Pipe Working Pressures Seamless Welded 01

Pipe Working Pressures – Seamless & Welded

Barlows Formula:

Bursting Pressures: P = 2 x S x t

P = Pressure Rating (MPa)
S = Minimum tensile strength (MPa) (S= 517MPa)*
t = Wall Thickness (mm)
D = Outside Diameter of Pipe (mm)

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.

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

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  
Bar 10 
kgf/cm² 10.2
Kilopascal 1000
Hectopascal 10000
Millibar 10000
kgf/m² 101971.6
Pascal 1000000


1 Bar 14.7 psi