Abstract

Corrosion defect on pipelines shows a time-dependent growth in service environments. Prediction of corrosion defect growth and failure pressure of corroded pipelines as a function of time has remained a big challenge to industry. In this work, a finite element (FE)-based model was developed to quantify 3-dimensional (3-D) growth of a corrosion defect on an X100 steel pipe and predict the failure pressure as a function of time by considering a mechano-electrochemical (M-E) interaction. Parametric effects, including internal pressure, axial tensile stress and initial defect length, were investigated. Distributions of von Mises stress and anodic current density (i.e., corrosion rate) at the corrosion defect were determined. Results demonstrated that the growth rate of the corrosion defect followed the order of defect depth > defect length > defect width. With increased stresses resulted from internal pressure and axial tensile loading, the maximum defect depth and defect length increased apparently, but the defect width changed slightly. For example, the defect length increased by 11% and 16% after 10 years of service at internal pressures of 18 MPa and 26 MPa, respectively, and the defect depth increased by 27% and 34% correspondingly. However, the corrosion width increase maintained at about 22% when the internal pressure increased from 18 MPa to 26 MPa. As the corrosion defect grew with time, the failure pressure of the pipeline decreased. It is expected that, upon further validation by substantial data from field and the laboratory, the developed model could contribute to improved pipeline integrity management.

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