What are AN fittings?
The AN thread (also A-N) is a particular type of fitting used to connect flexible hoses and rigid metal tubing that carry fluid. AN fittings are a flare fitting, using 37° flared tubing to form a metal-to-metal seal, meet SAE Aerospace (AS) standards They are similar to other 37° flared fittings, such as JIC, which is their industrial variant. DO NOT use AN fittings with different flare-type fittings. This will cause leaks and damage to the fittings. AN fittings remain prevalent today. However, the U.S. Military is canceling many of the true AN/AND standards and replacing them with AS (Aerospace Standards) standards developed, again, by SAE.
AN fittings differ from commercial threads in that they are class 3 instead of class 2 and generally UNJF rather than commercial UNF. Threadform: UNJ -3A or 3B.
AN fittings range in size from -2 (dash two) to -32 in irregular steps that each equates to the outer diameter of the tubing. The outer diameter of the tube or hose that each fitting is to be used for is correlated with the inner diameter of the fitting itself.
The table below lists the size specifications of AN fittings ranging from dash-two to dash-thirty-two, along with the corresponding SAE thread sizes.
