THE EFFECT OF FeSO4 CONTAINING SOLUTION ON MICROBIOLOGICAL INFLUENCED CORROSION BY DESULFOVIBRIO BACULATUS BACTERIA ON API 5L X65 STEEL

Abstract

Microbiological Influenced Corrosion (MIC) is a common cause of metallic failure and currently known as one of the important case in pipeline failure. Sulfate Reducing Bacteria (SRB) is a bacteria that frequently caused corrosion in steel surface by creating pits. In this research, the corrosion test was done by using one species of SRB which is Desulfovibrio Baculatus. The water that contains bacteria growth medium (API Sulfate Broth) is used as a media for API 5L X65 steel corrosion test. Sulfate for the growing of SRB was added in the solution for 8.56, 17.12, 42.8 and 85.64 ppm, and the immersion test was carried out for 1, 7, 14 and 21 days. The source of sulfate is FeSO₄.7H₂O, and this compound was also considered as a source of Iron (II). The result shows that the weight loss increased at 7 to14 days of immersion time with immersion period as well as the increase of FeSO4 content. But, it decrease after 14 days of immersion that represents a maximum weight loss attained at this moment. Morphologic observation revealed that the corrosion product consists of Iron Oxide and biological deposits that formed at the beginning of corrosion test, and after that, the formation of Iron Sulfide occurred were associated with the increase of corrosion rate. So, the increase of FeSO4 content as the SRB nutrition in the solution, gives a strong influence in the increasing of corrosion rate and formation of an unstable corrosion product.