There are different types of flange faces, such as Flat Face (FF), Raised Face (RF), Lap Joint, Ring Type Joint (RTJ), Male and Female types, and Tongue and groove (T&G). Among them, FF, RF and RTJ faces are regularly used in piping.
Flat face flanges are used when the counter flange has a flat face. This condition occurs mainly in connection to Cast Iron equipment, valves, and specialties. Full face non-metallic gasket is used when a flat face flange is used. This type of flange not used in high pressure and temperature application.
Raised face flange has a small portion around the bore that is raised from the face. The gasket seat on this raised face. The height of the raised face depends on the flange pressure-temperature rating that is known as a class of the flange. This type of flange is used in high pressure and temperature application.Ring joint type face flange has a specially designed grove in which metal gasket seat. This type of flange is used in very high pressure and temperature services.
