Flange Types: The 13 Essential Types for Piping in ASME B16.5 Standard

Texas Flanges
6 min readNov 15, 2024

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Flanges have an important role in piping systems when building reliable ones. These are usually best for connecting pipes, valves, pumps, and other equipment for leakproof, secure seals for inspections and maintenance.

ASME B16.5 specification is the well-known world of flange specifications, designs, dimensions, and pressure ratings of the flanges. Learning the keys to industrial piping flange types, you are in the right place! In this guide, we will be discussing these 13 essential pipe flange types found in the ASME B16.5 standard.

Why Are Flanges Important in Piping Systems?

Any piping system must have flanges since they very effectively connect sections. However, they make it easy to clean, inspect, and repair the piping system and keep it working efficiently.

This ensures strong and leakproof joints, which is a must in industries like oil and gas, chemical processing, or power plants. Flanges follow specific standards of requirements like safety, performance, and quality, thus ensuring the ASME B16.5 standard of safety.

What Is the ASME B16.5 Standard?

The American Society of Mechanical Engineers (ASME) specifies the ASME B16.5 standard. It defines the requirements for flange manufacturing, design, and testing pipe flanges and flanged fittings. This standard is for flanges up to 24 inches and covers the size of the flanges from ½ inch to 24 inches and the pressure and temperature ratings of those flanges.

It is the standard ASME B16.5, which guarantees that flanges can be used in the same piping system without any inconvenience.

Now, let’s dive into the 13 essential pipe flange types you need to know.

1. Weld Neck Flange

The welded neck flange has a long-tapered hub that supports high-pressure applications. It’s directly welded to the pipe for a strong, strong connection, and that really keeps stress at a minimum.

In such critical applications in oil and gas pipelines where temperature and pressure are very high, they are used typically in welded neck flanges.

Key Features:

  • Offers strong, leak-proof connection
  • Ideal for high-pressure environments
  • Reduces stress concentration on the pipe

2. Slip-On Flange

The slip-on flange is easy to install as it slips on the pipe. Inside and outside, it gets welded for a secure fit. There is also a less expensive type of flange of this sort, which is used more commonly in lower-pressure applications where leakage is not an issue.

Key Features:

  • Easy to align and install
  • Suitable for low-pressure applications
  • Cost-effective and versatile

3. Blind Flange

A blind flange is a fitting used to seal the end of a pipe, valve, or pressure vessel. It is also not a bore and works well-stopping the flow.

In testing systems, blind flanges are best to check for leaks and to ensure that the systems are ready to begin operation.

Key Features:

  • Fills the pipe ends entirely
  • Useful for pressure testing
  • Can handle high pressure

4. Socket Weld Flange

Designed for small-diameter, high-pressure pipes, the socket weld flange has the advantage of low erosion resistance. It has a socket where the pipe gets inserted and then welded because this has a smooth bore and good flow.

For leak prevention, this flange is perfect for systems.

Key Features:

  • For small high-pressure pipes
  • Produces a good, strong, and leakproof joint
  • The stopping turbulence ensures a smooth flow

5. Threaded Flange

It features internal threads so that part of the threaded flange goes onto the thread of the pipe, and the pipe gets screwed into the threaded flange without welding.

It is best in low-pressure systems or areas where welding is not feasible.

Key Features:

  • Quick and easy to install
  • No welding required
  • Ideal for low-pressure applications

6. Lap Joint Flange

The lap joint flange works with a stub end and is often present in systems that require frequent disassembly.

The design is loose for ease of alignment and flexibility.

Key Features:

  • Provides flexibility in alignment
  • Ideal for systems needing regular maintenance
  • Works well with stub ends

7. Orifice Flange

The orifice flange is particularly designed for use with orifice plates to determine the flow rate of fluids flowing through a pipeline.

Its faces are tapped on the ends to attach pressure measurement devices.

Key Features:

  • Used for flow measurement
  • Comes with pressure taps for easy readings
  • Ensures accurate flow

8. Ring-Type Joint (RTJ) Flange

RTJ flanges have a groove that allows a metal ring gasket to fit into the ring-type joint (RTJ). It has high sealing integrity and is, therefore, very suitable for high-pressure / high-temperature applications.

Key Features:

  • Ensures a leakproof seal
  • For use under high-pressure/high-temperature applications
  • Commonly present in oil and gas industries.

9. Long Weld Neck Flange

Weld long weld neck flange has the same body as weld neck flange but has an extended neck. This feature is present in high pressure vessels and equipment and provides an additional support feature.

Key Features:

  • Provides additional support and strength
  • Used in high-pressure applications
  • Extends the length of the neck for added stability

10. Reducing Flange

It offsets pipes of two or more different diameters to connect. It dispenses with the need for a pipe reducer in the piping layout.

Key Features:

  • Connects pipes of varying sizes
  • Saves space and reduces the need for extra fittings
  • Commonly used in systems with size transitions

11. Expander Flange

It is the expander flange that can enlarge the pipe size using the same principle. It prevents added fittings and is a good way to make a transition to a larger pipe.

Key Features:

  • Increases pipe size
  • Simplifies the piping design
  • Ideal for expanding the flow capacity

12. Nipo Flange

A nipo flange is a welded neck flange in combination with a nipple. Used in special piping setups where a short length of pipe extension is needed.

Key Features:

  • Combines flange and nipple design
  • Used for unique piping configurations
  • Offers compact and efficient connections

13. Swivel Flange

The swivel flange allows it to be rotated for easier alignment of bolt holes when installed.

It is widely used in subsea or offshore piping systems where precise alignment is very critical.

Key Features:

  • Rotatable design for easy alignment
  • Ideal for subsea and offshore applications
  • Reduces installation time and effort

How to Choose the Right Flange Type

When choosing an industrial flange type, it should be in terms of pressure, temperature, pipe size, and the fluid being transported.

If working with systems at high pressure or high temperature, always opt for either the weld neck or RTJ flanges. Threaded or slip-on flanges may be sufficient for lower-pressure systems.

Conclusion

The selection of the right pipe flange type is essential when building a safe and efficient piping method. Once you understand the 13 essential flange types described in the ASME B16.5 standard, you will be able to carefully choose the flange type that best meets your project needs.

In both cases of working with a high-pressure pipeline or a simple low-pressure system, you can avoid leaks, improve safety, and have a stronger connection if you choose the right flange.

Ever in need of choosing the right flange? Texas Flange is a specialist when it comes to high-quality products made to fit ASME standards; do not hesitate to contact us for expert advice.

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Texas Flanges
Texas Flanges

Written by Texas Flanges

Texas Flange has served the petrochemical, process, and waterworks industries for over 3 decades. For more information, contact us today!

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