The most frequent 7 types of flanges sealing surface: FF, RF, M, FM, T, G, RTJ

The joint between valve and pipeline, there are Flanges. Do you know all the 7 types of flanges sealing surfaces?  Those are: FF, RF, MF, M, T, G, RTJ, Let me explain the meaning and applications basically, 

Face to Face: FF
Raised Face: RF
Female Face: FM
Male Face: M
Tongue Face: T
Groove Face: G
Ring Joint Face: RJ (RTJ) 

According to the different working conditions, mediums, pressures, specifications, temperatures, etc., the selection of types are different. Let’s get to know those types of flanges together!

FF-Face to Face:
FF type sealing surface is completely flat and suitable for applying occasions where the pressure is not high as well as the medium is non-toxic.

FF  flange 

RF-Raised Face:
The RF flanges are the most widely used among those types. Both of the international standards, European system and American standards are all set height for the Raised face, it should be noted that the RF height will increase accordingly when the medium pressure increases. There are also many types of gaskets are used. Gaskets are suitable for raised face sealing surface flanges include various non-metallic flat gaskets, coated gaskets; metal-wrapped gaskets; spiral wound gaskets (including outer ring or inner and outer ring).

flange RF

Male: M
Female: FM
The two types of sealing surfaces, Male Face and Female Face, are used for a pair, one female and one male. They must be used together. They are simple to align and they prevent the gasket from being extruded. Suitable for occasions with higher pressure.
The suitable sealing gaskets for the concave-convex sealing surface include: various non-metallic flat gaskets and coated gaskets; metal-clad gaskets; basic type or winding stopper with inner ring, etc.

flange FM-M

T-Tongue Face
G-Groove Face
Tongue Face and Groove Face are similar to the FM surface. They are also a male and female matched sealing surface type, and they are also used in a pair. The gasket is located in the annular groove and is restricted by the metal walls on both sides. It can prevent the gasket from being compressed and deformed and squeezed into the pipeline. Since the gasket is not in direct contact with the fluid medium in the pipe, it is less eroded or corroded by the fluid medium, so it can be used for high pressure, flammable, explosive, and toxic mediums that require strict sealing. This kind of sealing surface gasket has good installation and neutrality, but it is difficult to process the sealing surface. It is easy to damage the sealing surface when replacing the gasket, and the flange must be separated in the axial direction during installation and disassembly. Therefore, consideration should be given to the pipeline design. It is possible to separate the flange in the axial direction.
Suitable gaskets for the sealing surface of the tongue and groove surface include: various metal and non-metal flat gaskets, metal-clad gaskets and basic spiral wound gaskets.

flange-TG

RTJ(RJ)-Ring Joint Face
The flange of the Ring Joint Face seal is a narrow-face flange, and an annular trapezoidal groove is opened on the flange surface as the flange sealing surface, which is the same as the tongue-and-groove flange. The flange must be separated in the axial direction during installation and disassembly. Therefore, the possibility of separating the flange in the axial direction should be considered in the pipeline design.
The sealing surface is specially designed to cooperate with solid metal gaskets processed into octagonal or elliptical shapes from metal materials to achieve a sealed connection. Since the metal ring gasket can be based on the inherent characteristics of various metals, the sealing performance of this sealing surface is good, and the installation requirements are not too strict. It is suitable for high temperature and high pressure working conditions, but the processing accuracy of the sealing surface is relatively high. (According to the Pipe Fittings, Pumps and Valves Alliance)

                                                                  Flange-RTJ-RJ