Localised biological corrosion of X52 steel exposed within sea water pipelines

Abstract A study of microbiologically induced corrosion has been conducted on X52 pipeline steel using bioelements which were located in a bioprobe located at the inner surface of a sea water pipeline and exposed for 60 days. Severely attacked surfaces with pits of various diameters and depths and a great deal of metal loss were observed after removing the biofilm that had deposited on the bioelement surfaces. This behaviour was not expected under the normal operating conditions of the pipeline. Pit depths were measured and a depth distribution curve was obtained. Different aerobic or facultative bacteria types were cultured from the biofilm removed from the X52 steel bioelement surface while a negative growth in the anaerobic bacteria culture was observed. The morphological and chemical characteristics of the aerobic bacteria were determined and results based on 16S rRNA gene sequence similarity suggest that these aerobic or facultative bacteria could be a new species in this kind of environment.