What is the meaning of "DN" and "Phi" in the dimensioning of steel pipe diameter and how to apply the mark?
DN refers to the nominal diameter of the pipe, but this is neither the outside diameter nor the inside diameter, and the "Phi" means the outer diameter of the steel pipe. For example, the same nominal diameter of the steel pipe due to its different wall thickness, corresponding to the outer diameter is also different. As can be seen from the chart below:Project control table (commonly used) diameter pressure pipe standard pressure pipe standard pressure pipe standard specification DN- nominal diameter: diameter of large diameter series DN15- 22mm DN20- 27mm DN25- phi, Phi Phi Phi Phi 34mm, DN32- 42mm DN40- 48mm DN50- 60mm DN65-, Phi Phi 76 (73) mm, DN80- 89mm DN100- 114mm DN125- and Phi Phi Phi. 140mm DN150- 168mm DN200- 219mm DN250- phi, Phi Phi Phi Phi 273mm, DN300- 324mm DN350- 360mm DN400- 406mm DN450- 457mm DN500- and Phi Phi Phi Phi, 508mm DN600- 610mm, DN15- 18mm series of small diameter Phi Phi Phi, DN20- 25mm DN25- 32mm DN32- 38mm DN40- 45mm DN50- Phi Phi, Phi Phi Phi 57mm DN65- 73mm, DN80- 89mm DN100- 108mm, DN125- 133mm DN150- 159mm DN200- and Phi Phi Phi Phi, 219mm DN250- 273mm DN300- 325mm DN350- 377mm, Phi phi,
DN represents the path of the tube". Fair represents diameter. Path is the diameter of the fluid through which it should be inside. The diameter may be the outer diameter or the inner diameter. The diameter is only used when the pipe is used for flow through. Fair as long as the garden can be used. According to the requirements of mechanical drawing fair, DN text notes.
DN is a kind of Engineering path, not the actual value, due to the different standards, so the actual corresponding values is not the same; phi is refers to the actual value, the same national standard pipe inside the steel pipe, the actual value is the same, for example, GB/T8163 and GB GB fluid pipe spiral pipe and GBT/T9711.1 GB/T12459 the same nominal diameter corresponding to the actual value is the same as the actual value; and American Standard steel standard ANSI B 16.38 and ANSI B 16.9 standard American Standard fitting the same nominal correspondence is the same. If marked, the nominal diameter should be added DN, and the actual value can be omitted.
