Aging Investigation of Polyethylene-Coated Underground Steel Pipelines

The aging of three-layer polyethylene-coated buried steel pipelines for oil/gas and water transport poses significant challenges for public safety, environmental integrity, and economic sustainability. Over time, these pipelines become increasingly susceptible to corrosion and eventual failures, which can pose environmental hazards, safety risks, and costly repairs. Consequently, predicting the service life of polyethylene-coated steel pipelines is critical for mitigating corrosion risks, extending operational lifespan, and planning effective maintenance strategies. Current international standards lack clear methodologies and criteria for assessing the aging behavior of polyethylene-coated underground pipelines. Current studies have examined two techniques—Line Current Attenuation (LCA) and Drainage Test (DT)—to estimate aging rates in polyolefin-coated pipelines following soil exposure during service. The present study introduces an innovative approach for evaluating aging behavior. It includes a comprehensive analysis using an exponential aging model to estimate the coating’s average specific electrical resistance at any service time, as well as quantitative criteria for the failure of oil/gas and water pipelines. Moreover, it is based on the modified LCA as the most suitable aging methodology with some limitations. Finally, the study concludes with a derived correlation between the coating’s initial specific electrical resistance and its aging rates, and the prediction of the residual life of the polyethylene coating. This integrated framework provides a robust foundation for regulatory bodies, design engineers, maintenance planners, quality assurance/control teams, and researchers to ensure the long-term integrity and sustainability of underground polyethylene-coated steel pipelines.