As a graduate chemical engineer, you are expected to know how to read a P&ID. Learn to read before you can make one.

The intent of P&IDs is that it should reflect design, operation, maintenance and safety of the plant.

Knowing how to read P&IDs, allows you to understand better the design intent.

Understanding of process and interacting parameters helps to know about the process, and vice-versa, you can make better P&ID provided you understand the process and interaction parameters.

When you first see P&ID, you will come across number of symbols representing equipments, valves, instruments, pipelines, etc

Those symbols vary from company to company and client to client but only to an extent and for that, you must always ask or refer legends, for better understanding.

You can refer to Instrument Society of America (ISA) symbols for basic knowledge and usage.

You will see Tag numbers for various equipments and instruments. Line numbers for pipelines. Each line is with Type of Fluid, Size, M.O.C, whether or not Insulated, control loops with bypass line, etc

Whenever you read try to interpret the associated meaning with it:

●     How and where safety relief valves are used.

●     Standby Pumps and power supply.

●     Drain and Vent lines.

●     What symbols are used for different valves and instruments?

●     Whether the instrument is field mounted, primary or auxiliary.