Edges

Edges represent connections and relationships between nodes in the P&ID graph.

Edge Types

Edge Type	Description	Connects
physically_connected_to	Physical piping connection	Component ↔ Component
has_a	Logical containment/membership	Parent → Child
physically_has_a	Physical containment	Equipment → Equipment Component
starts_at	Where a pipe segment begins	PNSG → First Component
ends_at	Where a pipe segment ends	PNSG → Last Component
associated_with	Signal/control connection	Instrument ↔ Control Unit

Relationships Overview

┌─────────────────────────────────────────────────────────────────┐
│                    PIPING HIERARCHY                             │
├─────────────────────────────────────────────────────────────────┤
│                                                                 │
│  Piping Network System (PNS)                                    │
│        │                                                        │
│        │ has_a                                                  │
│        ▼                                                        │
│  Piping Network Segment (PNSG)                                  │
│        │                                                        │
│        ├── has_a ──────► Components (valves, reducers, tees)    │
│        │                                                        │
│        ├── starts_at ──► First Component in segment             │
│        │                                                        │
│        └── ends_at ────► Last Component in segment              │
│                                                                 │
└─────────────────────────────────────────────────────────────────┘

┌─────────────────────────────────────────────────────────────────┐
│                    PHYSICAL CONNECTIONS                         │
├─────────────────────────────────────────────────────────────────┤
│                                                                 │
│  Component ◄── physically_connected_to ──► Component            │
│                                                                 │
│  Example: Valve ──physically_connected_to──► Reducer            │
│                                                                 │
└─────────────────────────────────────────────────────────────────┘

┌─────────────────────────────────────────────────────────────────┐
│                    INSTRUMENTATION                              │
├─────────────────────────────────────────────────────────────────┤
│                                                                 │
│  Instrumentation Loop                                           │
│        │                                                        │
│        │ has_a                                                  │
│        ▼                                                        │
│  Instruments (transmitters, indicators, controllers)            │
│                                                                 │
└─────────────────────────────────────────────────────────────────┘

┌─────────────────────────────────────────────────────────────────┐
│                    EQUIPMENT                                    │
├─────────────────────────────────────────────────────────────────┤
│                                                                 │
│  Equipment (Pump, Vessel, Heat Exchanger)                       │
│        │                                                        │
│        │ physically_has_a                                       │
│        ▼                                                        │
│  Equipment Components (Nozzles)                                 │
│                                                                 │
└─────────────────────────────────────────────────────────────────┘

Edge Structure

Every edge has these fields:

{
  "id": "edge-456",
  "edge_type": "physically_connected_to",
  "edge_classification": "process_line.secondary_process_line",
  "from": {
    "tag": "FV-101",
    "id": "abc-123",
    "node_type": "pid_component",
    "node_classification": "piping_component.gate_valve"
  },
  "to": {
    "tag": "R-001",
    "id": "def-456",
    "node_type": "pid_component",
    "node_classification": "piping_component.reducer"
  },
  "orig_from_x": 100.0,
  "orig_from_y": 200.0,
  "orig_to_x": 300.0,
  "orig_to_y": 200.0,
  "attributes": [...]
}

Field	Description
id	Unique edge identifier
edge_type	Type of relationship (see table above)
edge_classification	Specific classification
from	Source node (embedded node object)
to	Target node (embedded node object)
orig_from_x, orig_from_y	Start coordinates on drawing
orig_to_x, orig_to_y	End coordinates on drawing
attributes	Additional properties

Edge Classifications

Classification	Edge Type	Description
process_line.secondary_process_line	physically_connected_to	Pipe connection
signal_line.*	associated_with	Signal/control connection
pns_has_pnsg	has_a	PNS contains PNSG
pnsg_has_component	has_a	PNSG contains component
loop_has_component	has_a	Loop contains instrument
equipment_has_component	physically_has_a	Equipment contains nozzle
pnsg.starts_at	starts_at	PNSG start point
pnsg.ends_at	ends_at	PNSG end point

Querying Edges

Get all physical connections

{"query": ".pid_graph.edges | filter(.edge_type == \"physically_connected_to\")"}

Get all hierarchy relationships

{"query": ".pid_graph.edges | filter(.edge_type == \"has_a\")"}

Get PNSG start/end points

{"query": ".pid_graph.edges | filter(.edge_type == \"starts_at\" or .edge_type == \"ends_at\")"}

Get equipment-component relationships

{"query": ".pid_graph.edges | filter(.edge_type == \"physically_has_a\")"}

Get edges connected to a specific node

{"query": ".pid_graph.edges | filter(.from.tag == \"FV-101\" or .to.tag == \"FV-101\")"}