Exploring the Different Types of API Flanges

API flanges come in various types, each designed for specific industrial applications, from oil and gas to chemical processing. This article explores the different types of API flanges, their unique features, and ideal use cases to help you choose the right one for your project.

Types of API Flanges

1. API 6A Flanges

API 6A flanges are primarily used in wellhead and Christmas tree equipment. They are designed to withstand high-pressure and high-temperature conditions encountered in oil and gas extraction operations.

Key Features:

  • Designed for critical applications in upstream oil and gas.
  • Available in pressure ratings up to 20,000 psi.
  • Various sizes and configurations to meet specific wellhead requirements.

2. API 6B and API 6BX Flanges

API 6B and API 6BX flanges are used in drilling and production operations, providing reliable sealing and connection solutions. They are commonly used with API 6A wellheads and offer robust performance in demanding environments.

Key Features:

  • Higher pressure ratings compared to API 6A flanges.
  • Designed for offshore and onshore drilling applications.
  • Suitable for critical connections in production systems.

3. API 605 Flanges

API 605 flanges are large diameter carbon steel flanges used in industrial applications requiring high-pressure and temperature resistance. They are commonly used in refining, chemical processing, and power generation industries.

Key Features:

  • Available in sizes NPS 26 through NPS 60.
  • Designed to ANSI B16.47 series A and B standards.
  • Suitable for applications requiring large bore sizes and high-pressure ratings.

4. API Threaded Flanges

API threaded flanges offer versatility in assembly and disassembly. They feature internal threads that allow for easy connection to pipes without welding, making them ideal for applications that require frequent maintenance or modification.

Key Features:

  • Simplified installation and removal.
  • Suitable for low-pressure systems and small bore piping.
  • Available in various materials and pressure ratings.

5. API Weld Neck Flanges

API weld neck flanges are known for their high strength and reliability in high-pressure and high-temperature applications. They feature a long tapered hub that provides an enhanced connection to pipes, reducing stress concentration and improving flow characteristics.

Key Features:

  • Suitable for critical applications requiring high integrity joints.
  • Available in standard and heavy wall thicknesses.
  • Ideal for oil and gas pipelines, refineries, and petrochemical plants.


Choosing the right type of API flange depends on your specific application requirements, including pressure ratings, temperature conditions, materials compatibility, and installation methods. By understanding the different types of API flanges and their unique features, you can select the optimal solution for your industrial project.

For expert advice on API flanges and customized solutions, visit Texas Flange.

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