An extension approach to estimate soil corrosivity for buried pipelines

Underground oil and gas pipelines are usually expected to be long-lasting. Corrosion of these steel pipelines may cause structural failures that significantly threaten life and cause environmental hazards. Therefore, developing a reliable approach to estimate soil corrosivity is important for designing a targeted anti-corrosion structure and performing risk assessment. In this study, an extension-based approach is proposed to evaluate soil corrosivity based on the following seven soil properties: redox potential, soil resistivity, pH, pipe-to-soil potential, water content, Chloride (Cl) concentration, and salt content. Specifically, the soil was classified into five corrosivity levels, and the classic domain element, joint domain element, and element to be evaluated were established by the matter-element theory. Then, the corrosivity level was determined based on the maximum correlation degree of the multi-index to the five levels, and the final classification was obtained from the eigenvalues of the grade variables. Finally, the case study was examined to validate the application of the approach, and the results were compared to the method of buried metal specimens, which was used as a criterion. The present approach, which provided a more detailed classification, was demonstrated to be a superior choice for classifying soil corrosivity levels.