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Pipe Schedules

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, commonly 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.
 
What Standards Govern Pipe Sizes?
In the oil and gas and related down stream industries the the most common standards are
- ASME/ANSI B 36.10 Welded and Seamless Wrought Steel Pipe, and
- ASME/ANSI B36.19 Stainless Steel Pipe
 
Does Pipe Schedule Change With Pipe Size?
For all pipe sizes the outside diameter remains relatively constant. Therefore any variation schedule i.e. wall thickness, affects only the inside diameter. As the schedule number increases, the wall thickness increases, and the actual bore is reduced.
 
Pipe Schedule Charts
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)
Schedule510203040
STD
6080
EH
100120140160DBL EH
ID (ins)10.48210.4210.2510.13610.029.7509.5649.3149.0648.7508.500---
ID (mm)266.24264.67260.35257.45254.5247.65242.93236.58230.23222.25215.9---

 
 12" NBOD = 12.750 inch (323.85 mm)
Schedule510203040
STD
6080
EH
100120140160DBL EH
ID (ins)12.4212.3912.2512.0911.938
12.000
11.62611.376
11.750
11.06410.7510.5010.126---
ID (mm)315.47314.7311.15307.1303.22
304.8
295.3288.95
298.45
281.03273.05266.7257.2---

 
pipe schedules

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