Microbiologically influenced corrosion of X80 pipeline steel by nitrate reducing bacteria in artificial Beijing soil

In this work, we investigated microbiologically influenced corrosion (MIC) of X80 pipeline steel caused by nitrate-reducing bacteria Brevibacterium frigoritolerans (B. frigoritolerans) in an artificial Beijing soil using electrochemical measurements and surface analyses under aerobic conditions. The B. frigoritolerans was isolated from the surrounding soil of the X80 pipeline steel specimen in Beijing using culturing and molecular biology techniques. Confocal laser scanning microscopy images showed that the largest pit depth after 14 days due to B. frigoritolerans was approximately 7.16 μm. Electrochemical tests showed that the B. frigoritolerans could change the stability of the corrosion products on the 7th day. Inhomogeneous biofilm and the conductivity of Fe₂O₃ accelerated the corrosion process. The presence of NH₄ ⁺ on the surface of the X80 pipeline steel revealed that the B. frigoritolerans acted as a biological cathode to promote the cathodic reaction.