18.104.22.168 Other flange standards
In addition to the listed vacuum flanges there are numerous other flange standards which are used, for example, in industrial and process engineering, but are not as widespread in vacuum technology. Often, their surfaces are rough and designed for flat seals. For systems that operate under vacuum and overpressure, vacuum flanges can only be used to a very limited extent. For this purpose, flanges according to EN 1092-1 are used, for example. To design flanges that are suitable for vacuum, the sealing surfaces must be reworked; for example, a flange with an O-ring groove and a flange with a smooth sealing surface are paired. Therefore, the relevant statutory regulations for pressure vessels and piping must be observed.