oil & gas calculator
Hydrostatic Test & Barlow Pressure Calculator
Estimate a pipe's Barlow burst/design pressure and the volume of water needed to fill it for a hydrostatic test.
How it works
Barlow: P = 2 x S x t / D, where S = allowable stress, t = wall, D = outside diameter. Fill volume uses the pipe inside diameter.
Worked example
6.625 in OD, 0.280 in wall, 35,000 psi allowable: P = 2 x 35000 x 0.28 / 6.625 = 2,958 psi.
When to use it
- Use the allowable stress for the pipe's material and grade, and apply the code test factor.
- Thin-wall Barlow estimate only; follow the governing pressure-test code.
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All results are an engineering estimate — not for custody transfer. Field measurement and certified tables govern.