Os flanges com pescoço soldado estão entre os tipos de flange mais utilizados em sistemas de tubulação industrial. Reconhecidos pela sua durabilidade, força, e capacidade de lidar com condições de alta pressão e alta temperatura, they are a top choice in industries like oil and gas, petroquímica, geração de energia, e construção naval.

This complete guide will cover everything you need to know about weld neck flanges, including their types, dimensões, materiais, vantagens, e aplicações comuns.

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What is a Weld Neck Flange?

A weld neck flange (Flange WN) is a type of flange with a long tapered hub and a smooth transition to the wall thickness of a pipe or fitting. It is designed to be butt-welded to the pipe, criando um forte, leak-proof connection that can withstand high stress. The tapered hub also reduces stress concentration at the base of the flange.

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Key Features of Weld Neck Flanges

• Butt-Weld Connection: Ensures strength and minimizes stress at the joint.

• Tapered Hub: Provides reinforcement and smooth stress distribution.

• Bore Matching: The flange bore matches the pipe’s inner diameter for smooth fluid flow.

• High Integrity: Ideal for critical service conditions.

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Types of Weld Neck Flanges

1. Standard Weld Neck Flanges

• Commonly used in pipelines where pressure and temperature are high.

• Suitable for a wide range of applications.

2. Flanges de pescoço longo para solda

• Feature an extended hub, often used in equipment like nozzles or vessels.

• Provide additional reinforcement.

3. Reducing Weld Neck Flanges

• Used to connect pipes of different diameters.

• Maintain system integrity while accommodating size changes.

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Weld Neck Flange Dimensions

Weld neck flanges are manufactured according to international standards such as ASME B16.5, ASME B16.47, DIN, EN, e outros. Dimensions vary based on nominal pipe size (NPS), classe de pressão, and standard.

Key Dimensional Factors:

• Diâmetro Externo (DE): Overall flange size.

• Bore Diameter: Matches the pipe ID.

• Hub Length: Length of the tapered section.

• Grossura: Affects pressure rating.

• Diâmetro do Círculo do Parafuso: Distance between bolt holes.

Common Pressure Ratings:

• Aula 150

• Aula 300

• Aula 600

• Aula 900

• Aula 1500

• Aula 2500

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Materials Used for Weld Neck Flanges

The choice of material depends on operating temperature, pressão, e tipo de fluido.

Materiais Comuns:

• Aço carbono: ASTM A105, A350LF2 (low-temp service)

• Aço inoxidável: ASTM A182 F304, F316

• Liga de aço: ASTM A182 F11, F22

• Dúplex & Superduplex: UNS S31803, S32750

• Ligas de Níquel: Inconel, Monel, Hastelloy

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Processo de Fabricação

1. Seleção de Materiais – Choose appropriate grade for service conditions.

2. Forjamento – The flange is shaped through forging for strength.

3. Usinagem – Precision machining ensures dimensional accuracy.

4. Tratamento térmico – Relieves stress and enhances mechanical properties.

5. Inspeção & Teste – Includes dimensional checks, END, and pressure testing.

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Vantagens dos flanges de pescoço soldado

• Alta resistência: Butt-welded connection provides excellent structural integrity.

• Leak Resistance: Adequado para aplicações de alta pressão e alta temperatura.

• Smooth Flow: Bore matching minimizes turbulence.

• Durabilidade: Long service life under extreme conditions.

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Desvantagens

• Higher Cost: More expensive than slip-on or threaded flanges.

• Installation Time: Requires welding, which can be time-consuming.

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Applications of Weld Neck Flanges

1. Óleo & Gasodutos

Used in upstream, meio do caminho, and downstream applications due to their strength and reliability.

2. Plantas Petroquímicas

Ideal for transporting chemicals under high pressure and temperature.

3. Geração de energia

Used in steam, água de resfriamento, and fuel systems.

4. Construção naval & No mar

Withstand harsh marine environments and high-pressure systems.

5. High-Temperature Services

Maintain integrity under extreme heat in refineries and chemical plants.

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Inspeção e Controle de Qualidade

Weld neck flanges must undergo rigorous testing before being approved for service:

• Inspeção Visual: Checks for surface defects.

• Verificação Dimensional: Garante a conformidade com os padrões.

• Testes Não Destrutivos (END): Ultrasonic or radiographic testing for internal flaws.

• Teste Hidrostático: Confirms pressure containment.

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Diretrizes de instalação

1. Alinhamento: Ensure the pipe and flange bores align perfectly.

2. Soldagem: Perform butt-welding using approved procedures.

3. Bolt Tightening: Use a cross-pattern method for even gasket compression.

4. Seleção de juntas: Match gasket type to service conditions.

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Weld Neck vs Other Flange Types