Effect of sulphate reducing bacteria (SRB) on corrosion of JIS G3101 low carbon steel with grade SS400 on crude oil under aerobic and anaerobic conditions

Microbiological Influenced Corrosion (MIC) is corrosion exacerbated by the activity of microorganisms. One environment that contains microorganisms is crude oil where there is anaerobic bacterium of Sulphate Reducing Bacteria (SRB) [1]. To study the effect of SRB on corrosion, a study was conducted on JIS G3101 low carbon steel with grade SS400 on crude oil under aerobic and anaerobic conditions. In a mixture of 50 mL crude oil and 10 mL SRB (one solution), and 30 mL of crude oil was added 30 mL SRB (other solution) was immersed specimen with the dimension of 20 x 20 x 4 mm. The bacterium used is SRB of Desulvofibrio desulfuricans genus with conditioning time for 60 days. In every 15 days periodically, there was done an observation of the corrosion phenomena occurring on the specimen, the test of corrosion product compounds on the metal surface layer, and the calculation of bacterial counts. The results of this research indicate that the activity of SRB metabolism in crude oil caused damage to the metal shown by the color change on the specimen surface with the occurrence of pitting corrosion. The more SRB is in crude oil, the more bacteria grow on the specimen surface so that the damage on the specimen surface is getting worse. It caused a more and deeper pitting corrosion. In addition, the anaerobic condition exacerbated the corrosion occurred.