The limit loads of circular arch pipelines for volume defects under combined loads

This paper presents plastic limit loads of circular arch pipelines for volume defects under the internal pressure, in-plane and out-of-plane bending and torsion moment. The stress of the pipeline is analyzed by nonlinear finite element method. The geometric variables associated with volume defects (long axis, short axis and depth) and pipelines (diameter, wall thickness and bend radius) are systematically varied. The combination of the internal pressure, in-plane and out-plane bending and torsion moment is considered. The results show that the wall thickness, depth of defect and the direction of the defects have more effect on the limit loads.