Design of Radial Nozzles in Cylindrical Shells for Internal Pressure

Abstract

A design method is presented that allows a designer to predict the maximum allowable working pressure of an opening reinforcement using an allowable stress basis. Primary application of the method is directed toward large openings as defined by ASME Section VIII, Division 1, paragraph UA-7. Recent hydrotests conducted on several production pressure vessels have demonstrated that existing paragraph UA-7 area replacement rules are inadequate in certain d/D and D/T ranges. The inadequate designs were initially indicated by leakage at a flange located close to the nozzle shell intersection. Later, another vessel hydrotest was terminated because of distortion and high readings from strain gages located at the nozzle-to-shell intersection. The proposed empirical design method produces nozzle reinforcements that should remain in the elastic stress range for internal pressure up to the Code-required hydrotest.

The Development of Reinforcement Pad Design for Pressure Vessel

“…Study in repad design has been recorded since 1970s by [7][8] and [12][13] performed parametric and numerical study while [10][11] performed experimental studies on various repad design. Beginning of 1990s, FEA has been used as tool to perform the analysis for repad at nozzle of pressure vessels [14].…”

“…Earlier works by [10] had performed experiment on prototype pressure vessel with repad thickness of 14.3 mm carbon steel material installed outside the vessel. It was found that the used of repad had reduced the stress from internal pressure.…”