The flat, raised, and ring-type joints are the three most prevalent forms of flange faces (RTJ). Other flange face designs, primarily the tongue-and-groove (T&G), lap joint, and male-and-female (M&F) designs, are also available, but they are less common. The precise geometry, measurements, substance, and surface quality of a flange face are specified by piping standards.
Flat Face (FF)
Raised Face (RF)
Male and Female Face (M&F)
Tongue and Groove Face (T&G)
Ring Joint Face (RTJ or RJ)
Flat Face (FF) Flange
FF type sealing surface is completely flat, suitable for occasions with low pressure and non-toxic medium.
Raised Face (RF) Flange
RF sealing face is the most commonly used one. International standards, European standards and domestic standards all adopt fixed height. However, in American standard flanges, it should be noted that the height of high pressure will increase the height of sealing surface. There are also many types of gaskets.
The gaskets applicable to raised face flanges include various non-metallic flat gaskets and wrapped gaskets; Metal gasket; Spiral wound gasket (including outer ring or inner ring), etc.
Male and Female Face (M&F) Flange
MF and FF are a pair of sealing surface types, which must be used together to facilitate alignment during installation and prevent the gasket from being extruded. Suitable for high pressure applications.
The sealing gaskets applicable to the concave convex sealing surface are: various non-metallic flat gaskets and cladding gaskets; Metal gasket; Basic type or spiral wound gasket with inner ring, etc.
Tongue and Groove Face (T&G) Flange
TF and GF are similar to the concave and convex surfaces, and they are also the type of mating sealing surfaces of one male and one female, which are also used in pairs. The gasket is located in the annular groove, limited by the metal walls on both sides, which can avoid the gasket being squeezed into the pipeline due to compression deformation. As the gasket does not directly contact with the fluid medium in the pipe, and is less subject to the erosion or corrosion of the fluid medium, it can be used in high-pressure, flammable and explosive, toxic media and other places with strict sealing requirements. This kind of sealing face gasket is good for neutral installation, but it is difficult to process the sealing face. The sealing face is easy to be damaged when replacing the gasket, and the flange must be separated axially during installation and disassembly. Therefore, the possibility of separating the flange axially should be considered during pipeline design.
Ring Joint Face (RTJ or RJ) Flange
The flange sealed by RJF ring connection surface is also a narrow face flange, and a circular trapezoidal groove is cut out on the raised face of the flange as the flange sealing surface. Like the tongue and groove face flange, this flange must be axially separated during installation and disassembly. Therefore, the possibility of axially separating the flange should be considered during pipeline design.
The sealing surface is specially used for matching with solid metal gasket with octagonal or oval shape processed from metal materials to achieve sealing connection. Since the metal ring gasket can be based on the inherent characteristics of various metals, this sealing surface.
