Barlows Formula and Bursting Pressure of pipes and tubes
Barlow's formula can be used to estimate burst pressure of pipes or tubes.
P = 2 s t / (do SF) (1)
where
P = max. working pressure (psig)
s = material strength (psi)
t = wall thickness (in)
do = outside diameter (in)
SF = safety factor (in general 1.5 to 10)
The Barlow's estimate is based on ideal conditions at room temperature.
Material Strength
The strength of a material is determined by the tensile strength tension test, which measure the tension force and the deformation of the test specimen.
- the stress which gives a permanent deformation of 0.2% is called the yield strength
- the stress which gives rupture is called the ultimate strength
Strength of some common materials:
| Material |
Yield Strength
(psi) |
Ultimate Strength
(psi) |
| Stainless Steel, 304 |
30,000 |
75,000 |
| 6 Moly, S31254 |
45,000 |
98,000 |
| Duplex, S31803 |
65,000 |
90,000 |
| Nickel, N02200 |
15,000 |
55,000 |
|
