Industrial Safety

What is a P&ID Diagram?

Learn all about P&ID diagrams

Listen to this article

Today you will learn all about P&ID Diagrams.

You may be thinking, “What in the world is a P&ID Diagram?” In industry, these are piping and instrumentation diagrams. P&ID for short.

Most manufacturing facilities have compressed air, steam, chilled water, and other processes that require the use of piping.

All of these forms of energy and processes require instrumentation to control them which is usually in the form of valves and gauges, along with pumps and accumulators.

A P&ID diagram and the P&ID symbols legend will have all of these for a maintenance person, operator, engineer, or other employees to read and perform their job. At first glance, a P&ID diagram may look pretty intimidating. There can be several processes on one P&ID.

What I like to do is break it down into sections to make it a little easier to understand.

For example, let’s take a look at a pneumatic system P&ID. First, you should start at the air compressor, which you will find the correct symbol for on a Legend of all symbols used.

You would then follow the line which represents a pipe to the next component. In most cases, it will be some form of instrumentation, like a pressure transmitter or indicator that reads air pressure, or a valve to allow air to pass through to the next component or block the air from passing through.

There are many types of valves, be sure to compare the symbols on your P&ID to the legend. The P&ID will then show piping leading to the next component which in the case of our pneumatic system could be an accumulator.

An accumulator is simply a tank or storage device for air or fluids. Most P&ID diagrams will then have a symbol with an arrow labeled for another specific piece of machinery in the facility or it may simply say to Process.

This will indicate that if you need to trace the system further, you will need the diagrams for that specific equipment.

Hopefully by now you are getting a feel for following a P&ID diagram. Just remember to break the overall diagram down into smaller, more specific sections, and simply trace the system that you need more information from.

Always refer to the P&ID symbols Legend to make sure you know what the symbols indicate on the diagram.

Thank you, as always, for being here and sharing your thoughts, questions and support. Leave a comment to let us know what you think and make sure to subscribe to our newsletter to get the latest content first.