O’Donnell Consulting Engineers, Inc. was requested to perform structural analysis of upgrades on waterboxes that are used in an alumina fluid cooler.
The purpose was to determine the structural integrity of the waterboxes for a MAWP of 80 psi, and if necessary, to redesign and/or stiffen them accordingly. (ANSYS) Finite element analysis was used to simulate the structural responses of the waterboxes when subjected to internal pressure.
A detailed three-dimensional model of the entire waterbox was modelled, including inlet/outlet openings, cover plate, tubesheet, and tubes. The waterbox structure was modeled with 3-D solid elements, while the tubes were simulated with beam elements. Equivalent material properties were used for the perforated areas of the tubesheets. These properties were calculated based on the tube and tubesheet geometries and ligament efficiency of the perforation.
Various deformation and stress results were determined on the waterbox (shown above) when subjected to an increase in internal pressure to 80 psi. The analysis determined that this pressure increase would not cause failure. However, in order to meet the allowable stress limits of Section VIII Div. 2 of the ASME Code, the MAWP should be less than 76 psi.
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