Pioneer Industries is a globally renowned manufacturer and exporter of Brass Flare Nuts, engineered to provide high-torque mechanical clamping for 45° flared copper, brass, and aluminum tubing in high-pressure refrigeration, HVAC, and industrial piping circuits.
The Brass Flare Nut manufactured by Pioneer Industries is the indispensable mechanical clamping component of any 45° SAE flared tubing assembly. Featuring precision-tapped Unified National Fine (UNF) straight female threads and a carefully contoured internal 45-degree thrust shoulder, this nut slides over the tubing prior to flaring and threads onto the male fitting body, exerting immense, uniform axial clamping force against the flared tube lip.
Engineered to SAE J512, SAE J513, and ASME B16.26 refrigeration standards, our brass flare nuts are precision CNC-turned from high-tensile extruded brass bar stock (BS 249 / CW614N / ASTM B16 C36000) or hot-forged brass blanks (BS 218 / CW617N). The high-density metallurgy prevents thread stripping, flaring bell-mouthing, and stress-cracking under heavy wrenching torque and cyclic thermal conditions.
Pioneer Industries exports millions of Brass Flare Nuts annually to commercial refrigeration manufacturers, air conditioning OEMs, automotive brake line builders, and plumbing distributors across more than 85 countries worldwide. Large inventory reserves in Mumbai guarantee rapid dispatch of standard fractional sizes from 1/8" to 3/4" tube OD.
Every batch is manufactured under an ISO 9001:2015 certified quality system. Thread pitch tolerances, bore concentricity, and internal shoulder angles are verified using computerized optical measurement systems. Dispatched lots are certified with EN 10204 Type 3.1 material test certificates.
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The integrity of a 45° flare joint depends directly on the quality of the flare nut. Poorly machined nuts with eccentric bores, rough internal shoulders, or undersized hex flats lead to uneven tube compression, galling, and catastrophic refrigerant leaks. Pioneer Industries’ Brass Flare Nut is engineered with a micro-smooth internal 45° bevel that supports the back of the copper flare uniformly around its entire 360-degree perimeter.
Our nuts are manufactured with precision Class 2B threads that engage smoothly by hand, eliminating cross-threading risks during awkward field installations. When tightened to specified torque, the nut creates an impenetrable metal-to-metal wedge seal between the tube flare and the male cone, operating reliably up to 5,000 PSI across temperatures from -54°C to +121°C.
Pioneer Industries manufactures Brass Flare Nuts in standard fractional sizes from 1/8" to 3/4" tube OD with SAE UNF straight female threads. Operating pressures up to 5,000 PSI (345 bar). Conforms to SAE J512, SAE J513, ASME B16.26, and ASTM B16 standards.
Explore comprehensive engineering dimensional configurations for Fractional Inch Series, Metric Series, and Certified Material Specifications. Manufactured according to SAE J512, SAE J513, ASME B16.26, and international standards.
| Part No. | Tube O.D. (T) | Straight Thread (UNF) | Hex Size (F) | Overall Length (L) | Bore Dia (D) | Weight (approx) | Working Pressure |
|---|---|---|---|---|---|---|---|
| PI-FN-02 | 1/8" | 5/16-24 UNF | 3/8" | 0.50" | 0.130" | 12 g | 5,000 PSI |
| PI-FN-03 | 3/16" | 3/8-24 UNF | 7/16" | 0.56" | 0.193" | 16 g | 5,000 PSI |
| PI-FN-04 | 1/4" | 7/16-20 UNF | 9/16" | 0.62" | 0.256" | 24 g | 5,000 PSI |
| PI-FN-05 | 5/16" | 1/2-20 UNF | 5/8" | 0.69" | 0.318" | 32 g | 4,500 PSI |
| PI-FN-06 | 3/8" | 5/8-18 UNF | 3/4" | 0.81" | 0.382" | 48 g | 4,000 PSI |
| PI-FN-08 | 1/2" | 3/4-16 UNF | 7/8" | 1.00" | 0.507" | 76 g | 3,500 PSI |
| PI-FN-10 | 5/8" | 7/8-14 UNF | 1-1/16" | 1.12" | 0.632" | 115 g | 3,000 PSI |
| PI-FN-12 | 3/4" | 1-1/16-14 UNS | 1-1/4" | 1.38" | 0.758" | 185 g | 2,500 PSI |
| Part No. | Tube O.D. (mm) | Thread Profile (UNF) | Hex Size (mm) | Overall Length (mm) | Bore Dia (mm) | Weight (g) | Working Pressure (bar) |
|---|---|---|---|---|---|---|---|
| PI-FN-M06 | 6 mm | 7/16-20 UNF | 14 mm | 15.8 mm | 6.2 mm | 24 g | 345 bar |
| PI-FN-M08 | 8 mm | 1/2-20 UNF | 16 mm | 17.5 mm | 8.2 mm | 32 g | 310 bar |
| PI-FN-M10 | 10 mm | 5/8-18 UNF | 19 mm | 20.6 mm | 10.2 mm | 48 g | 276 bar |
| PI-FN-M12 | 12 mm | 3/4-16 UNF | 22 mm | 25.4 mm | 12.3 mm | 76 g | 241 bar |
| PI-FN-M16 | 16 mm | 7/8-14 UNF | 27 mm | 28.5 mm | 16.3 mm | 115 g | 206 bar |
| PI-FN-M18 | 18 mm | 1-1/16-14 UNS | 32 mm | 35.0 mm | 18.4 mm | 185 g | 172 bar |
| Component | Material Specification | Standard Specification | Chemical Composition | Mechanical Properties | Temperature Limits | Key Features |
|---|---|---|---|---|---|---|
| Precision Extruded Nut Body | Forging Brass (BS 218 / CW617N) | BS EN 12165 / ASTM B283 C37700 | Cu: 57.0–59.0%, Pb: 1.6–2.5%, Zn: Rem. | Tensile ≥ 440 MPa, 110–150 HB | -54°C to +121°C | Contoured grain flow, dense wall structure, zero porosity, high shock resistance |
| Internal 45° Thrust Shoulder | Free Cutting Brass (BS 249 / CW614N) | IS 319 Gr. 1 / ASTM B16 C36000 | Cu: 58.0–60.0%, Pb: 1.5–3.0%, Zn: Rem. | Tensile ≥ 400 MPa, 100–140 HB | -54°C to +121°C | Precision CNC machining, exact 45° cone angle, micro-inch surface finish |
| SAE Flare Nut | Extruded Brass / Forged Brass | SAE J512 / SAE J513 / ASTM B16 | Cu: 58.0–61.0%, Zn: Rem. | Tensile ≥ 380 MPa | -54°C to +121°C | Short and long skirt options, internal 45° beveled shoulder for tube support |
| Tubing Interface | Flared Copper / Brass Tube | ASTM B88 / ASTM B280 / ASTM B135 | Cu ≥ 99.9% (DHP) | Soft Annealed Temper | -54°C to +121°C | 100% metal-to-metal seal, zero elastomeric degradation in refrigerants/LPG |
Brass Flare Nut fittings find deployment across demanding thermal, fluid, and gas piping circuits:
Connects indoor and outdoor unit interconnecting refrigerant copper line sets.
Clamps suction, discharge, and liquid lines on supermarket display cases and walk-in freezers.
Secures flared copper tubing in residential and commercial liquefied petroleum gas distribution.
Provides vibration-resistant tube fastening on commercial truck hydraulic brake circuits.
Fastens flared tubing lines inside industrial automation and robotic control cabinets.
Secures high-pressure copper-nickel pilot control lines on mobile and industrial hydraulic systems.
Connects copper pilot feed tubes to main burner control valves.
Fastens flared copper piping on marine condenser and refrigeration seawater loops.
Pioneer Industries’ Brass Flare Nut are widely used in numerous industries like:
Expert engineering insights and technical guidance regarding design specifications, pressure tolerances, flare cone sealing mechanics, tubing compatibility, and installation best practices for industrial Brass Flare Nut.
A Brass Flare Nut is a mechanical threaded sleeve that slides over tubing prior to flaring. When threaded onto a male flare fitting, its precision internal 45-degree shoulder pushes against the back of the flared copper tube, driving the front face of the flare into firm, leak-tight metal-to-metal contact with the male 45° cone.
No. The bore of the flare nut is sized just slightly larger than the tube outer diameter, and smaller than the flared lip. Therefore, the nut MUST be slipped onto the tubing before flaring. Forgetting to install the nut before flaring is a common field error that requires cutting the flare and re-doing it.
Brass Flare Nuts utilize Unified National Fine (UNF) straight threads adhering to SAE J512 and SAE J513 standards. These straight threads generate axial clamping force and are not designed to seal along thread flanks.
No. Applying thread sealant or PTFE tape to flare nut threads is unnecessary and discouraged. Sealing is 100% metal-to-metal between the flared copper lip and the male brass cone. Sealant on threads can introduce friction errors during torquing or contaminate the piping system.
Recommended tightening torque values: 1/4" tube: 10–15 ft-lbs (14–20 N-m); 3/8" tube: 20–30 ft-lbs (27–41 N-m); 1/2" tube: 35–50 ft-lbs (47–68 N-m); 5/8" tube: 50–65 ft-lbs (68–88 N-m); 3/4" tube: 75–90 ft-lbs (102–122 N-m).
Over-tightening can thin, deform, or split the copper flare lip, or crack the internal 45° shoulder of the nut. Always use a calibrated torque wrench or follow standard manufacturer turn recommendations (typically 1/6 to 1/4 turn past hand-tight).
Our flare nuts are machined from high-tensile BS 249 / CW614N (ASTM B16 C36000) extruded brass bar or hot-forged BS 218 / CW617N brass, providing tensile strength exceeding 400 MPa and superior resistance to stress cracking.
Yes. Our flare nuts are engineered with heavy wall thicknesses and reinforced hex shoulders specifically rated for the elevated pressures of modern R-410A and R-32 systems (operating pressures up to 600+ PSI, burst rated above 5,000 PSI).
Yes. A flare nut can be reused multiple times provided its threads are clean and undamaged, the hex flats are not stripped, and the internal 45° shoulder is smooth and free from cracks or deep gouges.
Pioneer Industries supplies EN 10204 Type 3.1 Mill Test Certificates verifying raw material chemical composition, mechanical properties, and dimensional conformity with each shipment.
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