Eliminating Damage of Retaining Rings by Using Redesigned "Profiled" Keys

Abstract

Retaining rings are used to locate pump impellers axially on the shafts of high speed, high pressure Siemens Delaval boiler feed pumps. Upon repairing and refurbishing the inner barrels, the retaining rings were found to be badly worn and in some instances broken. This damage was eliminated by using a “profiled” key. This case study discusses the pump design, the location and function of the retaining rings, the location and function of the keys and the failures observed. The reason for redesigning the key to a “profiled” is presented. The new key design shields the leading edge of the retaining from impinging water and this is discussed in detail. No damaged retaining rings were observed after implementing “profiled” keys.