Valve and actuator symbols on Process and Instrumentation Diagrams (P&IDs) standardised by ANSI/ISA-5.1-2009 use, among others, two triangles pointing at each other, with centre shapes indicating type (gate, ball, globe) and top symbols indicating actuation method (electric, pneumatic, manual). Common symbols include gate valves (rectangles), check valves (arrows), and actuators showing fail-safe modes.
Example PID Drawing
Gate Valves
Two triangles pointing toward each other, with or without a vertical line between them.
Globe Valves
A circle between the two triangles.
Ball Valves
A circle or a filled diamond between the two triangles.
Butterfly Valves
A circle with a diagonal line.
Check Valves (Non-return)
An arrow inside a circle or a simple arrow on the line, pointing in the direction of flow.
Plug Valves
A plug between the two triangles.
Diaphragm Valves
A dome between the two triangles.
Angle Valves
Two triangles at an angle.
Reducing Valves and Sustaining Valves
Two triangles with an actuator and pipe.
Safety Valves and Relief Valves
Safety Valve (left), Relief Valve (right).
Fail-Safe Position
This shows the position the valve will go back to if the actuator looses power (electrical or pneumatic).
End Connections
Add to the valve symbol to indicate the connection type.
Quarter Turn Acutuators
Add to the valve symbol if an actuator is fitted.
Other Equipment
Other commonly used equipment found on a drawing.