Flanges são componentes críticos em sistemas de tubulação, permitindo conexões seguras e eficientes entre tubos, válvulas, bombas, e equipamentos. Para garantir a segurança, compatibilidade, e desempenho, the production and use of flanges are governed by padrões internacionais. Entre estes, ANSI e ASME are the most widely recognized, but there are also other standards like DIN, JIS, Bobagem, e PT. Understanding these standards is essential for engineers, especialistas em compras, and industries dealing with global supply chains.

This article explains the major flange standards—ANSI, ASME, and others—highlighting their scope, key features, and importance in industrial applications.

---

Why Flange Standards Are Important

1. Safety and Reliability
   Standards ensure flanges can withstand the pressure and temperature conditions of different industries.

2. Intercambialidade
   Flanges from different manufacturers must fit together, which requires adherence to common standards.

3. Global Trade
   International projects often involve equipment from multiple countries, making standardized flanges critical for compatibility.

4. Quality Assurance
   Standards specify material composition, classificações de pressão, dimensões, e procedimentos de teste.

---

ANSI Flange Standards

ANSI (Instituto Nacional Americano de Padrões) establishes guidelines for various products, incluindo flanges. ANSI flange standards specify:

• Dimensões (diâmetro, grossura, círculo de parafuso, etc.)

• Classificações de pressão-temperatura

• Facing types (rosto levantado, cara plana, RTJ)

ANSI flange standards are widely used in the United States and in industries such as oil and gas, petroquímica, e geração de energia.

---

ASME Flange Standards

ASME (American Society of Mechanical Engineers) issues detailed codes for pressure vessels, sistemas de tubulação, e flanges.

• ASME B16.5: Flanges up to 24 polegadas de diâmetro

• ASME B16.47: Flanges de grande diâmetro (26–60 inches)

• ASME B16.36: Flanges de orifício

• ASME B16.48: Line blanks

ASME standards are stricter than ANSI in terms of design rules, testando, and quality control. Many engineers today use the terms ANSI and ASME interchangeably, but technically, ASME has replaced ANSI for flanges in modern practice.

---

Other International Flange Standards

1. DIN (Deutsches Institut für Normung – Germany)

• Common in Europe and Asia

• Specifies PN (Pressão Nominal) ratings such as PN6, PN10, PN16, PN40

• Used in chemical plants, refinarias, e centrais eléctricas

2. EN (European Norms)

• Harmonized standard across the European Union

• Replaces older DIN standards in many regions

• Ensures compatibility across EU member states

3. Bobagem (British Standards)

• Historically used in the UK

• Cobre flanges, juntas, and bolting specifications

• Now gradually aligned with EN standards

4. JIS (Padrões Industriais Japoneses)

• Widely used in Japan and some Asian markets

• Specifies flanges for industrial piping systems

• Popular in shipbuilding, automotivo, and petrochemical sectors

5. ISO (International Organization for Standardization)

• Provides global harmonization

• Ensures compatibility in international trade and projects

---

Pressure Classes in Flange Standards

Different standards classify flanges by pressure capability:

• ANSI/ASME Classes: 150, 300, 600, 900, 1500, 2500

• DIN/EN PN Ratings: PN6, PN10, PN16, PN25, PN40, PN64, PN100

• Classificações de pressão JIS: 5K, 10K, 16K, 20K, 30K

These classifications indicate the maximum pressure a flange can handle at a specific temperature.

---

Flange Facing Types Defined by Standards

1. Rosto levantado (RF): Mais comum, allows better gasket compression.

2. Rosto plano (FF): Used when bolting against cast iron or non-metallic surfaces.

3. Junta tipo anel (RTJ): Para alta pressão, aplicações de alta temperatura.

4. Língua e sulco: Provides tight sealing in specialized applications.

Standards specify exact dimensions for these facings to ensure seal integrity and compatibility.

---

Materials Specified in Flange Standards

• Aço carbono: For general applications with moderate pressure and temperature

• Aço inoxidável (304, 316, 321, 347): For corrosive and high-temperature environments

• Liga de aço (F11, F22, F91): For high-pressure and high-temperature service

• Aço Inoxidável Duplex e Super Duplex: For offshore and marine environments

• Ligas de Níquel (Inconel, Monel, Hastelloy): For extreme chemical and thermal conditions

By adhering to standards, manufacturers and buyers ensure materials match required service conditions.

---

Key Differences Between ANSI, ASME, and Other Standards