Fitting family

ORFS O-ring face seal fittings

Parallel UN thread with a flat face and an O-ring in a groove on the male end. The leak-free standard on modern high-pressure machines.

  1. JIC 37°
  2. ORFS
  3. BSP
  4. NPT
  5. Metric DIN
  6. JIS / Komatsu
  7. O-ring boss
  8. SAE flange

What it is

An ORFS fitting seals with an O-ring that sits in a groove in the flat face of the male end. Tightening the swivel nut presses the flat face of the female against the O-ring.

Because the seal is an elastomer rather than metal to metal, ORFS tolerates vibration and repeated assembly well and is the usual choice where leaks are not acceptable.

Thread
Parallel UN/UNF, counted in threads per inch
Seal
Elastomer O-ring compressed against a flat face
Standard
SAE J1453 / ISO 8434-3
Also called
O-ring face seal, flat face, FFOR

What it looks like

O-ring in the flat face — seals hereEnd viewHexParallel thread
Flat face with O-ring. Male end shown; the sealing surface is orange. Illustration, not to scale.

How to recognise it

  1. The male end is flat, with a circular groove holding an O-ring.
  2. There is no cone on either half.
  3. The thread is parallel and coarser-looking for its size than JIC: -08 ORFS is 13/16-16, against 3/4-16 for -08 JIC.
  4. The female swivel has a flat sealing face behind the nut.

Where it is used

Used on most current high-pressure mobile equipment. Common on Caterpillar, John Deere, Komatsu, Hitachi and Volvo machines built in recent decades, often together with older standards on the same machine.

Size chart

ORFS (O-ring face seal) — SAE J1453 / ISO 8434-3
SizeThreadMale thread OD (nominal)Pitch
-049/16-1814.29 mm / 0.563 in18 TPI
-0611/16-1617.46 mm / 0.688 in16 TPI
-0813/16-1620.64 mm / 0.813 in16 TPI
-101-1425.40 mm / 1.000 in14 TPI
-121-3/16-1230.16 mm / 1.188 in12 TPI
-161-7/16-1236.51 mm / 1.438 in12 TPI
-201-11/16-1242.86 mm / 1.688 in12 TPI
-242-1250.80 mm / 2.000 in12 TPI

Seal: Flat face with an O-ring in a groove on the male end. The male end is flat with an O-ring groove in the face. The thread is parallel.

Match a measured thread with the thread identifier →

Commonly confused with

JIC 37°
Both use UN threads but in different sizes for the same dash number. ORFS has a flat face; JIC has a cone.
SAE O-ring boss (ORB)
Both have an O-ring. On ORB the O-ring sits around the base of the male thread, not in the end face.
Flat-face quick couplers
A different product entirely. ORFS is a threaded connection, not a push-to-connect coupler.

Interchangeability

ORFS connects only to ORFS. A missing or damaged O-ring is the usual cause of a leak; replace it with the correct size and material every time the joint is opened.

Frequently asked questions

What does ORFS stand for?

O-ring face seal. The sealing O-ring sits in a groove in the flat end face of the male fitting.

What thread is a -08 ORFS fitting?

A -08 ORFS fitting has a 13/16-16 UN thread, with a male thread outside diameter of about 20.6 mm (0.813 in).

Is ORFS better than JIC?

ORFS seals more reliably under vibration and at high pressure because it uses an O-ring. JIC is cheaper, has no O-ring to lose and is more widely stocked. Machines use whichever the manufacturer designed in.

Related

Dimensions are nominal reference values. Confirm against the standard or the fitting manufacturer before ordering.

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