Prediction method on minimum residual wall thickness of internal corroded pipeline at uniform corrosion rate

In this paper, a 3D nonlinear finite element model was established to study the internal corroded pipelines. Based on this model, the failure pressure of pipeline was predicted and the effects of pipe wall thickness, internal pressure and defect size on the minimum residual wall thickness were analyzed. And it is shown that at uniform corrosion rate, the minimum residual wall thickness is dominantly influenced by wall thickness, internal pressure and defect depth and length, but less by defect width, so the size variation along the width can be neglected. The minimum residual wall thickness calculated in the finite element model is in good agreement with the experimental results. The minimum residual wall thickness is in linear relation to the pipe wall thickness and internal pressure, but approximately in negative exponent relation to the defect length-depth ratio. The formula for the minimum residual wall thickness is fitted on the basis of finite element calculation results. The results obtained from the formula are close to the experimental burst results. Obviously, it can provide the reference for remaining life evaluation of corroded pipeline.