing bacterium. It was found that 100 ppm (w/w) THPS added to the enriched artificial seawater (EASW) culture medium before incubation resulted in approximately 3-log reduction in sessile cell count after a 7-d incubation at 28oC, leading to 94% weight loss reduction. The X80 dogbone coupon incubated with 100 ppm THPS for 7 d suffered only 3% loss in ultimate tensile strain and 0% loss in ultimate tensile strength compared with the abiotic control in EASW. In comparison, the no-treatment X80 dogbone suffered losses of 13% in ultimate tensile strain and 6% in ultimate tensile stress, demonstrating very good THPS efficacy.