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Pump discharge supports

KevinNZ

Mechanical
Joined
Jun 12, 2003
Messages
877
Location
NZ
Hi all

I have been presented with the piping arrangement below. Canned pump discharge, bellows, steel pipe spool with valve, FRP Piping, I need to design the supports for the pipe spool, As we all know allowable pump nozzle loads are low.

Operating case needs the supports to flex or slide a little so the bellows tie rods become engaged and there is a path for pressure tension load.

The problem is earth quake loads from the mass of the pipe spool and valve. This load will either tension the tie rods and over load the pump nozzle or slacken the rods and put a pressure load on the pump body.

I do not want to anchor the spool because thermal expansion will slacken the rods, then, as above, pump and anchor would see the pressure load.

Am I over thinking this?
Are pump bodies and anchorage designed for pressure trust loads?

Thanks in advance.

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I thought the bellows was meant to isolate the two sides so that the pump didn't have to take longitudinal loads. In this case all the loads from the right hand side have to be taken by the supports; vertical, longitudinal, and lateral.
Do you have a senior engineer you can talk to?
 
Have you done a Seismic Analysis for piping before? If not, it could be the tough part.
 
Fully anchoring an expansion bellows on both ends as you show is sort of pointless. Might as well be solid pipe.

Your bellows manufacture almost certainly has an application guide. That's a good place to start.
 
The clients has provided the layout and now we have make it work. We would not do it this way from scratch.
Had had to convince a few engineers that bellows tie rods do transfer loads.
The design temperature is not high (<50C). Considering a pipe anchor close the pumps and no bellows and let the pump body flex take the thermal load.
 
I'm not following thi design or indeed what purpose the bellows are having.

AFAIK, in operation the tie rods should not "be engaged" or if they are the bellows is basically becoming solid pipe and any movement of the pipe up or down or moment gets transferred through to the pump nozzle.

Surely you fix the pump and allow the pipe to move within a set of sliding restraints fixed to the pipe within the limits of the bellows for axial and angular movement?

What do you mean by "pressure load"? The pump will always see thrust from pressure as pressure acts in all directions. The pump body is big and strong to resist this. It's NOZZLE load which they don't like.
 
Operating case needs the supports to flex or slide a little so the bellows tie rods become engaged
Don't worry about this, the bellows is shipped and installed at the 'tie rods engaged' length, so the bellows can be treated as a fixed length element. Either the tie rods are engaged and it is effectively axially rigid, or they aren't engaged and the nozzle is seeing the pressure thrust. The bellows is there to provide in plane flexibility, not axial flexibility.

The design temperature is not high (<50C). Considering a pipe anchor close the pumps and no bellows and let the pump body flex take the thermal load.
I would explore this option unless the in plane flexibility provided by the bellows is critical to have.
 

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