P = 2 s t / (do SF)whereP = 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
steel pipes 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 Stainless Steel, S31803 | 65,000 | 90,000 |
Nickel Stainless Steel, N02200 | 15,000 | 55,000 |
- 1 psi (lb/in2) = 6,894.8 Pa (N/m2) = 6.895x10-2 bar
steel pipes Bursting Pressure
Bursting pressure of low carbon steel pipes are indicated in the table below:
OD (in) | Bursting Pressure (psi) | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Wall Thickness (in) | ||||||||||||
0.028 | 0.035 | 0.049 | 0.065 | 0.095 | 0.12 | 0.134 | 0.148 | 0.165 | 0.18 | 0.203 | 0.22 | |
1/4 | 13475 | 17325 | ||||||||||
5/16 | 10588 | 13475 | ||||||||||
3/8 | 8800 | 11000 | 16088 | 23375 | ||||||||
1/2 | 6463 | 8113 | 11688 | 15950 | 24613 | |||||||
5/8 | 6463 | 9213 | 12513 | 18975 | 25025 | |||||||
3/4 | 5363 | 7563 | 10175 | 15538 | 20213 | 22963 | 25713 | |||||
7/8 | 4539 | 6463 | 8663 | 13063 | 16913 | 19250 | 21450 | 24475 | ||||
1 | 3988 | 5638 | 7563 | 11000 | 14575 | 16500 | 18425 | 20900 | 23100 | |||
1 1/4 | 6050 | 8968 | 11413 | 12925 | 14438 | 16225 | 17875 | 20488 | ||||
1 1/2 | 4950 | 7288 | 9350 | 10588 | 11825 | 13200 | 14575 | 16775 | 18288 | |||
1 3/4 | 6188 | 7975 | 8938 | 10038 | 11275 | 12375 | 14025 | 15400 | ||||
2 | 5500 | 6875 | 7838 | 8663 | 9763 | 10725 | 12100 | 13200 |
- 1 in (inch) = 25.4 mm
Source: Zhejiang Yaang Pipe Industry Co., Limited (www.yaang.com)