The flare angle required for aluminum tubing used with AN fittings is which degree value?

The flare angle required for aluminum tubing used with AN fittings is which degree value?

• A. 33 degrees
• B. 45 degrees
• C. 30 degrees
• D. 37 degrees

Answer: (D)

AN fittings with aluminum tubing use a 37-degree flare. The tube end is formed into a 37-degree cone so it seats against the corresponding 37-degree surface inside the fitting. When the nut is tightened, the flare is pressed into that seat, creating a tight metal-to-metal seal that resists vibration and temperature changes. If the flare angle isn’t 37 degrees, the surfaces won’t contact properly and the joint won’t seal reliably. So the required flare angle is 37 degrees.

AN fittings with aluminum tubing use a 37-degree flare. The tube end is formed into a 37-degree cone so it seats against the corresponding 37-degree surface inside the fitting. When the nut is tightened, the flare is pressed into that seat, creating a tight metal-to-metal seal that resists vibration and temperature changes. If the flare angle isn’t 37 degrees, the surfaces won’t contact properly and the joint won’t seal reliably. So the required flare angle is 37 degrees.