Weld Neck Flanges (WNRF) Supplier & Stockist in India

The strongest common flange type: a tapered neck butt-welded to the pipe, bored to the pipe schedule. For high pressure, high or low temperature, vibration and hazardous fluids.

WNRF / WNFF / WN RTJASME B16.5 Class 150–1500A105, LF2, F304L, F316LBored to scheduleBevel to ASME B16.25½" to 24"

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Weld neck flange drawing showing tapered neck and butt weld to pipe — The tapered neck spreads load from the flange ring into the pipe wall.

Why engineers specify weld neck flanges

A weld neck flange has a long tapered hub that ends in a bevel the same size as the pipe. It is joined with a single full-penetration butt weld, and its bore matches the pipe's inside diameter, so there is no step for the flow to hit. The taper moves bending stress from the flange ring into the pipe gradually.

That design makes weld neck flanges the standard choice for steam, hydrocarbons, high-pressure process lines, cryogenic service and lines that vibrate or heat and cool repeatedly. The butt weld can also be radiographed, which many codes require.

Why engineers specify weld neck flanges: specification summary
Materials	ASTM A105 / A105N, A350 LF2, A182 F304 / F304L / F316 / F316L; alloy F11 / F22 on request
Standards	ASME B16.5 (½" to 24"), Class 150 to 1500, 2500 on request; ASME B16.47 to order; EN 1092-1 Type 11
Bore	Matched to pipe schedule: Sch 10S, 40, STD, 80, XS, 160, XXS
Weld end	Bevel to ASME B16.25
Facing	RF, FF, RTJ
Sizes	½" (15 NB) to 24" (600 NB)
Marking and documents	Grade, class, size, schedule and heat number; mill test certificate on request

Why the bore must match your pipe schedule

A weld neck flange is bored to the inside diameter of the pipe it welds to. Order the wrong schedule and the bore will not line up with the pipe, leaving a step inside the weld that causes turbulence, erosion and poor weld fit-up. Always give the pipe schedule with the size and class. Some common bores:

Size	Pipe OD (mm)	Sch 40 bore (mm)	Sch 80 bore (mm)
2" (50 NB)	60.3	52.5	49.2
3" (80 NB)	88.9	77.9	73.7
4" (100 NB)	114.3	102.3	97.2
6" (150 NB)	168.3	154.1	146.4
8" (200 NB)	219.1	202.7	193.7

Bores calculated from ASME B36.10M pipe OD and wall thickness. Thin-wall stainless lines (Sch 10S) need a matching 10S bore.

Where weld neck flanges are used

Steam, condensate and boiler lines
Refinery, petrochemical and gas processing piping
Pump discharge and compressor connections
Cryogenic and low-temperature lines (A350 LF2 or stainless)
Lines with thermal cycling or vibration
Hazardous, toxic or flammable fluid service

Facings and variants

Raised face (WNRF) is standard. Flat face (WNFF) is used against flat-faced equipment, and ring type joint (WN RTJ) for higher classes and severe service. Long weld neck flanges, with an extended hub used as a vessel nozzle, are available on request.

Welding and inspection

Weld neck flanges are joined with a full-penetration butt weld, so the joint can be examined by radiography or ultrasonic testing as your piping code requires. Check that the bevel angle and root face match your welding procedure, and that flange and pipe grades are compatible.

Pipes and fittings to go with weld neck flanges

Pipe or fitting	Use it with these flanges when…
Carbon steel pipes (A106 Gr B)	the flange is A105 on a process or steam line
MS seamless pipes	you need seamless pipe in Sch 40 / 80
SS seamless pipes	the flange is F304L or F316L
Heavy wall pipes	the class needs Sch 160 or XXS pipe
Alloy steel pipes (P11, P22)	high-temperature service calls for alloy flanges

Have a flange schedule from your consultant?Send the list with class, schedule and grade. We will quote line by line.

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Flange types we supply

Each page covers materials, standards, sizes and where that flange fits. All flanges can be quoted with matching pipes and fittings.

MS FlangesIS 2062 mild steel, Table E / IS 6392 / ASA 150

Stainless Steel FlangesSS 304, 304L, 316, 316L to ASME B16.5

Carbon Steel FlangesForged ASTM A105, A350 LF2, Class 150 to 1500

Slip-On Flanges (SORF)Pipe slides in, two fillet welds

Weld Neck Flanges (WNRF)Butt-welded, bored to pipe schedule

Blind FlangesClose pipe ends, nozzles and test points

Socket Weld FlangesSmall-bore, high-pressure lines

Threaded FlangesNPT / BSP, no welding, GI lines

Lap Joint FlangesLoose flange with stub end

Plate FlangesFlat flanges, Table D/E/F/H, custom

Flange Size & Class ChartASME B16.5 OD, PCD, bolts and ratings

FAQ

Frequently Asked Questions

WNRF means weld neck raised face: a flange with a tapered welding neck and a raised gasket face. WN RTJ is the ring type joint version.

They use more forged material for the neck, need more machining, and must be bored to the pipe schedule. In return they give the best strength and fatigue life of the common flange types.

Size (NPS or NB), pressure class, pipe schedule for the bore, material grade, facing (RF, FF or RTJ) and quantity. Add the standard if it is not ASME B16.5.

Yes. Order the flange bored to the same schedule as the pipe, for example Sch 10S, so the bore matches the pipe.

A long weld neck has a much longer, straight hub and is mostly used as a nozzle on vessels and columns. It is supplied on request.

Yes, mill test certificates are available on request. Please mention it in your enquiry.

Buyer Guides & Tools

Flange Size Chart & Pressure ClassesASME B16.5 OD, PCD, bolts, Class 150 to 2500 ERW vs Seamless PipeWhich pipe to use with your flanges Pipe & Tube Weight CalculatorMS / SS / GI round, square & rectangular Steel Pipe Buying Guide for IndiaChecklist before you request a quote SS 304 vs SS 316Choosing the stainless grade

Free Quotation

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Tell us the flange type, size, class or table, material and quantity. We reply on call, WhatsApp or email.

MS, carbon steel and stainless steel flanges on one quotation
Matching pipes, elbows, tees and reducers from the same order
Dispatch from Thane / Panvel to sites across India

WhatsApp Us Call +91 98678 43347