What Is a JIC Fitting? 37° Flare Connection and Size Table
A JIC fitting is an inch-sized connection that seals through a 37 degree flare seating metal against metal. This page gives the size table, thread equivalents and guidance on when to use it.
6 min read · 10-row dimension table · 5 frequently asked questions
The JIC fitting in short
A JIC (Joint Industry Council) fitting seals by pressing the 37 degree flare on the end of the tube or hose against a seat machined to the same angle in the mating part. There is no gasket, O-ring or thread sealant involved; the seal is made purely by metal seating on metal.
The standard is SAE J514, with ISO 8434-2 as its international equivalent. Threads are inch-based UNF (fine pitch), not metric.
How to tell whether the part in your hand is JIC
Three types get confused with one another in the field. The practical way to separate them:
- 37° cone with a bare metal face → JIC. The cone is noticeably shallow.
- 24° cone → metric DIN 2353. The cone is steeper and is normally used with a cutting ring.
- No cone at all — a flat face with an O-ring groove in it → ORFS.
To be certain, measure the thread: JIC threads read as "diameter – threads per inch", such as 7/16-20, 9/16-18 or 3/4-16. A metric fitting gives you something like M16×1.5 instead.
JIC size table
The table below shows the dash number used when ordering (–4, –6, –8…) alongside tube outside diameter and thread equivalent. Quoting the dash number over the phone is enough.
What pressure will it hold?
The working pressure of a JIC fitting falls as the size goes up. Small sizes (–4, –6) reach the 310–350 bar range, while 1" and larger drop below 200 bar. Remember that the line is limited not by the fitting but by whichever component is weakest: hose, ferrule and fitting must all be assessed together.
Where it works well — and where it does not
JIC connections are common on American-built construction machinery, agricultural equipment and forklifts. They are easy to break and remake, and the same joint can be opened and closed many times.
On the other hand, in high-vibration lines the metal-to-metal seat can loosen over time and begin to weep. On breakers, presses and any line running under constant impulse, an ORFS connection is the safer choice.
Points to watch during assembly
- The cone face must be free of scratches, dents and corrosion; on a metal-to-metal seat even a light scratch will leak.
- Do not over-tighten the nut. Excess torque crushes the cone and the joint will never seal again.
- After seating the joint hand-tight, the additional turn with a spanner is typically 1/4 to 1/2 of a turn.
- Wrapping thread tape around a leaking JIC joint does not fix anything — the problem is on the cone face.
JIC 37° sizes and thread equivalents (SAE J514)
| Dash | Tube OD | Thread (UNF) | Spanner size | Approx. working pressure |
|---|---|---|---|---|
| –4 | 1/4" | 7/16" – 20 | 9/16" | 350 bar |
| –5 | 5/16" | 1/2" – 20 | 5/8" | 350 bar |
| –6 | 3/8" | 9/16" – 18 | 11/16" | 310 bar |
| –8 | 1/2" | 3/4" – 16 | 7/8" | 275 bar |
| –10 | 5/8" | 7/8" – 14 | 1" | 240 bar |
| –12 | 3/4" | 1.1/16" – 12 | 1.1/4" | 210 bar |
| –14 | 7/8" | 1.3/16" – 12 | 1.3/8" | 210 bar |
| –16 | 1" | 1.5/16" – 12 | 1.1/2" | 170 bar |
| –20 | 1.1/4" | 1.5/8" – 12 | 1.7/8" | 140 bar |
| –24 | 1.1/2" | 1.7/8" – 12 | 2.1/8" | 100 bar |
The table scrolls horizontally. Values are for guidance; we recommend confirming the size before ordering.
Frequently Asked Questions
What angle is a JIC fitting?
A JIC fitting is 37 degrees. The cone face is machined at 37° and the seal is made by that face seating metal-to-metal against the mating part. A 24 degree connection is not JIC — it is a metric DIN 2353 fitting.
What is the difference between JIC and ORFS fittings?
JIC seals metal-to-metal on a 37 degree cone. ORFS seals with an O-ring set into a flat face. ORFS resists vibration better and reaches higher pressures; JIC is more common and less expensive.
Is a gasket used in a JIC fitting?
No. A JIC joint uses no gasket, O-ring or thread tape. The seal is made by the 37 degree cone face. If the joint leaks, either the cone face is scratched or dented, or the torque is wrong.
Are JIC threads metric?
No, JIC threads are inch-based UNF threads. For 1/2" tube, for example, the thread is 3/4"-16 UNF. If you are reading a size such as M16×1.5, the part in your hand is a metric fitting, not JIC.
What pressure does a JIC fitting hold?
It depends on the size. Small sizes such as –4 and –6 reach 310–350 bar, while 1" (–16) drops to roughly 170 bar and 1.1/2" to around 100 bar. The real limit of the line is set by whichever of the fitting, hose and ferrule is weakest.