Stress linearization application of oblique nozzles with welded pad reinforcement in cylindrical pressure vessels

Abstract

In pressure vessel applications, one of the most feasible and economical ways of reinforcing an isolated nozzle is to use a pad or compensating plate. Where a pad is used, the extra material is considered to as effective as provided by a thick vessel plate, so a good fit in the vessel shell is required. Considering this information, in this study, welded pad reinforcement is applied to the oblique nozzle-cylinder intersections in the cylindrical pressure vessels and membrane stress and total stress (membrane + bending) cases are examined. It is well-known that the maximum stress is at the crotch corner (nozzle-cylinder junction) in the vertical junction of the radial nozzle. However, as the nozzle connection angle increases, the direction and magnitude of the stress should be investigated. For this reason, six critical paths were determined for the nozzle-cylinder junction and the stress distributions along these paths were examined with the help of Stress Linearization Analysis. In the analysis, cases such as oblique nozzle angle, pad reinforcement rates according to shell thickness, effect of increase in pad diameter are examined in detail. In conclusion, this study provides researchers with an alternative stress analysis for critical locations in the intersection area in the design and analysis of cylinder-oblique nozzle connections.