The meaning of symbol - DN, De, D, d, Φ

Jun. 01, 2020

DN-nominal diameter

De- outer diameter

D- inner diameter

d-concrete pipe diameter

Φ- diameter of normal circle

Generally speaking, the diameter of pipe can be divided into outer diameter (De), inner diameter (D) and nominal diameter (DN).

1. DN refers to the nominal diameter of pipe, also called nominal diameter, which is a standard artificially stipulated for the convenience of design, manufacture and maintenance, and is the specification name of pipe (or pipe fitting).Note: This is neither the outside diameter nor the inside diameter. Water, gas pipe (galvanized pipe or non-galvanized pipe), cast iron pipe, steel-plastic composite pipe and polyvinyl chloride (PVC) pipe shall be marked with nominal diameter "DN" (e.g. DN15, DN50).

2. De mainly refers to the outer diameter of pipe, PPR, PE pipe and polypropylene pipe, which are generally marked by De and shall be marked in the form of outer diameter * wall thickness, such as De25×3.

3. D generally refers to the pipe diameter.

4. d concrete pipe diameter, reinforced concrete (or concrete) pipe, clay pipe, acid-resistant ceramic pipe, cylinder tile pipe and other pipe materials, pipe diameter should be expressed as inner diameter d (such as d230, d380, etc.).

5. Φ is the diameter of normal circle, can also be said of pipe diameter, but at this time should be in later times the wall thickness. Such as: Φ 25 x 3, says 25 mm outside diameter, wall thickness is 3 mm pipe. For seamless steel pipe or non-ferrous metal pipe, shall be marked "outer diameter × wall thickness". For example Φ 108 x 4, Φ can be omitted. China, ISO and Japan part of the steel pipe standard wall thickness size for steel pipe wall thickness series. For this kind of steel tube specifications of the said method x wall thickness for pipe diameter, such as Φ 60.5 x 3.8.