Fitting family

JIC 37° flare fittings

Parallel UN thread with a 37° cone on the male nose. The most common hydraulic connection on North American equipment.

What it is

A JIC fitting seals where a 37° cone on the male nose meets a matching 37° flare inside the female swivel nut. The thread only pulls the two cones together; it does not seal. No O-ring or sealant is used.

Sizes are given as dash numbers in sixteenths of an inch of the tube size, and each dash size has one fixed thread. A -08 JIC is always 3/4-16.

Thread: Parallel UN/UNF, counted in threads per inch
Seal: Metal-to-metal on a 37° cone
Standard: SAE J514 / ISO 8434-2
Also called: JIC, 37° flare, AN (aerospace version)

What it looks like

37° cone seat. Male end shown; the sealing surface is orange. Illustration, not to scale.

How to recognise it

The male nose ends in an external cone, visibly sloped at 37° from the axis.
The thread is parallel: the diameter is the same along its length.
Thread pitch is in threads per inch, for example 16 TPI on -08.
The female has a free-turning swivel nut with a flared seat inside.

Where it is used

Standard on most North American construction, agricultural and industrial machines, and widely used worldwide as an adapter standard. Common on Caterpillar, John Deere and Case equipment alongside O-ring face seal.

Size chart

JIC 37° flare — SAE J514 / ISO 8434-2
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

Seal: 37° cone seat, metal to metal. Look for a 37° flared cone on the male nose (74° included angle). The thread is parallel. SAE O-ring boss ports (SAE J1926) use the same UN threads but seal with an O-ring at the base of the male thread instead of a flare.

Match a measured thread with the thread identifier →

Commonly confused with

SAE 45° flare: Shares the same thread in -04, -05, -08 and -10. The seat is 45° instead of 37°. They screw together but do not seal.
SAE O-ring boss (ORB): Uses the same UN threads. ORB has no cone on the nose and has an O-ring at the base of the male thread.
JIS 30° and Komatsu 30° flare: Look similar with a cone seat, but the thread is BSP or metric and the angle is 30°.

Interchangeability

JIC connects only to JIC. It is dimensionally matched to AN fittings, but AN parts are made to aerospace specifications and JIC parts are not approved substitutes there.

Frequently asked questions

What does JIC stand for?

Joint Industry Council, the body that standardised the 37° flare fitting. The current standards are SAE J514 and ISO 8434-2.

What thread is a -06 JIC fitting?

A -06 JIC fitting has a 9/16-18 UN thread, with a male thread outside diameter of about 14.3 mm (0.563 in).

Do JIC fittings need thread sealant?

No. The seal is made on the 37° cone. Sealant or tape on the thread does nothing useful and can contaminate the system.

Is JIC the same as AN?

They share the 37° angle and thread sizes, but AN fittings have tighter tolerances and a different thread class. Industrial JIC fittings are not rated as replacements for AN in aircraft.

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