1. Test Parameters
kPa a
—
2. System Volume
Pipe Calculation
Direct Input
3. Safety Distance Screening
m/kg1/3
m
Hazard Analysis
--
Stored Energy (E)
--
TNT Equivalent
Safety Distances (Screening)
| Scaled Distance (R = Z·W1/3) | -- |
| Recommended Exclusion Zone | -- |
Calc Details
| Absolute Pressure (Pabs) | -- |
| Total System Volume (V) | -- |
| Expansion Factor (k) | -- |
Warning: This tool is a theoretical engineering check
based on ASME PCC-2. It does not replace a formal Risk Assessment,
site-specific safety procedures, or exclusion zone mandates.
Technical Notes
Variable Definitions
- Pg: Test pressure (gauge).
- Patm: Atmospheric pressure (absolute).
- Pabs: Absolute test pressure = Pg + Patm.
- V: Total system volume under test (converted internally to m³).
- k: Isentropic exponent (Cp/Cv), must be > 1.
- E: Stored energy released on rapid decompression (J).
- WTNT: TNT equivalent mass (kg).
- Z: Scaled-distance coefficient (m/kg1/3) for screening.
- R: Screening stand-off distance (m).
Formulas / Logic
-
Stored Energy (Isentropic / Ideal Gas):
E = (Pabs · V)/(k − 1) · [ 1 − (Patm/Pabs)(k − 1)/k ] - TNT Equivalent: WTNT = E / 4,266,920 (kg)
- Scaled Distance (screening): R = Z · (WTNT)1/3
- Recommended Exclusion Zone: Rfinal = max(Rmin, R)
- Pipe-mode volume: Internal diameter computed from embedded OD & schedule thickness; volume = area × length + extra volume.
Assumptions / Notes
- Adiabatic, isentropic expansion of an ideal gas (screening method).
- Valid only when Pabs > Patm and V > 0. Otherwise energy is reported as zero.
- Z-factor and minimum distance are HSE / project-specific. Use client/company standards for final exclusion zones.
- This tool provides a theoretical check and does not replace a formal risk assessment or site procedure.
Standards / References
- Stored Energy: ASME PCC‑2 (pneumatic test energy screening; user should verify the applicable appendix/edition used by the project).
- Pipe dimensions: Embedded database based on common ASME B36.10M NPS OD and schedule thickness values (subset).
- Blast scaling: Hopkinson–Cranz scaled-distance method (screening approach).
- Conversions: 1 bar = 100,000 Pa; 1 psi = 6,894.757 Pa; 1 ft = 0.3048 m; 1 ft³ = 0.0283168 m³; 1 L = 0.001 m³.