SYMBOLS FOR PROCESS FLOW DIAGRAMS
AND PIPING & INSTRUMENT DIAGRAMS
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The purpose of this note is to determine standardised graphical symbols to be used in piping and instrumentation diagrams.
The standard used for instrumentation and actuators is derived from the ISA-S5.1 standard (1986) : "Instrumentation Symbols and Identification".
The pneumatic and hydraulic control diagrams are drawn using the symbolisation defined by specialised standards.
1 GENERAL SYMBOLS USED IN PIPING AND INSTRUMENT DIAGRAMS
SYMBOL DUTY REMARKS
MAJOR PIPING
MINOR PIPING
MINOR / SMALL BORE PIPING
ELECTRICAL HEAT TRACING
HYDRAULIC SIGNAL
ELECTRICAL SIGNAL
PNEUMATIC SIGNAL
CAPILLARY TUBING
SCOPE OF SUPPLY BOUNDARY
FLOW DIRECTION ARROW
INDICATION OF PIPING SLOPE AT VALUE INDICATED OR IN MM/M
FREE DRAINING LINE IN DIRECTION OF ARROW LINE ROUTED IN HORIZONTAL AND VERTICAL SECTIONS
SOURCE OR DESTINATION
PIPELINE DELIMITTER TO INDICATE CHANGE OF LINE NUMBER
FLANGED CONNECTION
LINE CONNECTING POINT
UNCONNECTED PIPELINE
FLEXIBLE HOSE
QUICK RELEASE BAYONET UNION WITH HOSE
SELF SEALING FEMALE QUICK RELEASE COUPLING
VENTS
MALE QUICK RELEASE COUPLING
CONCENTRIC REDUCER INDICATION OF NOMINAL DIAMETER IS OPTIONAL
ECCENTRIC REDUCER INDICATION OF NOMINAL DIAMETER IS OPTIONAL
WELDED CAP
SW CONNECTION OR END CAP
THREADED CONNECTION OR END CAP
FLAME ARRESTOR
ORIFICE PLATE (FLANGED)
ORIFICE PLATE (WELDED)
MULTI ORIFICE PLATE
BURSTING DISC BETWEEN FLANGES
HAND OPERATED VALVE NORMALLY OPEN UNSPECIFIED VALVE TYPE.
ANY VALVE TYPE THAT IS SHADED
HAND OPERATED VALVE NORMALLY CLOSED INDICATES THE NORMAL OPERATING POSITION IS CLOSED
GATE VALVE
BUTTERFLY VALVE NORMALLY OPEN
BUTTERFLY VALVE NORMALLY CLOSED
DIAPHRAGM VALVE
GLOBE VALVE
NEEDLE VALVE
PLUG VALVE
BALL VALVE NORMALLY OPEN
BALL VALVE NORMALLY CLOSED
UNSPECIFIED ANGLE VALVE
GLOBE ANGLE VALVE
NEEDLE ANGLE VALVE
UNSPECIFIED THREE-WAY VALVE
THREE-WAY PLUG VALVE
FOUR-WAY VALVE
RELIEF VALVE OR VACUUM BRAKER VALVE
NON-RETURN VALVE
SCREW DOWN CHECK VALVE
DASH-POT CHECK VALVE
COMBINED LEAK-OFF AND CHECK VALVE
SPECIAL CHECK VALVE FOR MAIN CW PUMP DISCHARGE ALWAYS PISTON ACTUATED
FLOAT OPERATED VALVE
WAFER CHECK VALVE
SELF ACTING REGULATOR WITH EXTERNAL IMPULSE LINE ) ACCORDING TO FLUID
) DIRECTION / UPSTREAM
SELF ACTING REGULATOR WITH INTERNAL IMPULSE LINE ) OR DOWNSTREAM SELF ACTING
) REGULATOR
PRESSURE/DEPRESSURE VALVE
SPECIAL ITEM CONTROLLED BY ACTUATOR
PISTON ACTUATOR
SOLENOID ACTUATOR
DIAPHRAGM ACTUATOR
DOUBLE ACTING DIAPHRAGM ACTUATOR
ELECTRIC ACTUATOR
DIAPHRAGM ACTUATOR WITH MANUAL JACKING
DIAPHRAGM ACTUATOR WITH POSITIONER FOR CONTROL VALVES
DIAPHRAGM ACTUATOR WITH POSITIONER AND MANUAL JACKING
DIAPHRAGM ACTUATED VALVE "FAIL OPEN" INDICATION
DIAPHRAGM ACTUATED VALVE "FAIL CLOSE" INDICATION
DIAPHRAGM ACTUATED VALVE "FAIL FIX" INDICATION
"FAIL INDETERMINATE" INDICATION
HANDWHEEL GENERALLY ASSUMED PRESENT AND NOT SHOWN
HANDWHEEL WITH VACUUM TIGHT PACKING ONLY TO BE USED IF NOT DEFINED BY PIPE OR VALVE CLASS
DRAIN POT (WELDED)
DRAIN POT (FLANGED)
LIMIT OF SUPPLY
LIMIT OF SUPPLY WITH TERMINAL POINT NUMBER - INTERFACES
WITCH'S HAT FILTER
FILTER
Y FILTER
SPECIAL STRAINER
DRAIN TRAP
THERMOSTATIC DRAIN
NORMALLY CLOSED SPECTACLE PLATE
BLANKING PLATE
NORMALLY OPEN SPECTACLE PLATE
SPACER
EXPANSION JOINT
BELLOWS
TIED EXPANSION JOINT
JINGED EXPANSION JOINT
DISPERSER
SPRAY NOZZLE
EQUIPMENT INSULATION
TUNDISH (OPEN TYPE)
TUNDISH (CLOSED TYPE)
FLOOR DRAIN
FLOOR SUMP
SILENCER
SEPARATOR
PULSATION DAMPER/ ACCUMULATOR
GAS CYLINDER
CRITICAL PROCESS ELEVATION
AUXILIARY TURBINE
FAN OR BLOWER
- F = FAN
- C = COMPRESSOR
- V = VACUUM PUMP
PUMP (general)
CENTRIFUGAL PUMP
POSITIVE DISPLACEMENT PUMP
AGITATOR
COMBUSTION ENGINE
EJECTOR
ATTEMPERATOR/DESUPERHEATER
MIXING POT
MINOR HEAT EXCHANGER
TUBE TYPE COOLER
PLATE HEAT EXCHANGER
ELECTRIC HEATER
WASH BASIN
EYE WASH
SHOWER
FB FULL BORE SHOW NEAR VALVE AS REQUIRED
LO LOCKED OPEN SHOW NEAR VALVE AS REQUIRED
LC LOCKED CLOSED SHOW NEAR VALVE AS REQUIRED
2 SYMBOLS USED FOR THE INSTRUMENTATION
SYMBOL DUTY REMARKS
FIELD MOUNTED INSTRUMENT
INSTRUMENT WITH FUNCTION
VARIABLE AREA FLOW INDICATOR
PITOT TUBE
TURBINE FLOWMETER
ACOUSTIC FLOWMETER
VORTEX FLOWMETER
MAGNETIC FLOWMETER
FLOW NOZZLE
VENTURI
SURFACE MOUNTED TEMPERATURE ELEMENT
THERMOWELL MOUNTED TEMPERATURE ELEMENT