If you are interested to know more about subjects like Purpose, Owner and Contents & Conventions. read our free introduction to these concepts in our article P&ID Diagram Basics – Part 1 – Purpose, Owner and Contents.

If you are interested to know more about subjects like Standards and Guidelines. read our free introduction to these concepts in our article P&ID Diagram Basics – Part 2 – International Standards

This third article on P&ID diagrams deals with the functional identification and the conventions when naming the elements present in a P&ID diagram.

The reason is quite simple, users of instrumentation and control systems need some method to identify the equipment so that they can administer the engineering, the purchases, the installation and the maintenance of those systems.

But the identification must follow some basic rules to have a good documentation.Good documentation is the basis for good engineering and good maintenance of the facilities.

Piping and Instrumentation Diagrams (P&IDs) use specific symbols to show the connectivity of equipment, sensors, and valves in a control system. These symbols can represent actuators, sensors, and controllers and may be apparent in most, if not all, system diagrams. P&IDs provide more detail than a process flow diagram with the exception of the parameters, i.e. temperature, pressure, and flow values. “Process equipment, valves, instruments and pipe lines are tagged with unique identification codes, set up according to their size, material fluid contents, method of connection (screwed, flanged, etc.) and the status (Valves – Normally Closed, Normally Open).” These two diagrams can be used to connect the parameters with the control system to develop a complete working process. The standard notation, varying from letters to figures, is important for engineers to understand because it a common language used for discussing plants in the industrial world.