The nominal diameter is indicated by the letter "DN" followed by a numerical symbol, which is used as a symbol, and the size in millimeters is indicated after the symbol. Nominal diameter refers to the nominal diameter of pipes such as cast iron pipes, slotted steel pipes and concrete pipes, but this representation is not applicable to seamless steel pipes. For example, DN50 is a pipe with a nominal diameter of 50 mm .. inch NB and a nominal diameter DN and an outer diameter OD.
Size identification of the combination of letters and numbers of piping system components. It consists of the letter DN followed by a dimensionless integer, which is directly related to the feature size (such as the aperture or outer diameter of the port connector). Unless otherwise specified in relevant standards, the number after the letter DN does not represent the measured value and cannot be used for calculation purposes. For standards that adopt DN identification system, the relationship between DN and the size of pipeline components should be given.
Extended data
The nominal diameters of some parts, such as flanges and brackets, refer to the nominal diameters of cylinders and cylinder heads that match them. DN2000 flange refers to the flange matching with DN2000 cylinder (container) or head. DN2000 saddle refers to the saddle bearing that supports DN2000mm container.
The nominal diameter of some parts is represented by the nominal diameter of the matching pipeline. Such as pipeline flange, DN200 pipeline flange refers to the pipeline flange connecting DN200mm pipeline. In addition, the nominal diameter of some container parts refers to an important dimension in the structure, such as the viewing hole of the mirror and the shaft diameter of the stuffing box. DN80(Dg80) mirror, its peephole diameter is 80mm.
Baidu encyclopedia-nominal diameter