Joining tubes


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

Single flaring is the most used and the simplest process of flaring The single flare is available in both 37 and 45 degrees. There are two ways to accomplish a flared tube end - rotary or spinning, and a ram forming the flared end.

If you flare the tubing properly with the proper tools (best pipe cutter) and right technique you'll get the leak-proof joint Firstly, you need to cut the tubing to the proper length using the appropriate tool. Second thing is to slide the compression nut on the tubing. The last step is to use a flaring tool kit to make a flaring itself.

If the tube ends are subjected to stress and fatigue the Double-lap flaring will offer additional strength. 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. Double-lap flaring usually is formed in the same shapes and meets the same specifications as the Single Flare.

Different sizes of tubes require specific sets of equipment, but most flaring kits are easy to find and relatively inexpensive. To cut a tube the special cutting tool is used. A flaring tool kit usually consists of two main pieces - a reamer and a flare form. 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 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. The AN/JIC style generally has a higher pressure rating for a given size tubing. SAE and AN/JIC connections are completely incompatible due to the different flare angle. The hydraulic hoses are usually 37-1/2° flare connections, and the refrigeration and air conditioning industry usually uses 45° flare connections. According to NFPA 54/ANSI. Z223.1 National Fuel Gas Code, copper tubes used for natural gas, Liquefied Petroleum, or propane may use flared brass fittings of single 45°-flare type 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