ASME B31.3, B31.1, VIII
Hydrotest pressure calculator
Choose the code and enter the design pressure, or the MAWP for a vessel, and the allowable stresses at test and design temperature where the code uses them. The calculator returns the minimum test pressure in bar and psi with the formula.
Minimum test pressure
34.5bar
In psi
500psi
Multiplier on design
1.73x
Advisory result. Provisional until a qualified inspector or engineer verifies it against the governing code edition.
How it works
- 01ASME B31.3 hydrostatic: PT = 1.5 P x ST/S, the stress ratio capped at 6.5.
- 02ASME B31.3 pneumatic: PT = 1.1 P, subject to the stored-energy and distance limits.
- 03ASME B31.1 hydrostatic: PT = 1.5 P, not exceeding 90 percent of yield at test temperature.
- 04ASME VIII Div 1 hydrostatic: PT = 1.3 MAWP x ST/S per UG-99(b).
Formulas
PT = 1.5 P (ST / S)PT = 1.3 MAWP (ST / S)Read before you rely on it
- The test pressure must not stress any component past the code's yield limit at test temperature; the weakest component sets the ceiling.
- Flanges, valves and instruments have their own test limits; isolate or verify them.
- Edition-specific rules on hold time, temperature and gauge accuracy apply and are not computed here.
Answers
Questions about this calculator
What is the hydrotest pressure for B31.3 piping?
At least 1.5 times the design pressure, multiplied by the ratio of allowable stress at test temperature to allowable stress at design temperature, with that ratio capped at 6.5, and never so high that any component exceeds its yield limit.
When is a pneumatic test used instead?
When water would damage the system or cannot be tolerated, or the structure cannot carry the water weight. B31.3 sets the pneumatic test at 1.1 times design pressure with strict stored-energy and exclusion-distance limits.
How does the vessel test differ?
ASME VIII Division 1 tests at 1.3 times the MAWP, adjusted by the stress ratio, per UG-99. Division 2 uses different factors.
Does intelliSPEC record the test?
Yes. Pressure test records, gauge identity, hold times and witness sign-off are captured as forms in the equipment record with the signature widget and workflow approvals.