WNRF Flanges — Weld Neck Raised Face Flange Manufacturer

Stainless Steel A182 F316L WNRF Flange — DN250 PN16 (DIN 2633), Laser-Marked

What is a WNRF Flange?

Two design features do the work. The tapered hub transfers pressure and bending stress gradually from the flange ring into the pipe wall, instead of dumping it at a single weld line — which is why weld neck flanges outlast every other type under fatigue, vibration and thermal cycling. And because the bore is machined to match the mating pipe schedule, flow passes through the joint with no step, no turbulence and no erosion pocket, and there is no high stress concentration at the base of the hub.

The raised face (RF) itself is a machined pad, serrated with a concentric or spiral groove, that stands 1.6 mm proud of the flange face on Class 150 and 300, and 6.35 mm on Class 400 through 2500. Compressing the gasket over this smaller, controlled area multiplies the seating stress the bolts can generate — the reason RF facings hold pressures that a plain flat face cannot. The same body can alternatively be faced flat (WNFF) or grooved for a ring joint (WNRTJ); see our weld neck flanges overview for the full family.

WNRF Flange Specifications

The Raised Face — Heights, Finish & Gaskets

Under ASME B16.5 the raised face is 1.6 mm (1/16″) high on Class 150 and 300 and 6.35 mm (1/4″) high on Class 400, 600, 900, 1500 and 2500 — and take care when stacking dimensions, because published flange thickness includes the 1.6 mm face but excludes the 6.35 mm one. European EN 1092-1 Type 11 and DIN weld neck flanges carry a shallower raised face, typically 2 mm. We machine the face to the standard stock finish — a serrated concentric or spiral groove of Ra 3.2–6.3 µm (125–250 µin AARH) that bites into soft and spiral-wound gaskets — or to a smooth finish where your gasket type demands it.

Alloy Steel A182 F91 RFWN Flange — 3″ Sch 160, Class 2500, Black-Coated

WNRF Flange Materials — All Grades We Manufacture

WNRF flanges are forged in every material family from our range. The grade is driven by the service — A105 for general hydrocarbon and steam, LF2 for sub-zero, 316L and duplex for chlorides, F11/F22/F91 for high-temperature steam, and nickel alloys where the chemistry gets aggressive:

How We Manufacture WNRF Flanges

Every WNRF flange starts as a certified forged blank — forging aligns the grain flow around the hub, exactly where the stress lives. Blanks are heat treated (normalized, quenched-and-tempered or solution annealed to suit the grade), then CNC-turned: the tapered hub profiled, the bore matched to your pipe schedule, the weld end bevelled to 37.5°, bolt holes drilled on the correct circle, and the raised face serrated to finish. Marking, final inspection and face protection close the loop before packing.

Why Specify a WNRF Flange

Where WNRF Flanges Are Used

Oil & gas takes the largest share — wellheads and flowlines, gathering stations, refinery process units and gas processing, where the provable butt weld and high pressure classes are non-negotiable. Chemical and petrochemical plants specify WNRF in 316L, duplex, Hastelloy and Inconel wherever the medium attacks ordinary steel. Power stations run F11, F22 and F91 WNRF flanges on high-temperature steam lines, while LNG and cryogenic plants use A350 LF2/LF3. Shipbuilding and offshore lean on copper nickel 90/10 and 70/30 for seawater, and water treatment, fertilizer, pharmaceutical and food processing plants round out the range in stainless grades. If the line is hot, pressurized, cycling or hazardous, a WNRF flange is the default answer.

WNRF Flange Dimensions

Full dimension charts — outside diameter, thickness, hub, bore, bolt circle, bolting and weights — are published for every ASME class:

European and other standards are covered on their own pages — EN 1092-1 Type 11 (PN 2.5–400), DIN 2631–2635, BS 4504, BS 3293, JIS B2220 30K/40K/63K and API 6A Type 6B/6BX.

Packing, Marking & Dispatch

Faces and weld bevels are protected, small-bore flanges are individually wrapped and boxed with size, grade and heat number on the label, and larger flanges are strapped or crated in lined seaworthy packing. Coated carbon steel flanges ship wrapped against moisture; stainless ships pickled and passivated.

Price List & How to Order

WNRF flange pricing depends on size, class, material grade and quantity — and moves with raw material markets, so we quote live rather than publish a static list. Standard carbon and stainless items ship from ready stock at highly competitive export prices. To get a firm quotation, usually within 24 hours:

WNRF Flanges — Frequently Asked Questions