Valve Test Pressure Calculator
Enter the pressure rating of the valve and get the shell (body strength) test pressure and the seat (sealing) test pressure, using the 1.5× and 1.1× rule that GB/T 13927 and API 598 both apply.
Body strength / hydrostatic —
Sealing / tightness —
How the calculation works
A valve is tested at pressures derived from its pressure rating at the reference temperature — not from the line pressure it will see in service. Both GB/T 13927 and API 598 use the same two multipliers.
- Shell test = 1.5 × rating. The body and bonnet are pressurised with the valve partly open, so the pressure acts on the whole pressure-containing envelope. This is the hydrostatic strength test.
- Seat test = 1.1 × rating. The valve is closed and pressure is applied to one seat at a time, to prove sealing in each direction. For gas or air seat testing the same 1.1× figure applies, but the medium and the safety measures change.
- Reference temperature matters. GB/T 13927 uses the 20 °C rating; API 598 and ASME B16.34 use the 38 °C rating. Keep the basis consistent with the standard your customer quotes.
PN and ASME Class equivalents
The two rating systems are not exact conversions, but these are the pairings that are treated as equivalent in practice. The bar figure in the right column is the ASME B16.34 Group 1.1 (WCB) rating at 38 °C.
| PN (bar) | ASME Class | WCB rating at 38 °C | Shell test (1.5×) | Seat test (1.1×) |
|---|---|---|---|---|
| PN20 | Class 150 | 19.6 bar | 29.4 bar | 21.6 bar |
| PN50 | Class 300 | 51.1 bar | 76.7 bar | 56.2 bar |
| PN64 | Class 400 | 68.0 bar | 102.0 bar | 74.8 bar |
| PN100 | Class 600 | 102.1 bar | 153.2 bar | 112.3 bar |
| PN150 | Class 900 | 153.1 bar | 229.7 bar | 168.4 bar |
| PN250 | Class 1500 | 255.6 bar | 383.4 bar | 281.2 bar |
| PN420 | Class 2500 | 425.5 bar | 638.3 bar | 468.1 bar |
Ratings change with body material and temperature. For anything other than WCB at 38 °C, take the rating from ASME B16.34 or GB/T 12224 for your own material, then enter that figure in the calculator.
What the machine has to do with the result
The test pressures above are what the valve must see. Choosing equipment that can apply and hold them — at the valve sizes you actually run — is the other half of the problem.
- The clamping force has to hold the valve closed against the seat test pressure without distorting the body, which is why machines are sized from the largest seat bore and the highest test pressure rather than from nominal size alone.
- The pump duty has to fill the valve quickly and then hold pressure steadily. A large pump ramps fast and then heats the medium during a long hold; those are two different requirements.
- The pressure circuit and the clamping circuit must be separate, so the pressure a valve sees is set by the test circuit and never by the clamping pressure.
- For gas seat testing the valve has to be turned through 90° while clamped, so the seat is immersed or shielded — the feature the KY-Z immersed benches and the KY series turnover were designed around.
Tell us the size, the pressure and the standard
We will confirm which KY series machine reaches and holds those test pressures at your valve sizes, and what the clamping and sealing arrangement has to be.