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# Determining Pressure Rating (PN) of Valves and Pipes (Water)

## Determining Pressure Rating (PN) of Valves and Pipes (Water)

(OP)
Hello guys,
Hope you're all doing well.

For as long as I remember, the rule of thumb for determining the PN of pipes and valves is 1.5 times the working pressure in the network. But lately I've been digging deeper. So here's my question:
How do you guys determine the pressure rating of the pipes/valves (discharge side of the pump. Water.):
A - 1.5 x pump head
or (another factor) x pump head
B- 1.5 x pump shut-off head
or (another factor) x pump shut-off head
C- 1.5 x (maximum surge pressure with surge protection)
or (another factor) x (maximum surge pressure with surge protection)

Any specific code of standard that mandates this?

Moreover, some engineers add the suction pressure to the pump head in order to estimate the PN. Do you agree? When I normally selected my pump, it's at the intersection of the system curve with the pump curve. And, as we know, the system curve already reflects the suction pressure from its starting point at the Y-axis. So, to get the pressure at the pump discharge, do we really need to ADD the suction pressure to the pump produced head? (the intersection point already reflects the suction pressure, is what I am saying). I might be missing something (?)

Hope you're having great holidays!
Paul

### RE: Determining Pressure Rating (PN) of Valves and Pipes (Water)

You should delete this, and your other post and re-post in forum378: Pipelines, Piping and Fluid Mechanics engineering

Please do not duplicate postings, as that tends to cause confusion and replication. The entire forum list can be found here https://www.eng-tips.com/forumlist.cfm

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