Finite element modeling of local corrosion accelerated by the mechano-electrochemical coupling effect at defects on pipelines under combined effects of internal pressure and axial applied stress

finite element model was built to assess the combined effects of internal pressure and axial applied stress ( σ_A) on localized stress concentration and electrochemical corrosion at defects on pipelines under the mechano-electrochemical (M-E) interaction. When defect angle α (i.e., included angle between the major axis of the defect and longitudinal direction of the pipe) is 90°, the maximum stress of the defect is enlarged remarkably with the increase in σ_A , leading to electrochemical corrosion at the defect affected greatly under the M-E interaction. However, when α is 0°, the maximum stress and electrochemical corrosion are affected slightly by the σ_A . Besides, when the hoop stress of the pipe is larger than its total axial stress, the largest corrosion rate at the defect with α of 0° would be higher than that at the defect with α of 90°. Thus, for the improvement of pipeline integrity management, the combined effects of internal pressure and σ_A should be taken into account for a more accurate prediction of local corrosion rate at the defect especially with α of 90°.