According to different criteria, there are more classification methods for bolt flange metal joints. According to the different sealing principles, bolt flange connection can be divided into two types of floating and metal contact bolt flange connection

For floating flange metal joints, the bolt load is fully borne by the gasket seal ring. Common interactive gaskets include: non-metallic gaskets, such as PTFE gaskets, rubber gaskets, non-asbestos avant-garde rubber gaskets, etc. ; Semi-metallic gaskets, such as metal winding gaskets, metal-coated gaskets, flexible graphite composite gaskets, etc .; metal gaskets, such as metal flat gaskets, tooth-shaped gaskets, elliptical gaskets, octagonal gaskets, etc.

For metal-to-metal contact flange metal joints, the bolt load part is borne by the gasket seal ring. This is because there is a compression limiter between the two flange faces, which acts as a stopper. The device can be a part of the gasket or an independent component. When the gasket is compressed to the specified thickness, the continued application of the load will be borne by the compression limiting device to ensure the best sealing effect of the flange metal joint.

There are two main metal contact types for bolt flange metal joint clocks: one is the contact between the upper and lower flange sealing end faces; the other is the contact between the flange sealing end face and the metal outer ring of the gasket.