Section VIII Divisions 1 and 2 require shell openings to be reinforced using a cross sectional area replacement philosophy. Although the state of stress in a shell opening varies with the location along the nozzle to shell intersection most nozzle reinforcement is designed as though there is no variation. Openings in the shell which are reinforced with excess thickness available in the shell, nozzle neck, or weld are defined as “integrally reinforced.” Section VIII acknowledges the variation in stress for these integrally reinforced nozzles with respect to the orientation of a section cut through the opening. The use of a factor F to reduce the required reinforcement proportionally is allowed. In this paper, stresses developed due to internal pressure in integrally reinforced shell openings reinforced continuously are evaluated. These stresses are compared with those in the case where reinforcement is varied using the F factor. Continuously integrally reinforced nozzles have a constant amount of reinforcement area about the nozzle centerline while those reinforced with a variable area of reinforcement do not. This lack of symmetry is most likely to be developed through additional weld buildup on either the shell or nozzle neck or with a larger fillet on the attachment weld. The costs of each type of construction are compared. It is found that in some cases reinforcing a nozzle with a variable reinforcement area applied through weld buildup may be substantially less expensive than the typical reinforcing pad approach. A guideline of having 70% of the area required available within the shell and nozzle and weld is suggested as a criteria to evaluate the potential to benefit from a variable reinforcement approach.

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