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Hydrostatic Test Pressure Calculator

49 CFR 192.505 & ASME B31.8 Compliant

Professional Hydrostatic Test Pressure Calculator
Calculates minimum and maximum test pressures per 49 CFR 192.505, ASME B31.8 Section 847, and B31.3 Section 345. Verifies test pressure does not exceed 90% SMYS and provides test duration requirements.

Design Code

Gas transmission per DOT requirements. Test factors based on location class.

Pipe Geometry

in
in

Operating Conditions

psig

Material Properties

psi

Common API 5L grades:
• Grade B: 35,000 psi
• X42: 42,000 psi
• X52: 52,000 psi
• X65: 65,000 psi
• X70: 70,000 psi

Location Class (49 CFR 192)

Per 49 CFR 192.505: Class 1 & 2 require 1.25× MAOP minimum. Class 3 & 4 require 1.40× MAOP minimum. Industry practice often uses 1.50× for new construction.

Elevation Correction

ft

Water column adds ~0.433 psi per foot of elevation. Enter positive value for downhill test sections.

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Understand facility piping standards, testing requirements, and code compliance

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Hydrostatic Test Requirements (49 CFR 192.505)

Class 1 & 2 Locations:
  • Minimum: 1.25× MAOP
  • Duration: 8 hours minimum
Class 3 & 4 Locations:
  • Minimum: 1.40× MAOP
  • Duration: 8 hours minimum
Maximum Test Pressure:
  • Should not exceed 90% SMYS
  • At any point in the test section

Technical Notes

  • Pressure at Low Point: Account for static head of water column. P_low = P_gauge + (0.433 psi/ft × elevation difference)
  • Temperature Stability: Wait for temperature equilibrium before starting hold period. Typical: 4-6 hours stabilization.
  • Test Medium: Water preferred for safety. Air/gas testing requires additional safety precautions due to stored energy.
  • Recording: Document test pressure, duration, temperature, and any pressure changes during hold period.

Limitations & Assumptions

  • Calculations assume uniform pipe wall thickness (no corrosion)
  • Does not account for connected fittings, valves, or components with lower ratings
  • Test section should be isolated from operating equipment
  • Results are for preliminary planning - verify with PE-stamped test procedures

Standards & References

  • 49 CFR 192.505
    Strength test requirements for steel pipe
  • ASME B31.8-2022
    Gas Transmission & Distribution Piping, Section 847
  • ASME B31.3
    Process Piping, Section 345
  • ASME B31.4
    Liquid Petroleum Pipelines, Section 437

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