Expansion Joints with FPS pipe

[nucleareng78]

Some of the pumps I am replacing currently have expansion joints. Does anyone have some good resources on why we should use expansion joints? The pumps' suction operate under a slight vacuum and the system engineer told me there may be some flashing going on at the impeller....this indicates to me that the pumps are operating pretty rough. Our replacement pumps have a better base design but will expansion joints help the vibration issues with the pumps??

Thanks in advanced.

 

[Frank1344]

Your pumps have definitely allowable's for their suction and discharge nozzles.

EJ helps reducing the nozzle loads.

EJ is not for vibration remedy and as a matter of fact vibration can be very detrimental to EJ.

Are you limited in space around pump suction? If yes, then we can not deal with required flexibility with adding pipe fittings e.g. elbows, ..

 

[nucleareng78]

The suction comes from a straight pipe from the exit of the Circulating Water system (from condenser tubes). We cannot move the suction to the left or right but can adjust the height with the concrete pad.

Since the pipe is just FPS, there shouldn't be any major loads on the suction or discharge correct?

 

[Frank1344]

My apology, but what this "FPS" is?
Is it a non-metallic material? Like PVS, FRP, HDPE,...

 

[Frank1344]

One more thing,
The existing piping were carbon steel (metal)?

 

[nucleareng78]

Sorry I may have the acronym wrong but it is indeed FRP piping...sorry.

There are a total of 4 identical pumps we are replacing, where two of them indeed have expansion joints on the suction/discharge. Since Fiberglass piping is fairly brittle, this may be why they used expansion joints? Reduced nozzle loads would be helpful since the existing pumps are operating pretty rough.

Here are the expansion joints we are wanting to use.

http://www.mercer-rubber.com/mercer/html/5.htm

Thanks for your help so far!

 

[Frank1344]

Absolutely no problem.

I concur with what you said.

And as these are rubber EJ, they help isolating the vibrations.

Just watch for the temperature, FRP and rubber can go up to 70 to 90 degree C.

 

[nucleareng78]

Temperature shouldn't be too big of a problem from what the design basis says.

As far as length of exp joints. Is there a rule of thumb for the maximum recommended length you should have them? we are connecting to a 12" pump flange...

 

[stanier]

Make sure the EJ on the doschrge side has tie rods. Otherwise the pressure will impose a force on the pump nozzle.

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