| ProjectSample Project — Demonstration Only | Job No.SAMPLE-001 | Client— |
| CalculationHydrostatic / Pneumatic Leak Test Pressure Calculator (ASME B31.3) | Calc byPiping Toolset (calc-core) | Checked byUNCHECKED — sample |
| Date2026-09-03 | Rev0 | BasisASME B31.3 ¶345.4.2 Eq. (24) / ¶345.5.4; B31.1 ¶137.4.5 via factors |
Design pressure 300 psi; allowable stress 20,000 psi at ambient test temperature and 17,500 psi at design temperature; B31.3 factors.
| Design pressure P | 300 | psi |
| ST at test temperature | 20,000 | psi |
| S at design temperature | 17,500 | psi |
| Hydro factor | 1.5 | — |
| Pneumatic factor | 1.1 | — |
Phydro = 1.5 · P · (ST / S) (ST/S capped, default 6.5)
Ppneumatic = 1.1 · P
where ST is the allowable stress at test (ambient) temperature and S the allowable stress at design temperature. The logic of Eq. (24) is that a test performed cold must demonstrate a stress condition at least proportionate to the design-temperature condition: when the design temperature is high enough to depress S, the ratio ST/S exceeds 1.0 and the test pressure rises above the bare 1.5×P. The calculator computes the ratio, applies the cap (6.5 by default, per the note to Eq. 24), multiplies out the hydrostatic minimum, and reports the pneumatic alternative at 1.1×P alongside it. The 1.5 hydro factor, 1.1 pneumatic factor, and the stress-ratio cap are all inputs rather than constants, so the same card serves B31.1 (¶137.4.5: 1.5×, no stress ratio — enter a cap of 1.0) and company standards with stricter factors. Both allowables come from you; the card does no table lookups. The worked example shows the mechanics at moderate scale — a ratio of 1.14286 lifts a 300 psi design to a 514.3 psi hydro target — and the same arithmetic runs smoothly up to the cap for designs deep in the temperature range.
| Stress ratio ST/S | 1.14286 | — |
| Hydrostatic test pressure | 514.3 | psi |
| Pneumatic test pressure | 330 | psi |
The result values above are locked as fixture leak-test-pressure.json, case
“P=300, ST/S=20000/17500, B31.3 factors”, tolerance 0.001, in the calc-core continuous
verification gate (see https://pipingtoolset.com/trust/validation.html). Allowable-stress and factor data are
user-supplied inputs; citations: ASME B31.3, Process Piping — ¶345.4.2 Eq. (24) hydrostatic test; ¶345.5.4 pneumatic test. · ASME B31.1, Power Piping — ¶137.4.5 (same card with factor 1.5 and ratio 1.0).