
What are P&IDs?
Piping and Instrumentation Diagrams (P&IDs) use a standardized set of symbols, notation and abbreviation to represent the various components of a process. These symbols are designed to be easily recognizable and convey important information about the component they represent. In this guide, we will walk through the basics of P&ID symbols, notation and abbreviation and how to read them.
Important
P&IDs are living documents, and it is important to keep them updated as the process changes over time. Practice is key to understanding P&ID symbols, notation and abbreviation, and interpreting them correctly.
Table of Contents
P&ID symbols can be broadly classified into 7 categories:
Piping Symbols
Examples include pipes, tubes, ducts, multi-line, separators, connectors, end caps, flanges, reducers, and coupling.

Pipe

Jacketed pipe

Thermally insulated pipe

Cooled or heated pipe

Covered gas vent

Curved gas vent

Flange

Butt weld

Reducer

Flexible hose

Steam trap

Viewing glass
Pump Symbols
Pumps are an essential part of the majority of industrial plants that need pumps. These pumps can be used for suction, compression, moving fluid, and also for pressure control. There are many p and id symbols for pumps.

Pump

Vacuum pump or compressor

Centrifugal pump

Gear pump

Screw pump

Screw pump

Vacuum pump

Fan

Axial Fan

Radial Fan
Valve and Control Symbols
Represented by various shapes to indicate the type and function of the control device. Examples include valves, actuators, and controllers.

Pressure reducing valve

Valve

Control valve

Manual valve

Needle valve

Butterfly valve

Ball valve

Globe valve

Diaphragm valve
Vessel Symbols
A vessel is used to store fluids or also be used to alter the characteristics of the fluid during storage. This includes tanks, cylinders, columns, bags.