Flare fittings are a type of

compression fitting A compression fitting is a fitting used in plumbing and electrical conduit systems to join two tubes or thin-walled pipes together. In instances where two pipes made of dissimilar materials are to be joined (most commonly PVC and copper), the ...

used with metal tubing, usually soft steel, ductile (soft) copper and aluminum, though other materials are also used. In a flare fitting the tube itself is "flared" i.e. expanded and deformed at the end. The flare is then pressed against the fitting it connects to and is secured by a close-fitting nut that ensures that no leakage happens. Tube flaring is a type of

forging Forging is a manufacturing process involving the shaping of metal using localized compressive forces. The blows are delivered with a hammer (often a power hammer) or a die. Forging is often classified according to the temperature at which i ...

operation, and is usually a

cold working In metallurgy, cold forming or cold working is any metalworking process in which metal is shaped below its recrystallization temperature, usually at the ambient temperature. Such processes are contrasted with hot working techniques like hot r ...

procedure. During assembly, a flare nut is used to secure the flared tubing's tapered end to the also tapered fitting, producing a pressure-resistant, leak-tight seal. Flared connections offer a high degree of long-term reliability and for this reason are often used in mission-critical and inaccessible locations. The tool used to flare tubing consists of a die that grips the tube and either a

mandrel A mandrel, mandril, or arbor is a gently tapered cylinder against which material can be forged or shaped (e.g., a ring mandrel - also called a triblet - used by jewelers to increase the diameter of a wedding ring), or a flanged or tapered or ...

or rolling cone is forced into the end of the tube to form the flare by cold working. The most common flare fitting standards in use today are the 45° SAE flare, the 37° JIC flare, and the 37° AN flare. SAE 45° flare connections are commonly used in automotive applications as well as for refrigeration and air conditioning. SAE fittings are typically made from brass. SAE and AN/JIC connections are incompatible due to the different flare angle. JIC 37° flare connections are used in higher pressure hydraulic applications. JIC fittings are typically steel or stainless steel. JIC fittings are not permissible where AN connections are specified, due to differing quality standards. AN 37° flare connections are typically specified for military and aerospace applications. Fittings can be made from a large variety of materials. The “AN” standard (for Army/Navy) has been replaced by other military and aerospace standards, though in practice these fittings are still referred to as AN. Flared fittings are an alternative to solder-type joints that is mechanically separable and doesn’t require an open flame. Copper tube used for propane,

liquefied petroleum gas Liquefied petroleum gas (LPG or LP gas) is a fuel gas which contains a flammable mixture of hydrocarbon gases, specifically propane, propylene, butylene, isobutane and n-butane. LPG is used as a fuel gas in heating appliances, cooking e ...

, or natural gas may use flared brass fittings of single 45°-flare type, according to NFPA 54/ANSI. Z223.1 National Fuel Gas Code. Many plumbing codes, towns, and water companies require copper tube used for water service to be type-L or type-K. All National Model Codes permit the use of flare fitting joints, however, the authority having jurisdiction (AHJ) should be consulted to determine acceptance for a specific application.Copper Development Association: Flared Joint
Flared Joints
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References

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External links

Flared JointsSAE thread chart
showing the dimensions of tubing and fittings
JIC thread chart
showing the dimensions of tubing and fittings Plumbing

See also

References

External links