Flanges são componentes essenciais em sistemas de tubulação, servindo como conectores mecânicos para unir tubos, válvulas, bombas, e outros equipamentos. Eles fornecem um ambiente seguro, conexão à prova de vazamentos, permitindo fácil desmontagem, inspeção, e manutenção. Flanges are used in industries such as oil and gas, processamento químico, tratamento de água, geração de energia, construção naval, e sistemas HVAC. To ensure proper application and performance, flanges are classified into several types based on their structure, método de conexão, classificação de pressão, and application environment. This article provides a detailed classification of commonly used flanges, offering insight into their features, vantagens, and typical uses.

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1. Classification by Connection Method

Flange de pescoço soldado

A weld neck flange features a long tapered hub that is welded to the pipe. This design transfers stress to the pipe, reducing the concentration at the base of the flange. Weld neck flanges are suitable for high-pressure, high-temperature applications where strength and durability are critical.

Vantagens:

• Excellent strength and fatigue resistance

• Smooth bore transition reduces turbulence

• Ideal for repeated bending and temperature cycles

Aplicativos: Oleodutos e gasodutos, plantas químicas, high-pressure steam lines.

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Flange deslizante

Slip-on flanges are slipped over the pipe and welded on both the inside and outside. They are easier to align than weld neck flanges and are widely used in low- to medium-pressure systems.

Vantagens:

• Simple installation and alignment

• Lower initial cost than weld neck flanges

• Suitable for applications with limited space

Aplicativos: Sistemas de tratamento de água, HVAC piping, low-pressure industrial lines.

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Flange de solda de soquete

This flange has a socket where the pipe is inserted before being fillet welded at the outside. Socket weld flanges are used for smaller diameter, tubulação de alta pressão.

Vantagens:

• Smooth bore flow path

• Adequado para alta pressão, small-size pipelines

• Good fatigue strength

Aplicativos: Sistemas hidráulicos, chemical process piping, high-pressure gas distribution.

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Flange Rosqueada

Threaded flanges have internal threads that match the pipe threads, allowing connection without welding. They are ideal for low-pressure, aplicações não críticas.

Vantagens:

• Não é necessária soldagem

• Suitable for flammable environments where welding is hazardous

• Fácil de instalar e remover

Aplicativos: Sistemas de proteção contra incêndio, linhas de serviços públicos, compressed air piping.

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Flange de junta sobreposta

Os flanges de junta sobreposta são usados ​​com uma extremidade em ponta, allowing the flange to rotate freely for easy bolt alignment. They are often used in systems requiring frequent disassembly.

Vantagens:

• Fácil alinhamento durante a instalação

• Reusable in different piping assemblies

• Ideal for systems subject to frequent maintenance

Aplicativos: Processamento de alimentos, plantas farmacêuticas, corrosive environments where flanges can be made from a less expensive material and the stub end from a corrosion-resistant alloy.

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Flange cego

A blind flange has no bore and is used to seal off the end of a piping system or pressure vessel opening.

Vantagens:

• Allows access for inspection and cleaning

• Can be installed or removed without disturbing the piping system

• Available in high-pressure ratings

Aplicativos: Pressure vessel closures, pipeline isolation points, maintenance access ports.

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2. Classification by Face Type

Rosto levantado (RF)

The most common flange facing type, the raised face has a small raised area for gasket seating, improving the sealing capability.

Aplicativos: Petróleo e gás, processamento químico, sistemas de água.

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Rosto plano (FF)

The gasket surface is in the same plane as the bolt circle face. Commonly used with cast iron equipment.

Aplicativos: Tratamento de água, aplicações de baixa pressão, non-metallic piping.

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Junta tipo anel (RTJ)

Uses a metal ring gasket to achieve a high-integrity seal for high-pressure, aplicações de alta temperatura.

Aplicativos: Refinery equipment, high-pressure steam lines, plataformas petrolíferas offshore.

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Língua e sulco (T&G)

A male (tongue) flange fits into a female (groove) flange, providing precise gasket positioning.

Aplicativos: Specialty chemical processing, high-integrity sealing systems.

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3. Classification by Pressure Rating

ASME Pressure Classes

• Aula 150

• Aula 300

• Aula 600

• Aula 900

• Aula 1500

• Aula 2500

The higher the class, the thicker and stronger the flange to withstand higher pressures.

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EN / DIN PN Ratings

PN 6, PN 10, PN 16, PN 25, PN 40, PN 63, PN 100, PN 160.
PN stands for nominal pressure in bars at a reference temperature.

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JIS Pressure Ratings

5K, 10K, 16K, 20K, 30K.
Commonly used in Japanese and some Asian market applications.

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4. Classification by Manufacturing Method

Flanges Forjadas

Produced by forging steel billets, offering superior mechanical properties and grain structure.

Aplicativos: Tubulações de alta pressão, offshore structures, usinas de energia.

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Flanges fundidos

Manufactured by casting molten metal into molds. More economical for complex shapes but may have lower mechanical strength than forged flanges.

Aplicativos: Sistemas de água, low-pressure chemical processing.

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Flanges de Placa

Cut from plate material and machined to specifications. Economical but generally limited to lower pressure ratings.

Aplicativos: Low-pressure piping, ventilation systems.

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5. Special Purpose Flanges

Flanges de Orifício

Designed for use with orifice meters to measure flow rate in pipelines. Includes tapped holes for pressure measurement.

Aplicativos: Flow measurement in oil, gás, and water pipelines.

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Flanges cegos para óculos

Consist of a connected pair of metal discs, one solid and one with an opening, used to isolate a section of pipe.

Aplicativos: Maintenance operations, system isolation in refineries and chemical plants.

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Reduzindo Flanges

Allow connection between pipes of different diameters without the need for a separate reducer fitting.

Aplicativos: Space-constrained piping layouts, projetos de modernização.

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Importance of Choosing the Right Flange Type

The correct flange classification ensures safety, compatibilidade, and performance in the intended application. Mismatched flange types can lead to leaks, pressure loss, or mechanical failures. Selecting the correct flange also simplifies maintenance and ensures compliance with applicable standards.

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Standards Governing Flanges

Flanges must conform to international standards to ensure quality and interchangeability. Os padrões comuns incluem:

• ASME B16.5 (Flanges de tubo e acessórios flangeados)

• ASME B16.47 (Flanges de aço de grande diâmetro)

• EN 1092-1 (European Standard for Steel Flanges)

• JIS B2220 (Japanese Industrial Standard for Flanges)

Fabricantes como sasa oblonga produce flanges in compliance with these standards to guarantee performance in diverse applications.

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Conclusão

Flanges are critical components in any piping system, and understanding their classification helps in selecting the right product for specific operational requirements. Whether based on connection type, tipo de rosto, classificação de pressão, manufacturing method, or special function, each flange type serves a unique purpose.

By aligning flange selection with industry standards and application needs, engineers and procurement teams can ensure long-term reliability, segurança, and cost-effectiveness in their piping systems. Partnering with experienced manufacturers like sasa oblonga ensures that flanges are produced to precise specifications, ready to perform in even the most demanding environments.