MICROBIOLOGICALLY INFLUENCED CORROSION ANALYSIS ON CARBON STEEL COUPONS

The paper is focused on investigating the nature of the internal corrosion of a pipeline transporting residual injection water. The study was carried out using removable carbon steel disk coupons, for reproducing the effects of pipeline corrosion. Chemical composition, surface roughness and microstructure of the metal were determined and corresponded to a carbon steel used for pipelines manufacturing. Examination of corrosion morphology on metal surface was performed by analytical techniques, including optical microscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The localized corrosion morphology (terraced pitting) observed on the disk coupons and the presence of bacteria associated with MIC in deposit samples confirmed the internal corrosion of the pipeline as microbiologically influenced corrosion.