Butt welded flange, also known as high neck flange, is rigid and suitable for high pressure and temperature occasions. There are three types of flange sealing surface: flat sealing surface, which is suitable for situations with low pressure and non-toxic medium; concave and convex sealing surface, which is suitable for situations with slightly higher pressure; mortise sealing surface, which is suitable for situations with flammable, explosive, toxic medium and high pressure. Gasket is a kind of ring which can produce plastic deformation and has certain strength. Most gaskets for butt-welded flanges are cut from non-metallic plates or manufactured by professional factories on a regular scale. The data are asbestos rubber sheets, asbestos sheets, polyethylene sheets, etc. There are also metal-clad gaskets made by wrapping asbestos and other non-metallic materials with thin metal sheets.
There is also a surround gasket made of thin steel strip and asbestos strip. Ordinary rubber gaskets are suitable for applications where the temperature is lower than 120 C; asbestos rubber gaskets are suitable for situations where the steam temperature is lower than 450 C, the oil temperature is lower than 350 C and the pressure is lower than 5 MPa. For general corrosive media, acid-resistant asbestos board is the most commonly used. According to the parts connected, they can be divided into container flange and pipe flange. According to the structure type, there are all flanges, looper flanges and threaded flanges. Flat welding flange and butt welding flange are common for all flanges. It can be cast (the drawing is missing), or it can be made of threaded joints or welding. The flange connection consists of a pair of flanges, a gasket and several bolts and nuts.