Hi everybody
We have flowserve virtical condensate extraction pumps in our power plant.
API 13 in combination with API 32 urea used for supporting the mechanical seal of the pumps.
There is a problem on the sealing lines (API 32) on the both pumps, the check valve allows backflow through it, so water flow from seal chamber of the running condensate pump to the seal chamber of the SB pump.
What is the reason of the two check valves are damaged?
What is the effect of the problem on the running pump and the SB pump?

 

can you send your condensate system P&ID ?

it doesn't seem strange to me that both mechanical seals are feed when a condensate pump is running

as the condenser is under vacuum, sealing must be provided to the running and stand by pump, to avoid air getting sucked in the circuit

at my plant, supply water for mechanical seal comes from condensate pumps discharge line, therefore both mechanical seals are feed as soon as one condensate pump runs

 

Yes the SB pump must be sealed but from condensate discharge line not from seal line of the running pump.
Note:
API 32 seal line is used to seal mechanical seal just at startup or at shutdown. When the pump is running, it will be sealed from API 13 line

 

thanks,

i'm not a mechanic, what i've learn faulty check valve can be due to:

oxydation / rust preventing the flap to fully close or stuck it open

also, some check valve need to be mounted only in a specific direction, in order to function poperly (like heads up or only verticaly) this type of information is found in check valve manufacturer data sheet

As soon as condensates pumps are shutdown and no vacuum is maintain, i would close the 202 valve and unmount one check valve to take a look at it inside...

again, i'm not a mechanic, and running with this type of problem doesn't seem a big deal, as the mechanical seal continue to seal the pump, and there is no excessive leakage to the outside

How do you discover that mechanical seal were backflowing ??