Three Most Common Types of Flange Faces
1. Flat Face Flange
Starting with a flat face flange, these flange get their name because they have a flat face without any protrusions or raised surfaces. These flanges use a “full face” gasket and have a large contact sealing area. They are normally cast iron and are used during low pressure applications and for pressure classes 125 and 200. Flat face flanges are easy to align during installation and are typically a more affordable option compaired to the other two flange types. The easiest way to protect these from damage and corrosion are by applying an adhesive or magnetic flange protector.
2. Raised Face Flange
Raised face flange are the most common types of flanges and are used in a wide variety of industries. These flanges this get their name because the flange face is raised off the bolting circle plane. The raised face acts as a sealing surface when the flanges are bolted to another flange or piece of equipment. These flanges are available in 150# - 2500# pressure classes and are normally used in process plant applications.
Raised face flanges focus pressure on a small area of the gasket to improve sealing/pressure control. This design helps prevent leaks and ensures that the system operates properly, so it is crucial to do regular inspection of the raised face. Tools such as the P3-GIT are designed to help you identify whether or not your raised face flanges passes inspection. The cut-out window mimics where the gasket sealing surface will come in contact with the flange face.
There are also several types of raised face flanges, each designed for specific applications and operating conditions. The three more common types of raised face flanges are weld neck, slip-on, and blind flanges.
3. Ring-Type Joint (RTJ)
Ring-type joint or RTJ flanges are typically used for more sever applications, particularly for high pressure or high temperature applications. They are designed to provide a leak-proof seal in critical environments where traditional gaskets may fail. The sealing surface on these types of flanges are in a machined groove. This metal-to-metal groove creates a seal that is highly resistant to extreme pressures and temperatures.
All three of these flange types are used in a wide variety of industries such as oil and gas, petrochemical, power generation, etc. and need to be properly maintained and protected in order to preform correctly.
