Flange Overview
A flange is a mechanical component used to connect pipes, valves, pumps, and other equipment, typically used to create sealed pipe connections.
Flanges are generally circular metal discs with holes, which are bolted to another identical or similar flange disc to form a strong, detachable connection. The design of the flange makes it easier to install, maintain, and repair pipeline systems.
Basic Structure of a Flange
Flange Body: Typically a thick circular disc designed to provide a sufficient contact surface to withstand pressure.
Sealing Face: The surface that contacts the gasket to ensure a seal during the connection.
Bolt Holes: Multiple holes on the flange used to install bolts, ensuring a secure connection through bolted fastening.
Gasket: Placed between the two flanges to fill small gaps and ensure a tight seal.
Flange Knowledge Overview
Flange Types
Flange types are defined by their design and intended use.
Common flange types include:
Slip-on Flange: Suitable for low-pressure applications, easy to install.
Weld Neck Flange: With a long neck, suitable for high-pressure and high-temperature environments, offering strong welding strength.
Threaded Flange: Connected by threads, ideal for situations where welding is not possible.
Blind Flange: Used to seal the ends of pipes
Socket Weld Flange: Suitable for small diameter, high-pressure pipes.
Lap Joint Flange: Convenient for disassembly and adjustment.
Ring Type Joint Flange (RTJ): Typically used for high-pressure and high-temperature harsh environments.
These flange types provide different connection strengths and sealing performance depending on the application.
Flange Faces
The flange face is the surface that comes into contact with another flange or equipment and forms the seal. Depending on the sealing method, there are different types of flange faces:
Flat Face (FF): A flat surface, suitable for low-pressure connections.
Raised Face (RF): Features a raised area on the flange face to compress the gasket, ideal for high-pressure applications.
Ring Type Joint (RTJ): Contains a ring groove for a metal sealing ring, used in extreme pressure and temperature applications.
Tongue and Groove: One side has a protruding part (“tongue”), and the other side has a matching groove for enhanced sealing. Choosing the appropriate flange face type is critical to ensuring seal integrity and pressure resistance.
Flange Surface Finish
The smoothness of the flange is typically measured by the Ra value (arithmetical average roughness).
In some standards, Rz (average maximum height) or Rt (total height of surface profile) may also be used. Common Ra ranges include:
- Low Roughness: Ra ≤ 0.8 µm (very smooth, suitable for high-precision applications).
- Medium Roughness: Ra ≈ 1.6 µm (common in general industrial applications).
- Higher Roughness: Ra ≈ 3.2 µm (suitable for low-pressure, less stringent sealing requirements).
Flange Connection
Flanges come with various connection methods, depending on factors such as pressure, temperature, fluid type, system operation characteristics, and surrounding environment. Common connection types include:
- Welded Connections: Suitable for high-pressure, high-temperature, corrosive, or high-vibration environments. Welding provides a strong, durable connection, particularly for large-diameter pipes or systems requiring high sealing performance.
- Threaded Connections: Suitable for low-pressure and low-temperature environments. Threaded flanges are easy to install and remove, especially for small diameter pipes or where welding is not feasible.
Working Principle of Flanges
The working principle of a flange is based on mechanical connection and sealing. Bolting two components together, and using the sealing face and gasket ensures that the connection does not leak gas or liquid.
The flange can withstand high pressure, temperature, and mechanical stress in pipeline systems, while also being convenient for maintenance and repairs.
It is an essential component to ensure the safe and stable operation of pipeline systems, equipment, and various installations.
SSM manufactures flanges, and we welcome your technical inquiries and purchases.
