1. Nominal inner diameter and corresponding outer diameter:
DN15: The nominal inner diameter is 15 mm and the corresponding outer diameter is 21.3 mm.
DN20: The nominal inner diameter is 20 mm and the outer diameter is 26.9 mm.
DN25: The nominal inner diameter is 25 mm and the outer diameter is 33.7 mm.
DN32: the nominal inner diameter is 32 mm and the outer diameter is 42.3 mm (some also 42.25 mm).
DN40: the nominal inner diameter is 40 mm and the outer diameter is 48.3 mm.
DN50: the nominal inner diameter is 50 mm and the outer diameter is 60 mm.
DN65: the nominal inner diameter is 65 mm and the outer diameter is 76.1 mm.
DN80: the nominal inner diameter is 80 mm and the outer diameter is 88.9 mm.
DN100: the nominal inner diameter is 100 mm and the outer diameter is 114.3 mm.
DN125: the nominal inner diameter is 125 mm and the outer diameter is 140 mm.
DN150: the nominal inner diameter is 150 mm and the outer diameter is 168.3 mm.
DN200: the nominal inner diameter is 200 mm and the outer diameter is 219.1 mm.
2. Wall thickness: Galvanised pipes with different nominal internal diameters have different wall thicknesses. For example, for small sizes of galvanised pipes such as DN15, the wall thickness is usually thin and may be around 2 mm; for medium sizes such as DN50-DN100, the wall thickness is usually 3-4 mm; for large sizes such as DN150 and above, the wall thickness may be 4.5 mm and above. The specific wall thickness will vary according to different production standards, usage requirements, etc.
3. Length: Generally speaking, the common length of galvanised pipe is 6 metres, although there may be other special lengths of customised products according to actual requirements.
