How are blind flanges classified based on their facing

Blind flanges can be classified based on their facing, which refers to the finish or texture of the sealing surface around the bolt holes. The facing of a blind flange is crucial for creating a proper seal when connecting to another flange or equipment. The two main classifications based on facing are:

1. Raised Face Blind Flange (RF): Raised face blind flanges have a raised surface around the bolt holes. This raised portion, typically in the form of a small ring, helps create a better seal by providing a surface for a gasket. The raised face design ensures a tighter and more secure connection, which is important for applications where a reliable seal is essential to prevent leaks. RF blind flanges are commonly used in various industries, including petrochemical, oil and gas, and water treatment.

2. Flat Face Blind Flange (FF): Flat face blind flanges have a flat sealing surface around the bolt holes, without a raised portion. These flanges are used when the mating flange or surface they connect to is also flat and does not require a raised face for sealing. Flat face flanges are typically used in low-pressure applications where gaskets or other sealing methods are employed to create a secure and leak-free connection. They are often used in industries such as HVAC and plumbing.

The choice between raised face (RF) and flat face (FF) blind flanges depends on the specific requirements of the piping system and the compatibility with the facing of the mating flange or equipment. It is important to select the appropriate facing type to ensure a proper and effective seal in the given application.