This paper investigates the effect of nozzles and nozzle loadings on the overall buckling capacity of a vessel subject to external pressure designed to ASME VIII Div 1.
ASME VIII Div 1 provides a well-established design-by-rule (DBR) approach for vessels subject to external pressure, but this takes no consideration for the presence of openings or nozzles. There are empirical rules regarding nozzle reinforcement for external pressure, but these do not directly consider the buckling capacity of the overall vessel.
This paper therefore assesses the impact of nozzles on the buckling capacity of a cylindrical shell, where the nozzle is reinforced as per code requirements. The effect of reduced reinforcement is also analyzed.
Subsequently the effect of nozzle loads is also assessed. Nozzles are loaded with ‘allowable’ loads, determined using finite element analysis in accordance with industry practice and code principles.
The buckling capacities are assessed using ASME VIII Div 2 Part 5 methods, using a parametric study with over 500 models. Variables considered are vessel diameter, vessel length, nozzle diameter, and both integral and pad-reinforced nozzles are used.
