Pioneer Industries is a premier manufacturer and exporter of Brass Flare Short Union Nuts, designed with a compact overall body length for tight clearance installations in mini-split air conditioning units, compact refrigeration manifolds, and high-density instrumentation panels.
The Brass Flare Short Union Nut from Pioneer Industries is an ultra-compact mechanical fastener engineered to clamp 45° flared tubing securely in installations with limited spatial clearance. Featuring an abbreviated overall axial body length compared to standard long nuts, the short union nut allows technicians to assemble leak-tight flare connections in tight chassis compartments, compact heat pump service valves, and crowded gauge manifolds where standard nuts would interfere with adjacent tubing or casing walls.
Manufactured strictly in compliance with SAE J512, SAE J513, and ASME B16.26 standards, our short union nuts are precision CNC-machined from high-tensile extruded brass bar stock (BS 249 / CW614N / ASTM B16 C36000). The internal Class 2B Unified National Fine (UNF) straight threads and precision 45-degree thrust shoulder deliver tremendous clamping pressure without distortion or thread stripping.
Pioneer Industries exports Brass Flare Short Union Nuts to air conditioning OEMs, commercial refrigeration contractors, appliance fabricators, and pneumatic skid builders 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 of short union nuts undergoes rigorous automated optical inspection for bore concentricity, thread pitch lead, and thrust shoulder geometry. Complete material traceability is certified through EN 10204 Type 3.1 inspection documents provided with every export shipment.
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In modern high-efficiency HVAC equipment, such as ductless mini-split outdoor condensing units and multi-zone VRF systems, service valves and line-set connections are housed within extremely compact access recesses. Pioneer Industries’ Brass Flare Short Union Nut solves these clearance constraints by minimizing overall length while retaining full thread engagement and wrenching hex width.
Despite its compact profile, the short union nut features a reinforced hex body that withstands full rated assembly torque without spreading or bell-mouthing. The precision 45° internal shoulder provides complete 360-degree contact with the back of the flared copper lip, creating a bubble-tight metal-to-metal seal rated up to 5,000 PSI across temperatures from -54°C to +121°C.
Pioneer Industries manufactures Brass Flare Short Union Nuts in 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-FSN-02 | 1/8" | 5/16-24 UNF | 3/8" | 0.44" | 0.130" | 10 g | 5,000 PSI |
| PI-FSN-03 | 3/16" | 3/8-24 UNF | 7/16" | 0.50" | 0.193" | 14 g | 5,000 PSI |
| PI-FSN-04 | 1/4" | 7/16-20 UNF | 9/16" | 0.56" | 0.256" | 20 g | 5,000 PSI |
| PI-FSN-05 | 5/16" | 1/2-20 UNF | 5/8" | 0.62" | 0.318" | 26 g | 4,500 PSI |
| PI-FSN-06 | 3/8" | 5/8-18 UNF | 3/4" | 0.75" | 0.382" | 40 g | 4,000 PSI |
| PI-FSN-08 | 1/2" | 3/4-16 UNF | 7/8" | 0.88" | 0.507" | 65 g | 3,500 PSI |
| PI-FSN-10 | 5/8" | 7/8-14 UNF | 1-1/16" | 1.00" | 0.632" | 98 g | 3,000 PSI |
| PI-FSN-12 | 3/4" | 1-1/16-14 UNS | 1-1/4" | 1.19" | 0.758" | 150 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-FSN-M06 | 6 mm | 7/16-20 UNF | 14 mm | 14.2 mm | 6.2 mm | 20 g | 345 bar |
| PI-FSN-M08 | 8 mm | 1/2-20 UNF | 16 mm | 15.8 mm | 8.2 mm | 26 g | 310 bar |
| PI-FSN-M10 | 10 mm | 5/8-18 UNF | 19 mm | 19.0 mm | 10.2 mm | 40 g | 276 bar |
| PI-FSN-M12 | 12 mm | 3/4-16 UNF | 22 mm | 22.4 mm | 12.3 mm | 65 g | 241 bar |
| PI-FSN-M16 | 16 mm | 7/8-14 UNF | 27 mm | 25.4 mm | 16.3 mm | 98 g | 206 bar |
| PI-FSN-M18 | 18 mm | 1-1/16-14 UNS | 32 mm | 30.2 mm | 18.4 mm | 150 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 Short Union Nut fittings find deployment across demanding thermal, fluid, and gas piping circuits:
Connects copper line sets to outdoor condensing unit service valves in cramped service recesses.
Installed on high-density valve blocks where adjacent valve solenoids restrict wrench clearance.
Secures capillary tubes and freeze-protection probe lines inside compact chiller electrical cabinets.
Connects copper tubing inside compact kitchen range and boiler control compartments.
Fastens flared tubing lines onto dense pneumatic multi-port distribution blocks.
Used in automotive and transport refrigeration line assemblies where space is at a premium.
Connects miniature pressure transducers and gauge lines on mobile fluid testing carts.
Secures evaporator line connections inside restricted galley refrigeration compartments.
Pioneer Industries’ Brass Flare Short Union 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 Short Union Nut.
A Brass Flare Short Union Nut is a compact female-threaded fastening nut designed with an abbreviated body length. It is primarily used in tight spaces, such as ductless mini-split service valve recesses, refrigeration solenoid manifolds, and dense instrument panels where standard long nuts cannot physically fit.
No. Pioneer Industries Brass Flare Short Union Nuts are engineered with sufficient thread engagement to achieve full tensile clamp load, matching the 5,000 PSI burst pressure rating of standard flare nuts without stripping or distorting.
Choose a Long Union Nut in high-vibration applications (e.g., directly mounted on reciprocating compressors or diesel engines) because its extended barrel supports the tubing and damps vibration. Choose a Short Union Nut where vibration is low-to-moderate and spatial clearance is severely restricted.
These nuts feature Class 2B Unified National Fine (UNF) straight threads conforming to SAE J512 and SAE J513 standards, ensuring 100% interchangeability with all standard 45° SAE male flare fittings.
No. The flare joint seals mechanically metal-to-metal between the flared copper tube and the male fitting cone. Applying tape or sealant to the nut threads serves no purpose and can interfere with accurate torquing.
Standard torque recommendations for mini-split connections: 1/4" tube (7/16-20 thread): 10–13 ft-lbs (14–18 N-m); 3/8" tube (5/8-18 thread): 24–31 ft-lbs (33–42 N-m); 1/2" tube (3/4-16 thread): 37–46 ft-lbs (50–62 N-m); 5/8" tube (7/8-14 thread): 46–60 ft-lbs (63–82 N-m).
Yes, provided the internal threads and 45° thrust shoulder remain in pristine condition without galling, burrs, or deformation. Always inspect the nut carefully prior to reassembly.
They are precision CNC-machined from BS 249 / CW614N (ASTM B16 C36000) extruded brass bar, providing tensile strength exceeding 400 MPa and superior resistance to cracking under heavy wrenching.
Yes. Pioneer Industries short union nuts have thick, reinforced hex walls engineered specifically to withstand the elevated operating pressures (450–600 PSI) and torque requirements of modern R-410A and R-32 systems.
Every production lot undergoes 100% thread gauging with calibrated go/no-go gauges, automated optical measurement for bore concentricity, and sample tensile pull testing. EN 10204 Type 3.1 certificates accompany every dispatch.
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