P&ID Symbols (Complete List & PDF)

A complete collection of the most used P&ID symbols for lines, piping, valves, instruments, pumps, compressors, pressure equipment and other mechanical equipment, and the PDF file for P&ID symbols to download

WHAT IS P&ID?

P&ID is the acronym for “Piping and instrumentation diagram”, i.e. a very detailed diagram showing the processes happening within a plant, the involved equipment, and their interconnections.

A set of standardized P&ID symbols is used by process engineers to draft such diagrams. P&ID symbols exist for all major components and lines, such as valves, vessels, instruments, pumps, compressors, and towers. The ISA S5.1, ISO 10628, and BS 5070 cover the standardization of P&ID symbols and guide process engineers in their plant design activities.

The most common P&ID symbols are listed below:

• lines
• piping components (pipes, flanges, and fittings)
• valves
• filters
• instruments and instrumentation
• pumps
• compressors
• vessels
• electrical machines (motors, generators, and turbines)
• heat exchangers

LINES P&ID SYMBOLS

PIPING P&ID SYMBOLS

	Clamped Flange Coupling symbol
	Coupling symbol
	End Caps 01 symbol
	End Caps 02 symbol
	Flange symbol
	Flanges symbol
	Reducers symbol
	Removable Spool symbol
	Union symbol

VALVES P&ID SYMBOLS

Gate Valve symbol
Normally Closed Gate Valve symbol
Ball Valve symbol
Normally Closed Ball Valve symbol
Globe Valve symbol
Butterfly Valve symbol
Check Valve symbol
Plug Valve symbol
Needle Valve symbol
Self Draining Valve symbol
Integrated Block and Bleed Valve symbol
Auto Recirculation Valve symbol
Angle Valve symbol
Angle Globe Valve symbol
3-way Valve symbol
Y Blowdown Valve symbol
Angle Blowdown Valve symbol

FILTERS P&ID SYMBOLS

INSTRUMENTS P&ID SYMBOLS

	Analyzer Transmitter symbol
	AND Gate symbol
	Averaging Pitot Tube symbol
	Behind Control symbol
	Behind Local Control symbol
	Computer symbol
	Computer Indicator symbol
	Coriolis Flow Sensor symbol
	Correcting Element symbol
	Diamond symbol
	Diaphragm Meter symbol
	Displayed Configurable symbol
	Displayed Programmable Indicator symbol
	Double symbol
	Flow Controller symbol
	Flow Element  symbol
	Flow Indicator  symbol
	Flow Meter symbol
	Flow Nozzle Meter symbol
	Flow Recorder symbol
	Flow Transmitter symbol
	Flowmeter symbol
	Flume Meter symbol
	Indicator 01 symbol
	Level Alarm symbol
	Level Controller symbol
	Level Gauge symbol
	Level Indicator symbol
	Level Meter symbol
	Level Recorder symbol
	Level Transmitter symbol
	Magnetic Flow Meter symbol
	Manhole symbol
	NOT Gate symbol
	Odometer symbol
	On Central Control Panel symbol
	On Local Control Panel symbol
	OR Gate symbol
	Pitot Tube symbol
	Pitot Tube Type Flow Meter symbol
	Pressure Controller symbol
	Pressure Gauge symbol
	Pressure Gauges symbol
	Pressure Indicating controller symbol
	Pressure Indicator symbol
	Pressure Recorder symbol
	Pressure Recording Controller symbol
	Pressure Transmitter symbol
	Programmable Indicator symbol
	Quick Change Meter symbol
	Rotary Meter symbol
	Rotometer symbol
	Sampler symbol
	Shared Indicator 01 symbol
	Shared Indicator 02 symbol
	Socket Connection  symbol
	Specialty Item symbol
	Steam Tracer symbol
	Straightening Vane symbol
	Support Bracket symbol
	Support Leg symbol
	Support Ring symbol
	Support Skirt symbol
	Target Meter symbol
	Temperature Controller symbol
	Temperature Element symbol
	Temperature Indicator symbol
	Temperature Recorder symbol
	Temperature Transmitter symbol
	Thermometer symbol
	Thermometers symbol
	Transducer symbol
	Turbine Meter symbol
	Ultrasonic Meter symbol
	Unit Control Panel symbol
	V Cone Meter symbol
	Venturi symbol
	Venturi Meter symbol
	Vortex Sensor symbol
	Wedge Meter symbol
	Weir Meter symbol

ISA SYMBOLOGY

The symbology for the identification of the measurement and control instrumentation on the flow and process diagrams and on the P&ID (Piping & Instrument Diagram), commonly called P&I (Piping & Instrumentation), is generally compliant with the Standard ISA (Instrumentation Society of Automation) identified as S.5, that is composed of identification codes and graphic symbols.

The symbology of the instrument it is placed in a circle of 7/16 “or 12 mm (see below), was in the top there is the functional identification (of the instrument or device) composed with max 5 letters, and in the bottom there is identification of the loop (measurement and/or control) consists of a progressive number of 3 or 4 numbers, followed by a literal suffix to identifies two or more identical instruments inserted in the same chain and therefore having the same functional identification;

The circle that identifies the instrument or device has:

• Continue Line in the center: for an instrument suitable for control room mounting
• The dotted line in the center: for an instrument suitable for technical room mounting
• No line in the center: for an instrument suitable for field application

If an instrument has a circumscribed square means that it is an integrated instrument as a function in a DCS (Distributed Control System) or PLC (Programmable Logic Controller).

T First Letter (Measured variable)	RC Later letters (Functions)	101 Loop number	A Suffix
Functional identification		Loop identification

Graphical representation of a temperature recorder controller of the 101A loop, suitable for control room mounting
The following tables show:
– Table 1 identifying the function of the instruments or devices
– Table 2 the graphic identification of the valves
– Table 3 the graphic identification of the actuators
– Table 4 identifying the safety conditions of the valves and actuators

At the end will also be reported the literal and graphic symbols of the power supplies and signals of the instrumentation.

TABLE 1 – FUNCTIONS OF INSTRUMENTS

LETTER	FIRST LETTER		FOLLOWING LETTERS
	Measured variable	Modified	Passive function	Active function	Modifier
A	Analysis		Alarm
B	Burner or combustion
C	User (1) choice			Control
D	User (1) choise	Differential
E	Voltage		Element (primary)
F	Flow	Fraction
G	User (1) choice		Glass (2)
H	Hand				High (3)
I	Current		Indicate
J	Power	Scan
K	Time schedule	Time rate              of change		Control station
L	Level		Light		Low (4)
M	User (1) choise	Momentary			Meddle or intermediate
N	User (1) choice
O	User (1) choice		Orifice or restriction
P	Pressure or vacuum		Point test
Q	Quantity	Totalize or integrate
R	Radioactivity		Record
S	Speed or frequency	Safety		Switch
T	Temperature			Transmit
U	Multivariable		Multifunction	Multifunction	Multifunction
V	Vibration			Valve
W	Weight or force		Well
X	Danger	Axis X	Unclassified	Unclassified	Fault
Y	Event	Axis Y		Calculation module (5)
Z	Position                   or dimension	Axis Z		Unclassified final element
(1) It must be chosen uniquely for each project. For example C – Conductivity; D – Density; etc. (2) Glass instruments that allow the visualization of process data (3) Very high or maximum is indicated with HH (4) Very low or minimum is indicated with LL (5) To define the Y function on a diagram, add the specific symbol of the relay or convert to a square of 6 mm on the side of the graphical sign of the instrument (in the north-east position).

TABLE 2 – INSTRUMENTATION VALVES SYMBOLS

TABLE 3 – ACTUATORS FOR INSTRUMENTATION VALVE SYMBOLS

TABLE 4 – IDENTIFICATION OF SAFETY CONDITION FOR VALVES AND ACTUATORS (WITHOUT SUPPLY)

SYMBOLOGY FOR POWER SUPPLY

AS –  Ais Supply:
IA – Instrument Air
PA- Plant Air
ES –  Electrical Supply
GS –  Gas Supply
HS –  Hydraulic Supply
NS –  Nitrogen Supply
SS  – Steam Supply
WS – Water Supply

SYMBOLOGY FOR INSTRUMENTATION SIGNALS

The table shows the symbology of control signals for instrumentation

PUMPS P&ID SYMBOLS

	Cavity Pump symbol
	Centrifugal Pumps 01 symbol
	Centrifugal Pumps 02 symbol
	Centrifugal Pumps 03 P&ID symbol
	Centrifugal Pumps 04 P&ID symbol
	Centrifugal Pumps 05
	Gear Pump symbol
	Horizontal Pump symbol
	ISO Centrifugal Pump symbol
	ISO Diaphragm Pump symbol
	ISO Gear Pump symbol
	ISO Liquid Pump symbol
	ISO Positive Displacement Pump symbol
	ISO Progressive Pump symbol
	ISO Screw Pump symbol
	Liquid Ring Vacuum Pump symbol
	Peristaltic Pump symbol
	Positive Displacement Pump 01 symbol
	Positive Displacement Pump 02 symbol
	Positive Displacement Pump 03 symbol
	Proportionating Pump symbol
	Pump 01 symbol
	Reciprocating Pump 01 symbol
	Reciprocating Pump 02 symbol
	Rotary Gear Pump symbol
	Rotary Pump symbol
	Screw Pump 01 symbol
	Screw Pump 02 symbol
	Submersible Pump symbol
	Sump Pump symbol
	Turbine Pump symbol
	Vacuum Pump symbol
	Vertical Pump 01 symbol
	Vertical Pump 02 symbol

COMPRESSORS P&ID SYMBOLS

	AC Air Compressor symbol
	Air Compressor symbol
	Axial Compressor symbol
	Centrifugal Blower symbol
	Centrifugal Compressor 01 symbol
	Centrifugal Compressor 02 symbol
	Centrifugal Compressor 03 symbol
	Centrifugal Compressor 04 symbol
	Compressor 01 symbol
	Compressor 02 symbol
	Compressor Silencers symbol
	Compressor Vacuum Pump symbol
	Diaphragm Compressor symbol
	Ejector Compressor symbol
	Gas Blower symbol
	Liquid Ring Compressor symbol
	Piston Compressor symbol
	Reciprocating Compressor 01 symbol
	Reciprocating Compressor 02 symbol
	Reciprocating Compressor 03 symbol
	Ring Compressor symbol
	Roller Vane Compressor symbol
	Rotary Compressors 01 symbol
	Rotary Compressors 02 symbol
	Rotary Compressors and Silencers symbol
	Screw Compressor symbol
	Selectable Compressor symbol
	Turbo Compressor symbol

VESSELS P&ID SYMBOLS

	Bag symbol
	Bag ISO symbol
	Barrel P&ID symbol
	Barrel ISO symbol
	Bin symbol
	Boiler symbol
	Brackets Vessel symbol
	Column symbol
	Cone Roof Tank symbol
	Covered Tank symbol
	Dished Ends Vessel symbol
	Dome Boiler symbol
	Dome Roof Tank symbol
	Double Wall Tank symbol
	Drum symbol
	Electrical Heating Vessel symbol
	Floating Roof Tank symbol
	Fluidized Bed Column symbol
	Gas Bottle symbol
	Heating Cooling Jacket Vessel symbol
	Hot Liquid Boiler symbol
	Internal Floating Roof Tank symbol
	Knockout Drum symbol
	Mixing Vessel symbol
	Onion Tank symbol
	Open Bulk Storage symbol
	Open Tank symbol
	Packed Tower symbol
	Packing Column 01 symbol
	Packing Column 02 symbol
	Pit Vessel symbol
	Plate Tower symbol
	Staggered Baffle Tray Column symbol
	Tank 01 symbol
	Tank 02 symbol
	Tank 03 symbol
	Tank 04 symbol
	Thermal Insulation Vessel symbol
	Tray Column symbol
	Vertical Vessel symbol
	Wastewater Treatment symbol

MOTORS, GENERATORS, TURBINES P&ID SYMBOLS

	AC Generator symbol
	AC Motor symbol
	DC Generator symbol
	DC Motor symbol
	Diesel Motor symbol
	Electric Moto symbol
	Gear symbol
	Generator symbol
	Motor 01  symbol
	Motor 02 symbol
	Motor Driven Turbine symbol
	Motor Generator  symbol
	Step Motor symbol
	Turbine  symbol
	Turbine Driver symbol
	Vertical Turbines symbol

HEAT EXCHANGERS P&ID SYMBOLS

 

DOWNLOAD P&ID SYMBOLS IN PDF

You can download most P&ID symbols in PDF format by clicking on the following link:

P&ID symbols for piping

 

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About the Author

Author: Dott. Prof. Alessandro Brunelli – Professor of Instrumentation, Automation, and Safety of Industrial Plants

Cavaliere dell’ Ordine al Merito della Repubblica Italiana (OMRI N. 9826 Serie VI)

Author of “Instrumentation Manual” (available in IT):

• Part 1: illustrates the general concepts on industrial instrumentation, the symbology, the terminology and calibration of the measurement instrumentation, the functional and applicative conditions of the instrumentation in normal applications and with the danger of explosion, as well as the main directives (ATEX , EMC, LVD, MID, and PED);
• Part 2: this part of the book deals with the instrumentation for measuring physical quantities: pressure, level, flow rate, temperature, humidity, viscosity, mass density, force and vibration, and chemical quantities: pH, redox, conductivity, turbidity, explosiveness, gas chromatography, and spectrography, treating the measurement principles, the reference standard, the practical executions, and the application advantages and disadvantages for each size;
• Part 3:illustrates the control, regulation, and safety valves and then and simple regulation techniques in feedback and coordinates in feedforward, ratio, cascade, override, split range, gap control, variable decoupling, and then the Systems of Distributed Control (DCS) for continuous processes, Programmable Logic Controllers (PLC) for discontinuous processes and Communication Protocols (BUS), and finally the aspects relating to System Safety Systems, from Operational Alarms to Fire & Gas Systems, to systems of ESD stop and finally to the Instrumented Safety Systems (SIS) with graphic and analytical determinations of the Safety Integrity Levels (SIL) with some practical examples.

Download the PDF – Instrumentation Handbook

You can download an excerpt of the “Instrumentation Manual” (Brunelli, 2018-2019) by clicking on the following link:

Instrumentation Handbook