When a weeping hydraulic fitting comes to the counter, the first question is: "Is that JIC or ORFS?" Both are common on hydraulic hose and tube, and after 20 years in the instrumentation valve and fitting business, I can tell you a wrong guess gets expensive. Here's how to tell them apart and when to use each.
What a 37° JIC Flare Fitting Is
A 37° flare fitting (SAE J514, usually called JIC) seals metal to metal. The tube end is flared to 37°, and the nut pulls that flare tight against a 37° cone on the male fitting. There's no O-ring in the seal.
The tradeoff: metal-to-metal doesn't forgive much. Over-tighten and you can crack the flare; under-tighten, or add heavy vibration, and it can weep.
What an ORFS Fitting Is
An O-ring face seal fitting (SAE J1453, ORFS) seals with an O-ring. The male fitting has a flat face with an O-ring in a groove, and the nut pulls it against a flat mating face. Because the O-ring does the sealing, ORFS holds up well in high-pressure, high-vibration hydraulic systems.
The tradeoff: you depend on that O-ring. It has to be there, be the right compound for the fluid and temperature, and be replaced whenever the joint comes apart.
How to Tell Them Apart in 10 Seconds
- Look at the male end. A cone-shaped nose is JIC. A flat face with an O-ring groove is ORFS.
- Measure the thread. Both use straight UN/UNF threads, but not the same size for the same dash size. A -4 JIC is 7/16-20; a -4 ORFS is 9/16-18. Use a thread gauge, not your eyes.
- Watch the 9/16-18 trap. A -6 JIC and a -4 ORFS share the 9/16-18 thread. They'll spin together but never seal. That mix-up causes a lot of "mystery leaks."
When to Use Each
Use JIC to match existing JIC equipment, on moderate-pressure, low-vibration systems, or when you need an odd shape fast. Use ORFS for high pressure, pressure spikes, heavy vibration, or anywhere a leak would be costly or dangerous. On a repair, match what's already there. Never mix JIC and ORFS parts on the same joint.
We stock DK-Lok in both: ORFS 90° elbows and 45° elbows, plus K series 37° flare tube to male pipe fittings and caps and plugs. Replacing a hose? Bring the old one in; we build hose assemblies while you wait. See our hose assemblies page.
Install Tips That Prevent Callbacks
- Cut tube square with a RIDGID tube cutter made for stainless steel, with the GRIP-IT TOOL locked on so the tube doesn't spin in your hand. Deburr inside and out with a deburring tool before flaring or sleeving. All are on our tools page.
- JIC seals on the flare, not the threads, so keep thread sealant off the threads and the seat.
- On ORFS, check that the O-ring is seated in its groove and lightly lubricate it with system fluid or o-ring lube before you make up the nut.
- Tighten to the manufacturer's torque or flats.
Running Compression Fittings Too?
Many systems also use two-ferrule compression fittings. DK-Lok compression tube fittings are 100% interchangeable and intermixable with Swagelok and Parker A-Lok for like size and material, properly assembled per the DK-Lok catalog. In ASTM F1387 testing witnessed by TÜV Rheinland, 14 combinations of intermixed DK-Lok and Swagelok nuts, ferrules and bodies passed 100% of the testing, with "No failure observed." DK-Lok also confirms it in its Parker A-Lok interchangeability letter. (That applies to compression fittings only, not to JIC or ORFS.)
Leak Test Every Joint You Touched
Once the line is pressurized per site procedure, apply Gator Leak Detector all the way around each joint you touched and watch for bubbles or foam. On tube-to-male-pipe fittings, check the pipe-thread joint as well as the tube nut, since the NPT side is often skipped. If something leaks, isolate and depressurize before putting a wrench on it. Never tighten a fitting under pressure.
Not Sure What You've Got?
Bring it in or send a photo, and A-Best Industrial Inc. Fittings, Valves, and Tubing will match it. Call 310-833-3353 or email sales@abesttube.com. We're open Monday–Friday, 8:00 AM–5:00 PM Pacific, with after-hours emergency service.
Swagelok and Parker A-Lok are trademarks of their respective owners.