Neqsim Pid Process Operations

P&ID to Process Operations

This skill bridges P&ID interpretation, NeqSim process simulation, and plant historian data. It is for operational questions such as "what happens if this valve closes?", "which train is active?", "what inventory is trapped between these valves?", and "how will pressure, level, flow, flare load, or emissions change?"

Keep this public skill plant-agnostic. Do not include real facility names, operator-specific document numbers, internal historian source names, real tag maps, credentials, or private operating procedures. Put those details in a private prompt file or local private skill.

When to Use

• Reading P&ID symbols, line numbers, valves, instruments, drains, vents, interlocks, and equipment connections.
• Converting P&ID topology into a NeqSim ProcessSystem, ProcessModel, or PipingRouteBuilder route.
• Mapping P&ID instrument tags to plant historian tags read by tagreader.
• Determining active train/equipment state from valves, flows, pressures, levels, temperatures, and run-status tags.
• Evaluating steady-state process effects of valve position changes, blocked outlets, bypasses, recycles, drains, or alternate routing.
• Evaluating dynamic effects of valve actions using runTransient, controllers, measurement devices, or dedicated blowdown/depressurization models.
• Preparing WaterHammerStudy or MCP runWaterHammer inputs for fast liquid-line valve closure, pump trip, or check-valve slam.
• Generating governed DEXPI engineering packages from a simulated ProcessSystem or multi-area ProcessModel, including available mechanical, piping, PSV, blowdown/flare and materials calculations.

Required Skill Stack

Use this skill with:

• neqsim-technical-document-reading for P&ID image/document extraction,
• neqsim-process-extraction for topology to JSON/route conversion,
• neqsim-plant-data for tagreader reads, tag maps, and data quality,
• neqsim-controllability-operability for steady-state operating envelopes and control valve checks,
• neqsim-dynamic-simulation for transient valve-action studies,
• neqsim-water-hammer for hydraulic surge screening from fast liquid-line events,
• neqsim-depressurization-mdmt for blowdown and minimum-temperature cases,
• neqsim-professional-reporting for evidence traceability and report outputs.

P&ID Symbol Interpretation Model

Read a P&ID as a process graph plus operational annotations:

When symbol meaning is uncertain, record alternatives and confidence. Never infer a valve's current open/closed state from a P&ID alone; use live data, operator input, or the approved procedure basis.

P&ID Extraction Schema

Extend the standard PID_EXTRACTION object with operational semantics:

{
  "pid_operational_model": {
    "equipment_nodes": [
      {"id": "V-101", "type": "separator", "neqsim_type": "Separator"}
    ],
    "process_edges": [
      {
        "id": "L-101",
        "from": "V-101.gasOut",
        "to": "PV-101.inlet",
        "line_number": "L-101",
        "nominal_size_in": 8.0,
        "normal_service": "gas outlet"
      }
    ],
    "valves": [
      {
        "tag": "PV-101",
        "symbol_type": "control_valve",
        "normal_position": "modulating",
        "failsafe": "unknown",
        "neqsim_role": "ThrottlingValve",
        "scenario_actions": ["set outlet pressure", "change Cv", "close"]
      }
    ],
    "instruments": [
      {
        "pid_tag": "PT-101",
        "function": "pressure transmitter",
        "measured_object": "V-101",
        "logical_tag_name": "separator_pressure"
      }
    ],
    "control_links": [
      {"controller": "PIC-101", "measurement": "PT-101", "manipulated_valve": "PV-101"}
    ],
    "operational_boundaries": [
      {"name": "separator outlet isolation", "boundary_valves": ["XV-101", "XV-102"]}
    ]
  }
}

Connecting P&ID Tags to Plant Data

Create a logical tag map first, then bind logical names to private historian tags in a private skill or task-local tag_mapping.json:

{
  "separator_pressure": "PRIVATE_HISTORIAN_TAG",
  "separator_level": "PRIVATE_HISTORIAN_TAG",
  "separator_temperature": "PRIVATE_HISTORIAN_TAG",
  "gas_outlet_valve_position": "PRIVATE_HISTORIAN_TAG",
  "gas_outlet_flow": "PRIVATE_HISTORIAN_TAG",
  "compressor_run_status": "PRIVATE_HISTORIAN_TAG"
}

In Java workflows, use the plant-agnostic helpers in neqsim.process.operations so private historian names can stay outside public models while NeqSim still uses its existing measurement devices and automation API:

OperationalTagMap tagMap = new OperationalTagMap()
  .addBinding(OperationalTagBinding.builder("separator_pressure")
    .historianTag("PRIVATE_HISTORIAN_TAG")
    .unit("bara")
    .role(InstrumentTagRole.INPUT)
    .build())
  .addBinding(OperationalTagBinding.builder("outlet_valve_position")
    .historianTag("PRIVATE_HISTORIAN_TAG")
    .automationAddress("Outlet Valve.percentValveOpening")
    .unit("%")
    .role(InstrumentTagRole.INPUT)
    .build());

ValidationResult validation = tagMap.validate(process);
Map<String, Double> applied = tagMap.applyFieldData(process, fieldData);
Map<String, Double> modelValues = tagMap.readValues(process);

This is a bridge only. Keep using MeasurementDeviceInterface tags, tag roles, ProcessSystem.setFieldData, ProcessSystem.applyFieldInputs, and ProcessAutomation for the actual model interaction.

For active-state inference, use at least two independent indicators: flow, pressure, temperature, level movement, valve position, controller output, run status, speed, power, or trip status. Save raw historian data as CSV inside the task folder before running calculations.

Converting to NeqSim

Generating a governed DEXPI engineering package

When the direction is NeqSim-to-P&ID, use the engineering project layer rather than calling DexpiXmlWriter alone. It adds a versioned design basis, standards traceability, deterministic control/safeguarding proposals, approval state, validation findings, and referenced compressor-map datasets:

EngineeringProject project = NorsokOffshoreEngineeringBuilder
    .from("Gas compression engineering model", process)
    .registerProposedInstruments(true)
    .build();

EngineeringValidationReport validation = project.validate();
DexpiEngineeringExporter.ExportResult files =
    DexpiEngineeringExporter.export(project, Paths.get("engineering-package"));

The generated plant.dexpi.xml is a native DEXPI 2.0 semantic process model and is validated against the bundled official DEXPI XML schema during export. plant-proteus.xml is the backward-compatible graphical P&ID containing requirement-linked instrumentation functions, logic functions, information flows, control/protective valves, and equipment associations. It references engineering-manifest.json, the proposed cause-and-effect.json, simulation-backed engineering-calculations.json, and any datasets/<tag>-compressor-map.json sidecars. Use plant-pydexpi.xml for pyDEXPI import and inspect interoperability-report.json; native schema validity, semantic-profile validity, pyDEXPI import and commercial-CAE round-trip are distinct gates. Do not flatten large vendor maps into P&ID attributes.

Do not call the Proteus graphical file DEXPI 2.0. Antisurge recycle topology is connected discharge-to-suction; PSV/BDV proposals use dedicated equipment nozzles and a separate relief/blowdown network. Treat every UnresolvedBoundary=YES as a required line, flare-header, vent, drain or utility tie-in before engineering completion. Represent controlled tie-ins with EngineeringBoundary so process inlet/outlet, flare, vent, closed-drain, utility and recycle connections become directional off-page connectors in native DEXPI rather than free-text assumptions.

For a full process-to-engineering run, follow the eight controlled stages in docs/integration/process-to-engineering-simulator.md. Require convergence of both physical design variables and process values. Use typed equipment, network-piping, valve/instrument, safety, materials and mechanical calculation modules for independent evidence. Compile the final project with EngineeringDeliverableCompiler; do not assemble datasheets or registers from ad-hoc notebook dictionaries when coordinated compiler artifacts are available. Use examples/notebooks/process_to_engineering_simulator.ipynb for the closed loop and coordinated-package pattern, and examples/notebooks/engineering_roadmap_steps_1_to_8.ipynb for executable typed calculation examples across equipment, piping, valve/instrument, safety, materials and preliminary mechanics.

When qualifying rather than screening a typed calculation, build an EngineeringCalculationContext with productionQualification=true, controlled standard references and evidence references. In this mode, do not accept equipment screening defaults, reference-diameter piping scaling, an unresolved valve failure position, or an unreferenced two-phase relief method. Use ReliefSizingCalculation for governed gas/liquid/steam orifice selection and only for two-phase flow when a specialist mass-flux result and controlled method reference have been supplied.

Treat unresolved-engineering-actions.json as a mandatory review input. A calculated DEXPI package is never equivalent to HAZOP/LOPA acceptance, vendor certification, code mechanical design, final metallurgy approval or construction authorization.

Represent those external decisions with EngineeringExternalEvidenceRegister, starting from productionMinimum(projectRevisionScope) and adding equipment-, SIF- and package-specific requirements. EngineeringExternalEvidenceRecord must carry the controlled document revision, SHA-256 hash, issuer, governed scope, decision authority, decision date and workflow/signature reference. Independent validation additionally needs an independence statement; construction authority evidence needs the applicable jurisdiction. Inspect engineering-external-evidence-register.json and keep draft, rejected, incomplete, conflicting or superseded evidence open. The register verifies receipts; it never creates approval.

Also inspect engineering-production-readiness.json. Do not describe a package as production-ready merely because the design loop converged or package validation passed. QUALIFIED_FEED_SUPPORT additionally requires independent benchmarks for every executed method version, project method qualifications, an explicit no-hidden-default auto-configuration result, named-tool DEXPI round-trip evidence, approved safety-lifecycle evidence, three accepted pilots, and release-quality evidence. Even that level always retains fitnessForConstruction=false and does not grant final engineering approval.

For the first complete inlet-separator/compressor/cooler/export facility slice, run ProductionVerticalSlicePreflight.assess first and use ProductionVerticalSliceSimulator.runStrictAndCompile for controlled execution. Inspect engineering-vertical-slice-qualification.json. Require the declared topology, ten case types, converged physical design, active compressor surge and stonewall curves, zero map extrapolation, executable dynamic safe-state tests, coupled PSV/blowdown/flare capacity, controlled standards and evidence. Add the map check through the revision-controlled policy with addCompressorOperatingEnvelope. Passing all vertical-slice gates means only a controlled pilot; never translate it to FEED approval or fitness for construction.

For JPype workflows, use VerticalSliceCaseMatrixFactory to create explicit, evidence-linked scalar boundary conditions for every required case type. Do not treat those steady boundary changes as substitutes for transient initiating events, HAZOP credibility decisions, or shutdown logic.

Retain engineering-vertical-slice-execution-manifest.json with the package. Its SHA-256 fingerprint binds the project and policy revisions, case inputs, dynamic scenarios, coupled safety studies, standards and evidence. A fingerprint change requires recalculation and revision-impact review; it never grants engineering approval.

Also inspect engineering-qualification-plan.json. Use its exact method keys and open actions to drive EngineeringBenchmarkDataset, DexpiToolQualificationRunner, EngineeringPilotQualificationRunner, and EngineeringReleaseQualificationRunner. These runners convert actual measurements and named external results into evidence; they do not perform an independent review or create an acceptance record. Keep missing external evidence open.

Use examples/notebooks/engineering_production_qualification_workflow.ipynb as the API pattern for the executable qualification workflows. Its data are synthetic and must never be promoted to project evidence.

The calculation handoff automatically runs available equipment mechanical-design and materials-screening models. It can run API 520/521 PSV sizing from attached credible relief scenarios, and readiness-gated dynamic blowdown, flare load, radiation, capacity, and header checks from a DynamicBlowdownFlareStudyDataSource. A blocked-outlet PSV screen may be generated from simulated full inflow only when declared design and relief-set pressures exist. Treat missing-input statuses as data gaps; never fill them with generic values merely to obtain a size.

For an engineering-readiness package, attach the governed project inputs that correspond to the source documents:

• LineDesignInput for line-list dimensions, schedule, wall, material, piping class, corrosion allowance, design conditions and evidence reference;
• ReliefScenarioBasis for hazard-review-required API 521 causes, with matching scenarios in OverpressureProtectionStudy;
• SafetyFunctionDesign for LOPA/SRS-backed target SIL, sensor/logic/final-element failure data, MooN voting, proof-test interval, diagnostic coverage and beta factor;
• ShutdownSequence for cause/effect actions, safe positions, timing budget, linked requirement IDs, HAZOP/SRS references and reset/restart definition;
• ReliefDeviceDesignInput for the selected device, inlet/outlet geometry, allowable losses, two-phase method, fire zone, concurrency group and evidence;
• EngineeringEvidenceRecord for revision-controlled HAZOP, LOPA, SRS, line-list, vendor and calculation records linked to equipment and requirements;
• EmergencyShutdownTestResult from EmergencyShutdownTestRunner, linked to the applicable sequence with addShutdownVerificationResult(...).

Inspect engineeringReadiness in engineering-calculations.json. It reports coverage percentage, missing-input count, severity, responsible discipline and approval state. Never interpret 100% calculation/evidence coverage as engineering approval or fitness for construction. Failed or blocked calculation objects must not be counted as completed merely because they are present in the handoff.

Also inspect engineeringCoverageMatrix, installedReliefDeviceVerification, reliefDisposalNetworkLoads, engineeringEvidenceStatus, and the dynamic result inside shutdownSequenceVerification. Review dexpi-validation.json, every CSV/JSON under registers/, and package-manifest.json. If the project provides its controlled DEXPI XSD, call DexpiEngineeringValidator.validate(dexpiFile, xsdFile); do not silently download or choose a schema edition.

For multi-area models, call NorsokOffshoreEngineeringBuilder.fromProcessModel(...) and export each returned EngineeringProject to its own area directory. Use examples/notebooks/dexpi_engineering_full_processsystem.ipynb and examples/notebooks/dexpi_engineering_processmodel.ipynb as the executable reference patterns. Never bypass the governed exporter with DexpiXmlWriter when the requested output includes safety, instrumentation, sizing or standards traceability.

Safety governance is mandatory: rule-generated trips use SIL_UNASSIGNED and REVIEW_REQUIRED; generated controller tuning, trip set points, and voting architectures remain NOT_ASSIGNED unless a controlled SafetyFunctionDesign supplies them. Never derive SIL from equipment type, a generic tag template, or normal operating conditions. Set a SIL target only from an identified HAZOP/LOPA/QRA record and approve it through the project SRS workflow per IEC 61511. See neqsim-process-safety for the risk-analysis handoff.

Steady-State Model

1. Build the base flowsheet from the P&ID graph and process model.
2. Use live plant data to set boundary pressure, temperature, flow, level, and selected valve positions where available.
3. Run process.run() and compare simulated outputs with historian tags.
4. Save a base-case result before applying any change.

For large plants, use ProcessModel with one ProcessSystem per area. For line-only questions, use PipingRouteBuilder rather than a full process model.

Valve or Route Change Scenarios

Define every action as a model delta:

Always state whether the action is physically possible from the P&ID and whether additional hidden paths, non-return valves, or interlocks may change the result.

For generic Java studies, represent simple action sequences with OperationalScenario and run them with OperationalScenarioRunner. The runner delegates valve opening changes to existing SetValveOpeningAction, variable writes to ProcessAutomation, steady-state calculations to process.run(), and dynamic calculations to process.runTransient(dt, id):

OperationalScenario scenario = OperationalScenario.builder("partly close outlet")
  .addAction(OperationalAction.setValveOpening("Outlet Valve", 15.0))
  .addAction(OperationalAction.setVariable("Outlet Valve.outletPressure", 45.0, "bara"))
  .addAction(OperationalAction.runSteadyState())
  .build();

OperationalScenarioResult result = OperationalScenarioRunner.run(process, scenario);

For controller tuning screens based on simulated or historian time series, use ControllerTuningStudy.evaluateStepResponse(...). It computes mean and maximum error, IAE, ISE, overshoot, settling time, output saturation fraction, and a short tuning recommendation without replacing NeqSim's controller classes.

For operating-envelope screening on the same P&ID/tagreader snapshot, use OperationalEnvelopeEvaluator or MCP runOperationalStudy with action="evaluateOperatingEnvelope". Provide designCapacities from STID, line lists, datasheets, or vendor curves when available; provide fieldData through OperationalTagMap; provide marginHistory when a tagreader trend is available. The output ranks margins, reports simple trip predictions, and returns advisory mitigation suggestions without writing to plant systems.

MCP Access

MCP clients can use runOperationalStudy for the same plant-agnostic workflow. Supported actions are getSchema, validateTagMap, applyFieldData, runScenario, runEvidencePackage, and evaluateControllerResponse. Use runEvidencePackage when the task needs one auditable output containing field data application, BENCHMARK tag comparison, base-case bottleneck detection, scenario bottleneck reports, document evidence references, assumptions, and quality gates. The tool operates on local simulation copies and does not write to plant historians or control systems. Governed MCP profiles block it in read-only digital-twin and enterprise modes.

Steady-State Evaluation Pattern

Use a base/change comparison table:

{
  "scenario": "close gas outlet valve",
  "mode": "steady_state",
  "base_case": {"pressure_bara": 20.0, "gas_flow_kg_hr": 10000.0},
  "changed_case": {"pressure_bara": 25.0, "gas_flow_kg_hr": 0.0},
  "deltas": {"pressure_bar": 5.0, "gas_flow_kg_hr": -10000.0},
  "constraints_triggered": ["upstream pressure increase"],
  "confidence": "medium"
}

Preferred checks:

• mass balance before/after the valve action,
• pressure feasibility at upstream and downstream equipment,
• separator level and residence time,
• compressor surge or recycle effect,
• flare or drain destination capacity,
• hydrate, wax, or low-temperature risks if pressure drops.

Dynamic Evaluation Pattern

Use dynamic simulation when time response matters: closing a valve, blocked outlet pressure rise, separator level change, controller response, blowdown, startup/shutdown, or recycle instability.

Minimum dynamic output:

{
  "scenario": "close outlet valve over 30 s",
  "mode": "dynamic",
  "event_schedule": [
    {"time_s": 300.0, "action": "ramp_close", "object": "PV-101", "duration_s": 30.0}
  ],
  "time_series": "step2_analysis/scenario_timeseries.csv",
  "key_results": {
    "max_pressure_bara": 0.0,
    "min_temperature_C": 0.0,
    "max_level_m": 0.0,
    "peak_flare_flow_kg_s": 0.0,
    "time_to_alarm_s": 0.0
  }
}

Run steady state first. Then use runTransient(dt) or a dedicated safety model for blowdown. Use timestep sensitivity if the result depends on fast valve movement.

Governed engineering simulation

When the result will feed DEXPI or discipline deliverables, prefer the engineering-simulator contracts over mutating the live process:

1. Put normal, maximum, turndown, startup, shutdown, trip, blocked-outlet, fire, and utility-loss configurations in EngineeringCaseSet.
2. Run them with EngineeringCaseRunner; require convergence and retain both definition and result fingerprints.
3. Implement new discipline calculations as EngineeringCalculationModule<I, O> so readiness blockers, method version, inputs, evidence, standards, uncertainty, and review state are explicit.
4. Use CoupledReliefBlowdownFlareCalculation when steady relief groups and dynamic blowdown share a disposal system. Never infer credible causes or concurrency groups from topology alone.
5. Use DynamicSafetyScenarioRunner for response-time verification. Build logic through a LogicFactory against equipment in the isolated process copy; never retain valve/controller references from the live base model.
6. Use EngineeringSimulationRunner to execute all configured layers before generating the governed DEXPI package.

For process-to-engineering work, configure discipline modules with ProcessToEngineeringDesignBuilder and execute ProcessToEngineeringSimulator. Use InletCompressionExportReferenceFacility.build() as the executable acceptance fixture when extending the first production vertical slice. Require directed stream paths for the main process, anti-surge recycle, separator liquid outlet, PSV and BDV; tag/type presence alone is insufficient. Run its strict preflight, common design loop, dynamic scenario, coupled flare calculation and package compilation after any change to engineering orchestration. For revision-controlled automatic configuration, use an explicit EngineeringAutoConfigurationPolicy and require EngineeringAutoConfigurator.Result.isExecutionReady() before running or publishing results. Inspect its dependency graph, configuration fingerprint and revision impact; never suppress an unconfigured recognized equipment blocker. For a ProcessModel, use ProcessModelEngineeringSimulator with one policy and controlled case set per area, then review shared-stream dependencies in process-model-engineering-manifest.json. Represent utility, flare, blowdown, electrical and other common systems with EngineeringSharedSystemPolicy; require controlled concurrency and evidence references. Use runIncremental only with a retained baseline result and review both executedAreas and reusedAreas. Never reuse an area invalidated through a shared stream or shared-system dependency. Validate the root manifest with ProcessModelEngineeringPackageValidator before release. The EngineeringDesignLoop must converge both case simulations and physical design variables. Use EngineeringDesignUpdate.Applier only against the isolated working process; the source ProcessSystem must remain unchanged. Prefer discrete pipe, Cv, driver, area, and volume candidates so the result is a selectable engineering proposal rather than an unpurchasable continuous size. Compile DEXPI only after the loop has run so the canonical graph, equipment registers, calculation package, and exchange model use the designed process copy. Preserve fitnessForConstruction=false until accountable approvals are recorded.

Dynamic pass/fail verifies the supplied model and acceptance criteria. It does not infer SIL, approve the SRS, establish independence, or authorize a field action.

Reporting Requirements

For each operational change study, report:

• P&ID evidence: symbols, route, valves, instruments, and uncertainty,
• historian evidence: tag map, time window, data quality, active state,
• base-case NeqSim result and comparison with plant data,
• action definition and model delta,
• steady-state impact,
• dynamic impact when relevant,
• safety and operability constraints,
• emissions or flare source terms if material is vented or flared,
• limitations and required qualified review before field execution.

Common Mistakes

Validation Checklist

• P&ID symbols are classified by function, not only by shape.
• Topology is represented as nodes and directed edges.
• Every scenario action has a model delta and evidence source.
• Historian data and tag maps are saved in the task folder.
• Base case is compared with live or design data before changes are simulated.
• Steady-state and dynamic scopes are explicitly separated.
• Safety, flare, emissions, and low-temperature effects are checked when material is released.
• Private plant details remain outside public repo files.
• Process-to-engineering loops rerun all cases after geometry or rating changes.
• DEXPI and registers use the designed process copy and retain approval boundaries.