# P&ID diagram

A P&ID documents process plant: vessels, pumps, valves and the instruments that monitor them, using symbols that are standardised for a reason.

The shapes ship with the draw.io editor, so the diagram lives on the page rather than in a CAD file only one person can open.

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## When to reach for one

* Process and manufacturing documentation.
* Maintenance procedures that reference specific valves and tags.
* Handover documents where the notation is expected.

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## How to draw it in Capable

| **Route**  | **Use when**                                                |
| ---------- | ----------------------------------------------------------- |
| draw.io    | The P&ID shape libraries, laid out by hand.                 |
| Excalidraw | A sketch for a discussion, never for a controlled document. |

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## Symbol families you will need

| **Family**            | **Examples**                                            |
| --------------------- | ------------------------------------------------------- |
| Vessels and equipment | Tanks, columns, heat exchangers, pumps                  |
| Valves                | Gate, globe, check, control, relief                     |
| Instruments           | Indicators, transmitters, controllers, with tag bubbles |
| Lines                 | Process, instrument signal, pneumatic, electrical       |

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## A few things that catch people out

* Tag numbers are the point. A P&ID without instrument tags is decoration.
* Line types carry meaning: process, signal, pneumatic and electrical are not interchangeable.
* Keep the legend on the diagram. Readers will not have the standard to hand.

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## Related

[Network diagramFrom one office to many sites.](https://help.gocapable.com/diagrams/network-diagram.html)

[Network topology diagramStar, mesh, bus, ring, and hybrids.](https://help.gocapable.com/diagrams/network-topology-diagram.html)

[ExamplesWorking diagrams you can copy.](https://help.gocapable.com/diagrams/examples.html)

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_Somebody will read this at 3am. Be kind._