Effects of local reinforcement on nozzles in dished ends

The results of a parametric design study, to determine the optimum diameter of reinforcing pad for nozzles in the knuckle region of an ellipsoidal pressure vessel head are presented herein. The study utilised a linear elastic finite element model, created using ANSYS finite element analysis software. Nozzle parameters of diameter, offset, and wall thickness were varied to ensure the results obtained were achieved through a thorough analysis. Optimum pad sizes were obtained for thrust, in plane moment and out-of-plane moment nozzle loads. Design curves were produced, allowing maximum permitted applied stress, to be calculated for any nozzle size subject to one of the three loading conditions. Recommendations for allowable offset and treatment of loading combinations are also presented