Technical
Pipe Working Pressures
NOMINAL WORKING PRESSURES
Figures shown in tables are nominal working pressures for seamless pipe under constant operating conditions. Where pressures or temperature fluctuations occur, increased safety factors should be adopted. Listed are factors of safety recommended for varying pressure conditions.
APPLY
5 to bursting pressure for no pressure fluctuations
8 to bursting pressure for small/regular pressure fluctuations
12 to bursting pressure for small/regular fluctuations
* Tensile strength of 304 at room temperature
BARLOWS FORMULA
Bursting Pressures: P = 2 x S x t
D
P = Pressure Rating (MPa)
S = Minimum tensile strength (MPa) (S= 517MPa)*
t = Wall Thickness (mm)
D = Outside Diameter of Pipe (mm)
Note: The figures given for nominal working pressures and factor of safety are for quick reference purposes only. Detailed design calculations should be in accordance with the applicable design standard.
CONVERSION TABLE
Megapascal | 1 |
Bar | 10 |
kgf/cm2 | 10.2 |
Kilopascal | 1000 |
Hectopascal | 10000 |
Millibar | 10000 |
kgf/m2 | 101971.6 |
Pascal | 1000000 |
NOMINAL WORKING PRESSURES CHART - GENERAL AUSTENITIC GRADES
Note: This chart is based on a nominal safety factor of 4 and applies to seamless pipe only.
Nominal Bore Size | Temp °C | ||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schedule 10S | Schedule 40S | Schedule 80S | |||||||||||||||||||||||
mm | In | 50 | 100 | 150 | 200 | 250 | 300 | 350 | 400 | 50 | 100 | 150 | 200 | 250 | 300 | 350 | 400 | 50 | 100 | 150 | 200 | 250 | 300 | 350 | 400 |
6 | 0.125 | 30.1 | 26.8 | 23.4 | 21.7 | 20.2 | 19.2 | 18.5 | 17.9 | 42.1 | 37.3 | 32.6 | 30.3 | 28.2 | 26.7 | 25.9 | 25 | 58.6 | 52 | 45.5 | 42.2 | 39.3 | 37.3 | 36 | 34.8 |
8 | 0.25 | 30.1 | 26.8 | 23.4 | 21.7 | 20.2 | 19.2 | 18.5 | 17.9 | 40.9 | 36.3 | 31.8 | 29.5 | 27.5 | 26 | 25.2 | 24.3 | 55.2 | 49 | 42.8 | 39.7 | 37 | 35.1 | 33.9 | 32.8 |
10 | 0.375 | 24.1 | 21.4 | 18.7 | 17.4 | 16.2 | 15.4 | 14.9 | 14.4 | 33.8 | 30 | 26.2 | 24.3 | 22.7 | 21.5 | 20.8 | 20.1 | 46.8 | 41.6 | 36.4 | 33.7 | 31.4 | 29.8 | 28.8 | 27.8 |
15 | 0.5 | 24.8 | 22 | 19.2 | 17.9 | 16.6 | 15.8 | 15.3 | 14.7 | 32.5 | 28.9 | 25.3 | 23.4 | 21.8 | 20.7 | 20 | 19.3 | 43.8 | 38.9 | 34 | 31.6 | 29.4 | 27.9 | 27 | 26 |
20 | 0.75 | 19.8 | 17.6 | 15.4 | 14.2 | 13.3 | 12.6 | 12.2 | 11.8 | 26.9 | 23.9 | 20.9 | 19.4 | 18.1 | 17.1 | 16.6 | 16 | 36.6 | 32.5 | 28.4 | 26.4 | 24.6 | 23.3 | 22.6 | 21.8 |
25 | 1 | 20.8 | 18.4 | 16.1 | 14.9 | 13.9 | 13.2 | 12.8 | 12.3 | 25.3 | 22.5 | 19.7 | 18.2 | 17 | 16.1 | 15.6 | 15.1 | 34.1 | 30.3 | 26.5 | 24.6 | 22.9 | 21.7 | 21 | 20.3 |
32 | 1.25 | 16.4 | 14.6 | 12.8 | 11.8 | 11 | 10.5 | 10.1 | 9.8 | 21.1 | 18.7 | 16.4 | 15.2 | 14.2 | 13.4 | 13 | 12.5 | 28.8 | 25.5 | 22.3 | 20.7 | 19.3 | 18.3 | 17.7 | 17.1 |
40 | 1.5 | 14.4 | 12.7 | 11.1 | 10.3 | 9.6 | 9.1 | 8.8 | 8.5 | 19.1 | 16.9 | 14.8 | 13.7 | 12.8 | 12.1 | 11.7 | 11.3 | 26.3 | 23.4 | 20.4 | 19 | 17.7 | 16.7 | 16.2 | 15.6 |
50 | 2 | 11.5 | 10.2 | 8.9 | 8.3 | 7.7 | 7.3 | 7.1 | 6.8 | 16.2 | 14.4 | 12.6 | 11.7 | 10.9 | 10.3 | 10 | 9.6 | 23 | 20.4 | 17.8 | 16.6 | 15.4 | 14.6 | 14.1 | 13.7 |
65 | 2.5 | 10.5 | 9.3 | 8.1 | 7.5 | 7 | 6.7 | 6.4 | 6.2 | 17.7 | 15.7 | 13.7 | 12.7 | 11.9 | 11.3 | 10.9 | 10.5 | 24 | 21.3 | 18.7 | 17.3 | 16.1 | 15.3 | 14.8 | 14.3 |
80 | 3 | 8.6 | 7.6 | 6.7 | 6.2 | 5.8 | 5.5 | 5.3 | 5.1 | 15.5 | 13.7 | 12 | 11.1 | 10.4 | 9.8 | 9.5 | 9.2 | 21.5 | 19.1 | 16.7 | 15.5 | 14.4 | 13.7 | 13.2 | 12.8 |
90 | 3.5 | 7.5 | 6.7 | 5.8 | 5.4 | 5 | 4.8 | 4.6 | 4.5 | 14.1 | 12.6 | 11 | 10.2 | 9.5 | 9 | 8.7 | 8.4 | 19.9 | 17.7 | 15.4 | 14.3 | 13.4 | 12.7 | 12.2 | 11.8 |
100 | 4 | 6.7 | 5.9 | 5.2 | 4.8 | 4.5 | 4.2 | 4.1 | 4 | 13.2 | 11.7 | 10.2 | 9.5 | 8.8 | 8.4 | 8.1 | 7.8 | 18.7 | 16.6 | 14.5 | 13.5 | 12.6 | 11.9 | 11.5 | 11.1 |
125 | 5 | 6 | 5.3 | 4.7 | 4.3 | 4 | 3.8 | 3.7 | 3.6 | 11.6 | 10.3 | 9 | 8.4 | 7.8 | 7.4 | 7.1 | 6.9 | 16.9 | 15 | 13.1 | 12.2 | 11.3 | 10.7 | 10.4 | 10 |
150 | 6 | 5.1 | 4.5 | 3.9 | 3.6 | 3.4 | 3.2 | 3.1 | 3 | 10.6 | 9.4 | 8.2 | 7.6 | 7.1 | 6.7 | 6.5 | 6.3 | 16.3 | 14.5 | 12.7 | 11.7 | 11 | 10.4 | 10 | 9.7 |
200 | 8 | 4.3 | 3.8 | 3.3 | 3.1 | 2.9 | 2.7 | 2.6 | 2.6 | 9.3 | 8.3 | 7.3 | 6.7 | 6.3 | 5.9 | 5.7 | 5.6 | 14.5 | 12.9 | 11.3 | 10.4 | 9.7 | 9.2 | 8.9 | 8.6 |
250 | 10 | 3.8 | 3.4 | 3 | 2.8 | 2.6 | 2.4 | 2.4 | 2.3 | 8.5 | 7.5 | 6.6 | 6.1 | 5.7 | 5.4 | 5.2 | 5 | 11.6 | 10.3 | 9 | 8.4 | 7.8 | 7.4 | 7.2 | 6.9 |
300 | 12 | 3.5 | 3.1 | 2.7 | 2.5 | 2.4 | 2.2 | 2.2 | 2.1 | 7.4 | 6.5 | 5.7 | 5.3 | 4.9 | 4.7 | 4.5 | 4.4 | 9.8 | 8.7 | 7.6 | 7.1 | 6.6 | 6.2 | 6 | 5.8 |
Nominal working pressures are shown in MPa
Nominal working pressures for welded pipe can be calculated by multiplying the figure in the tables by 0.85 (weld joint efficiency factor).