POLYMER SEAL USE IN CENTRIFUGAL COMPRESSORS – TWO USERS’ EXPERIENCES OVER 15 YEARS

Abstract

For over 20 years now, the efficiency and reliability of centrifugal compressors has been enhanced by the application of engineered thermoplastic materials to the eye, shaft, and balance piston labyrinth seals. Traditionally these seals have been manufactured from metallic materials (such as aluminum) and have required relatively large clearances for reliability reasons. By upgrading to carefully selected engineered thermoplastics the clearances can be reduced without sacrificing reliability. Polymer seals maintain their clearances even after typical start up rubs, whereas metallic seals open up during these rubs and are then open for the remainder of that run cycle (3, 4, 5 years or more). Polymer seal upgrades result in increased compressor efficiencies with the added benefit of easier installation. Of course whenever an upgrade of this type is first pursued the question of reliability and long term sustained success needs to be considered. Replacing a metallic component with a plastic one, in a service where running 24/7 for several years is imperative, needs to be carefully considered. Now that the seals have been successfully applied for over 20 years now, and individual seals have run for 9 years and more, we can evaluate the applicability of these materials to this type of application.