| minal Size | Carbon / Stainless Steel Pipe OD (mm) | BS 1387:1985 OD (mm) | Cu-Ni Pipe - OD (mm) | ASTM B88M copper tube | ||||||||
| DN/OD | Inch (in) | ISO | DIN | BSP | JIS/KS | USA ASTM | Light | Medium/ Heavy | Metric | USA Inch size | Metric OD (mm) | |
| 6 | ||||||||||||
| 8 | ||||||||||||
| 6* | 1/8 | 10.2 | 10.2 | 10.2 | 10.5 | 10.3 | 10 | |||||
| 8* | 1/4 | 13.5 | 13.5 | 13.5 | 13.8 | 13.7 | 13.6 | 13.9 | 12 | |||
| 15 | ||||||||||||
| 10 | 3/8 | 17.2 | 17.2 | 17.2 | 17.3 | 17.1 | 17.1 | 17.4 | 18 | |||
| 15 | 1/2 | 21.3 | 21.3 | 21.3 | 21.7 | 21.3 | 21.4 | 21.7 | 22 | |||
| 20 | 3/4 | 26.9 | 26.9 | 26.9 | 27.2 | 26.7 | 26.9 | 27.2 | 28 | |||
| 25 | 1 | 33.7 | 33.7 | 33.7 | 34 | 33.4 | 33.8 | 34.2 | 30 | 28.24 | 35 | |
| 32 | 1 1/4 | 42.4 | 42.4 | 42.4 | 42.7 | 42.2 | 42.5 | 42.9 | 38 | 34.59 | 42 | |
| 40 | 1 1/2 | 48.3 | 48.3 | 48.3 | 48.6 | 48.3 | 48.4 | 48.8 | 44.5 | 40.94 | ||
| 50 | 2 | 60.3 | 60.3 | 60.3 | 60.5 | 60.3 | 60.2 | 60.8 | 57 | 54.05 | 54 | |
| 65 | 2 1/2 | 76.1 | 76.1 | 76.1 | 76.3 | 73 | 76 | 76.6 | 76.1 | 66.75 | 67 | |
| 80 | 3 | 88.9 | 88.9 | 88.9 | 89.1 | 88.9 | 88.7 | 89.5 | 88.9 | 79.85 | 79 | |
| 90 | 3 1/2 | 101.6 | 101.6 | 101.6 | 101.6 | 101.6 | ||||||
| 100 | 4 | 114.3 | 114.3 | 114.3 | 114.3 | 114.3 | 113.9 | 114.9 | 108 | 106.27 | 105 | |
| 125 | 5 | 139.7 | 139.7 | 139.7 | 139.8 | 141.3 | 140.6 | 133 | 131.67 | 130 | ||
| 150 | 6 | 168.3 | 168.3 | 165.1** | 165.2 | 168.3 | 166.1 | 159 | 157.68 | 156 | ||
| 200 | 8 | 219.1 | 219.1 | 219.1 | 216.3 | 219.1 | 219 | 208.48 | 206 | |||
| 250 | 10 | 273 | 273 | 273 | 267.4 | 273 | 267 | 260.5 | 257 | |||
| 300 | 12 | 323.9 | 323.9 | 323.9 | 318.5 | 323.8 | 323.8 | 312.11 | 308 | |||
| 350 | 14 | 355.6 | 355.6 | 355.6 | 355.6 | 355.6 | 368 | 363.72 | ||||
| 400 | 16 | 406.4 | 406.4 | 406.4 | 406.4 | 406.4 | 419 | 414.52 | ||||
| 450 | 18 | 457 | 457 | 457 | 457 | 457.2 | 457.2 | 465.32 | ||||
| 500 | 20 | 508 | 508 | 508 | 508 | 508 | 508 | 516.94 | ||||
| JIS = Japanese Industrial Standard | KS = Korean standard |
| **Depending upon the standard number, this may also be 168.3 mm | *Not in ISO 6708 |
|
ISO 6708
1. DN: An alphanumeric designation of size for components of a pipework system, which is used for reference purposes. It comprises the letters DN followed by a dimensionless whole number which is indirectly related to the physical size, in millimetres, of the bore or outside diameter of the end connections. |
2. The number following the letters DN does not represent a measurable value and should not be used for calculation purposes except where specified in the relevant standard.
3. In those standards which use the DN designation system, any relationship between DN and component dimensions should be given, e.g. DN/OD or DN/ID. |
US 20283 
GB 13948 
BR 12962 
CA 10975 
AU 9366 
IE 5985 
NZ 1552 
TR 1148 
