We are a brass flare nut manufacturer and produce custom flare nuts according to customer drawings and samples. We support custom thread size, hole, dimensions, and design as per buyer requirements. For flare nut material, we make it according to the customer's required grade, but if the grade is not mentioned in the drawing, then our default grade is IS 319 Type 1 free-cutting brass. We use CNC turning, threading, boring, and machining according to the flare nut design. We support both inch and metric thread configuration.
We manufacture custom brass flare nuts in various designs such as short flare nut, long flare nut, inverted flare nut, and reducing flare nut. Our brass flare nuts are used in refrigeration, air conditioning, fuel and gas lines, and automotive systems.
We support prototypes, as well as medium- to high-volume repeat orders. We supply brass flare nuts to customers in the USA and across European markets, including Germany, France, Spain, the Czech Republic, the Netherlands, the UK, and Italy.
Request a Quote for Custom Brass Flare NutsA brass flare nut is an internally female-threaded nut used with a flared tube and a compatible flare fitting body. The nut is placed on the tube before the tube end is flared. During assembly, the nut draws the flared tube against the mating fitting seat. This produces the sealing contact at the flare interface and is used for a metal-to-metal flare connection.
Material: Brass IS 319 Grade 1
Flare Nut Size: 5/8 inch
Thread: 7/8"-14 UNF
Thread OD: 20.3 mm
Hole: 16.2 mm
Overall Height: 22.5 mm
Tube OD: 15.88 mm
We manufacture this brass flare nut for 5/8 inch tubing with a 7/8"-14 UNF thread, 20.3 mm thread OD, 16.2 mm hole, and 22.5 mm overall height. The flare nut fits a 15.88 mm tube outside diameter for tube connection applications.
Material: Brass IS 319 Grade 1
Flare Nut Size: 3/8 inch
Thread: 5/8"-18 UNF
Thread OD: 14.5 mm
Hole: 9.7 mm
Overall Height: 18 mm
Tube OD: 9.52 mm
Custom brass flare nut for 3/8 inch tubing with a 5/8"-18 UNF thread, 14.5 mm thread OD, 9.7 mm hole, and 18 mm overall height. The brass flare nut accommodates a 9.52 mm tube outside diameter for copper tube connection.
| Item | Specification |
|---|---|
| Material | Brass, including C36000, CW614N / CuZn39Pb3, IS 319 Grade 1, and customer-specified brass grades |
| Manufacturing Process | CNC turning, drilling and boring, thread machining, secondary machining, and machining of forged blanks for forged designs |
| Flare Type | SAE 45° flare, inverted flare, refrigeration flare designs, and customer-specified flare designs |
| Flare Nut Designs | Short, long, forged, reducing, inverted-flare, and custom designs |
| Tube OD | According to the specified tube outside diameter and flare system |
| Thread Size | According to tube OD, flare system, thread diameter, thread pitch, and customer drawing |
| Dimensions | Tube OD, thread diameter, thread pitch, hex size, nut length, bore, and other drawing dimensions |
| Surface Finish | Natural brass, tin plating, tumbled finish, and customer-specified finishes |
| Tolerance | According to customer drawing, with tighter tolerances for specified critical dimensions |
| Inspection | Dimensional and thread inspection according to drawing requirements, using calipers, thread gauges, and other suitable measuring equipment |
| Material Certification | Available on request, according to order requirements |
| Drawing Formats | STEP, PDF, DXF, DWG, and customer-specified formats |
| Packaging | Poly bags, boxes, master cartons, pallets, and custom packaging |
| MOQ | Based on part geometry, material, tooling, quantity, and production requirements |
| Lead Time | According to the quantity |
We make different types of brass flare nuts, such as brass SAE 45° short flare nut, brass SAE 45° long flare nut, brass reducing flare nut, and brass inverted flare nut, according to customer requirements. Common brass flare nut tube sizes are 1/4 inch (6.35 mm), 3/8 inch (9.52 mm), 1/2 inch (12.7 mm), and 3/4 inch (19.05 mm).
Brass short flare nuts are used with compatible 45° flared tubing and fitting bodies. The nut clamps the tube flare against the fitting seat to form the required metal-to-metal connection. We manufacture short flare nuts in different thread configurations according to the requirements.
Long brass flare nuts have an extended body compared to short flare nuts, and they provide greater support to the tube than short flare nuts. They are used in applications that need additional tube support in higher-vibration assemblies.
A reducing flare nut accommodates different connection sizes within the flare arrangements and is used in flare connections that require different tube sizes. The sizes must match the specified mating fitting and tubing. Common sizes are 5/16 × 1/4, 3/8 × 1/4, 1/2 × 3/8.
An inverted flare nut is designed for an inverted-flare tube connection. The tubing is formed into an inverted flare before assembly, and the nut secures the tube against the mating seat.
Brass flare nut size is identified mainly by the tube outside diameter and the thread used with the mating flare fitting. The correct flare nut must match the tube OD, flare system, thread diameter, thread pitch, and mating fitting. SAE 45° flare and inverted flare both use different thread combinations. SAE 45° flare and inverted flare can share thread combinations for some tube sizes and use different thread combinations for others.
| Tube OD | Inch-to-millimeter conversion | SAE 45° Thread Size |
|---|---|---|
| 1/8 in | 3.18 mm | 5/16-24 |
| 3/16 in | 4.76 mm | 3/8-24 |
| 1/4 in | 6.35 mm | 7/16-20 |
| 5/16 in | 7.94 mm | 1/2-20 |
| 3/8 in | 9.52 mm | 5/8-18 |
| 7/16 in | 11.11 mm | 11/16-16 |
| 1/2 in | 12.70 mm | 3/4-16 |
| 5/8 in | 15.88 mm | 7/8-14 |
| 3/4 in | 19.05 mm | 1-1/16-14 |
We manufacture brass short and long flare nuts for different SAE tube sizes. The thread size corresponds to the specified tube OD and flare system, and the nut length changes between the short and long designs.
| Tube OD | Inch-to-millimeter conversion | SAE Inverted Flare Thread |
|---|---|---|
| 1/8 in | 3.18 mm | 5/16-28 |
| 3/16 in | 4.76 mm | 3/8-24 |
| 1/4 in | 6.35 mm | 7/16-24 |
| 5/16 in | 7.94 mm | 1/2-20 |
| 3/8 in | 9.52 mm | 5/8-18 |
| 7/16 in | 11.11 mm | 11/16-18 |
| 1/2 in | 12.70 mm | 3/4-18 |
| 5/8 in | 15.88 mm | 7/8-18 |
| 3/4 in | 19.05 mm | 1-1/16-16 |
To choose the correct brass flare nut, check the tube outside diameter, flare system, thread diameter, thread pitch, and mating fitting. Tube OD and nut thread size are different dimensions, so both must match the fitting system. Tube material, wall thickness, pressure, temperature, and installation conditions should also match the fitting specification.
Measure the actual tube OD.
Determine whether the connection uses SAE 45°, SAE inverted flare, a refrigeration flare system, a metric automotive flare system, or another specified system.
Measure thread diameter and pitch using a caliper and thread gauge.
The nut must match the fitting body and flare geometry.
The tube must be suitable for the specified flare operation and service conditions.
We manufacture brass flare nuts as per the customer's requirements mentioned in the drawing. If the flare nut brass grade is not mentioned in the product drawing, then our default brass grade is IS 319 Grade 1 free-cutting brass.
UNS C36000 is a recognized U.S. free-cutting brass grade. It is commonly used for screw-machine parts and is available in rod, bar, wire, and shape forms.
CW614N / CuZn39Pb3 is a European free-machining brass grade.
IS 319 is an Indian Standard for free-cutting brass supplied as bars, rods, and sections.
We manufacture brass flare nuts according to customer drawings, material grade, dimensions, thread, and flare type. Depending on part requirements, we choose a production route of forging or machining from brass rod. Our main manufacturing operations include material preparation, forging when required, machining, threading, deburring, finishing, inspection, and packaging.
Our first step for manufacuring process starts with a review of the customer drawing and details. We check all details, including brass grade, tube OD, thread size and pitch, hex, nut length, flare type, tolerances, and surface finish, before production starts.
Next, we follow the brass grade according to customer requirements from the product drawing. We purchase material from our trusted supplier. Depending on the flare nut design, the supplier provides brass bar, forged blanks, and cast blanks for further machining. We verify the required alloy, grade, material condition, and diameter.
After material purchase, we perform CNC machining according to the product drawing. CNC turning and related machining operations can produce the outer profile, hex size, overall length, tube-side bore, internal clearance, and other parts features according to the nut design.
We machined internal threads according to the required thread standard, diameter, and pitch as per the product drawing.
We perform additional secondary machining according to the flare nut design. This can include chamfers, counterbores, reducing features, special body dimensions, and other custom details in the drawing.
After machining, burr and loose machining debris are removed from the flare nut. We clean parts so threads, bores, and finished surfaces are free from material that could interfere with assembly.
Surface finishing depends on the customer drawing. Natural brass, Tin plating, nickel plating, and tumbled finish according to requirements.
We inspected the flare nut against the customer drawing. Depending on the part requirements, inspection can include overall dimensions, hex size, bore dimensions, thread diameter, thread pitch, thread fit, and other critical features. Thread gauges and caliper and other measurement equipment can be used according to requirements.
After inspection, the final step is final inspection and packaging. Standard packaging includes a poly bag, a small box, a master box, and a wooden pallet for sea route. Custom labeling and packaging are also supported according to customer requirements.
Brass flare nuts are used in flared tube connections for refrigeration, air conditioning, fuel, gas, automotive, hydraulic, and pneumatic applications.
Brass refrigeration flare nuts are commonly used in refrigeration and air-conditioning tubing connections. They are used for refrigerant line and service connections with compatible flared tubing and fitting bodies.
Brass flare nuts are used in LP gas, natural gas, propane, and fuel and gas line applications.
Brass flare nuts and inverted-flare tube fittings in automotive tube connections. Brass inverted-flare tube nuts are commonly used in brake line fittings.
Brass flare nuts are used in hydraulic and pneumatic tube connections.
A brass flare nut holds the flared end of the tube against the matching seat in the fitting body. When the nut is tightened correctly, the tube flare is clamped against the fitting seat to form a metal-to-metal sealing interface. The nut thread provides the clamping force; the flare provides the sealing surface.
Yes, when the flare nut and fitting are designed for the selected tube material and flare system. Brass SAE 45° flare products are available for use with copper and aluminum tubing. The tube outside diameter, flare type, fitting design, and application requirements must match the selected connection.
Some SAE 45° flare products are designed for repeated assembly and disassembly. Before reuse, the nut threads, fitting seat, and tube flare should be checked for damage. Reuse also depends on the product specification and the application.
A flare connection can leak when the tube flare is damaged, incorrectly formed, contaminated, misaligned, or tightened incorrectly. A damaged fitting seat can also cause leakage. Overtightening can damage the fitting or split the tubing at the flare. Check the tube flare, fitting seat, alignment, and tightening method before reassembling the connection.
No, a standard flare connection does not use PTFE tape or pipe sealant on the flare sealing surface. The seal is made at the tube flare and fitting seat when the connection is tightened correctly. Any separate pipe-thread connection on an adapter follows the sealing requirements for that thread type.
Both connection types use a 45° tube flare, but the fitting geometry is different. A standard 45° flare connection clamps the tube flare against the fitting body seat. An inverted flare fitting places the sealing interface inside the fitting body.
To request a brass flare nut quotation, send your drawing and RFQ details.
Please include:
Send your RFQ and drawings to receive a quotation with pricing and indicative lead time.
