Effect of external wall defect growth on internal wall corrosion of oil pipelines under mechano‐electrochemical interaction

The corrosion mechanism of X80 steel in simulated solutions of acid red soil and product oil sediment under mechano‐electrochemical interaction (MEI) was researched to build a new finite element model through multi‐physical field coupling simulation technology. Based on the new model, the effect of external wall defect growth on the internal wall corrosion of oil pipelines was analyzed in detail. The results showed that the distributions of stress and corrosion of the internal wall were extremely affected by the external wall defect depth, and the corrosion rate of the internal wall was enlarged remarkably by the external wall defect growth. Moreover, attributing to the local galvanic cell effect under MEI, the growth rates of corrosion defects in the depth and length directions of the external defect were accelerated because these directions were associated with larger stress and equivalent to the anode, but the corrosion rate in the width direction of the external defect was inhibited because this direction was associated with smaller stress and equivalent to the cathode.