Long Weld Neck Flange

What is Long Weld Neck Flange

A Long Weld Neck Flange, also called LWN Flange, is a special type of weld neck flange with an extended neck or nozzle-like hub. It is designed to provide a smooth transition from flange to pipe, vessel, or equipment connection.

The long tapered neck helps transfer stress away from the flange base and into the adjoining pipe or vessel wall. This design reduces stress concentration and improves fatigue resistance under pressure, temperature cycling, and vibration conditions.

Long weld neck flanges are commonly used as nozzles for pressure vessels, tanks, columns, heat exchangers, and high-pressure piping systems.

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Long Weld Neck Flange Specifications

Additional Specifications:

• Face Types: Raised Face (RF), Flat Face (FF), MFM, TG, Ring Type Joint (RJ)
• Neck Type: Straight neck, tapered neck, customized long neck
• End Type: Bevel end, weld end, customized pipe end
• Bore Type: Standard bore, schedule bore, customized bore
• Surface Finish: 125-250 μin Ra for sealing surfaces
• Custom Service: Special neck length, special wall thickness, special drilling available

Long Weld Neck Flange Materials & Grades

Long weld neck flanges are available in a wide range of materials. The material should be selected according to pressure, temperature, medium, corrosion environment, and project standard.

Carbon steel long weld neck flanges are commonly used in oil and gas, pressure vessel, power generation, and general industrial systems. Stainless steel long weld neck flanges are suitable for chemical, food, pharmaceutical, and corrosive environments. Alloy steel and duplex materials can be used for high-temperature, high-pressure, cryogenic, or special working conditions.

Long Weld Neck Flange Dimensions

long-weld-neck-flange-dimension-drawing 

Long weld neck flanges can be manufactured according to standard dimensions or customer drawings. Key dimensions include flange outside diameter, bore size, neck length, hub diameter, flange thickness, bolt circle diameter, bolt hole diameter, and sealing face type.

Advantages of Long Weld Neck Flange

Superior Structural Strength

The extended neck provides better reinforcement for pressure vessel nozzles and high-pressure pipeline connections.

Excellent Stress Distribution

The long tapered hub transfers stress smoothly from the flange to the pipe or vessel wall, reducing stress concentration.

Suitable for Severe Service

Long weld neck flanges are suitable for high pressure, high temperature, cryogenic service, vibration, and cyclic loading conditions.

Reliable Butt Weld Connection

The butt-weld design provides high joint integrity and is suitable for critical pipeline and equipment connections.

Flexible Customization

Neck length, bore size, wall thickness, sealing face, material, and drilling pattern can be customized according to project drawings.

Long Service Life

Strong structure and accurate machining help reduce leakage risk, fatigue damage, and maintenance cost.

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Applications

Pressure Vessel Nozzles

Used as reinforced nozzle connections for pressure vessels, tanks, columns, reactors, and heat exchangers.

Oil and Gas Industry

Suitable for high-pressure oil pipelines, gas transmission systems, refineries, and offshore platforms.

Petrochemical Plants

Used in process pipelines and equipment connections under high temperature, high pressure, or corrosive working conditions.

Power Generation

Applied in steam lines, boiler systems, cooling systems, and auxiliary equipment connections.

Chemical Processing

Stainless steel, alloy steel, and nickel alloy long weld neck flanges are suitable for corrosive and hazardous media.

Cryogenic Systems

Used in low-temperature and cryogenic pipelines where strong weld integrity and stable sealing are required.

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Why Choose Us

Comprehensive Manufacturing Capability

We coordinate forging, heat treatment, machining, drilling, inspection, coating, and packaging under one production system.

Custom Long Neck Processing

We can manufacture long weld neck flanges with customized neck length, bore size, wall thickness, bevel end, and drilling pattern.

International Standards Compliance

Our products meet ASME, EN, DIN, JIS, GOST, and customer drawing requirements.

Wide Material Options

Carbon steel, stainless steel, alloy steel, duplex steel, nickel alloy, copper alloy, and titanium materials are available.

Strict Quality Inspection

Each batch is inspected for material grade, dimensions, neck length, bore accuracy, bolt hole alignment, sealing surface, and appearance.

Export Packaging Support

Anti-rust treatment, wooden case packaging, and customized marking are available for international shipment.

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FAQ

Q: What is a Long Weld Neck Flange?

A: A long weld neck flange is a weld neck flange with an extended neck, commonly used for pressure vessel nozzles, tanks, equipment connections, and high-pressure piping systems.

Q: What is the difference between Weld Neck Flange and Long Weld Neck Flange?

A: A standard weld neck flange has a shorter tapered hub, while a long weld neck flange has an extended neck that provides additional reinforcement and can act as a nozzle connection.

Q: What standards are available?

A: Long weld neck flanges can be supplied according to ASME B16.5, ASME B16.47, EN 1092-1, DIN, JIS, GOST, and custom drawings.

Q: Can the neck length be customized?

A: Yes. Neck length, bore size, wall thickness, bevel end, material, and drilling pattern can be customized according to project drawings.

Q: Where are Long Weld Neck Flanges commonly used?

A: They are commonly used in pressure vessels, petrochemical plants, oil and gas pipelines, power plants, cryogenic systems, and critical equipment connections.

Contact Us

Ready to enhance your piping systems with premium Weld Neck Flange solutions? Contact kevin.zhao@hkflange.com for technical specifications and competitive quotations today.

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