Threaded Union
Threaded Union Pipe Fittings
A Threaded Union is a three-piece pipe fitting used to easily assemble and disassemble piping systems without disturbing adjacent pipe sections. It provides a secure and tight connection via female threads and a central nut, making it ideal for frequent maintenance, inspection, or system replacements.
| Feature | Description |
|---|---|
| Product Name | ASME B16.11 Threaded Union |
| Standards | ASME B16.11, BS3799, ASTM A182, MSS SP-83, ANSI B1.20.1 (for threads) |
| Materials |
|
| Pressure Classes | Class 2000, 3000, 6000 (Threaded); Class 3000, 6000, 9000 (Socket Weld) |
| Sizes | 1/8″ NB to 4″ NB (Nominal Bore) |
| Components | Three parts: Nut, Female End, Male End |
| Connection Type | Female Threaded x Female Threaded, Female Threaded x Male Threaded |
| Pressure Ratings | Up to 3000 psi (Class 3000), 2000 psi saturated steam (varies by material and size) |
Threaded Union Dimensions
CLASS 3000
| Pipe Size | A | B | C | Weight (LBS) |
|---|---|---|---|---|
| 1/8 | 1.375 | 1.625 | 0.865 | 0.45 |
| 1/4 | 1.375 | 1.625 | 0.865 | 0.40 |
| 3/8 | 1.625 | 1.750 | 1.025 | 0.65 |
| 1/2 | 1.813 | 2.000 | 1.235 | 0.77 |
| 3/4 | 2.250 | 2.313 | 1.465 | 1.19 |
| 1 | 2.563 | 2.500 | 1.795 | 1.73 |
| 1-1/4 | 3.063 | 2.813 | 2.165 | 2.74 |
| 1-1/2 | 3.438 | 3.000 | 2.425 | 3.60 |
| 2 | 4.063 | 3.438 | 2.965 | 5.51 |
| 2-1/2 | 4.875 | 4.000 | 3.615 | 8.90 |
| 3 | 5.688 | 4.375 | 4.305 | 12.61 |
| 3-1/2 | 6.875 | 8.000 | 5.415 | 36.92 |
| 4 | 6.875 | 8.000 | 5.415 | 17.50 |
Class 6000
| Pipe Size | A | B | C | Weight (LBS) |
|---|---|---|---|---|
| 1/8 | 1.375 | 1.625 | 0.865 | 0.48 |
| 1/4 | 1.625 | 1.750 | 1.025 | 0.56 |
| 3/8 | 1.813 | 2.000 | 1.235 | 0.75 |
| 1/2 | 2.250 | 2.313 | 1.465 | 1.35 |
| 3/4 | 2.563 | 2.500 | 1.795 | 2.01 |
| 1 | 3.063 | 2.813 | 2.165 | 3.17 |
| 1-1/4 | 3.438 | 3.000 | 2.425 | 3.92 |
| 1-1/2 | 4.063 | 3.438 | 2.965 | 6.60 |
| 2 | 4.875 | 4.000 | 3.615 | 10.12 |
| 2-1/2 | 5.688 | 4.375 | 4.305 | 14.00 |
| 3 | 6.875 | 8.000 | 5.415 | 41.16 |
| 3-1/2 | — | — | — | — |
| 4 | — | — | — | — |
CLASS 9000
| Pipe Size | A | B | C | Weight (LBS) |
|---|---|---|---|---|
| 1/8 | 1.625 | 2.500 | 1.000 | 1.18 |
| 1/4 | 1.813 | 2.563 | 1.250 | 1.67 |
| 3/8 | 2.250 | 3.000 | 1.500 | 1.95 |
| 1/2 | 2.563 | 3.156 | 1.750 | 3.12 |
| 3/4 | 3.063 | 3.625 | 2.250 | 5.61 |
| 1 | 3.438 | 4.000 | 2.500 | 8.08 |
| 1-1/4 | 4.063 | 4.500 | 3.000 | 13.23 |
| 1-1/2 | 4.875 | 4.875 | 3.625 | 18.34 |
| 2 | 5.688 | 6.000 | 4.250 | 28.21 |
| 2-1/2 | 6.875 | 6.313 | 5.000 | 45.86 |
| 3 | — | — | — | — |
| 3-1/2 | — | — | — | — |
| 4 | — | — | — | — |
Advantages
- Easy to install and disassemble without pipe rotation
- Leak-proof connection
- Corrosion resistance (material-dependent)
- Suitable for frequent maintenance
- Dielectric unions prevent galvanic corrosion
Key Features
- Forged for high strength in high-pressure environments
- Dielectric unions with plastic liners to limit galvanic corrosion
- Rotary unions allow mechanical rotation while resisting leakage
Applications
- Oil and Gas (refineries, pipelines)
- Chemical Processing
- Water Supply and Drainage
- HVAC Systems
- Food and Beverage (for easy disassembly)
- High-pressure systems (e.g., boilers, hydraulic lines)