pump closed circuit

[jrwchem]

A bit of a brain twister:

What happens to either a centrigfugal or PD pump that has its discharge valve closed, and then subsequently the inlet valve closed.

I know it will overheat, and explode/melt eventually. For the PD pump assume a PSV opens and disharges back to the suction line. For the centrigual pump assume a min flow conrol valve opens to send pumpage back to suction(yes it is better to send back to tankage, but this doesnt always happen)

1)What is the suction/discharge pressure?
2)When does suction piping need to be designed for full discharge pressure?

Thnx.

 

[LucayaLive]

Both pumps will eventually over heat. The pumps are performing work on the fluid(s) which will manifest as temperature increases if the fluid continuously recycles.

There is not enough information to say what the suction and discharge pressures will be nor is there enough information to speak on what the design pressure of your suction lines should be. If you are recycling and there is chance that you can deadhead back to your line, why not design for maximum pressure? What other safety features are present?