Neqsim Water Hammer

Water Hammer and Liquid Hammer Screening

Use this skill when a task involves hydraulic surge from fast valve movement, pump trip, check-valve slam, ESD closure, or other rapid liquid-flow changes. The core model is WaterHammerPipe; the workflow facade is WaterHammerStudy; MCP clients use runWaterHammer.

When To Use

• Fast ESD or isolation-valve closure in water, condensate, oil, MEG, glycol, or other liquid-rich lines.
• Pump trip, pump start, check-valve slam, or sudden flow setpoint changes.
• STID/P&ID/E3D/stress-isometric route screening before a detailed surge study.
• Tagreader event-window replay where measured pressure, flow, temperature, and valve position should override design-basis values.
• Ranking which lines need detailed vendor or specialist surge analysis.

Do not use this as final pipe-stress approval. Treat it as a fast screening and evidence-pack workflow.

Workflow

1. Extract line geometry from STID/P&ID/E3D/stress isometrics: length, internal diameter, wall thickness, roughness/piping class, elevation change, fittings, valves, and source references.
2. Extract or infer event data: initiating valve, start time, closure/opening duration, start/end opening, pump trip status, and relevant controller action.
3. Pull plant data with tagreader when available: inlet pressure, temperature, flow rate, valve opening, pump speed/status, and downstream pressure.
4. Run WaterHammerStudy or MCP runWaterHammer with the equivalent route, field-data overrides, and event schedule.
5. Report wave speed, Courant time step, wave round-trip time, Joukowsky surge, max/min pressure envelope, design-pressure margin, assumptions, and evidence.
6. Recommend detailed surge analysis when peak pressure approaches design pressure, the route has varying diameters/branches, vapor cavities are likely, or support loads/stress checks are required.

MCP Input Pattern

{
  "studyName": "ESD valve closure screening",
  "model": "SRK",
  "temperature_C": 20.0,
  "pressure_bara": 45.0,
  "components": {"water": 1.0},
  "flowRate": {"value": 120000.0, "unit": "kg/hr"},
  "designPressure_bara": 95.0,
  "pipe": {
    "length_m": 1200.0,
    "diameter_m": 0.2032,
    "wallThickness_m": 0.0127,
    "roughness_m": 4.6e-5,
    "elevation_m": 8.0,
    "numberOfNodes": 80
  },
  "fieldData": {
    "inletPressure_bara": 46.0,
    "inletTemperature_C": 19.0,
    "flowRate_kg_hr": 118000.0,
    "valveOpening": 1.0
  },
  "eventSchedule": [
    {
      "type": "VALVE_CLOSURE",
      "startTime_s": 0.10,
      "duration_s": 0.15,
      "startOpening": 1.0,
      "endOpening": 0.0
    }
  ],
  "simulationTime_s": 4.0,
  "sourceReferences": [
    "generic STID line-list row",
    "generic tagreader event window"
  ]
}

For route extraction, use stidRoute.segments with segment lengths, diameters, wall thickness, roughness, elevation change, and minorLosses K values. The study facade aggregates a serial route into an equivalent single line for fast screening and warns when diameters vary.

Result Interpretation

• maxPressure_bara and minPressure_bara: pressure envelope extrema during the transient.
• pressureSurge_bar: calculated surge above the initial outlet pressure.
• joukowskySurgeEstimate_bar: independent screening estimate using rho times wave speed times velocity change.
• waveRoundTripTime_s: acoustic round-trip time; closure faster than this is a fast-closure case.
• maxStableTimeStep_s: Courant time-step limit used to control numerical stability.
• designPressureExceeded: true when the supplied design pressure is exceeded.

Standards And Review Triggers

Use applicable pipeline and piping standards as context: DNV-ST-F101, NORSOK L-001, ASME B31.3, ASME B31.4, ASME B31.8, API 14E, and company piping classes. Escalate to detailed study if any of these apply:

• Peak pressure exceeds design pressure or MAOP.
• Surge margin is small after including instrument uncertainty and model uncertainty.
• The route has branches, non-return valves, pump curves, relief devices, or vapor-cavity risk.
• Pipe stress, supports, nozzle loads, or valve actuator closure curves matter.
• The line contains multiphase fluid; simplify only with explicit assumptions.

Related Skills

• neqsim-pid-process-operations for valve actions and operational scenarios.
• neqsim-stid-retriever and neqsim-technical-document-reading for route and evidence extraction.
• neqsim-plant-data for tagreader snapshots and event windows.
• neqsim-process-safety for risk framing and escalation into safety studies.
• neqsim-flow-assurance for broader pipeline operating-envelope work.