AN Fuel Line Fittings — 37° JIC Flare

AN (Army-Navy) fittings — formally specified as SAE AS4395 — use a 37° JIC (Joint Industry Council) flare instead of the 45° flare used in HVACR. The 37° angle was selected by the US military during WWII for higher pressure capability and reduced sensitivity to over-tightening — and AN fittings remain the standard for high-pressure hydraulic, fuel-line, oil, brake, and power-steering plumbing in motorsport, military, aerospace, and high-performance automotive applications. Our brass AN fittings are CNC-machined from C36000 free-machining brass to SAE AS4395 dimensional requirements, with the 37° conical face finished to mirror smoothness for reliable leak-tight sealing at pressures up to 3,000 PSI. The standard AN size system uses dash numbers (-4 through -12 for our range) where each dash represents 1/16" tubing OD: -4 AN = 1/4" OD tubing, -6 AN = 3/8" OD, -8 AN = 1/2" OD, -10 AN = 5/8" OD, -12 AN = 3/4" OD. Threads are UNF (Unified National Fine) to SAE specifications — distinct from NPT or BSP — and use the 37° conical face for sealing rather than thread interference. AN fittings are reusable: the flare on the tubing can be re-mated multiple times without sealant or thread tape. Our standard AN range includes male and female straight unions, 45° and 90° elbows, tees, crosses, AN-to-NPT and AN-to-O-ring boss (ORB) adapters, swivel adapters, bulkhead fittings for firewall pass-throughs, and reducing unions for mixed-size connections. Anodized aluminum colored AN nuts and adapters available for retail motorsport applications (red, blue, black). Custom finishes (gold, satin, polished) on request.