AN and JIC Fittings: When Substitution Is Safe
Mar 15th 2023
AN and JIC fittings are often discussed together because they share the same general 37 degree flare connection concept. That does not mean every AN and JIC part should be substituted without checking the details.
The safe substitution question starts with thread identification. If the thread size, seat angle, material, pressure rating, and mating style do not match, the connection can leak or damage the system.
How AN and JIC Differ
AN stands for Army-Navy and is tied to military and aviation standards. AN fittings are typically made to tighter tolerance requirements for those applications.
JIC stands for Joint Industry Council and is widely used in hydraulic systems. JIC became the more common industrial fluid-power standard because it fits many hose, tube, and adapter applications.
Thread Size Naming
One source of confusion is the way sizes are named. JIC thread sizes are often described in inch measurements, while AN sizes are commonly shown as dash sizes such as -04, -06, or -08.
In many cases, the dash number relates to sixteenths of an inch, but the exact connection still has to be verified against a fitting chart. A 3/4 JIC connection and a -08 AN connection are often discussed as equivalent in size, but the actual mating parts should still be measured before replacement.
When Substitution Can Work
Substitution may be acceptable when the male and female parts share the same thread, the same 37 degree flare sealing geometry, compatible materials, and an appropriate pressure rating for the system.
The connection should engage smoothly by hand and seat on the flare, not bind in the threads. The seal is made at the flare faces, so those faces must be clean, undamaged, and matched.
When Not to Substitute
Do not substitute if the fitting uses a different seat angle, a different thread system, or an unknown material or pressure class. Do not assume an aircraft or motorsport-style AN fitting is automatically suitable for every hydraulic circuit.
Before replacing a JIC part with an AN part, confirm the dash size, thread diameter, pitch, seat angle, seal condition, material, pressure rating, and system fluid. If any of those points are uncertain, use the specified JIC replacement instead of treating AN as a universal substitute.