Classification of Thin-Walled Conical Vessels for Design Against Axisymmetric Plastic Collapse Under External Pressure

This paper presents the results of a study that investigates the propensity of thin walled vessels with cone-cylinder junctions to plastically collapse under external pressure. The investigation focuses on the conical portion of the vessel collapsing in an axisymmetric mode prior to buckling in a classical lobar mode. Using a parametric study, comparison is made between the factor of safety afforded by design-by-rule approaches such as that offered in ASME Section VIII Div. 1, ASME Section VIII Div. 2 Part 4.4 and elastic-plastic design by analysis approaches prescribed by ASME Section VIII Div.2 Part 5. Further, the results of the parametric study are used to determine the key parameters that result in the occurrence of an axisymmetric collapse mode before the classical lobar buckling mode. The research has led to the development of a set of criteria to indicate susceptibility of geometry to axisymmetric collapse prior to classical lobar buckling.