1. Piping and Instrument Diagrams
CM4120
Chemical Plant Operations

2. A P&ID is: A P&ID is not: Language of Symbols Schematic of Process
Displays Relative Orientation/Configuration
Communication Tool
Graphical Table of Contents
Piping Isometric
Equipment Fabrication Diagram
Scale Drawing
Control Logic Diagram
Something to Convey Process Information!

3. Line Designator - First Letter
W - Water or Heat Transfer
Fluid
L - Process Fluid
G – Gas (not a process fluid)
V - Vent or Vacuum
S - Steam
C - Condensate

4. Line Designator - Pipe Size
Following line number
is the line size
Given in inches

5. Line Designator - Pipe Spec.
A – 316 SS tubing
w/.038” wall
C SS pipe
Schedule 40
D - Carbon Steel
Sched. 40 (steam)
Sched. 80 (Syltherm)
H - Copper Tubing

6. Equipment Symbols

7. Equipment Symbols

8. Equipment Designations
D - Distillation Tower
E - Heat Exchanger
F - Filter
M - Misc. Equipment
P - Pump
R - Reactor
T - Tank

9. Manual Valve Symbols

10. Control Valve Symbols

11. Valve Failure Positions

12. Instrument Symbols

13. Control Symbols

14. ISA Instrument Identification
Transmitters/sensing elements:
FT – flow transmitter
LE – level element
Indicators:
AI – analytical indicator
LI – level indicator
PAH – pressure alarm high
Controllers:
TIC – temp indicating controller
FFIC – ratio flow controller
Controlled devices:
FY – flow transducer
LV – level valve

15. References for ISA symbols:
Riggs, Chemical Process Control, Appendix A
The Engineering Tool Box,