Effects of external corrosion defect growth on wall pipeline under internal pressure and various defect sizes with mechano-electrochemical interaction

The assessment of the impact of corrosion defects on the integrity and safe operation of through-wall pipelines is critical. In this work, a finite element-based model was developed to study the mechano-electrochemical (M-E) effects of external corrosion defects on 10CrMoAl steel pipelines. The effects of parameters such as defect sizes and internal pressures on pipeline conditions are also studied. The results show that increased corrosion depth leads to stress concentration at the center of the defect. The increase in internal pressure causes local plastic deformation and anodic current density concentration at the inner edge of the defect and in the adjacent areas of the defect. M-E interaction causes the growth of corrosion defects significantly at higher internal pressures. The corrosion defects increase with time. As the pressure increases, the failure pressure of the pipeline gradually decreases. The influence of defect depth on the corrosion rate at the defect is greater than that of defect width. With increasing in internal pressure and corrosion defect size, it will lead to more severe plastic deformation, resulting in accelerated corrosion.