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Joining tubes

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Mechanical joint is sometimes required or preferred to join copper or steel tubes together, instead of brazing, soldering, or welding. One of the ways to join tubes mechanically is flaring. The process called flaring is a tube’s end forming, used for creating a gas- or liquid-tight connection.

The 45-degree SAE style, and the 37-degree AN style, also used with the JIC system are the common standards for flare tube ends and flare fitting in use today. For a given size, the AN/JIC style tubing generally has a higher pressure rating SAE and AN/JIC connections are completely incompatible due to the different flare angle. The refrigeration and air conditioning industry usually uses 45° flare connections while hydraulic hoses are usually 37-1/2° flare connections. A copper tube used for propane, LP, or natural gas may use flared brass fittings of single 45°-flare type, according to NFPA 54/ANSI. Z223.1 National Fuel Gas Code. Nevertheless, all National Model Codes permit the use of flare fitting joints, the one should be consulted by the authority having jurisdiction (AHJ) to determine acceptance for a specific application

Double-lap flaring offers additional strength for tube ends, that are subjected to more fatigue and stress. The joint is designed so that the inside surface of the flare has a larger diameter so it does not interfere with flow characteristics of the system. To meet the same specifications as the Single Flare, Double-lap flaring can be formed in the same shapes.

Most of flaring kits are relatively inexpensive and easy to find, despite the fact that different sizes of tubes require specific sets of equipment. You need to use a proper cutting tool to cut a tube. A common flaring tool kit has two main parts – a flare form and a reamer. A flare form is some kind of a clamp which has a number of holes designed to work with tubing of various diameter. The tubing is firmly held by the flare form, allowing you to flare the pipe using minimum strength The thing that makes the actual flaring is reamer, which has holding arms, a screw, and a conical point.

The simplest and the most used technique of flaring is called a single flaring. Both 37 and 45-degree single flares options are available. Rotary or spinning the flared end, and a ram forming are two available ways to accomplish single flared tube end.

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