AN Unions, Couplers & AN Fittings

An AN fitting is a threaded connector used to join flexible hoses as well as rigid metal pipe 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 is equal to 8/16", or 1/2" tubing size. The fitting is flared at a 37 degree angle. An AN hose fitting involves 2 pieces, which includes 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 and 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:

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. If the AN hose needs to be adapted to a hard line, a tube fitting is needed. 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. When properly tightened, the brass ferrule is squished, 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.

A JEGS expert is ready to answer your questions and help you find the AN fittings or AN union fitting that you require for your specific application.