A few Pipe/Tube Outside Diameter Comparisons

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.


 

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