Weld Neck Flange

The most frequently requested flange, the Weld Neck Flange, features a neck extension and weld bevel. Provides a natural form connection ideal for larger, high-pressure applications.

What is Weld neck flange?

Weld neck flanges, also known as WN flange, tapered hub flange or high-hub flange,s a kind of flange that can relocate stress to the pipes, ensuring a decrease in high-stress concentration at the bottom of the flange.

Welding Neck Flanges are easy to recognize as the long tapered hub, which gradually over to the wall thickness from a pipe or fitting. The long tapered hub provides an important reinforcement for use in several applications involving high pressure, sub-zero, and/or elevated temperatures. The smooth transition from flange thickness to pipe or fitting wall thickness effected by the taper is extremely beneficial, under conditions of repeated bending, caused by line expansion or other variable forces.

These WN flanges are bored to match the inside diameter of the mating pipe or fitting so there will be no restriction of product flow. This prevents turbulence at the joint and reduces erosion. They also provide excellent stress distribution through the tapered hub. The Weld neck flanges are attached by butt-welding to the pipes. These are used mainly for critical services where all the weld joints need a radiographic inspection.

While specifying these WN flanges, the thickness of the welding end also should be specified along with flange specification.

Standards for WN flanges:

ASTM A105 for carbon steel welding neck flanges.
ASTM A182 for alloy and stainless welding neck flange.
ASME B16.5
ASME B16.47
BS 3293
DIN 2630 PN 1 and PN 2.5, 2631 PN 6, 2632 PN 10, 2634 PN 16, 2634 PN 25, 2635 PN 40

Before ordering the weld neck flange, the companies shall need to confirm the material standard, outer diameter, pressure class, face type and thickness schedule.

A standard description for a welding neck flange is: “Flange, 10” Weld Neck, Class 150, RF, Schedule 40, ASTM A105 ASME B 16.5.”

Common materials for weld neck flanges include:

Carbon Steel (ASTM A105, A350 LF2) – General industrial use
Stainless Steel (ASTM A182 F304/F316) – For corrosive or high-purity applications
Alloy Steel (ASTM A694 F42-F70) – High-pressure & low-temperature performance
Duplex & Super Duplex (ASTM A182 F51/F53/F55)– For extreme environments
Nickel Alloys (Inconel, Monel, Hastelloy) –  Specialized industries like petrochemicals

Applications of Weld Neck Flanges

Weld neck flanges are used in situations where conditions are tough. Some common scenarios include:

• High-pressure systems
• Wide temperature and pressure fluctuations
• High-temperature environments
• Handling volatile and hazardous fluids
• Working in very cold conditions

The WN flanges are built to handle such challenging conditions, thanks to their strong construction and excellent stress distribution capabilities.

Manufacturing Processes

The forging process generally consists of the following steps:

• Selecting high-quality billet blanking
• Heating
• Forming
• Forging
• Cooling

Why Choose Rayoung Pipeline are your industry weld neck flange supplier?

The weld neck flange remains the definitive choice for engineers prioritizing safety, durability, and long-term performance in critical piping systems. Its engineered design is unmatched in managing mechanical stress and ensuring leak-free integrity under demanding conditions.

At Rayoung, we understand that reliability is non-negotiable. Our weld neck flanges are manufactured to exacting international standards, including ANSI/ASME B16.5 and B16.47, and are available in a range of material grades to suit specific service environments, from standard carbon steel to corrosion-resistant alloys.

For detailed technical data sheets, pressure-temperature ratings, or to discuss your project’s specific requirements, contact our technical specialists today.
We provide expert guidance to ensure you select the optimal flange solution for unparalleled system reliability.

1. Automated Painting Production Line
2. Compliant with International Standards
3. Diverse Material Options
4. Customization for Special Requirements
5. Certification Support