The norm DIN EN 1092‑1 describes flange types made of steel and specifies, among other things, requirements regarding dimensions, tolerances, materials, as well as the maximum permissible pressures. The range of the included nominal sizes extends from DN10 up to DN4000. The range of the included pressure ratings goes from PN2.5 up to PN100. Eight different flanges are specified, each identified by a number. The numbers are not consecutive to enable the future addition of further flange types. Essentially, the flange types differ in terms of the design of the connection between the flange and the component carrying the flange. In addition to the flange types, eight different forms of flange facings are specified, each identified by a character.
The maximum permissible pressure is referred to as PS in the norm. The maximum permissible temperatures as TS. For nominal sizes up to DN600, the maximum permissible pressures are given for the pressure ratings covered by the norm as a function of the material of the flange and the maximum permissible temperature. The values of the maximum permissible pressures decrease with increasing temperature, so that they only coincide with the value of the corresponding pressure rating at low temperatures. At higher temperatures the maximum permissible pressures are markedly reduced and can be significantly below the value of the pressure rating. For some materials, the values differ even at room temperature. For flanges bigger than DN600, the maximum permissible pressure must be calculated as a function of the required maximum permissible temperature or it must be proven through specific experience.