Strength analysis of a large centrifugal dredge pump case

Cracks in the cases of large dredge pumps have limited their performance. This paper describes optimization of the pump case design using a finite element analysis. The stress concentrations usually occur on the ribs or above the ribs. Therefore, the stress characteristics of the pump case were analyzed for several conditions with different thicknesses and placements of the strengthened ribs. The optimized result found by removing or shortening the ribs has a maximum stress in the pump case which is far less than the material is allowable stress. The simulation results were verified in a 2 MPa hydrostatic pressure test in which no crack appeared and predicted the distortion in the axial direction agreed well with the test result. Therefore, this method can be used to improve the designs of large dredge pump cases.