Which action best describes the purpose of two-piece tube connectors (sleeve and nut flare)?

• A. Eliminate the possibility of reducing the flare thickness by wiping or ironing during tightening
• B. Prevent leaking by using a sealant
• C. Allow easier bending at the joint
• D. Reduce overall assembly weight

Answer: (A)

Two-piece sleeve-and-nut flare fittings are designed to protect the flare from being deformed as the joint is tightened. The sleeve provides support behind the flare, so when you tighten the nut, the flare is pressed and seated correctly without being wiped thinner. Keeping the flare thickness constant is essential because thinning can compromise the seal and allow leaks. In these fittings, the seal is formed by the proper metal-to-metal contact of the flare against its seating surface, not by applying sealant. The design isn’t about easier bending or reducing weight, but about maintaining flare geometry and a reliable seal during tightening. If the flare were thinned, it could fail to seal properly, leading to leaks, which is exactly what this arrangement helps prevent.