Socket Weld Flanges
Giriraj Impex is a manufacturer, stockist, supplier and exporter of socket weld flanges to ASME B16.5 in Class 150, 300, 600, 900 and 1500, for small-bore piping from ½" NB, and to EN 1092-1 and other standards on request. We manufacture socket weld flanges in stainless steel, carbon steel, alloy steel, duplex and super duplex steel and nickel alloys, with raised face and ring type joint facings, bored to suit the pipe schedule, with mill test certificates.
A socket weld flange has a socket into which the pipe is inserted and fillet welded. It is used for small-bore, high-pressure process, hydraulic, steam and instrument lines where butt welding small pipe would be difficult.
What is a socket weld flange?
The socket weld (SW) flange has a counterbore – the socket – sized to the pipe's outside diameter, with a shoulder at the bottom. The pipe is pushed into the socket and attached with a single fillet weld at the hub. The bore below the shoulder matches the pipe bore, so flow is smooth. Socket weld flanges are stronger in fatigue than slip-on flanges because of the internal shoulder and single external weld, and easier to fit than small butt-weld flanges because the socket aligns the pipe.
Socket depth and the expansion gap
The socket depth is set by ASME B16.5 for each size and class, and must be at least long enough for a sound fillet weld. When the joint is made, the pipe should not be pushed hard against the bottom of the socket: a gap of about 1.5 mm (1/16") is left between the pipe end and the shoulder before welding, as piping codes such as ASME B31.3 require. The gap allows for weld shrinkage and thermal expansion, which would otherwise crack the fillet weld. Because a small crevice remains between pipe and socket, socket weld flanges are avoided in services where crevice corrosion or trapped fluid is a concern.
Specifications
| Item | Details |
|---|---|
| Dimensional standards | ASME B16.5; EN 1092-1 and other standards on request |
| Sizes | Small bore, from ½" NB up to the maximum size listed in ASME B16.5 for each class (generally up to 3" NB); larger sizes to other specifications on request |
| Classes | 150, 300, 600, 900, 1500 |
| Facings | Raised face (RF), ring type joint (RTJ) |
| Bore | To suit the pipe schedule (Sch 40, 80, 160, XXS) |
| Documents | Mill test certificate (MTC); third-party inspection on request |
Socket weld flange materials
- Stainless steel flanges – ASTM A182 F304/304L, F316/316L, F321, F347.
- Carbon steel flanges – ASTM A105, A350 LF2, A516 plate for spectacle blinds.
- Alloy steel flanges – ASTM A182 F5, F9, F11, F22, F91.
- Duplex steel flanges – ASTM A182 F51, F60.
- Super duplex flanges – ASTM A182 F53, F55.
- Inconel flanges – ASTM B564, and other nickel alloys.
All flange materials are on the flanges page.
Socket weld, slip-on or weld neck?
For small-bore lines, the socket weld flange combines easy fit-up with good strength, and needs only an external fillet weld that can be inspected by surface methods. Weld neck flanges remain the choice for the most severe cyclic, high-temperature or crevice-sensitive services, and where full radiography is required. Slip-on flanges are used mainly for larger, low-pressure lines. The piping specification sets which type is used for each size and class – see weld neck flanges and slip-on flanges.
How we manufacture socket weld flanges
We manufacture socket weld flanges from forged blanks of certified material, heat treated as the material specification requires. Machining covers the socket and bore to suit the pipe, the facing and face finish, the hub and the bolt holes. Every flange is marked with material, size, class, facing, schedule and heat number, and inspected for dimensions, face finish and marking before dispatch. Flange dimensions are in the flange dimensions chart.
Ordering socket weld flanges
Please give the material, size, class, facing, pipe schedule, quantity and any testing or inspection requirement.
Frequently Asked Questions
A socket weld flange has a socket into which the pipe is inserted and fillet welded, used for small-bore, high-pressure piping.
A gap of about 1.5 mm allows for weld shrinkage and thermal expansion, preventing cracking of the fillet weld.
They are small-bore flanges, from ½" NB up to the maximum size listed in ASME B16.5 for each class, generally up to 3" NB.
A socket weld flange has an internal shoulder and one external fillet weld; a slip-on flange has a through bore and two fillet welds.
In services where crevice corrosion or trapped fluid between pipe and socket is a concern, butt-weld connections are preferred.
The bore below the socket is machined to match the pipe schedule, such as Sch 40, 80 or 160.
Request a Quote for Socket Weld Flanges
Tell us the product, grade, size, standard, quantity and delivery location, and our sales team will reply with a quotation.
Inconel® is a trademark of Special Metals Corporation.