Nozzle - Planes of Reinforcement Methodology

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Last updated: Dec 19, 2016 by Mike Clark
1 min read

DesignCalcs determines tr as defined in UG-37(a) per circumferential stress (longitudinal plane). For a situation in which a hillside nozzle is designed where the developed opening is bigger when looking at the longitudinal plane and the code is allowing a value for F that is less than 1.0, design the nozzle as two separate nozzles to reap the most benefit from code allowances. It is also possible to check for the largest developed opening and keep F equal to 1.0 at the same time.

As defined in UG-37(a), F is the correction in the code for the fact that longitudinal stress (circumferential plane) is ½ of the circumferential stress (longitudinal plane). When in the longitudinal plane, the value must be 1.0. In other planes, the value may fall between 0.5 and 1.0 (dependent upon the plane) if the design meets certain requirements: the nozzle is attached to the vessel with full penetration groove welds and the nozzle is integrally reinforced (i.e., no repad).