Which coupling nut should be selected for use with 1/2 inch aluminum oil lines assembled using flared tube ends and standard AN nuts, sleeves, and fittings?

Which coupling nut should be selected for use with 1/2 inch aluminum oil lines assembled using flared tube ends and standard AN nuts, sleeves, and fittings?

• A. AN-818-4
• B. AN-818-6
• C. AN-818-8
• D. AN-818-10

Answer: (C)

In AN flare fittings, the nut size is chosen to match the outside diameter of the tubing. The nut, sleeve, and flare are a coordinated set, so each part must fit the tube it’s paired with to form a proper seal. For a 1/2 inch aluminum oil line, you use the coupling nut that is specifically made for that tubing size. This ensures the nut threads correctly, the sleeve seats properly, and the flare is compressed to create a leak-tight connection. Using a nut intended for a smaller tube would not fully enclose the flare and could leak, while a nut intended for a larger tube might not align or thread correctly. Therefore, select the nut designed for 1/2 inch tubing.

In AN flare fittings, the nut size is chosen to match the outside diameter of the tubing. The nut, sleeve, and flare are a coordinated set, so each part must fit the tube it’s paired with to form a proper seal. For a 1/2 inch aluminum oil line, you use the coupling nut that is specifically made for that tubing size. This ensures the nut threads correctly, the sleeve seats properly, and the flare is compressed to create a leak-tight connection. Using a nut intended for a smaller tube would not fully enclose the flare and could leak, while a nut intended for a larger tube might not align or thread correctly. Therefore, select the nut designed for 1/2 inch tubing.