Carbon steel flange according to different sealing surface has a variety of classification, flange sealing surface form and use environment has a direct relationship, the following small series to take you to understand the different types of sealing surface.

1. Full plane sealing surface type (FF): mostly used for flat flange matching, suitable for the environment with small pressure, such as the working condition of PN1.0.

2. Concave convex sealing surface type (FM): mostly appears in butt welding and socket welding flange, which is not commonly used in American system, but in European system, which mostly appears in pn4.0 and pn6.4mpa pressure level, but it is not conducive to the replacement of gasket.

3. Convex sealing surface type (RF): convex flange has the widest application range. It is mostly used in pn2.0, pn5.0 and pn10.0mpa pressure levels in American flange, and in pn1.6 and PN2.5MPa pressure levels in European flange.

4. Tenon surface type (TG): use the same as concave convex surface.

5. Ring groove sealing surface type (RJ): often used with butt welding connection, not used in socket welding, mostly used in high temperature and high pressure or both. It is used in pn10.0, pn15.0, pn25.0, pn42.0mpa pressure level in American system, and also used in European system

The force level is higher than the flange.