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SS 316 High performance fittings >Tube fittings > Overview > Soft-Seal, O-Ring Face Seal (ORFS)

  Tube fittings
Soft-Seal, O-Ring Face Seal (ORFS)
Soft-Seal tube & pipe fittings seal fluids and gases at very high pressures and vacuum. Each features a high durometer o-ring held in a precision-machined groove in the fitting
body. This elastomeric seal prevents fluids and gases from leaking.
The Soft-Seal fitting assembly consists of four parts: threaded fitting body with o-ring groove, o-ring, nut, and sleeve or tailpiece. 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 oring 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. Type SS 316 stainless steel is the standard material on all bodies and nuts. Type SS 316L (low carbon) is used for sleeves/tailpieces. Buna-N is the standard o-ring material for SAE and NavSea.
Suggested Applications
The Soft-Seal tube & pipe fitting is a very versatile fitting connector because it works exceptionally well on both fluids and
gases. After securing the sleeve onto the tube or pipe, it is then extremely easy to install. The fitting is also a "zero clearance" system, meaning you don't need to spring or pull the tubing to seat the fitting, or purge the system. This tube fitting can be disassembled and reassembled many times. Simply replace the o-ring and tighten to recommended torque. The elastomer softseal conforms well to irregularities in the fitting face or sleeve.
So, while proper technique and handling should be observed during assembly, the tube fitting is forgiving of assembly
variation. Soft-Seal tube & pipe fittings are highly recommended on high vibration systems because the soft-seal absorbs shock better than metal-to-metal sealing systems.
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. The NavSea Soft-Seal design is widely used in Naval and commercial ship building and repair. Other applications include test laboratories.
Characteristic Soft-Seal (ORFS) Tube Fitting Performance
Pressures Very high to 9200 psi
Temperature Nitrile/Buna: -30° to 250°F Viton: -15° to 400°F
Vibration Resistance Excellent
Materials Available TSS 316/SS 316L stainless steel; M405 Monel
Size Available (nominal) 1/8" - 2"
Tube & Pipe Compatibility Welded or Seamless All thickness/schedules
Seal Reliability Excellent Elastomeric seal
High tolerance to minor surface imperfections and damage High tolerance to assembly variation
Design Standard
Recommended Torque Valves for Soft-Seal NavSea Fittings
Dash Size Tube O.D. Torque in Inch-Pounds
-4 1/4 20-40
-6 3/8 25-50
-8 1/2 40-75
-10 5/8 60-120
-12 3/4 110-220
-16 1 180-350
-20 1 1/4 265-530
-24 1 1/2 360-720
-32 2 750-1490