Characterization of microbiological influence corrosion for API 5L X46 pipeline by sulphate-reducing bacteria (SRB)

Abstract

In this study, the microbiological corrosion behavior of API 5L X46 low steel taken from damaged petroleum transporting pipeline used in Babylon-Iraq were investigated. A swab of samples taken from the area of damage was analyzed by polymer chain reaction device to find out the type of corrosive bacteria present, Desulfovibrio sp was found, which is a sulfide reducing bacteria, and this was confirmed by the analysis of corrosive products X-ray diffraction. Two attacking media were used, the first medium (A) representing the surrounding dead water in the pipeline and the second (B) is a “medium bar” in which sulfur-reducing bacteria were cultivated, the specimens were placed in it for 28 days. Simple immersion test was don; the result show that the A medium has higher percentage of weight loss than B medium. Pure elements, compounds and ions were analyzed for the surrounding water. Scan electron microscope and Energy Dispersive Spectroscopy examination of the surface of the specimens was conducted, which gave pictures of the existing bacteria, as the medium (A) only the sulfide bacteria appeared in specimens grown, while the B medium has a completely different surface nature from other media, and this is due to the absence of the role of bacteria in it. X-ray diffraction test showed corrosion products taken from samples of all mediums, different results were shown, the compounds present in the medium (A) was associated with the products containing sulfur in their composition only is (FeS), and the medium (B) showed different compounds from the previous two mediums, the most prominent of which were the compounds (FeNO3), which is a compound that may have its source from the interaction of the surrounding environment with the mineral or through the fact that the area is agricultural and it is used in pest control.