Localized Loads Applied to a Spherical Pressure Vessel through a Cylindrical Insert

Abstract

A solution is obtained for the membrane and bending stresses in a thin spherical shell due to the action of a localized bending moment or radial load which is applied through a thin cylindrical insert, for example, a duct connection on a reactor pressure vessel. The stress distribution will be affected by the nature of the duct to vessel connection. In this paper attention is confined to the case of an unreinforced junction as sketched in Fig. 1. The solution is general in so far as it is reduced to a set of four simultaneous equations which can be solved readily when dealing with practical problems. As a numerical example, the case of the Hunterston reactor pressure vessel is considered, and it is shown how the localized stresses are affected by a change in duct thickness. Furthermore, these stresses are compared with those which would be induced in the sphere if the duct insert were rigid. It is found that in this practical example, the cylinder thickness has a significant effect on the calculated values for the stresses and displacements.