I am working on a cooling water pump with a 14" diameter suction nozzle that has a 16" flanged rubber expansion joint (after a eccentric reducer 16"x14"). The vendor give me:

Lateral displacement
rotation
axial displament
lenght of EJ.

I found for other catalogue but all give the same input.
Nothing about stiffness.
I'm finding a model to introduce the EJ with this input.
I was finding a way to convert this input in a equivalent (I'm not sure if it is possible)
I saw the caesar application guide and also I searched in this forum but I couldn't find a way. I try to model using a axial metallic EJ with the same axial displacment but I'm not sure about that
I model the pump nozzle like an anchor.
Also the pump's vendor give me the allowable load.

Any idea?

- You could ask the Vendor for the stiffness data,
- A rubber expansion joint will be VERY weak compared to steel piping and pumps casings
- It is OK to model the pump nozzle as an anchor
- With a rubber expansion joint and reasonable, controlled amounts of displacement put into it, I usually would not even bother caculating nozzle loads, they will automatically be low (especially for cooling water, low temperatures)
- If you really need to calculate loads, I would just assume a low stiffness for the expansion joint such as a couple of hundred pounds per inch.

Hi sghinaus

* i too encountered rubber expansion joint Connected to Cooling water pumps
with 24" suction & discharge

rubber expansion joint absorbs vibration or thermal movment.

i am wondering if you have read a FSA hand book Code based on Non metalic expansion joint and flexible pipe connectors ?

their hand books includes stiffness for rubber joint with axial stiffnes, bending stiffness , transfer stiffness ,and etc
but you must be aware of Assumption .

i would sugget that you make reference to FLUID SEALING ASSOCIATION of
Non metalic expansion joint division

good luck

http://infostore.saiglobal.com/store/Details.aspx?productID=1399378

Thank you, I put an axial stiffnes 30 N/mm (171 lb/in) from the vendor
but anyway there is a little chanche if a get an higher value.

The line is composed of a main line of 20" long 18 m (60 ft) near the plant limit and it is impossibile to change the position.
Perpendicular to it (in plane) there are the 3 suction nozzle of the pumps.
temp 50° and pressure 4 bar

I have had a very high axial load so I have thought was the results of friction and internal pressure (4 bar,60 psi) because EXP was very low.
I have tried to lengthen the suction line and all loads on nozzle (modeled as an anchor) have gone down expect sustained case and hydro test where I have had an axial load a few over the allowable.
The vertical load is very small so i thought there wasn't the results of friction but the results of pressure.
And more or less the load remains the same if I legthen more the line.
The question is: what does it mean? In the reality I don't have an axial restrain and therefore a reaction for the effect of internal pressure because there is fluid (in the reality) on the other side of the anchor.
I think there is a thrust on the internal part of pumps rather than the nozzle.
SO, i can neglect axial load in this case?

no, you can't

Read:

http://65.57.255.42/ubbthreads/ubbthreads.php?ubb=showflat&Number=34028

Regards,