AN to AN Fitting

AN to AN fittings are adapters with a 37° AN connection at both ends. They join two components or completed hose assemblies that already terminate in AN fittings. Male to male couplers connect two female AN ends, while female to female unions connect two male AN ends.

They are not the same as AN hose fittings. A hose fitting attaches directly to a specific hose construction, such as PTFE, CPE, or push lock hose. An AN adapter connects finished AN ends and does not determine whether the underlying hose is compatible with fuel, oil, coolant, or another fluid.

Identify both sides separately before ordering:

• End A connection type and AN size
• End B connection type and AN size
• Required straight, 45°, 90°, or branching layout
• Product specific fluid, pressure, and temperature rating

Do not identify an AN adapter from hose outside diameter alone. AN dash size is based on nominal tube outside diameter in sixteenths of an inch, while actual hose inside diameter varies by hose construction and manufacturer. Common thread references include 6AN at 9/16 inch 18 UNF, 8AN at 3/4 inch 16 UNF, and 10AN at 7/8 inch 14 UNF. Match both the AN size and the connection gender shown on the product page.

Use a straight union when two aligned AN ends only need to be joined or extended. Choose a 45° or 90° adapter when it creates a smoother route and prevents the hose from kinking or pulling sideways on the fitting. Use a reducer or expander when the two components have different AN sizes, but remember that the smallest internal passage still limits flow.

A tee or Y adapter should only be used when the system design requires a branch. Do not assume that a swivel fitting is a continuously rotating joint. Unless the product description specifically states otherwise, use the swivel feature for alignment during installation, then operate the system with the connection secured and free from movement.

Do not apply thread tape or thread sealant to the flare threads of a true AN fitting. The connection seals where the two 37° metal flare surfaces meet, not at the threads. Sealant cannot repair a scratched, contaminated, or mismatched flare seat and may introduce debris into the system.

A 37° AN flare must not be connected directly to a 45° SAE flare. Although the threads may appear to engage, the sealing surfaces do not match. If a separate adapter has an NPT end, only the NPT side should receive the compatible sealant specified by the component manufacturer.

Relieve system pressure and drain the affected section before starting. Inspect both 37° flare seats and reject a fitting with visible scratches, dents, contamination, or thread damage. Align the components without forcing the hose, start the threads by hand, then support both sides with correctly sized wrenches while tightening to the applicable product instructions.

Do not use extra force to stop a leak because overtightening can damage the flare seat. After assembly, pressure test the completed system and inspect the fitting, hose ends, and nearby adapters at normal operating pressure. If any seepage appears, shut the system down, release pressure, and inspect the sealing surfaces and alignment before attempting to retighten the connection.