Use this page to identify the maintained NeqSim safety capability that matches an engineering question. Start with the safety documentation hub for task-oriented guides and the process-safety API overview for lifecycle, unit, and validation boundaries.

NeqSim results are engineering evidence, not design approval. A competent engineer must still select credible scenarios, confirm inventories and boundary conditions, apply the project editions of governing standards, validate models against suitable references, and document uncertainty and acceptance criteria.

Current capability map

Engineering question Maintained capability Status and boundary
Which flowsheet disturbances should be screened? ProcessSafetyScenario and ProcessSafetyAnalyzer Available for blocked-outlet, utility-loss, controller-set-point, and custom-manipulator screening. Generated scenarios require HAZOP and relief-study review.
What is the time-dependent release source term? LeakModel and SourceTermResult Available for bounded leak and vessel-inventory screening with mass rate, temperature, pressure, phase fraction, velocity, and momentum histories. Validate the discharge model for the release regime.
Where are hydrate, wax, CO2-freezing, MDMT, and phase limits? SafetyEnvelopeCalculator and SafetyEnvelope Available as thermodynamic screening envelopes. Material selection and operating limits require project-specific review.
How can event frequencies and consequences be combined? RiskModel, RiskEvent, and RiskResult Available for event-tree, Monte Carlo, sensitivity, and F-N screening. Frequencies and conditional probabilities remain project inputs.
How does a vessel depressurize? VesselDepressurization and depressurization helpers Available for transient pressure, temperature, wall-temperature, fire-case, and flow-assurance screening. See the API 521 depressurization workflow.
How should a relief device be screened? SafetyValve, SafetyReliefValve, and ReliefValveSizing Gas-service screening is available. See relief-valve sizing screening; certify sizing and installation outside this example.
How are release cases handed to consequence work? ReleaseDispersionScenarioGenerator and source-term exports Available as a screening and handoff layer. See release and dispersion scenarios. CFD geometry, congestion, ventilation, and acceptance remain external engineering inputs.

Executable release-source-term starting point

This complete Java 8 program creates a methane inventory at 50 bar(a), screens a 10 mm horizontal release to 1.01325 bar(a), and checks that the result is physically usable. Diameter is supplied in millimetres, volume in m3, duration and time step in seconds, and the returned mass rates are in kg/s.

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import neqsim.process.safety.release.LeakModel;
import neqsim.process.safety.release.ReleaseOrientation;
import neqsim.process.safety.release.SourceTermResult;
import neqsim.thermo.system.SystemInterface;
import neqsim.thermo.system.SystemSrkEos;

public final class SafetySourceTermRoadmapExample {
  private static final Logger logger =
      LogManager.getLogger(SafetySourceTermRoadmapExample.class);

  private SafetySourceTermRoadmapExample() {}

  public static void main(String[] args) {
    SystemInterface methane = new SystemSrkEos(293.15, 50.0);
    methane.addComponent("methane", 1.0);
    methane.setMixingRule("classic");

    LeakModel release =
        LeakModel.builder()
            .fluid(methane)
            .holeDiameter(10.0, "mm")
            .vesselVolume(1.0)
            .backPressure(1.01325, "bar")
            .orientation(ReleaseOrientation.HORIZONTAL)
            .scenarioName("50 bar(a) methane release")
            .build();

    SourceTermResult result = release.calculateSourceTerm(4.0, 1.0);
    double initialMassRate = result.getMassFlowRate()[0];

    assert result.getNumberOfPoints() == 5;
    assert initialMassRate > 0.0;
    assert result.getPeakMassFlowRate() >= initialMassRate;
    assert result.getTotalMassReleased() > 0.0;
    assert result.getPressure()[0] > 1.01325e5;
    assert result.getTemperature()[0] > 0.0;

    logger.info(
        "{}: initial rate={} kg/s, released={} kg",
        result.getScenarioName(),
        initialMassRate,
        result.getTotalMassReleased());
  }
}

The example deliberately stops at source-term generation. Do not treat its default discharge coefficient, homogeneous phase treatment, inventory depletion approximation, or short duration as a project release basis. The release and dispersion guide describes the required downstream handoff and validation boundary.

Prioritized remaining work

  1. Couple relief-source calculations to time-dependent disposal-network back pressure without weakening the existing static screening route.
  2. Add traceable reaction-force and discharge-piping calculations with explicit standard-edition assumptions and benchmark cases.
  3. Extend and validate two-phase relief methods before presenting them as design calculations.
  4. Improve shared inventory and phase-state handoff between scenario execution, depressurization, release, and consequence models.
  5. Maintain benchmark datasets and uncertainty reporting for each safety calculation family.

These are capability gaps, not promises of calendar delivery. New methods need focused numerical tests, source-backed documentation, and comparison with accepted engineering tools or published benchmarks before their status changes here.