neqsim-hazid-fmea-eta-fta

name: neqsim-hazid-fmea-eta-fta version: "1.0.0" description: "Structured hazard-identification workflows — HAZOP worksheets with the seven IEC 61882 guidewords, FMEA failure-mode tables with RPN/criticality scoring, event-tree analysis (ETA) for outcome frequency, fault-tree analysis (FTA) with β-factor common-cause modelling and minimal cut sets, and escalation-graph (domino) screening. USE WHEN: a task requires systematic hazard identification, qualitative-to-quantitative scenario development, top-event decomposition, or escalation/domino analysis between adjacent equipment. Anchors on neqsim.process.safety.hazid, neqsim.process.safety.risk.eta, neqsim.process.safety.risk.fta, neqsim.process.safety.escalation." last_verified: "2026-06-23" requires: java_packages: - neqsim.process.safety.hazid - neqsim.process.safety.risk.eta - neqsim.process.safety.risk.fta - neqsim.process.safety.escalation - neqsim.process.safety.vibration

NeqSim HAZID / FMEA / ETA / FTA Skill

The four canonical hazard-identification and scenario-development techniques in one place — used together they produce auditable HAZOP / SIL / QRA documentation per IEC 61882, IEC 61508/61511, ISO 17776 and the CCPS guideline series.

When to Use

HAZOP node walkdown — apply guidewords to design intent at every node
FMEA / FMECA — equipment-level failure-mode tabulation with RPN scoring
Event-tree analysis (ETA) — outcome-frequency development from initiating event
Fault-tree analysis (FTA) — top-event decomposition, minimal cut sets, β-factor CCF
Escalation / domino analysis — graph of adjacency between fire/explosion sources

Pairs with neqsim-process-safety (LOPA / SIL / risk matrix) and neqsim-consequence-analysis (probit / IRPA roll-up).

Standards

IEC 61882 — HAZOP studies — application guide
IEC 60812 — FMEA / FMECA procedure
IEC 61025 — fault tree analysis
IEC 61508 / 61511 — β-factor common-cause modelling
CCPS Guidelines for Hazard Evaluation Procedures (3rd ed.)
ISO 17776 — major-accident hazard management

Method 1 — HAZOP Worksheet

import neqsim.process.safety.hazid.HAZOPTemplate;

HAZOPTemplate ws = new HAZOPTemplate("V-100", "HP separator pressure control node");
ws.addDeviation(HAZOPTemplate.GuideWord.MORE, HAZOPTemplate.Parameter.PRESSURE,
    "PCV stuck open",
    "Vessel rupture, gas release",
  "PSV-101; Operator response",
  "Verify PSV sizing per API 521");
String report = ws.report();

The seven IEC 61882 guidewords are defined in HAZOPTemplate.GuideWord. Use addDeviation(...) once per (guideWord, parameter) deviation per node, or generateGrid(...) to create empty rows for selected parameters.

For STID/P&ID + plant-data + NeqSim simulation workflows, use MCP runHAZOP. It accepts a standard runProcess JSON definition plus extracted nodes, safeguards, evidence references, failure modes, and an optional barrier register. It returns HAZOP rows with scenario-simulation evidence and report markdown.

Method 2 — FMEA / FMECA

import neqsim.process.safety.hazid.FMEAWorksheet;

FMEAWorksheet f = new FMEAWorksheet("Compressor train");
f.addEntry("K-101", "Centrifugal compressor",
    "Surge", "Suction valve closed too fast",
    "Bearing damage, unplanned shutdown",
    8, 4, 5);   // Severity, Occurrence, Detection
double rpn = f.totalRPN();

RPN = S × O × D (IEC 60812). Items above the company threshold (often RPN > 100 or S ≥ 9) trigger design changes. The criticalEntries(threshold) helper returns the subset above a cut-off.

Method 3 — Event Tree (ETA)

import neqsim.process.safety.risk.eta.EventTreeAnalyzer;

EventTreeAnalyzer eta = new EventTreeAnalyzer("Gas leak", 1.0e-4); // /yr
eta.addBranch("Immediate ignition?", 0.05);
eta.addBranch("Confined?", 0.30);
eta.addBranch("Delayed ignition?", 0.10);

double fJet  = eta.outcomeFrequency(new boolean[] {true,  false, false});
double fVCE  = eta.outcomeFrequency(new boolean[] {false, true,  true});
double fFlash = eta.outcomeFrequency(new boolean[] {false, false, true});
double fSafe = eta.outcomeFrequency(new boolean[] {false, false, false});
String tree = eta.toTextTree();

Branches multiply: f_outcome = f_init · Π p_branch (or 1-p) along the path. The text-tree output is suitable for embedding in HAZOP reports.

Method 4 — Fault Tree (FTA)

import neqsim.process.safety.risk.fta.FaultTreeAnalyzer;
import neqsim.process.safety.risk.fta.FaultTreeNode;

FaultTreeNode psvA = FaultTreeNode.basic("PSV-A fails", 0.005);
FaultTreeNode psvB = FaultTreeNode.basic("PSV-B fails", 0.005);
FaultTreeNode bothFail = FaultTreeNode.and("Both PSVs fail", psvA, psvB)
                                      .withCCF(0.10);  // β-factor 10 %

FaultTreeAnalyzer fta = new FaultTreeAnalyzer();
double pTop = fta.topEventProbability(bothFail);
java.util.Set<java.util.List<String>> cuts =
    fta.minimalCutSets(bothFail, /* maxCardinality */ 4);

Gate types: AND, OR, VOTING (k-of-n). Common-cause is applied via withCCF(β). Minimal cut sets are returned by brute-force enumeration up to a user-specified cardinality (sufficient for typical < 20-basic-event trees).

β-factor common-cause semantics

The implementation uses the IEC 61508 convex-combination form:

P(top with CCF) = (1 − β) · P_independent + β · max(P_basic_i)

For redundant (AND) configurations this increases the failure probability — the dominant safety effect. For series (OR) configurations it decreases the disjunction probability because the common-mode replaces independent co-occurrence.

Method 5 — Escalation / Domino Graph

import neqsim.process.safety.escalation.EscalationGraphAnalyzer;

EscalationGraphAnalyzer esc = new EscalationGraphAnalyzer();
esc.addEquipment("V-100", 1.0e-4);     // base release frequency
esc.addEquipment("V-101", 1.0e-4);
esc.addAdjacency("V-100", "V-101", 0.30); // 30 % escalation if V-100 ignites
double fEscalated = esc.escalatedFrequency("V-101");
java.util.List<String> chain =
    esc.criticalChain("V-100", "V-101"); // worst-case domino path

Used to screen plot-plan layouts before detailed CFD (KFX / FLACS) runs.

Method 6 — ISO 17776 Major-Accident-Hazard Bow-Tie

Generate a pre-populated bow-tie (threats → top event → consequences, with prevention/mitigation barriers) for each ISO 17776 major accident hazard from MahCatalogue / MahBowTieBuilder:

import neqsim.process.safety.hazid.MahType;
import neqsim.process.safety.hazid.MahCatalogue;
import neqsim.process.safety.hazid.MahBowTieBuilder;
import neqsim.process.safety.risk.bowtie.BowTieModel;

// One call builds a complete bow-tie with default threat freq + barrier PFD
BowTieModel bt = MahBowTieBuilder.build(MahType.TOPSIDE_HYDROCARBON_RELEASE);
bt.getThreats();        // ≥ 4 standard threats
bt.getConsequences();   // ≥ 3 standard consequences
bt.getBarriers();       // ≥ 5 prevention/mitigation barriers

// Or inspect the raw catalogue lists to tailor a custom bow-tie
MahCatalogue.threatsFor(MahType.WELL_BLOWOUT);
MahCatalogue.consequencesFor(MahType.FIRE_EXPLOSION);
MahCatalogue.barriersFor(MahType.TOXIC_RELEASE);

MahType covers the standard offshore MAHs: TOPSIDE_HYDROCARBON_RELEASE, RISER_LEAK, WELL_BLOWOUT, STRUCTURAL_COLLAPSE, DROPPED_OBJECT, HELICOPTER_LOSS, SHIP_COLLISION, FIRE_EXPLOSION, TOXIC_RELEASE, LOSS_OF_BUOYANCY, EXTREME_WEATHER. Defaults exposed as MahBowTieBuilder.DEFAULT_THREAT_FREQUENCY and DEFAULT_BARRIER_PFD. Quantify the assembled BowTieModel with the bow-tie analyzer (see neqsim-process-safety). Verified by MahBowTieBuilderTest.

Method 7 — EI AVIFF Flow-Induced-Vibration Screening

Screen piping for flow-induced vibration (FIV) likelihood-of-failure per the Energy Institute AVIFF guidelines with PipingFivScreening (static helpers):

import neqsim.process.safety.vibration.PipingFivScreening;
import neqsim.process.safety.vibration.PipingFivLikelihood;
import neqsim.process.safety.vibration.FivLikelihoodResult;

// screenGas(tag, rho[kg/m3], v[m/s], D[m], t[m], nBranches, pulsationFactor, supportFactor)
FivLikelihoodResult gas =
    PipingFivScreening.screenGas("Compressor discharge", 80.0, 30.0, 0.3, 0.006, 2, 4.0, 2.0);
gas.getLofScore();        // dimensionless LOF
gas.getLikelihood();      // VERY_HIGH

// screenLiquid(tag, v[m/s], D[m], t[m], nBranches, supportFactor)
FivLikelihoodResult liq =
    PipingFivScreening.screenLiquid("Pump discharge", 3.5, 0.15, 0.005, 1, 1.5);

PipingFivLikelihood band = PipingFivScreening.bandFor(0.7);  // HIGH
String json = gas.toJson();   // contains "lofScore", "likelihood"

Likelihood bands: LOW (< 0.3), MEDIUM (0.3–0.5), HIGH (0.5–1.0), VERY_HIGH (≥ 1.0). High/very-high lines feed detailed AVIFF assessment or CFD. Verified by PipingFivScreeningTest.

Workflow — From STID to Simulation-backed HAZOP

Retrieve STID/P&ID, C&E, SRS, line-list, and operating-data documents into the task references folder.
Extract nodes with nodeId, designIntent, equipment, safeguards, and evidenceRefs using the technical-document-reading and STID-retriever skills.
Build a NeqSim process JSON definition from extracted topology or existing models.
Run runHAZOP with selected failure modes, or enable all failure modes.
Review generated rows, scenario results, failed simulations, and evidence references with the chaired HAZOP team.
Pass accepted safeguards to runBarrierRegister, LOPA, SIL, bow-tie, and QRA workflows.

Detailed user documentation: docs/safety/automated_hazop_from_stid.md.

Workflow — From HAZOP to LOPA in One Notebook

HAZOP the node → identify deviation, cause, consequence
FTA the cause → quantify cause frequency from basic events
ETA the consequence → split into outcome branches
Probit + IRPA — see neqsim-consequence-analysis
LOPA + SIL — see neqsim-process-safety

A reference end-to-end workflow lives in the test class HAZOPFMEATest + EscalationGraphAnalyzerTest.

Common Pitfalls

Guideword ≠ cause — HAZOP guidewords describe the deviation, not the cause. Every deviation can have multiple causes; document each separately.
RPN inflation — companies vary on detection scales. Document the scale used (CCPS 1–10 vs IEC 60812 1–10) at the top of every FMEA.
β-factor for OR gates — does not represent "more failure" the way it does for AND gates. See semantics box above.
Cut-set explosion — limit maxCardinality to 4–6 for trees with > 15 basics; the enumeration is O(2^n) in basic-event count.

Verification Tests

./mvnw test -Dtest=HAZOPFMEATest,EventTreeAnalyzerTest,FaultTreeAnalyzerTest,EscalationGraphAnalyzerTest,MahBowTieBuilderTest,PipingFivScreeningTest