Pipe Pressure Rating Calculator (Barlow)
Allowable internal pressure of a pipe from wall thickness and material stress.
Barlow is the quick screen; code design (ASME B31.3) subtracts corrosion allowance and mill tolerance (−12.5%) from t before this math.
Formula
Pipe Pressure Rating Calculator (Barlow) is a free barlow formula for pump engineers, plumbers and plant designers — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Pipe Pressure Rating Calculator (Barlow)
Allowable internal pressure of a pipe from wall thickness and material stress. The calculation implements P = 2·S·E·t / D_o (ASME B31.3 — process piping). Barlow is the quick screen; code design (ASME B31.3) subtracts corrosion allowance and mill tolerance (−12.5%) from t before this math.
How to use Pipe Pressure Rating Calculator (Barlow)
- 1Enter Pipe outer diameter in mm.
- 2Enter Wall thickness in mm.
- 3Enter Allowable stress S in MPa (A106-B @ 38 °C ≈ 137.9 MPa).
- 4Enter Joint efficiency E.
- 5Read Allowable pressure, Allowable instantly — no submit button needed.
- 6Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Pipe Pressure Rating Calculator (Barlow)?
- ✓Implements the standard formula — P = 2·S·E·t / D_o
- ✓Reference cited on-page: ASME B31.3 — process piping
- ✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
- ✓Live worked example: the substitution recomputes from your numbers
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Pipe Pressure Rating Calculator (Barlow) use?+
It computes P = 2·S·E·t / D_o, per ASME B31.3 — process piping. The formula is displayed under the result along with a worked example substituted with your own inputs.
What should I keep in mind when using this calculator?+
Barlow is the quick screen; code design (ASME B31.3) subtracts corrosion allowance and mill tolerance (−12.5%) from t before this math.
Can I use this for pump selection?+
Use it to establish the duty (flow, head, NPSH, power) and then pick a pump whose curve passes through that point near best efficiency. The tool gives you the engineering numbers a supplier will ask for.
Is the Pipe Pressure Rating Calculator (Barlow) free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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