Effect of Pressure on Plastic Collapse Under the Combined Bending and Torsion Moments for Circumferentially Surface Flawed Pipes

Abstract

When a crack is detected in a stainless steel pipe during in-service inspection, the failure estimation method given in the codes such as ASME Boiler and Pressure Vessel Code Section XI or JSME S NA-1-2008 Appendix E-8 can be applied to evaluate the integrity of the pipe. In the current editions of these codes, the failure estimation method is provided considering bending moment and pressure. Torsion load is assumed to be relatively small and not considered in the method. In this paper, finite element analyses are carried out for 24-inch stainless steel pipe with a circumferential surface crack under the multi-axial loads including internal pressure. Based on the analysis results, the failure estimation method for cracked pipe subjected to the combined bending and torsion moments is developed considering the effect of internal pressure.