OEM manufacturer ASME B16.5 · ASME B16.47 · EN 1092-1 Type 11
Weld Neck Flanges — ASME B16.5 & B16.47
A weld neck flange is a forged flange with a long tapered hub that is butt-welded to the pipe. Teshi Group manufactures weld neck flanges to ASME B16.5 (NPS ½″–24″) and ASME B16.47 Series A/B (NPS 26″–60″) in carbon, low-temperature, alloy, stainless and duplex steels, bored to the pipe schedule you specify.
Also called: WN flange, WNRF flange, welding neck flange, weld neck raised face flange
What is a Weld Neck Flange?
A weld neck (WN) flange has a tapered hub whose small end is bored to match the pipe ID and bevelled for a full-penetration butt weld. The taper moves stress from the flange ring into the pipe wall gradually, so the joint handles high pressure, temperature swings, bending and cyclic loads better than slip-on or socket-weld types. The butt weld can be fully radiographed. Weld neck flanges are the default choice for process piping in Class 300 and above, hydrocarbon and steam service, and any line where the piping class calls for radiographed joints.
Key features
- Tapered hub butt-welded to pipe; weld is fully radiographable
- Bore matched to pipe schedule (Sch 10S to XXS) to avoid steps at the weld
- Raised face, flat face or ring-type joint facing
- Forged, then CNC machined; serrated RF finish to ASME B16.5 (125–250 µin Ra) unless specified otherwise
- Hub ends bevelled to ASME B16.25
Specification
| Supply | OEM manufacturer — Teshi Group, India |
|---|---|
| Standard | ASME B16.5 (NPS ½″–24″); ASME B16.47 Series A/B (NPS 26″–60″); EN 1092-1 Type 11 |
| Pressure class | Class 150, 300, 600, 900, 1500, 2500 (B16.5); Class 75–900 (B16.47, by series) |
| Facing | RF, FF, RTJ |
| Materials — carbon steel | ASTM A105 / A105N; ASTM A181 Cl 60, Cl 70; ASTM A266 Gr 2, Gr 4 (large forgings) |
| Materials — high-yield carbon steel | ASTM A694 F42, F46, F48, F50, F52, F56, F60, F65, F70 (MSS SP-44 grades F52–F70) |
| Materials — low-temperature carbon steel | ASTM A350 LF1, LF2 Cl 1, LF2 Cl 2, LF3, LF6, LF9 |
| Materials — alloy steel (Cr-Mo) | ASTM A182 F1, F2, F5, F5a, F9, F11 Cl 1 / 2 / 3, F12 Cl 1 / 2, F21, F22 Cl 1 / 3, F22V, F91, F92, F911; ASTM A336 F11, F22 (large forgings) |
| Materials — stainless steel | ASTM A182 F304, F304L, F304H, F304LN, F309H, F310, F316, F316L, F316H, F316LN, F316Ti, F317, F317L, F321, F321H, F347, F347H, F348 |
| Materials — 904L and 6Mo | 904L (ASTM A182 F904L, UNS N08904); 254 SMO / 6Mo (ASTM A182 F44, UNS S31254); AL-6XN (ASTM A182 F62, UNS N08367) |
| Materials — duplex stainless steel | ASTM A182 F51 (UNS S31803), F60 (UNS S32205, 2205) |
| Materials — super duplex stainless steel | ASTM A182 F53 (UNS S32750, 2507), F55 (UNS S32760), F61 (UNS S32550) |
| Materials — nickel alloys | ASTM B564 / B160 / B462: Nickel 200 / 201 (N02200 / N02201), Monel 400 (N04400), Monel K-500 (N05500), Inconel 600 (N06600), Inconel 625 (N06625), Inconel 718 (N07718), Incoloy 800 / 800H / 800HT (N08800 / N08810 / N08811), Incoloy 825 (N08825), Hastelloy C276 (N10276), Hastelloy C22 (N06022), Hastelloy B2 / B3 (N10665 / N10675), Alloy 20 (N08020) |
| Materials — titanium | ASTM B381 Grade F1, F2, F5 (Ti-6Al-4V), F7, F12 |
| Materials — copper-nickel | Cu-Ni 90/10 (UNS C70600) and 70/30 (UNS C71500), ASTM B151 bar; flanges to ASME B16.5 or EEMUA 145 |
| Grade availability | Every grade listed is made or supplied against order, with EN 10204 3.1 certificates (3.2 / third-party inspection when specified) and PMI on alloy, stainless, duplex and nickel grades. |
| Bore | To specified pipe schedule per ASME B36.10 / B36.19 |
| Testing | Visual and dimensional inspection, PMI on alloy and stainless grades, hardness; UT, MPI/DPI as specified |
| Documents | EN 10204 3.1 mill test certificate; 3.2 / third-party inspection when the order specifies; dimensional inspection report; IBR certification when specified |
Applications
- Refinery and petrochemical process lines
- Steam and boiler feed piping in power plants
- Oil and gas gathering and transmission piping
- High-pressure and high-temperature hydrocarbon service
- Cryogenic and low-temperature lines in A350 LF2 or stainless
Weld neck vs slip-on flange
A slip-on flange slides over the pipe and is fillet-welded inside and out; it is cheaper and easier to align but its calculated strength under internal pressure is roughly two-thirds of a weld neck and its fatigue life is far lower. A weld neck uses a single butt weld that can be radiographed and has a tapered hub that spreads stress. Choose slip-on for low-pressure utility lines; choose weld neck for Class 300 and above, cyclic, hazardous or high-temperature service.
Technical data sheets
Dimensions & weights
FAQ
Weld Neck Flange: common questions
What bore should I specify for a weld neck flange?
Specify the pipe schedule or the pipe wall thickness, for example NPS 6 Sch 40. The flange bore is then machined to the pipe ID so there is no step at the weld, which matters for flow, pigging and radiography.
Is the weld neck flange the same for ASME B16.5 and B16.47?
No. B16.5 covers NPS ½″ to 24″. Above NPS 24, B16.47 applies, and it has two series, A and B, with different outside diameters and bolt circles. They do not mate with each other, so the series must be stated on the order.
What facing do you supply as standard?
Raised face with a serrated spiral or concentric finish of 125–250 µin Ra, which suits spiral wound and non-metallic gaskets. Flat face and ring-type joint facings are machined when the piping class requires them.
Can you supply weld neck flanges with IBR certification?
Yes. For steam and boiler service covered by the Indian Boiler Regulations, weld neck flanges can be supplied with IBR certification, issued after inspection by the Inspecting Authority, in grades such as A105, F11 and F22.
How quickly can I get a quotation?
Send the NPS, pressure class, facing, bore schedule, material grade, quantity and any inspection or IBR requirement. Teshi Group quotes in 24–48 hours, with the mill test certificate type stated on the offer.
Need a size or grade not listed here?
Our engineering team manufactures against your drawing or datasheet, with dimensional sign-off before dispatch.
Send us your specificationTraceability
From mill heat to your site
- 01
Approved mill material
Received against the mill certificate; heat number registered.
- 02
Forging & machining
Heat number carried through every stage in our Indian works.
- 03
PMI, dimensional & NDT
Every lot inspected to the governing standard; TPI witness on request.
- 04
Stamped & certified dispatch
Hard-stamped pieces with EN 10204 3.1 / 3.2 certificates.
Quick RFQ
Quote for Weld Neck Flange in 24–48 hours
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