Documents Reviewed

Document Scope Key NeqSim Relevance
STS0131 (2026) Technical safety offshore — supplement to NORSOK S-001 Time-to-rupture criteria, overpressure frequency targets, dispersion LEL thresholds, subsea leak detection
NORSOK S-001:2020 Technical safety (26 clauses) ESD, EDP, fire/gas detection, PFP, structural, flare/vent
TR2237 Performance standards for safety barriers (onshore) PS-01 through PS-14+ definition, demand/capacity framework
TR1965 (v5.02) Gas scrubber design K-factor tables, surface tension derating, internals sizing, documentation requirements
NORSOK P-002:2023 Process system design Design P/T, line sizing, separator/scrubber/HX/compressor requirements
TR2329 (v2.02) PFD and P&ID requirements Drawing standards for flowsheet documentation
TR3031 Automation requirements Control system, SIS, F&G architecture

Executive Summary: Top 6 Recommendations

# Recommendation Value Effort Priority
1 TR1965 Scrubber Compliance Checker (extend ConformityRuleSet) Direct compliance verification for every scrubber design Medium High
2 STS0131 Time-to-Rupture Acceptance (extend DepressurizationSimulator) Fire-case acceptance against Equinor-specific criteria Low High
3 NORSOK P-002 Line Sizing Validator (new utility class) Automated pipe sizing compliance for process models Medium High
4 Subsea Leak Detection Sensitivity Model (new agent workflow) Mass balance sensitivity analysis for subsea systems Medium Medium
5 Performance Standard Auto-Population from TR2237 (extend BarrierRegister) Pre-populated PS templates from TR numbering Low Medium
6 Standards-Aware Design Review Agent (new agent) Automated TR/NORSOK compliance checking across full process models High Medium

Detailed Recommendations

1. TR1965 Gas Scrubber Compliance Checker

What exists: ConformityRuleSet with TR3500RuleSet implementation, GasScrubberMechanicalDesign with K-factor, internals, and inlet device configuration.

Gap: TR1965 (v5.02) defines a different/more detailed set of requirements than TR3500:

Implementation:

// In neqsim.process.mechanicaldesign.separator.conformity
public class TR1965RuleSet extends ConformityRuleSet {

    // K-factor limits per internals type (Table 2-1)
    private static final double K_MESH_PAD = 0.11;
    private static final double K_MESH_AFC = 0.15;
    private static final double K_MESH_HF_VANE = 0.15;
    private static final double K_COMPACT = 0.9;

    // Surface tension derating threshold
    private static final double SIGMA_DERATING_THRESHOLD_MNM = 10.0;

    // Max entrainment [litre/MSm3]
    private static final double MAX_ENTRAINMENT = 13.0;

    @Override
    public ConformityReport evaluate(GasScrubberMechanicalDesign design) {
        // 1. Select K-factor limit based on internals type
        // 2. Apply Weinaug-Katz surface tension derating if sigma < 10 mN/m
        // 3. Check design margins (gas 10-25%, liquid 20%)
        // 4. Check entrainment from DemistingInternal.getCarryOverFraction()
        // 5. Check internal distances (HHLL-to-inlet, inlet-to-mesh)
    }
}

Surface tension derating calculation (leverages NeqSim):

// NeqSim already calculates surface tension via PhysicalProperties
double sigma = fluid.getInterphaseProperties().getSurfaceTension(0, 1); // N/m
double sigmaMNm = sigma * 1000.0; // convert to mN/m
if (sigmaMNm < SIGMA_DERATING_THRESHOLD_MNM) {
    double deratingFactor = weinaugKatzDerating(sigmaMNm);
    effectiveKLimit = baseKLimit * deratingFactor;
}

Why this is high value: Every scrubber design study must document TR1965 compliance. NeqSim already has the fluid model (surface tension), separator model (K-factor), and conformity framework (ConformityRuleSet). Adding TR1965 is ~200 lines of Java.

2. STS0131 Time-to-Rupture Acceptance Criteria

What exists: DepressurizationSimulator with API 521 §5.20 acceptance (50% pressure in 15 min, 7 barg in 15 min).

Gap: STS0131 Req-14766 (Clause 5.6.3.4) defines additional Equinor-specific criteria:

Implementation:

// Extend DepressurizationResult with STS0131 acceptance
public class STS0131AcceptanceCriteria implements Serializable {
    private double maxEscalatedFireRate;      // kg/s
    private double timeToEscape;              // seconds
    private double maxPressureAtRupture;      // bara (from material derating curve)
    private double acceptableRemainingMass;   // kg

    public STS0131AcceptanceResult evaluate(DepressurizationResult result) {
        // Check at each time step:
        // 1. If rupture occurs (P(T_wall) > allowable stress), what is the fire rate?
        // 2. Is personnel escape complete before escalation?
        // 3. Is remaining inventory below acceptable mass at time of potential rupture?
    }
}

Data access integration: The time-to-rupture calculation needs:

Why this is high value: Equinor is participating in a JIP to create an industry standard for time-to-rupture. Having the calculation engine ready in NeqSim positions it as the reference implementation.

3. NORSOK P-002 Line Sizing Validator

What exists: PipeBeggsAndBrills for pipe flow, but no automated compliance checking against P-002.

Gap: NORSOK P-002 Clause 8 defines:

Implementation:

package neqsim.process.mechanicaldesign.piping;

public class NorsokP002LineSizingValidator {

    public static class LineSizingResult {
        private double velocity;          // m/s
        private double pressureDrop;      // Pa/m
        private double erosionalVelocity; // m/s (API RP 14E)
        private boolean velocityOK;
        private boolean pressureDropOK;
        private String service;           // "gas", "liquid", "two-phase"
        private String standard = "NORSOK P-002:2023";
    }

    /**
     * Check a NeqSim pipe segment against P-002 criteria.
     */
    public static LineSizingResult validate(PipeBeggsAndBrills pipe) {
        // 1. Determine service from fluid phases
        // 2. Calculate actual velocity
        // 3. Compare against P-002 limits for service type
        // 4. Check pressure drop against recommended values
        // 5. For two-phase: check erosional velocity ratio
    }

    /**
     * Check design pressure against P-002 Clause 5 rules.
     * DP >= max(MAOP, highest normal operating P + margin)
     */
    public static DesignPressureResult validateDesignPressure(
        double designPressure, double normalOperatingPressure, String systemType) {
        // Clause 5.2.1 rules
    }
}

Agent integration: The @make a neqsim process simulation agent could automatically run P-002 validation after building a process model, flagging any pipe segments that violate sizing criteria.

4. Subsea Leak Detection Sensitivity Model

What exists: NeqSim has PipeBeggsAndBrills for pipeline flow, mass balance capabilities, and the neqsim-plant-data skill for historian integration.

Gap: STS0131 Req-13704 requires subsea leak detection using:

The computational requirement is: What is the minimum detectable leak rate? This requires sensitivity analysis of the mass balance method.

Implementation (Agent workflow + Java utility):

package neqsim.process.safety.leakdetection;

public class MassBalanceLeakDetector {
    private ProcessSystem pipeline;
    private double flowMeasurementUncertainty;  // % of reading
    private double pressureMeasurementUncertainty; // bara
    private double temperatureUncertainty; // K
    private double linepackVolume; // m3

    /**
     * Calculate minimum detectable leak rate for a given
     * measurement configuration and steady-state conditions.
     */
    public LeakDetectionSensitivity calculateSensitivity() {
        // 1. Run base case with current pipeline model
        // 2. Introduce small perturbation (leak) at midpoint
        // 3. Calculate resulting signal change at inlet/outlet instruments
        // 4. Compare signal change against measurement uncertainty
        // 5. Find minimum leak rate that exceeds detection threshold
    }
}

Data access integration:

5. Performance Standard Auto-Population from TR2237

What exists: PerformanceStandard, SafetyBarrier, BarrierRegister, SafetySystemPerformanceAnalyzer — all fully implemented.

Gap: TR2237 defines a standard set of PS numbers (PS 01 through PS 14+) with specific functional requirements, demand modes, and acceptance criteria. Currently, engineers must manually create these. Pre-populating from a TR2237 template would save hours.

Implementation:

package neqsim.process.safety.barrier;

public class TR2237Templates {

    /**
     * Creates a pre-populated barrier register with all TR2237 onshore
     * performance standards as templates.
     */
    public static BarrierRegister createOnshoreTemplate() {
        BarrierRegister register = new BarrierRegister("TR2237-ONSHORE");

        // PS 01 - Process containment
        register.addPerformanceStandard(new PerformanceStandard("PS-01")
            .setTitle("Process Containment")
            .setSafetyFunction("Maintain primary containment of hydrocarbons")
            .setDemandMode(DemandMode.CONTINUOUS)
            .setRequiredAvailability(0.999)
            .addAcceptanceCriterion("No uncontrolled releases during normal operations"));

        // PS 08 - Emergency Depressurisation
        register.addPerformanceStandard(new PerformanceStandard("PS-08")
            .setTitle("Emergency Depressurisation")
            .setSafetyFunction("Reduce pressure to limit fire-exposed inventory")
            .setDemandMode(DemandMode.LOW_DEMAND)
            .setTargetPfd(0.01) // SIL 1 minimum
            .setResponseTimeSeconds(900.0) // 15 min per API 521
            .addAcceptanceCriterion("Reduce to 50% of initial pressure within 15 minutes")
            .addAcceptanceCriterion("Reduce to 7 barg within 15 minutes under fire"));

        // PS 09 - Active Fire Protection
        // PS 10 - Passive Fire Protection
        // ... etc.
        return register;
    }

    /**
     * STS0131 mapping: Equinor PS numbers → NORSOK S-001 clauses.
     */
    public static Map<String, String> getEquinorToNorsokMapping() {
        // PS 01 → S-001 Clause 6, PS 02 → Clause 7, etc.
    }
}

Why this is useful: When the @run neqsim safety and depressuring simulation agent creates a barrier register, it can auto-populate with TR2237 templates and then the SafetySystemPerformanceAnalyzer validates each barrier against the pre-defined criteria.

6. Standards-Aware Design Review Agent

Concept: A new agent (@review design against standards) that takes a completed ProcessSystem and systematically checks it against all applicable TR/NORSOK requirements.

Workflow:

  1. Identify equipment types in the process model (separators, scrubbers, compressors, pipes, HX)
  2. For each equipment type, look up applicable standards (TR1965 for scrubbers, P-002 for pipe sizing, TR3500 for separators, etc.)
  3. Run the relevant conformity checker / validator
  4. Produce a consolidated compliance report with PASS/FAIL/WARNING per requirement

Agent definition:

name: review design against standards
description: >
  Reviews a NeqSim process model against applicable TR/NORSOK requirements.
  Checks scrubber K-factors (TR1965), pipe sizing (P-002), design P/T (P-002),
  separator internals (TR3500), EDP acceptance (S-001/STS0131), and performance
  standards (TR2237). Produces a compliance matrix.

Skills it would load:

Additional Integration Opportunities (Lower Priority)

7. STS0131 Overpressure Frequency Table for LOPA

The existing LOPAResult class could include the STS0131 Clause 10.4.7 frequency targets:

Pressure Level Target Frequency (per year)
P > 2× DP ≤ 1×10⁻⁵
Test P < P ≤ 2× DP ≤ 1×10⁻⁴
DP < P ≤ Test P ≤ 1×10⁻³
P ≤ DP ≤ 1×10⁻²

This could be a lookup table in LOPAResult.evaluateOverpressureFrequency(pressure, designPressure, testPressure).

8. TR3031 Automation — SIS Architecture Validation

The SIS/SIF infrastructure (SafetyInstrumentedFunction, VotingLogic) already supports architecture specification. TR3031 could provide pre-defined voting architecture requirements for common SIF types (ESD, HIPPS, F&G) that the agent could validate against.

9. Gas Detection Coverage from STS0131

STS0131 requires specific gas detection coverage calculations (area coverage, detector placement). NeqSim’s GasDetector class and the consequence analysis (ReleaseDispersionScenarioGenerator) could feed a coverage assessment that checks if detectors would activate for modelled release scenarios.

10. NORSOK P-002 TEG Regeneration Compliance (Clause 16)

P-002 Clause 16 specifies TEG system requirements (reboiler temperature, stripping gas flow, contactor design). NeqSim already has TEG process models — adding a P-002 compliance check would automate verification.

Data Access / STID Integration Priorities

Data Source Use Case Integration Point
Material certificates (STID) Time-to-rupture material derating curves DepressurizationSimulator + STS0131AcceptanceCriteria
Instrument datasheets (STID) Measurement uncertainty for leak detection sensitivity MassBalanceLeakDetector
Fire zone drawings (STID) Fire exposure area for API 521 heat input ReliefValveSizing.calculateFireHeatInput()
Line list / piping specs (STID) Pipe diameters, materials, design P/T for P-002 validation NorsokP002LineSizingValidator
C&E matrices (STID) SIF architecture, voting logic, trip setpoints SafetyInstrumentedFunction population
Scrubber datasheets (STID) Internals type, K-factor rating, design parameters TR1965RuleSet input data
PI historian (tagreader) Operating conditions for real-time compliance checking Digital twin + compliance monitoring
  1. TR1965 Scrubber RuleSet — Minimal code (~200 lines), builds on existing ConformityRuleSet framework, immediate value for scrubber design studies
  2. STS0131 Depressurization Acceptance — Small extension (~100 lines) to existing DepressurizationResult, high relevance to ongoing JIP
  3. P-002 Line Sizing Validator — New class (~300 lines), enables automated pipe sizing checks for all process models
  4. TR2237 Performance Standard Templates — Pre-populated data (~150 lines), improves barrier register creation workflow
  5. Leak Detection Sensitivity — New capability (~400 lines), required by STS0131 for subsea projects
  6. Design Review Agent — Orchestration layer that ties 1-5 together into a single review workflow