{
  "version": "packet04-v1",
  "representation": "Functional schematics, not P&IDs, operating lineups, procurement drawings or capacity demonstrations",
  "pig_trap": {
    "nodes": [
      "balance_valve",
      "barrel_side_of_kicker_valve",
      "bypass",
      "bypass_side_of_kicker_valve",
      "closure",
      "drain_major",
      "drain_minor",
      "facility_isolation",
      "kicker_major_side",
      "kicker_valve",
      "main_line",
      "main_tee",
      "major_barrel",
      "minor_barrel",
      "pressure_bypass",
      "pressure_major",
      "pressure_minor",
      "purge",
      "reducer",
      "thermal_relief",
      "trap_isolation",
      "vent_major",
      "vent_minor"
    ],
    "connections": [
      {
        "from": "closure",
        "to": "major_barrel",
        "function": "loading/retrieval containment boundary"
      },
      {
        "from": "major_barrel",
        "to": "reducer",
        "function": "tool passage"
      },
      {
        "from": "reducer",
        "to": "minor_barrel",
        "function": "tool passage"
      },
      {
        "from": "minor_barrel",
        "to": "trap_isolation",
        "function": "trap/pipeline isolation interface"
      },
      {
        "from": "trap_isolation",
        "to": "main_tee",
        "function": "tool and fluid passage when permitted by adopted arrangement"
      },
      {
        "from": "main_tee",
        "to": "main_line",
        "function": "pipeline interface including passage signaller"
      },
      {
        "from": "main_tee",
        "to": "bypass",
        "function": "normal facility flow path"
      },
      {
        "from": "bypass",
        "to": "facility_isolation",
        "function": "facility boundary"
      },
      {
        "from": "bypass",
        "to": "kicker_valve",
        "function": "divert flow to barrel"
      },
      {
        "from": "kicker_valve",
        "to": "major_barrel",
        "function": "launcher near closure; receiver near reducer; bidirectional separately selected"
      },
      {
        "from": "kicker_major_side",
        "to": "balance_valve",
        "function": "balance line branches off kicker"
      },
      {
        "from": "balance_valve",
        "to": "minor_barrel",
        "function": "fill/pressurise opposite side near trap valve"
      },
      {
        "from": "bypass_side_of_kicker_valve",
        "to": "barrel_side_of_kicker_valve",
        "function": "conditional small pressurising bypass around kicker valve"
      },
      {
        "from": "major_barrel",
        "to": "vent_major",
        "function": "vent/purge closure-side compartment, selected destination"
      },
      {
        "from": "minor_barrel",
        "to": "vent_minor",
        "function": "horizontal trap: reach region behind stuck pig"
      },
      {
        "from": "major_barrel",
        "to": "drain_major",
        "function": "horizontal closure-end liquid removal with tell-tale connection"
      },
      {
        "from": "minor_barrel",
        "to": "drain_minor",
        "function": "liquid removal near trap valve; vertical launcher single bottom drain"
      },
      {
        "from": "minor_barrel",
        "to": "purge",
        "function": "conditional flanged isolation/check-valve connection near trap valve"
      },
      {
        "from": "major_barrel",
        "to": "thermal_relief",
        "function": "protect identified trapped-liquid pressure case; adopted relief design required"
      }
    ],
    "horizontal_example": {
      "reducer": "eccentric with bottom alignment; internal-tray variants separately selected",
      "drain_points": [
        "near closure",
        "near trap valve"
      ],
      "vent_points": [
        "near closure",
        "near trap valve"
      ],
      "pressure_indicators": [
        "major near closure",
        "minor near trap valve",
        "pipeline side of bypass valve"
      ],
      "orientation": "drains bottom; vents/PI/purge/relief/signaller top quadrant; kicker/balance/bypass side or selected top",
      "valve_end_examples": "weld-end main isolation and flanged other valves; not universal",
      "additional_block_bleed": "where separately required; no isolation proof"
    },
    "vertical_launcher_example": {
      "reducer": "concentric",
      "drain": "single point near bottom trap valve, to closed drain in illustrated offshore example",
      "kicker": "major-barrel closure end",
      "balance": "kicker major side to minor near trap valve",
      "vent": "major/closure end; illustrated blowdown and relief paths to selected flare/vent system",
      "valves": "all-flanged example with double block/bleed locations, not universal",
      "chemical_injection": "not included in this source example",
      "boundary": "facility isolation upstream, pipeline side including main-line signaller; riser ESD outside boundary illustration"
    },
    "signaller_locations": {
      "launcher": "beyond main tee by selected maximum tool length under adopted method",
      "receiver": "minor barrel, maximum tool length from trap valve under adopted method",
      "meaning": "passage evidence only at actual point; not all-compartment pressure proof"
    },
    "destinations": {
      "drain": "closed system or designated open drain under adopted service basis; receiving pressure/blow-by evaluated",
      "vent": "selected vent/flare/blowdown basis including air/hydrocarbon mixtures; no automatic atmosphere permission"
    },
    "limits": [
      "No open/closed valve state specified",
      "No sequence or automatic depressurisation",
      "No safe closure-opening acceptance",
      "No line/vent/drain/relief sizing",
      "Small bypass cannot defeat shutdown boundary; adopted protection design required"
    ]
  },
  "barred_tee": {
    "purpose": "exclude selected pig from internal side branch while maintaining main-run passage and intended branch flow",
    "alternatives": [
      {
        "name": "two bars",
        "representation": "qualitative small-branch arrangement"
      },
      {
        "name": "three bars",
        "representation": "qualitative middle arrangement"
      },
      {
        "name": "bars and bridge plate",
        "representation": "qualitative larger branch arrangement"
      }
    ],
    "interfaces": [
      "internal branch mouth",
      "main-run swept bore",
      "tee curvature",
      "bar attachment welds",
      "ground and rounded profiles"
    ],
    "source_conditions": [
      "Suggested design is not complete procurement specification",
      "Historical bar counts/dimensions not universal fabrication inputs",
      "Full-penetration weld detail depicted; actual adopted weld/examination basis required",
      "No sharp corners; grind profile to installation angle and tee curvature",
      "Structural/fatigue/flow and tool passage checks separate"
    ],
    "tool_conditions": [
      "Spheres and soft foam can stall, damage or be lost at normal/barred tees",
      "Sphere tee alternative selected for intended spheres/foam, with fabrication/corrosion implications",
      "Receiver catching basket can keep tools out of kicker but adds retrieval/debris duty",
      "Branch spacing versus actual cup/disc spacing remains relevant"
    ],
    "numeric_policy": "No bar dimensions or nominal-size procurement table transferred into authored figure"
  },
  "secondary_containment": {
    "paths": [
      {
        "name": "carrier",
        "from": "drain hub",
        "through": "selected vapor/water seal",
        "to": "carrier main and sewer box liquid path"
      },
      {
        "name": "secondary",
        "from": "carrier leakage into annular space",
        "through": "outer pipe/penetration continuity",
        "to": "local secondary drain and selected collection"
      },
      {
        "name": "vapor vent",
        "from": "cleanout lateral communication",
        "to": "selected open or closed disposal system",
        "condition": "destination service assessment required"
      },
      {
        "name": "inspection",
        "from": "accessible cleanout",
        "to": "carrier/selected collection cleaning paths",
        "condition": "keep plug/removal and cleaning access"
      },
      {
        "name": "optional annular sensor",
        "from": "annular leakage observation point",
        "to": "selected detection arrangement",
        "condition": "optional; no sensitivity/coverage claim"
      },
      {
        "name": "box sampling",
        "from": "top of effluent carrier",
        "to": "accessible detector line through box top",
        "condition": "portable periodic or permanent selected device; not automatic whole-annulus monitoring",
        "drawing_reference": "samplingtakeoffontopofoutletcarrieratbox, distinctfromannularsensor"
      },
      {
        "name": "box collection",
        "from": "box low liquid region",
        "through": "dip collection line",
        "to": "selected contaminant removal facility",
        "condition": "cleaning and removal access; no guaranteed segregation from carrier effluent"
      }
    ],
    "boundaries": [
      "carrier pipe",
      "outer containment pipe",
      "carrier/outer upper seal at hub",
      "sealed box penetration and wall plate",
      "exterior polyethylene membrane liner",
      "sealed service/cleanout penetrations"
    ],
    "alternatives": [
      "P-trap water seal",
      "running trap",
      "sewer-box seal",
      "selected commercial insert with caulk/screen/cleanout; no invented valve mechanism"
    ],
    "supports": "carrier positioning supports and outer pipe size selected with vendor/material system; no generic spacing or load design",
    "limits": [
      "Variable downstream flow can remove P-trap water seal",
      "Detector observation differs from containment and from collection",
      "Portable and permanent devices have different maintenance/coverage demands",
      "No current regulatory compliance, leak-tightness, storage/collection capacity or detection performance established"
    ]
  }
}