Chapter 23 - Overlooked key areas of centrifugal pump maintenance

Abstract

This chapter addresses four principle areas of centrifugal pump maintenance—replacement of mechanical seals and maintenance of seal peripherals, replacement of rolling element bearings, impeller clearance adjustments and impeller replacement, and pump-driver alignment and coupling care. Many of today's centrifugal pump mechanical seals are supplied in cartridge form. The areas of prime importance when a seal repair or replacement is performed, if a satisfactory length of service is to be realized are—seal cavity checks for perpendicularity, concentricity, shaft run-out and throat bushing clearance; and cleanliness of seal flush piping and seal peripherals. Further, impeller clearances are essentially the clearances that exist between the impeller rotating surfaces and the parts of the pump casing in close proximity to these surfaces. In addition, the two areas of pump maintenance that are often overlooked during pump overhaul, or during cleaning of a suction strainer that requires removal of a spool piece—adjustment for pump growth due to temperature in hot service and the need to re-align after a piping disturbance. Many large companies have developed maintenance standards for repair of equipment, including pumps.