Trapped liquid fire rupture screening evaluates blocked-in pipework or equipment volumes that can be heated by an external fire while thermal relief, depressurization, or other safeguards are unavailable or uncertain.

The NeqSim workflow is generic and industry-standard based. It does not encode operator-specific acceptance criteria. Project teams should configure the acceptance thresholds, material data, flange data, and required endurance for the jurisdiction and design basis under assessment.

Workflow

  1. Define the isolated inventory with TrappedInventoryCalculator using P&ID, line-list, datasheet, or other traceable evidence.
  2. Select a fire exposure with FireExposureScenario, typically API 521 pool-fire heat input or a documented incident heat flux.
  3. Select material strength using MaterialStrengthCurve, preferably from verified material records. The built-in API 5L lookup is a screening default.
  4. Run TrappedLiquidFireRuptureStudy with pipe geometry, wall thickness, optional flange class, optional relief set pressure, and time controls.
  5. Review event times for relief demand, vapor-pocket indication, pipe rupture, and flange failure.
  6. Convert the result to a passive fire protection demand or a release source term when consequence analysis is needed.

Java Example

SystemInterface oil = new SystemSrkEos(298.15, 10.0);
oil.addComponent("n-heptane", 100.0);
oil.setMixingRule("classic");

InventoryResult inventory = new TrappedInventoryCalculator()
    .setFluid(oil)
    .setOperatingConditions(10.0, "bara", 25.0, "C")
    .addPipeSegment("TL-001", 0.10, 10.0, 1.0, null)
    .calculate();

TrappedLiquidFireRuptureResult result = TrappedLiquidFireRuptureStudy.builder()
    .segmentId("TL-001")
    .fluid(oil)
    .inventory(inventory)
    .pipeGeometry(0.10, "m", 3.0, "mm", 10.0, "m")
    .api5lMaterial("X52")
    .fireScenario(FireExposureScenario.api521PoolFire(3.4, 1.0))
    .flangeClass(900)
    .timeControls(1800.0, 2.0)
    .build()
    .run();

double failureTime = result.getMinimumFailureTimeSeconds();
SafetySystemDemand pfpDemand = result.toPassiveFireProtectionDemand("PFP-TL-001", 1800.0);

The calculation returns JSON-ready results through result.toJson(), including time histories, standards applied, warnings, and recommendations.

Standards Basis

The default screening basis is aligned with common industry methods:

Topic Typical standard or method
Fire heat input and relief screening API 521 / ISO 23251
Pressure piping stress screening ASME B31.3, ASME B31.4, ASME B31.8
Flange pressure-temperature class screening ASME B16.5
Line pipe material strength API 5L / ISO 3183
Subsea pipeline design checks DNV-ST-F101 / ISO 13623
Consequence handoff CCPS and TNO source-term / effect-model practice

Engineering Notes

This is a screening model. It is appropriate for identifying segments that need thermal relief, passive fire protection, drain/vent changes, operating procedures, or detailed analysis.

Final design decisions should verify: