The ASME Design by Analysis (DBA) procedures, namely the stress categorization and limit load approaches were applied to the spiral casing of a centrifugal pump. The spiral casing, which has stay vanes inside the spiral duct, has a more complicated structure than other pressure vessels, and therefore, the stress categorization procedure cannot be directly applied to it. We simplified the spiral casing into a finite element shell model. The membrane and bending stresses were determined by measuring the shell stresses, and then those stresses were classified into primary and secondary stresses. The limit load approach is simpler to apply, but requires an inelastic analysis. The allowable loads of the limit analysis are calculated using the solid and shell models of the spiral casing. In addition, the calculated allowable loads were assessed and compared for the different methods.

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