What is the diameter of the steel tube DN20?
Stress: the nominal diameter is not the outer diameter of the pipe, nor the inner diameter of the tube. It is not the average value of the inside and outside diameter (the nominal diameter of the equipment refers to the outer diameter).
Pipe installation without conversion, because in the same standard in the same diameter connecting dimensions of the same nominal pressure level of the same, and the same material have the same diameter, the nominal diameter of the purpose is to facilitate connectivity
Usually the nominal diameter is nominal for cast iron pipe, steel pipe joints, concrete pipe pipe, seamless steel pipe does not use this notation (with diameter * wall thickness). With nominal diameter pipeline accessories, meaning with tube.
The symbol is DN, the unit is mm, but omitted to write. Also available in English in.
1, nominal diameter is nominal diameter, or nominal diameter, or nominal size.2, nominal diameter is a variety of pipe and pipe accessories generic caliber. The same nominal diameter of the tube and pipe accessories can connect with each other, with interchangeability. It is not a real sense of the pipe diameter or diameter, although its value is closer with the pipe diameter or equivalent, is a convenient integer for reference only, are not strict with processing size. Nominal diameter is not the outer diameter, nor the inner diameter, but a nominal size similar to the diameter of the ordinary steel pipe. In order to connect the pipe and pipe fittings in a uniform dimension, each nominal diameter corresponds to an outer diameter, and the inner diameter value varies with the thickness.
