AN Fittings and Adapters: What They Are

AN fittings and adapters come from the Army-Navy standard family and are widely associated with fluid lines, flexible hoses, and metal tubing. AN fittings, AN thread sizes, and AN adapters are connection details that help join hose and tube assemblies.

For hydraulic buyers, the important point is that AN language often appears near JIC language, but the application and specification still have to be confirmed before substituting parts.

What AN means

AN stands for Army-Navy. The connection family is commonly used in aerospace, racing, performance, and other fluid transfer applications. AN fittings are often identified by dash size, with the dash number tied to tube or hose size increments.

AN fittings are parts used to connect flexible hoses and fluid-carrying metal tubing. That makes them similar in purpose to many hydraulic fittings, but the service conditions, material, pressure, and standards still matter.

AN thread sizes

AN sizing uses dash numbers. The buyer should not treat the dash number as the only detail needed for ordering. The thread size, gender, seat, body style, hose compatibility, material, and rating all need to match.

AN size tables connect AN dash sizes with SAE thread references. Tables are useful, but the old part and mating component should still be measured and inspected because labels, aftermarket parts, and worn fittings can create confusion.

AN adapters

AN adapters are used to connect AN ends to other connection styles or to change size, shape, or direction. An adapter may connect an AN hose end to a pipe thread, port, tube connection, or another fitting family.

That adapter is only correct if both sides are correct. One side may follow AN expectations, while the other side may be NPT, BSP, ORB, JIC, metric, or another standard.

AN and JIC comparison caution

AN and JIC fittings are often compared because both are associated with a 37 degree flare. They should not be treated as automatically interchangeable without checking thread class, tolerances, application requirements, pressure rating, and material.

A part may physically connect while still being outside the intended specification. That matters when the line carries hydraulic pressure, fuel, oil, air, or another fluid where leakage is not acceptable.

Where AN language appears in sourcing

AN terminology often appears in performance, racing, aerospace, marine, and custom hose assembly work. Hydraulic buyers may see an AN label when a machine has been modified, when a custom line was installed, or when a supplier uses AN and JIC language loosely.

That does not make the part wrong, but it does mean the buyer should slow down and confirm the actual standard. The safest request includes photos, dash size, thread measurement, hose type, fluid, pressure, and whether the fitting was originally specified as AN or only described that way by a prior repair.

Fluid and material still matter

AN fittings may be aluminum, steel, stainless steel, or another material depending on the application. A lightweight aluminum part that works in one fluid line is not automatically correct for a high-pressure hydraulic circuit. Material, plating, temperature, and fluid compatibility should be checked with the same care as the thread.

If the original assembly used a colored aluminum fitting, do not assume the color identifies the standard or pressure rating. Treat it as a visual clue only, then measure and verify the specification.

Ordering checks

Before ordering AN fittings or adapters, record dash size, thread size, gender, flare or sealing style, hose or tube size, material, pressure, temperature, fluid, and the connection on the other end.

If the old fitting came from performance, aerospace, or a specialized assembly, keep the original specification in the order notes. The safest replacement matches both the geometry and the service requirement.