Fitting family
SAE O-ring boss (ORB) fittings
Parallel UN thread with an O-ring at the base of the male thread. The standard port connection on North American components.
What it is
An O-ring boss fitting screws into a port in a pump, valve or cylinder. The male has a straight thread and an O-ring seated against the underside of the hex. The port has a chamfer at its mouth, and the O-ring is squeezed into it as the fitting is tightened.
Adjustable versions add a locknut and back-up washer so an elbow can be pointed in the required direction before it is locked.
- Thread
- Parallel UN/UNF, same sizes as JIC
- Seal
- O-ring compressed into a chamfer at the port mouth
- Standard
- SAE J1926 / ISO 11926
- Also called
- ORB, SAE straight thread, O-ring port
What it looks like
How to recognise it
- An O-ring sits around the male thread next to the hex.
- The nose of the thread is plain: no cone and no face groove.
- The thread is parallel and uses the same sizes as JIC.
- The female is a port in a component, not a swivel nut.
Where it is used
Ports on pumps, valves, cylinders and manifolds on North American equipment, and increasingly worldwide. Usually the other end of the adapter is JIC or ORFS, where the hose connects.
Size chart
| Size | Thread | Male thread OD (nominal) | Pitch |
|---|---|---|---|
| -02 | 5/16-24 | 7.94 mm / 0.313 in | 24 TPI |
| -03 | 3/8-24 | 9.53 mm / 0.375 in | 24 TPI |
| -04 | 7/16-20 | 11.11 mm / 0.438 in | 20 TPI |
| -05 | 1/2-20 | 12.70 mm / 0.500 in | 20 TPI |
| -06 | 9/16-18 | 14.29 mm / 0.563 in | 18 TPI |
| -08 | 3/4-16 | 19.05 mm / 0.750 in | 16 TPI |
| -10 | 7/8-14 | 22.23 mm / 0.875 in | 14 TPI |
| -12 | 1-1/16-12 | 26.99 mm / 1.063 in | 12 TPI |
| -14 | 1-3/16-12 | 30.16 mm / 1.188 in | 12 TPI |
| -16 | 1-5/16-12 | 33.34 mm / 1.313 in | 12 TPI |
| -20 | 1-5/8-12 | 41.28 mm / 1.625 in | 12 TPI |
| -24 | 1-7/8-12 | 47.63 mm / 1.875 in | 12 TPI |
| -32 | 2-1/2-12 | 63.50 mm / 2.500 in | 12 TPI |
SAE O-ring boss uses these same UN threads for each dash size.
Commonly confused with
- JIC 37°
- Same threads. JIC has a cone on the nose and no O-ring.
- ORFS
- ORFS has its O-ring in the end face, not at the base of the thread.
- Metric and BSPP O-ring ports
- Similar design with metric (ISO 6149) or G threads. Measure the thread.
Interchangeability
An ORB male fits only an ORB port. A JIC male will thread into an ORB port because the threads match, but it has nothing to seal with and will leak.
Frequently asked questions
What is an O-ring boss fitting?
A port fitting with a straight UN thread and an O-ring at the base of the male thread. The O-ring seals in a chamfer at the mouth of the port.
Are ORB and JIC threads the same?
Yes, each dash size uses the same UN thread. The sealing method is different, so they are not interchangeable.
Can I use thread tape on an ORB fitting?
No. The O-ring makes the seal. Tape can keep the fitting from seating and can enter the system.
Related
- All hydraulic fitting types
- Hydraulic thread identifier
- Unit and dash-size converter
- Fitting code decoder
- Find hose length and fittings by machine model
Dimensions are nominal reference values. Confirm against the standard or the fitting manufacturer before ordering.