AN Unions, Couplers & AN Fittings

AN fittings are threaded connectors used to join flexible hoses and rigid metal pipes that carry fluid. AN fittings were created during World War II by the Army and Navy and thus named "AN fitting." After WWII, the fittings were used throughout the aviation and automotive performance industry and are still used today. AN fittings are usually made from stainless steel, aluminum or steel. Sizes range from -2 through -32, typically in even steps, with each step equating to 1/16" for the measurement of the outside diameter of the tubing. For example, a "-8" fitting equals 8/16" or 1/2" tubing size. The fitting is flared at a 37-degree angle. An AN hose fitting involves two pieces, including a socket and a nipple. The socket fits onto the end of the hose, and the nipple fitting pushes into the hose end, meeting up with the socket. The two pieces are joined together via threads. Once tight, the connection is complete as the hose is squeezed between the two. AN fittings can be used for the radiator, engine oil, fuel, brake, hydraulic clutch, and other performance plumbing systems. An AN union is a connector that is typically male or female on both ends, joining two hoses or other connectors.

AN fittings are measured by the thread size:

AN fittings are also measured by the equivalent tubing OD size:

To connect an AN fitting fuel line, first determine what connector is needed to adapt the fuel line to the component it needs to join with. Often, the component has NPT threads. This requires an AN to NPT adapter. A tube fitting is needed if the AN hose needs to be adapted to a hard line. This 3-piece fitting works by sliding the socket over the hardline, then the brass ferrule/olive is moved over the hard line. Finally, the male threaded fitting is tightened to the socket. The brass ferrule is squished when properly tightened, creating a leak-proof seal. In all cases, the fittings are tightened with a wrench. Aluminum wrenches are preferred as they are softer than steel and will not scratch anodized surfaces as much.

If you still have more questions about our selection of AN fittings, couplers and unions, a JEGS expert is here to help. When you contact our expert team, you'll get all the information you need to help you find the AN fittings or AN union fitting you require for your specific application.