A Cavitation Resistant Hydrostatic Seal For High Pressure Breakdown

Abstract

A unique hydrostatic throttle bushing concept has been developed and successfully tested. The throttle bushing is based on the concept of typical hydrostatic face seals, but incorporates improvements to minimize cavitation and maximize performance. Face geometry modifications include flow oriented feed slots to the hydropads and vortex pockets for minimizing cavitation damage. Parallelism between the throttle bushing and the mating ring is maintained with a face control groove, oriented to eliminate face distortion under high differential pressure loading. Additionally, materials selection has played a key role in the successful field operation of the hydrostatic throttle bushing. Currently there are three field installations in two stage, high energy, centrifugal pumps operating in urea production for ammonia feed. Operating successfully since 1997, the hydrostatic throttle bushing has proven to be a reliable, simple means of reducing stuffing box pressure in the applications.