Improvement and assessment of the plastic collapse bending moment equations in circumferentially cracked pipe

Desclaux, C.*; Lacroix, V.*; Hasegawa, Kunio

Proceedings of ASME 2021 Pressure Vessels and Piping Conference (PVP 2021) (Internet), 10 Pages, 2021/07

The plastic collapse bending stress for a pipe is defined in ASME Code Section XI, using simplified equilibrium equations. One of the authors demonstrated that the simplified equilibrium equations are not conservative for externally cracked pipes and he proposed taking into account the cracked ligament mean radius. This paper demonstrates that the accuracy of the collapse bending stress equation can be refined considering the neutral axis position of the cracked pipe section. This leads to exact collapse bending moment equations. As the results, it is shown that the ASME equations for externally cracked pipes might be less conservative collapse bending stress than with the exact equations.