Hydrostatic test pressure

ASME / API hydrotest pressure calculator

Computes the hydrotest pressure per ASME B31.3 / B31.1 / B31.4 / B31.8 / VIII Div 1 / Div 2 / API 650 / PED. Includes the 90 %-of-yield cap that B31.3 §345.4.2(b) imposes when temperature compensation drives the value too high.

Inputs

Code of record

Design pressure / MAWPbar

Allowable S at design TMPa

From ASME II Part D Table 1A/1B at design T

Allowable S at test TMPa

At test T (usually 20 °C = ambient)

Yield Sy at room TMPa

For 90 %-of-yield cap (B31.3 §345.4.2(b))

Hold timemin

B31.3 ≥ 10 min · ASME VIII ≥ 30 min · B31.4 4-hr typical

Results

Test factor1.50×

P_test (uncapped)94.1bar

Yield-cap triggered?no — uncapped stands

P_test final94.1bar

P_test final1365psi

Hold time10min

B31.3 §345.4.2: P_test = 1.5 × P_design × (S_T / S). Hold ≥ 10 min, examine all welds.

Download all inputs + calculations + outputs as a single PDF.