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What is a Pipe Schedule?
Pipes are designed to carry fluid, therefore their internal diameter is their critical dimension. This critical dimension is referred to as the nominal bore, appreviated as NB. Obviously, for pipes containing pressurised fluids the wall thickness, and by implication the pipe's strength, is important. Wall thickness is expressed in "schedules", refered to as pipe schedules.
The wall thickness associated with a particular schedule depends on the pipe size as can be seen from the charts below for some of the more common sized carbon steel pipes encountered.
Abbreviations used: NB - nominal bore, STD - Standard, EH - Extra Heavy, DBL EH - Double Extra Heavy.
| 2"NB | OD = 2.375 inch (60.32 mm) | ||||||||||||
| Schedule | 5 | 10 | 20 | 30 | 40 STD |
60 | 80 EH |
100 | 120 | 140 | 160 | DBL EH | |
| ID (ins) | 2.245 | 2.157 | --- | --- | 2.067 | --- | 1.939 | --- | --- | --- | 1.689 | 1.503 | |
| ID (mm) | 57.02 | 54.79 | --- | --- | 52.5 | --- | 49.25 | --- | --- | --- | 42.9 | 38.18 | |
| 3" NB | OD = 3.5 inch (88.9 mm) | |||||||||||||
| Schedule | 5 | 10 | 20 | 30 | 40 STD |
60 | 80 EH |
100 | 120 | 140 | 160 | DBL EH | ||
| ID (ins) | 3.334 | 3.260 | --- | --- | 3.068 | --- | 2.900 | --- | --- | --- | 2.624 | 2.300 | ||
| ID (mm) | 84.68 | 82.8 | --- | --- | 77.93 | --- | 73.66 | --- | --- | --- | 66.65 | 58.42 | ||
| 4" NB | OD = 4.5 inch (114.3 mm) | |||||||||||||
| Schedule | 5 | 10 | 20 | 30 | 40 STD |
60 | 80 EH |
100 | 120 | 140 | 160 | DBL EH | ||
| ID (ins) | 4.334 | 4.260 | --- | --- | 4.026 | --- | 3.826 | --- | 3.624 | --- | 3.438 | 3.152 | ||
| ID (mm) | 110.08 | 108.2 | --- | --- | 102.26 | --- | 97.18 | --- | 92.05 | --- | 87.33 | 80.06 | ||
| 6" NB | OD = 6.625 inch (168.275 mm) | |||||||||||||
| Schedule | 5 | 10 | 20 | 30 | 40 STD |
60 | 80 EH |
100 | 120 | 140 | 160 | DBL EH | ||
| ID (ins) | 6.407 | 6.357 | --- | --- | 6.065 | --- | 5.761 | --- | 5.501 | --- | 5.189 | 4.897 | ||
| ID (mm) | 162.74 | 161.47 | --- | --- | 154.05 | --- | 146.33 | --- | 139.73 | --- | 131.8 | 124.38 | ||
| 8" NB | OD = 8.625 inch (219.1 mm) | |||||||||||||
| Schedule | 5 | 10 | 20 | 30 | 40 STD |
60 | 80 EH |
100 | 120 | 140 | 160 | DBL EH | ||
| ID (ins) | 8.407 | 8.329 | 8.125 | 8.071 | 7.981 | 7.813 | 7.625 | 7.439 | 7.189 | 7.001 | 6.813 | 6.375 | ||
| ID (mm) | 213.54 | 211.56 | 206.38 | 205 | 202.72 | 198.45 | 193.67 | 188.95 | 182.6 | 177.83 | 173.05 | 161.93 | ||
| 10" NB | OD = 10.750 inch (273 mm) | |||||||||||||
| Schedule | 5 | 10 | 20 | 30 | 40 STD |
60 | 80 EH |
100 | 120 | 140 | 160 | DBL EH | ||
| ID (ins) | 10.482 | 10.42 | 10.25 | 10.136 | 10.02 | 9.750 | 9.564 | 9.314 | 9.064 | 8.750 | 8.500 | --- | ||
| ID (mm) | 266.24 | 264.67 | 260.35 | 257.45 | 254.5 | 247.65 | 242.93 | 236.58 | 230.23 | 222.25 | 215.9 | --- | ||
| 12" NB | OD = 12.750 inch (323.85 mm) | |||||||||||||
| Schedule | 5 | 10 | 20 | 30 | 40 STD |
60 | 80 EH |
100 | 120 | 140 | 160 | DBL EH | ||
| ID (ins) | 12.42 | 12.39 | 12.25 | 12.09 | 11.938 12.000 |
11.626 | 11.376 11.750 |
11.064 | 10.75 | 10.50 | 10.126 | --- | ||
| ID (mm) | 315.47 | 314.7 | 311.15 | 307.1 | 303.22 304.8 |
295.3 | 288.95 298.45 |
281.03 | 273.05 | 266.7 | 257.2 | --- | ||
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