UniRing Piston Seals

A one piece urethane dual durometer double acting seal


The Piston Uniring is a Dual Durometer, one piece double acting piston seal. It consists of a (Duro 60 D) dynamic sealing and wear lamina bonded to a (Duro 57 A) static sealing and activation lamina. The material used for the static lamina has a high resilience and extremely low compression set. It functions as a seal energizing spring element and assures positive sealing performance throughout a broad pressure range. The dynamic sealing element is made of a harder material, selected for its high abrasion resistant qualities.

Piston Unirings can readily be substituted in existing cavities to replace other types of double acting seals, such as TFE Piston rings and the T Cross Section seals.

Unirings can easily be installed on one piece pistons without costly and time consuming assembly fixtures. They simplify the task of eventual field replacement.

Piston Unirings permit substantial cost savings in cylinder design by allowing larger tolerances and poorer surface finishes.


  • Sealing Lamina: Unithane 460 D, Liquid Cast Polyurethane, Duro 60 D.
  • Activation Lamina: Unithane 157 A, Liquid Cast Polyurethane, Duro 57 A.
  • Fluid Compatibility: See Material Specifications: Technical Bulletin US-96.

UniRing™ Piston Seals replace these multi-piece systems with one part.

  • Spin molded at 3600 RPM in our exclusive Centrifugal Molding Process
  • Results cannot be duplicated by any other molding process
  • Over ten million seals sold without a seal problem
  • Competitively priced and cost efficient single piece design
  • Low friction moly impregnated wear surface
  • Dual durometer 60D outer lamina and 57A inner lamina.

Universal Seal developed the patented “spin cast” Centrifugal Molding Process, producing seals that are more durable and functional than those made by any other process. The innovative single piece UniRing™ Piston Seal, just one of our seals produced using this process, provides longer part life and, in most cases, lower front end costs. Since 1967, Universal Seal has been creating superior, trouble free seals and continues to be a major leader in seal innovation.