What symbols are these? (P&ID)

AV = Angle (control) Valve, I presume.

Odd thing that now that P&IDs are always CAD you often find weird symbols.

Is it because lesser-experienced people are now doing drawings or using only symbols that came in the box with the software?

I agree with #1 #2 expansion joint and centrifugal pump.

3 Do not know. It is quite artsie. And with no connections shown to that thing on top there isn't much of a clue.



Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

Should refer to the standard P&ID line symbol and line legend for the project.

just a guess,
MV - Manual valve
AV- Air control valve
PP- Pump
the weird component looks like a "flanged flexible hose"....

Should refer to the standard P&ID line symbol and line legend for the project.

#1 Piping Expansion Joint
#2 Centrifugal Pump
#3 Air vent

Ah, yes, air vent makes more sense than angle valve if that is a pump suction.

I agree with Bimr.

The pumps are quite badly drawn. I thought initially they were blowers but seem to be pumps.

No 3 could be auto vents?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

Yes, could be an Air release valve.

Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

Is there a prize?

Steve Jones
Corrosion Management Consultant


All answers are personal opinions only and are in no way connected with any employer.

No. No prises. Only surprises.

Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

Gator has put his finger on the cause of the problem ...

"Is it because lesser-experienced people are now doing drawings or using only symbols that came in the box with the software?"

Yes,.... yes indeed it is ...

There are more and more 18 year old CAD monkeys, hired right off the street or from a phone APP who could not care less about the quality of their work.

Confusion is further enhanced by a vast multitude of CAD/PID packages that were purchased by MBAs in the IT department.

Young CAD monkeys are, of course far too busy to make an index of PID symbols for each project ...

... and this mad dance is made worse by MBA PROJECT MANAGERS insisting that everything go out the door by Friday..

.... and, oh yes .... we are going to need a Process or Mechanical Engineer to PE stamp the PIDs on Thursday afternoon..

Boy, am I glad that I am retired ...

MJCronin PE
Sr. Process Engineer

#1 Flexible hose