Rationale for quantitative measures of corrosion performance and significant parameters at corrosion defects on underground oil pipelines

Corrosion defects are the dominant cause leading to accidental destruction development on underground pipelines. Underground corrosion is one of the most complex corrosion types due to the fact that it is multifactorial and differs in the progressive participation dynamics of each parameter in the metal destruction process. It is necessary to introduce the biocorrosive activity criterion (CBA) as an additional parameter of corrosive factors. We conducted soil corrosiveness assessment adjacent to underground pipelines surface using physicochemical parameters complex and microbiological factors. Studies have shown the presence of soil samples near the pipeline with moderately corrosive bio-corrosive activity, potentially aggressive and slightly corrosive samples. A high level of soil samples detection with moderately aggressive bio-corrosive activity has been established. Sulfate-reducing and thionic bacteria were identified as bacteriological factors with a pronounced ability to cause a biocorrosion process on a metal surface, as well as a mycological micromycetic factor — fungi belonging to the genus Penicillium and Mucor. The conducted studies emphasize the need to apply the CBA evaluation as an additional parameter of the corrosion-significant factors complex in the appointment of repair work on the pipeline.