Types of flange faces for Thermowells
Raised Face (RF)
The Raised Face type is the most applied flange type, and is easily to identify. It is referred to as a raised face because the gasket surfaces are raised above the bolting circle face.
Ring-Type Joint (RTJ)
RTJ flanges have grooves cut into their faces which steel ring gaskets. The flanges seal when tightened bolts compress the gasket between the flanges into the grooves, deforming (or Coining) the gasket to make intimate contact inside the grooves, creating a metal to metal seal.
Ring Type Joint gaskets are designed to seal by “initial line contact” or wedging action between the mating flange and the gasket. Ring Type Joint gaskets* are metallic sealing rings, suitable for high-pressure and high-temperature applications.
Flat Face (FF)
The flat face (full face) flange has a gasket surface in the same plane as the bolting circle face.
Applications using flat face flanges are frequently those in which the mating flange or flanged fitting is made from a casting. Flat face flanges are never to be bolted to a raised face flange.