Influence of Yield-to-Tensile Strength Ratio on Failure Assessment of Corroded Pipelines

This paper investigates the influence of yield-to-tensile strength ratio $(Y∕T)$ on failure pressure of pipelines without and with corrosion defects. Based on deformation instability and finite strain theory, a plastic collapse model for end-capped defect-free pipes is developed. The stress-strain response of materials is characterized by a power-law hardening curve, and the plastic deformation obeys the von Mises yield criterion and the deformation theory of plasticity. Two formulas to estimate the strain hardening exponent $n$ for a specific $Y∕T$ are obtained, and a closed-form solution to the limit pressure of pipes is derived as a function of $Y∕T$⁠. This plastic collapse model is then extended to predict the failure pressure of pipelines with corrosion defects. Numerical and experimental comparisons are presented that validate the present models which characterize the influence of $Y∕T$ on the failure behavior of pipeline.