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P&ID Symbols (Complete List)

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


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:


Line P&ID symbols


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


Gate Valve symbol Gate Valve P&ID symbol
Normally Closed Gate Valve symbol Normally Closed Gate Valve P&ID symbol
Ball Valve symbol Ball Valve P&ID symbol
Normally Closed Ball Valve symbol normally closed ball valve P&ID symbol
Globe Valve symbol globe valve P&ID symbol
Butterfly Valve symbol butterfly valve P&ID symbol
Check Valve symbol check valve P&ID symbol
Plug Valve symbol plug valve P&ID symbol
Needle Valve symbol needle valve P&ID symbol
Self Draining Valve symbol self draining valve P&ID symbol
Integrated Block and Bleed Valve symbol integrated block and bleed valve P&ID symbol
Auto Recirculation Valve symbol
Angle Valve symbol angle valve P&ID symbol
Angle Globe Valve symbol angle globe valve P&ID symbol
3-way Valve symbol 3way valve P&ID symbol
Y Blowdown Valve symbol Y blowdown valve P&ID symbol
Angle Blowdown Valve symbol Angle Blowdown valve P&ID symbol


Filters P&ID symbols


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


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).

First Letter
(Measured variable)
Later letters
Loop number
Functional identification Loop identification

Instrumentation symbology

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.


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)
O User (1) choice Orifice
or restriction
P Pressure or vacuum Point test
Q Quantity Totalize or integrate
R Radioactivity Record
S Speed
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).


Instrumentation valves symbols


Actuators for instrumentation valves symbols
Actuators for instrumentation valves symbols




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


The table shows the symbology of control signals for instrumentation

Symbology for instrumentation signals
Symbology for instrumentation signals


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


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


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


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


Heat Exchangers P&ID symbols


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