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).