Gaskets and Flanges
There are three types of gaskets used in process piping.
A gasket is meant to form a mechanical seal that fills the space between two or more mating surfaces. Its goal is to prevent leakage from, or into, the joined objects while under compression.
The full-face gasket is typically used with flat face flanges but can also be used with RF flanges. It sits on the raised flange faces but has the same outside diameter of the flange. For that reason, it has to have holes for the bolts securing the flanges to pass through.