SAE O-ring face seal (ORFS) fittings seal liquids and gases from vacuum to 6000 psig. ORFS fitting can be applied to tubing or pipe. They are very versatile fluid connectors because it works exceptionally well on both fluids and gases. They are "zero clearance" fittings meaning that they can be inserted and removed from systems without cutting or flexing the pipe or tubing. The makes them ideas for systems requiring frequent maintenance and for valves and other components requiring periodic maintenance or replacement.
The Soft-Seal fitting assembly consists of four parts: threaded fitting body with o-ring groove, o-ring, nut, and sleeve or tailpiece. The standard o-ring is Buna-N. Other o-rings have been tested and are available for special applications.
The fitting assembly seals when the bottom of the sleeve or tailpiece, which has been fixed to the tubing, compresses the o-ring in the face of the threaded fitting body as the fitting nut is threaded onto the external threads on the fitting body. The threading process draws the sleeve into full contact with the face of the fitting. Sleeves or tailpieces can be secured to the tubing either by brazing, welding, or mechanically flanging the tubing.
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The NavSea Soft-Seal design is widely used in Naval and commercial ship building and repair. Other applications include test laboratories. Soft-Seal tube and pipe fittings are highly recommended on high vibration systems because the soft-seal absorbs shock better than any metal-to-metal sealing system.
While the SAE Soft-Seal was originated for use in off-road construction machinery, it is gaining popularity in other transportation-related applications such as alternative fuel systems (CNG/LPG) for vehicles. It is endorsed by ISO Technical Committee 131 for all new hydraulic system design.