Large flanges not only have different use values, effects and functions when used, but also have various materials, production processes and processing methods. Thus, we have to pay special attention to the methods of both processing and utilizing large flanges.
Common large flanges include slip-on large flanges and weld neck large flanges. Slip-on large flanges have poor rigidity and are suitable for the conditions when the pressure is lower than or equal to 4Mpa. Weld neck large flanges, also known as high-neck large flanges, have high rigidity and are applicable to conditions with high pressure and temperature. There are three types of large flanges' sealing surfaces: flat type sealing surface, suitable for the conditions with low pressure and non-toxic media; concavo-convex sealing surface, suitable for the conditions with slightly high pressure; tongue and groove sealing surface, suitable for the conditions with flammable, easily explosive, toxic media and high pressure. Large flanges which good product performance in different fields are adaptive to different conditions and spaces and can result in different effects.
The gasket of the large flange is a ring with a certain strength, which can produce plastic deformation. Most of the gaskets are cut from non-metallic plates or produced by professional factories according to the specified sizes. The materials of gaskets include asbestos rubber sheets, asbestos boards and polyethylene plates. Some of the gaskets are metal gaskets which are produced by wrapping the non-metallic materials such as asbestos with the thin metal plates (white sheet iron, stainless steel sheets). There are also spiral wound gaskets produced by twisting the thin steel belts and the asbestos tapes together.
Large flanges used for high-pressure equipment and pipelines usually adopt lens-type gaskets or metal gaskets in other shapes made of copper, aluminum, stainless steel, etc. The contact between the high pressure gaskets and the sealing surfaces, both of which have high processing finish, is line contact.
The large flange connection is mainly used for the connections of cast iron pipes, rubber lined pipes, non-ferrous metal pipes, large flange valves, etc. Large flange connection features in easy disassembly, high strength as well as good sealing performance. When install large flanges, the two large flanges should be kept parallel, whose sealing surfaces should not be hurt and must be cleaned up.