The results of a limited parametric study on the stress levels in knuckle encroaching nozzles in a Klöpperböden torispherical head due to pressure and nozzle loads are presented. The results give support to the CEN TC 54 procedure which requires thickening of the knuckle region for such nozzles for pressure loading. Stress levels due to nozzle loads are shown to be of the same order of magnitude as those in the equivalent axisymmetric nozzle. Studies of interaction diagrams have confirmed the CEN TC 54 proposal for combined loading in axisymmetric nozzles but have shown that a linear interaction rule should be recommended for non-axisymmetric nozzles in heads.
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