Socket Weld Union
Socket Weld Union Manufacturer & Supplier
A Socket Weld Union is a three-piece forged pipe fitting designed to connect two pipes securely while allowing for easy disassembly without cutting the pipe. It’s widely used in high-pressure and small-bore piping systems (typically under 2” NPS) where maintenance or replacement is frequent.
| Attribute | Description |
| Product Name | Socket Weld Coupling (Forged Socket Weld Full or Half Coupling) |
| Function | Connects two pipes end-to-end to extend a pipeline or join pipes of the same or different diameters (full coupling) or cap a pipe end (half coupling). |
| Types | Full Coupling: Connects two pipes of the same or different diameters. – Half Coupling: Connects one pipe or caps a pipe end. – Reducing Coupling: Connects pipes of different diameters. |
| Size Range | 1/8″ to 4″ (DN6 to DN100) |
| Pressure Rating | Class 3000, 6000, 9000 (suitable for high-pressure applications). |
| Standards | ASME B16.11, BS3799, MSS SP-83, GB/T 14383 |
| Materials | Stainless Steel: ASTM A182 F304, F304L, F316, F316L, F310, F321, F347, F904L – Carbon Steel: ASTM A105, A350 LF2 – Alloy Steel: ASTM A182, A335, A234 (P1, P5, P9, P11, P22, P91) – Nickel Alloys: Inconel, Monel, Hastelloy (e.g., UNS 2200, 4400, 10276) – Duplex/Super Duplex Steel: ASTM A182 F51, F53, F55 – Copper Alloys: ASTM SB 111, SB 466 (C 70600, C 71500) – Others: Galvanized, Brass, Mild Steel, Titanium |
| Socket Weld Cross Section | Features a recessed socket for pipe insertion with a 1/16″ (1.6 mm) expansion gap to accommodate thermal expansion and prevent stress. |
| Applications | – Small-bore, high-pressure piping systems (e.g., oil and gas, chemical plants, power generation, fire sprinkler systems). – Conveying flammable, toxic, or expensive materials where leakage is critical. – Steam systems (300–600 PSI). |
| Connection Type | Socket Weld (fillet-type seal welds); can have mixed connections (e.g., socket weld one end, threaded the other). |
| Key Features | – High leakage integrity and structural strength. – Simple fit-up, no beveling required, reducing construction costs compared to butt-weld fittings. – Permanent connections with good flow characteristics. – Not suitable for highly corrosive or radioactive applications due to potential corrosion in the expansion gap. |
| Dimensional Tolerances | – Socket Bore (B): Max/min dimensions per ASME B16.11. – Bore Diameter (D): Max/min dimensions. – Socket Wall Thickness (C): Average thickness, with minimum at partial areas. – Center to Bottom of Socket (A): ±1.5 mm (NPS 1/2–3/4), ±2 mm (NPS 1–2), ±2.5 mm (NPS 2.5–4). – Depth of Socket (J): Minimum 9.5 mm. |
| Limitations | – Potential for stress due to thermal expansion in the socket gap. – Not ideal for hydrogen service or highly corrosive environments. – Limited to small-bore piping (NPS 2 or smaller). |
| Marking and Packaging | – Marked with alloy name, outside diameter, wall thickness, pressure class, and heat number. – Packaged in plastic bags, cartons, or seaworthy wooden cases/pallets for safe transportation. |
Socket Weld Union Dimensions
| NPS | DN | Class | Socket Bore (B) Max / Min | Bore Diameter (D) Max / Min | Socket Wall Thickness (C) Average | Center to Bottom of Socket (A) | Depth of Socket (J) Min | Length of Union (L) | Nut Diameter (N) |
|---|---|---|---|---|---|---|---|---|---|
| 1/8 | 6 | 3000 | 11.2 / 10.8 | 7.6 / 6.1 | 3.1 | 11.0 | 9.5 | 41.0 | 22.0 |
| 1/4 | 8 | 3000 | 14.6 / 14.1 | 10.0 / 8.5 | 3.3 | 11.0 | 9.5 | 41.0 | 27.0 |
| 3/8 | 10 | 3000 | 18.0 / 17.5 | 13.3 / 11.8 | 3.5 | 13.5 | 9.5 | 48.0 | 33.0 |
| 1/2 | 15 | 3000 | 22.2 / 21.7 | 16.6 / 15.0 | 4.1 | 15.5 | 9.5 | 48.0 | 38.0 |
| 3/4 | 20 | 3000 | 27.6 / 27.1 | 21.7 / 20.2 | 4.3 | 19.0 | 12.5 | 51.0 | 46.0 |
| 1 | 25 | 3000 | 34.3 / 33.8 | 27.4 / 25.9 | 4.9 | 22.0 | 12.5 | 57.0 | 56.0 |
| 1-1/4 | 32 | 3000 | 43.1 / 42.6 | 36.0 / 34.4 | 5.3 | 27.0 | 12.5 | 64.0 | 70.0 |
| 1-1/2 | 40 | 3000 | 49.2 / 48.7 | 41.7 / 40.1 | 5.6 | 32.0 | 12.5 | 70.0 | 80.0 |
| 2 | 50 | 3000 | 61.7 / 61.2 | 53.3 / 51.7 | 6.1 | 38.0 | 16.0 | 76.0 | 94.0 |
| 2-1/2 | 65 | 3000 | 74.4 / 73.9 | 64.2 / 61.2 | 7.7 | 41.0 | 16.0 | 89.0 | 110.0 |
| 3 | 80 | 3000 | 90.3 / 89.8 | 79.6 / plant76.6 | 8.3 | 48.0 | 16.0 | 102.0 | 130.0 |
| 1/8 | 6 | 6000 | 11.2 / 10.8 | 5.5 / 4.0 | 4.0 | 11.0 | 9.5 | 41.0 | 22.0 |
| 1/4 | 8 | 6000 | 14.6 / 14.1 | 7.9 / 6.4 | 4.3 | 13.5 | 9.5 | 48.0 | 27.0 |
| 3/8 | 10 | 6000 | 18.0 / 17.5 | 11.2 / 9.7 | 4.8 | 15.5 | 9.5 | 48.0 | 33.0 |
| 1/2 | 15 | 6000 | 22.2 / 21.7 | 14.4 / 12.9 | 5.6 | 19.0 | 9.5 | 51.0 | 38.0 |
| 3/4 | 20 | 6000 | 27.6 / 27.1 | 19.5 / 18.0 | 6.1 | 22.0 | 12.5 | 57.0 | 46.0 |
| 1 | 25 | 6000 | 34.3 / 33.8 | 25.1 / 23.6 | 7.0 | 27.0 | 12.5 | 64.0 | 56.0 |
| 1-1/4 | 32 | 6000 | 43.1 / 42.6 | 33.7 / 32.2 | 7.0 | 32.0 | 12.5 | 70.0 | 70.0 |
| 1-1/2 | 40 | 6000 | 49.2 / 48.7 | 39.4 / 37.8 | 7.5 | 38.0 | 12.5 | 76.0 | 80.0 |
| 2 | 50 | 6000 | 61.7 / 61.2 | 51.0 / 49.4 | 8.6 | 41.0 | 16.0 | 89.0 | 94.0 |
| 1/2 | 15 | 9000 | 22.2 / 21.7 | 11.0 / 9.5 | 8.2 | 22.0 | 9.5 | 57.0 | 38.0 |
| 3/4 | 20 | 9000 | 27.6 / 27.1 | 15.7 / 14.2 | 8.5 | 27.0 | 12.5 | 64.0 | 46.0 |
| 1 | 25 | 9000 | 34.3 / 33.8 | 21.0 / 19.5 | 9.8 | 32.0 | 12.5 | 70.0 | 56.0 |
| 1-1/4 | 32 | 9000 | 43.1 / 42.6 | 29.6 / 28.1 | 9.8 | 38.0 | 12.5 | 76.0 | 70.0 |
| 1-1/2 | 40 | 9000 | 49.2 / 48.7 | 35.3 / 33.7 | 10.2 | 41.0 | 12.5 | 89.0 | 80.0 |
| 2 | 50 | 9000 | 61.7 / 61.2 | 46.9 / 45.3 | 11.1 | 48.0 | 16.0 | 102.0 | 94.0 |
Benefits:
Easy assembly/disassembly for maintenance
Strong, leak-proof connection
Withstands high pressure & temperature
Ideal for frequent pipe servicing areas
Applications:
High-pressure steam & water systems
Oil & gas piping
Chemical processing units
Power generation plants
Instrumentation and utility piping