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O-Ring Face Seal (ORFS) Fittings

ORFS fittings seal with an O-ring held in a groove on the flat face of the male end. They are chosen where leak resistance and vibration resistance matter. This sheet covers how they are built, how they seal and how to identify them.

Ref HY-0014SAE J1453ISO 8434-3

Draft, open for review. Check every value against the governing standard and the manufacturer’s data before use.

What it is

O-ring face seal (ORFS) fittings are defined in SAE J1453 and internationally in ISO 8434-3. The male end has a flat face with a groove that holds an O-ring. The female has a flat face and a swivel nut. Tightening the nut presses the two flat faces together and squeezes the O-ring in its groove, which makes the seal. ORFS fittings are common on construction, agricultural and mobile equipment because they resist leaks from vibration and over-tightening better than metal-to-metal seals. Sizes use dash numbers in sixteenths of an inch of tube outside diameter.

How to identify

Look at the male end. A flat face with an O-ring in a groove means ORFS.
Measure the thread outside diameter and pitch. ORFS uses UN/UNF threads that differ from JIC at the same dash size. See the ORFS thread size chart.
The female has a flat seat with no cone.
Many ORFS male ends on hose and adapters also have an O-ring boss (ORB) stud on the other end. Identify each end separately.

ORFS vs other common fittings

Feature	ORFS (SAE J1453)	JIC 37° (SAE J514)	SAE ORB port end
Sealing method	O-ring compressed on a flat face	Metal to metal on a 37° cone	O-ring at the base of a straight thread, in a port
Male end look	Flat face with O-ring groove	Cone nose	Straight thread with O-ring under a backup washer or shoulder
Female end	Flat face with swivel nut	37° seat with swivel nut	Port in a manifold or component
Thread type	UN/UNF, ORFS sizes	UN/UNF, JIC sizes	UN/UNF, same as JIC for each dash size
Re-use	Replace O-ring each time	Reusable if seat is undamaged	Replace O-ring each time

Key points

Always replace the face O-ring when a joint is opened. Order it by fitting dash size or the fitting maker's part number, in the compound the maker specifies.
Hold the O-ring in the groove with a light film of clean system oil or the grease the maker approves. A pinched or missing O-ring is the main cause of ORFS leaks.
Faces must be clean and free of nicks.
Assembly torque comes from the fitting maker. Do not guess.

Common mistakes

Trying to mate an ORFS male with a JIC female. The threads and sealing surfaces are different.
Reinstalling a joint without a new O-ring.
Ordering an ORFS O-ring by measuring the old, swollen one.
Calling a fitting ORFS because it has an O-ring, when the O-ring is actually on an ORB stud.

Governing standards: SAE J1453 (O-ring face seal fittings); ISO 8434-3 (O-ring face seal connectors); fitting manufacturer assembly data.

Reference only. Verify against the current governing code or standard, the manufacturer's data and the project documents before use. Apps for Distributors disclaims liability arising from reliance on this reference.

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