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Welding Neck (WN) Flange
The Welding Neck (WN) Flange is a flange designed to be welded to a pipe. The flange has a long tapered hub that is welded to the pipe to form a strong, leak-free connection. The flange also has a flat circular plate with bolt holes to secure the flange to another flange or piece of equipment.

product description


A Welding Neck (WN) Flange is a type of flange used in piping systems to connect pipes and equipment together. It is designed to be welded to the pipe or fitting and then bolted to another flange or piece of equipment. The WN flange has a long tapered neck that is welded to the pipe or fitting, and a flat face that extends out from the neck. The flat face of the flange provides a surface for the gasket to seal against, and the bolts are tightened to compress the gasket and create a leak-tight seal. The neck of the WN flange also provides reinforcement to the connection, which makes it suitable for use in high-pressure and high-temperature applications. The tapered design of the neck reduces stress concentrations and distributes the load evenly across the flange, which helps to prevent leaks and failures.


Standard: ASNI/ASTMB16.5/16.36/16.47A/16.47B B2220-2001, DIN2527/2636/2637/2638/2566/2576/2633/2635/2642/2653/2655.

Pressure Rate: 150LBS to 2500LBS / PN10 to PN400

Dimension: 1/2" to 48"

Material: Carbon steel, Alloy Steel, Stainless steel.

Sealing type: RF, FF, MFM, TG, RTJ

Threaded (TH)

Welding Neck Flange Cross Section

Welding Neck (WN)

Pressure rating:
Class 150LBS、300LBS、400LBS、600LBS、900LBS、1500LBS、2500LBS

ANSI B16.5, ANSI B16.47, MSS SP44, ANSI B16.36, ANSI B16.48, API 605, AWWA AND DRAWING

· CS
Standard: ASTM / ASME A/SA 105 / 350 LF 2
· SS
Standards: ASTM / ASME A/SA 182
Steel Grade: F 304, 304L, 304H, 309S, 309H, 310S, 310H, 316, 316TI, 316H, 316L, 316LN, 317, 317L, 321, 321H, 347, 347H, 904L.
· AS
Standard: ASTM / ASME A/SA 182
ASTM A182 F1, F11, F12, F22, F5, F9, F91.
· Nickel Alloy
Standard: ASTM / ASME SB 564 / 160 / 472
Grade: UNS 2200 (NICKEL 200), UNS 4400 (MONEL 400), UNS 8825 INCONEL (825), UNS 6600 (INCONEL 600), UNS 6601 (INCONEL 601), UNS 6625 (INCONEL 625), UNS 10276 (HASTELLOY C 276), UNS 2201 (NICKEL 201), (ALLOY 20 / 20 CB 3)

Features of the WN flange

The WN flange has a long conical neck with the end welded to the connecting pipe. The inner diameter of the pipe is equal to the inner diameter of the flange, providing a substantially constant cross-section and no interruption or turbulence in the gas/liquid flowing through the pipe. Butt-weld flanges provide high load strength and uniform stress distribution.

Care must be taken at the joint between the flange and the pipe to be welded to avoid possible interruption of high velocity flow.

Why use weld neck flange?

WN flanges are suitable for activities involving high pressures and extreme conditions (cold or hot), flammable or corrosive content, etc., and most importantly, environments where leakage must be minimal or almost non-existent. They are used to minimize the number of welds on small parts, while helping to reduce corrosion in the joint itself.

They are used in steam lines; oil, gas and refined hydrocarbon pipelines; fire protection networks; petrochemical facilities, etc.

What types of materials are used to manufacture them?

Carbon steel

Alloy Steel

Stainless steel

Threaded (TH)

Threaded (TH)

Threaded (TH)


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