Systematization of Factors Influencing the Rate of Carbon Dioxide Corrosion during the Transportation of Untreated Hydrocarbons through Low-Alloy Steel Pipelines

Improving the reliability of unprocessed hydrocarbon transportation systems remains one of the key challenges in the oil and gas industry, as more than half of pipeline failures are due to CO2 corrosion. The lack of a unified approach to assessing the factors influencing the rate of CO2 corrosion complicates material selection and metal degradation prediction. This study is devoted to the analysis of existing classifications of factors determining the rate of CO2 corrosion in pipelines made of low-alloy steels and to identification the limitations inherent in present-day approaches. Special attention is paid to the comparison of metallurgical characteristics of materials, parameters of the transported medium, and operating conditions, which are interpreted incompletely or fragmentarily in literature. A comprehensive review of domestic and international studies, standards, and corporate methodologies was conducted, and scattered data on chemical, physical, material, and design and operational factors were systematized. Based on this analysis, a classification of factors affecting the rate of CO2 corrosion during the unprocessed hydrocarbon transportation in low-alloy steel pipelines is proposed, being divided into three categories: external, internal, and design and operational ones. This approach allows for consideration of the interrelations between the medium, material, and operating conditions, which was not previously considered in a unified structure. The main results of the study include the formation of a comprehensive system of factors influencing CO2 corrosion rate and the identification of key parameters that must be considered when predicting corrosion rates. The proposed classification provides a basis for developing a methodology for comprehensive assessment of corrosion resistance and environmental aggressiveness, as well as for improving mathematical models for corrosion prediction.