P&ID

The P&ID is the master document of a process facility. Process engineering produces it, and everyone else works from it: piping routes what it shows, instrumentation implements its loops, safety reviews walk it line by line in HAZOPs, operations trains on it, and maintenance isolates equipment by it. It is deliberately not to scale and not spatial — it shows what connects to what, not where anything is — which is exactly what makes it the reference for the facility's logic.

Because everything downstream depends on it, the P&ID is also where inconsistency shows up first: the line list disagreeing on a size, the datasheet on a rating, the model on a connection. Keeping the P&ID reconciled with the documents that orbit it is a permanent background task on every project.

The industry's larger P&ID problem is inheritance. Facilities outlive their tools, and much of the world's installed base is documented in P&IDs that exist as scans and flat CAD files — readable by people, opaque to systems — so that every revamp, every debottlenecking study and every digitalisation effort begins by re-extracting what the drawings already know.