Carbon Steel Coupling — Factory Direct Supplier | Huaxia-Steel
Carbon steel couplings are short-length pipe fittings used to connect two pipes of the same nominal diameter. As a factory-direct manufacturer, Huaxia-Steel produces threaded and socket-weld couplings to ASME B16.11, BS 3799, and DIN standards in sizes from 1/8″ to 6″. Our couplings are forged from ASTM A105 and A234 WPB carbon steel, delivering pressure ratings up to 6000 psi for threaded and Class 3000/6000/9000 for socket-weld applications. Full EN 10204 3.1 certification and heat number traceability ensure compliance with international piping codes.
Product Overview
A coupling is a cylindrical fitting with threads or sockets at both ends, designed to join two lengths of pipe in a straight line. Full couplings connect pipes of the same diameter, while reducing couplings connect pipes of different diameters. Carbon steel couplings are widely used in oil & gas, chemical processing, power generation, and water distribution systems where strength and pressure integrity are essential.
Huaxia-Steel manufactures couplings using a hot-forging process from rolled bar stock, followed by precision machining. The forging process ensures a fine, uniform grain structure with excellent mechanical properties. Threaded couplings are machined to ASME B1.20.1 NPT specifications with controlled thread taper (1:16) for pressure-tight joints. Socket-weld couplings feature a smooth socket bore with proper root clearance for fillet welding.
Specifications & Dimensions
Threaded Full Couplings — ASME B16.11, Class 2000/3000/6000
| NPS (in) | DN (mm) | Length (mm) | Body Dia (mm) | Class 6000 (psi) |
|---|---|---|---|---|
| 1/8 | 6 | 33 | 18 | 6000 |
| 1/4 | 8 | 38 | 22 | 6000 |
| 3/8 | 10 | 41 | 25 | 6000 |
| 1/2 | 15 | 48 | 32 | 6000 |
| 3/4 | 20 | 51 | 38 | 6000 |
| 1 | 25 | 60 | 48 | 6000 |
| 1-1/4 | 32 | 67 | 57 | 6000 |
| 1-1/2 | 40 | 70 | 64 | 6000 |
| 2 | 50 | 76 | 76 | 6000 |
| 2-1/2 | 65 | 92 | 92 | 6000 |
| 3 | 80 | 108 | 108 | 6000 |
| 4 | 100 | 121 | 140 | 6000 |
Socket-Weld Couplings — ASME B16.11, Class 3000/6000/9000
| NPS (in) | DN (mm) | Length (mm) | Socket Depth (mm) | Bore Dia (mm) |
|---|---|---|---|---|
| 1/2 | 15 | 38 | 9.5 | 21.3 |
| 3/4 | 20 | 41 | 12.5 | 26.7 |
| 1 | 25 | 44 | 12.5 | 33.4 |
| 1-1/4 | 32 | 48 | 12.5 | 42.2 |
| 1-1/2 | 40 | 51 | 12.5 | 48.3 |
| 2 | 50 | 60 | 16.0 | 60.3 |
| 3 | 80 | 86 | 16.0 | 88.9 |
| 4 | 100 | 106 | 19.0 | 114.3 |
Reducing Couplings — Threaded
| Reduction | Length (mm) | Body Dia (mm) | Approx Weight (kg) |
|---|---|---|---|
| 3/4 × 1/2 | 48 | 38 | 0.20 |
| 1 × 1/2 | 51 | 48 | 0.35 |
| 1 × 3/4 | 51 | 48 | 0.33 |
| 1-1/4 × 1 | 57 | 57 | 0.50 |
| 1-1/2 × 1 | 60 | 64 | 0.65 |
| 2 × 1 | 67 | 76 | 0.95 |
| 2 × 1-1/2 | 67 | 76 | 0.88 |
| 3 × 2 | 89 | 108 | 2.10 |
| 4 × 2 | 108 | 140 | 3.80 |
| 4 × 3 | 108 | 140 | 3.50 |
Available Grades & Materials
| Grade | Standard | Carbon (%) | Yield (MPa) | Tensile (MPa) |
|---|---|---|---|---|
| A105 | ASTM A105 | ≤0.35 | 205 | 485 |
| A234 WPB | ASTM A234 | ≤0.30 | 240 | 415 |
| ST37.0 | DIN 1629 | ≤0.17 | 235 | 360–510 |
| 20# | GB/T 699 | 0.17–0.24 | 245 | 410 |
| 16Mn | GB/T 1591 | 0.13–0.19 | 345 | 510 |
Manufacturing Standards
- ASME B16.11: Forged Fittings, Socket-Welding and Threaded
- BS 3799: Steel Pipe Fittings, Screwed and Socket-Welded
- DIN 2982/2994: Threaded and Welded Couplings (German standard)
- MSS-SP-83: Class 3000 Steel Pipe Couplings, Threaded and Socket-Weld
- GB/T 14383: Forged Steel Socket-Welding and Threaded Fittings
Applications
- Oil and gas pipeline construction and repair
- Refinery process piping systems
- Chemical and petrochemical plant piping
- Power plant steam and water lines
- Fire protection sprinkler systems
- Industrial compressed air and gas lines
- Water and wastewater treatment piping
- Instrument tubing and impulse lines
Quality Assurance
Huaxia-Steel implements comprehensive quality control for every coupling production batch:
Packaging & Shipping
- Standard packaging: wooden cases with polyethylene inner liner
- Small sizes (1/8″–1″): bulk-packed in bags, 500–2000 pcs per wooden case
- Medium sizes (1-1/4″–2″): individually wrapped, 100–500 pcs per case
- Large sizes (2-1/2″–4″): individually packed, 50–100 pcs per pallet
- Marking: size, grade, class, standard, heat number, country of origin
- ISPM-15 heat-treated pallets for export compliance
- VCI anti-corrosion paper for sea freight; desiccant bags for moisture protection
- Loading photos and packing list provided with every shipment
Conclusion
Carbon steel couplings are fundamental components in piping systems, providing reliable straight-line connections for pressure-containing applications. Huaxia-Steel’s factory-direct manufacturing ensures consistent quality, full material traceability, and competitive pricing across our coupling range. From standard full couplings to reducing configurations, we deliver products that meet international standards and your specific project requirements. Request a quotation today — our technical team will respond within 24 hours with detailed specifications and pricing.
