What is P&ID ?

As engineers/engineering students, we always heard about P&ID. But what is actually P&ID? Well, for the benefit those of you who are not sure on this, P&ID is piping and instrumentation diagram/drawing (P&ID). It is defined by the Institute of Instrumentation and Control as follows

A diagram which shows the interconnection of process equipment and the instrumentation used to control the process. In the process industry, a standard set of symbols is used to prepare drawings of processes. The instrument symbols used in these drawings are generally based on Instrumentation, Systems, and Automation Society(ISA) Standard S5. 1.

The primary schematic drawing used for laying out a process control installation.

For processing facilities, it is a pictorial representation of

· key piping and instrument details

· control and shutdown schemes

· safety and regulatory requirements

· basic start up and operational information

P&ID is an initialism that could mean:

· Piping and instrumentation diagram - a schematical diagram showing piping, equipment and instrumentation connections within process units in oil refineries, petrochemical and chemical plants, natural gas processing plants, power plants, water treatment and similar plants.

· Process and instrumentation diagram - a family of functional one-line diagrams showing hull, mechanical and electrical (HM&E) systems like piping, and cable block diagrams.

A P & ID is a full diagrammatic representation of a process plant. Each piece of equipment is shown along with its connectivity to other equipment. It may be regarded as an enhanced process flow diagram which shows, in addition to the process itself, details such as control and instrumentation equipment, pump and pipe sizes etc. Each instrument / piece of equipment is shown by a symbol denoting its type (pump, sensor, valve etc.) and a unique identification number or tag for differentiation from others.