Basically, The sealing surface of flange has:

1. Flat Face Full Face FF

2. Prominent surface RF

3. Concave FM

4. Convex M

5. Raised Face T

6. Groove surface G

There are five types of ring connection surface RTJ (RJ). The types used are not the same depending on the working conditions, medium, pressure, specifications, temperature, etc.,

Flat Face

The sealing surface of the flat face is fully flat and is suitable for occasions where the pressure is not high and the medium is non-toxic.

Raised Face

Raised Face: Raised Face is the most widely used of several types, and commonly used one. International standards and European systems and domestic standards are fixed heights. However, the height of the high pressure should be increased the height of the sealing surface in the American standard. The use of the gasket is also of many types.

The gaskets which suitable for the flange of the sealing surface have various non-metallic flat gaskets, coated gaskets, metal gaskets,wound gaskets (including outer rings or inner and outer rings), etc.

Male Face and Female Face

The two types of sealing surfaces are a pair, one female and one male, which must be used together. Easy alignment at when installed, and prevent the gasket from being squeezed out. And this is suitable for high pressure situations.

The sealing gaskets which suitable for the flange of the sealing surface for male face and female face have various non-metallic flat gaskets, coated gaskets, metal gaskets, wound gaskets, etc.

Tongue Face and Groove Face

Tongue Face and Groove Face are similar to male face and female face, It is the type of mating sealing surface of a male and a female which also used in pairing.
The gasket is located in the annular groove and is limited by the metal walls on both sides. It be extruded into the pipe without compression deformation.

Since the gasket does not directly contact the fluid medium in the tube, it is less subject to erosion or corrosion of the fluid medium.

Therefore, it can be used in high pressure, flammable and explosive, toxic media and other occasions where sealing requirements are strict.

Therefore, it can be used in occasions where the sealing requirements are strict, such as high pressure, inflammable, explosive, and toxic medium.

The gaskets of tongue face and groove face for sealing surface

Various metal and non-metal flat pads, metal pads and basic winding gaskets, etc.

Ring Joint Face

The sealing flange of the ring joint face is also a narrow flange.

And an annular trapezoidal groove is formed on the flange surface as a flange sealing surface, which is the same as the tongue and groove face flange.

This flange must be separated from the flange in the axial direction during installation and removal.

Therefore, the possibility of separating the flanges in the axial direction should be considered in the pipeline design.

This sealing surface is specially designed to be machined with a metal material into a solid metal gasket shaped like an octagonal or elliptical shape. Achieve a sealed connection. Since the metal ring pad can be based on the inherent characteristics of various metals, the sealing performance of the sealing surface is good.

The installation requirements are not too strict, suitable for high temperature and high pressure working conditions, but the sealing surface has high processing precision.