Reading P&ID Symbols: A Step-by-Step Guide

Reading P&ID Symbols: A Step-by-Step Guide – GetReskilledGerard Creaner

By: Donagh Fitzgerald B.Prod Eng and Gerry Creaner B.Chem Eng. Last Updated: February 2023

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Piping and Instrumentation Diagrams (P&IDs) use a standardized set of symbols, notation and abbreviations 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.

BTW, if you need to learn how to read P&IDs and qualify equipment systems within a pharmaceutical manufacturing plant, check out our Equipment Validation Training Course.

Piping Symbols
Pump Symbols
Valve and Control Symbols
Vessel Symbols
Instrument Symbols
Equipment Symbols
Heat Exchanger Symbols
Abbreviations

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

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

Pressure regulating valve (PRV)

Pressure safety valve (PSV)

Temperature control valve (TCV)

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.

Vessel

Pressurized horizontal vessel

Pressurized vertical vessel

Reaction vessel

Column

Packing column

Instrument Symbols

Temperature Transmitter

Temperature Indicator

Temperature Controller

Conductivity Transmitter

Conductivity Indicator

Conductivity Controller

Flow Transmitter

Flow Indicator

Flow Controller

Flow Switch

Level Transmitter

Level Indicator

Level Switch

Level Alarm

Pressure Transmitter

Pressure Indicator

Pressure Controller

Equipment Symbols

Equipment is made up of items that don’t fit into other categories. This group includes hardware like reactors, dryers, turbines, vacuums, and other mechanical devices.

Jacketed mixing vessel

Half-pipe mixing vessel

Agitator or mixer

Dryer

Backdraft damper

Furnace

Cooling Tower

Air filter

Funnel

Heat Exchanger Symbols

A heat exchanger is a device that’s designed to transfer heat from different medium to another mediums. For example, an airconditor or a radiator in a house. This includes boilers, condensers, and other heat exchangers.

Heat Exchanger

Cooler

Plate & frame heat exchanger

Fixed straight tubes heat exchanger

U-shaped tubes heat exchanger

Double pipe heat exchanger

Spiral heat exchanger

P&ID Symbols Abbreviations

P&IDs use a standardized set of notation and abbreviations to represent the various components of a process. These notations are used to indicate the type of fluid, the size, and the pressure rating of the component. These include:

CT	Conductivity Transmitter
CI	Conductivity Indicator
CC	Conductivity Controller
FL	Flow Transmitter
FI	Flow Indicator
FC	Flow Controller
FS	Flow Switch
LT	Level Transmitter
LI	Level Indicator
LS	Level Switch
LA	Level Alarm
PT	Pressure Transmitter
PI	Pressure Indicator
PC	Pressure Controller
PRV	Pressure Regulationg Valve
PA	Pressure Alarm
PC	Pressure Controller
TT	Temperature Transmitter
TI	Temperature Indicator
TC	Temperature Controller
TCV	Temperature Control Valve
ST	Steam Trap
SG	Sight Glass
S	Strainer
T	Tank
P	Pump
HX	Heat Exchanger
PSV	Pressure Sanitary Valve
PUW	Purified Water
XV	Actuated Valves

About the Author

Donagh Fitzgerald

Head of Marketing & Product Development
Mechanical/Production Engineer

Donagh looks after the marketing and product development including the training and pedagogical elements of our programs and makes sure that all GetReskilled’s users can have a great online learning experience. Donagh has lived and worked in many countries including Ireland, America, the UK, Singapore, Hong Kong and Japan. Donagh has also served as the Program Manager for the Farmleigh Fellowship based out of Singapore.

Donagh holds Degrees in Production Engineering and Mechanical Engineering from South East Technological University, Ireland.

Gerry Creaner

President
Senior Lecturer with GetReskilled

Gerry Creaner has over 30-years of experience in the Life Sciences Manufacturing industry across a range of technical, managerial and business roles. He established a very successful engineering consultancy prior to founding GetReskilled, an online education and learning business, with offices in Singapore, Ireland and Boston (USA), focussed on the manufacture of safe and effective medicines for the public.

He is also a founding Director of two Singapore based philanthropic organizations, the Farmleigh Fellowship and the Singapore-Ireland Fund, both of which deepen the well established and historical Singapore – Ireland relationship and deliver long-term benefits to both countries.

Gerry has an undergraduate degree in Chemical Engineering (UCD, 1980) and an MSc (Management) from Trinity College Dublin (2003) and is currently doing research for his Ph.D.

Reading P&ID Symbols: A Step-by-Step Guide – GetReskilled (2024)