How to choose the first flange sealing surface form of the pressure vessel using flange connection

How to choose the first flange sealing surface form of the pressure vessel using flange connection

The flange welded by the connecting pipe on the pressure vessel cylinder to the flange is the first flange connected to the pressure vessel flange, and the flange that is matched with it is not counted as the first flange, and other flanges. Not within the scope of this pressure vessel. The available sealing forms are full plane (FF), raised face (RF), concave-convex face (MFM), tongue and groove face (TG), and the most commonly used seal is the raised face (RF).

The flat (convex) flange sealing surface has the advantages of simple structure, convenient processing, and easy to carry out anti-corrosion lining. Due to the large contact area between the sealing surface and the gasket, the gasket is easy to be extruded if the pre-tightening is improper Sealing surface. It is not easy to compress, and the sealing performance is poor. It is suitable for occasions where the pressure is not high. It is generally used under the pressure of PN≤2.5MPa.

　　 Concave-convex flange sealing surfaces match the two flange joint surfaces, one is convex and the other is concave. It is easy to align during installation and can effectively prevent the gasket from being squeezed out of the sealing surface. The sealing performance is better than that of a flat sealing surface.

　　 Tongue and groove flange sealing surface is formed by matching one tongue and groove surface, therefore, the sealing surface is narrower. Because it is blocked by the groove surface, the gasket will not be squeezed out of the pressing surface, and it is less eroded and corroded by the medium. It is easy to align during installation, the gasket is uniformly stressed, and the seal is reliable. It is suitable for the application of flammable, explosive and toxic media. Only because the gasket is very narrow, it is more difficult to replace.