If you don't read this long topic, I understand, but I wanted to set the stage so whoever could help has enough information.

Here is my scenario:
A 16000 gallon (~61 m^3) process tank is supported near its bottom head on steel legs. Above this tank, an 8000 gallon (~30 m^3) tank is supported with steel legs as well near its center. A 12 inch, schedule 10 line runs between the two tanks, in a fairly short run of around eleven feet of pipe from the top head of the lower tank to the bottom head of the upper tank. The process is around 77 degrees C (~171 degrees F).

My question: I have modeled the pipe in CAESAR and applied two different anchoring styles: 1)Displacements using hand calculations and 2)Modeling both tanks from the support elevation to the nozzle elevation as rigids with an anchored node where the supports would be. This gives me displacements from CAESAR. The output results are very close to the same, which I assumed they would be. The pipe is not overstressing; it can handle the thermal growth of both vessels, however the nozzles and Stroman Valve within the line have very high loads. The process lead asked me to check whether slide plates on the lower tank would relieve some stress and loads on the pipe, as he doesn't want to use spring supports because both tanks have agitation equipment. This is my question. Instead of putting anchor supports on the lower rigid, I placed a +y support, X restraints with a 2" gap and a coefficient of friction (Mu) of .1, Z restraints with a 2" gap and Mu value of .1, and rotation restraints. When I change the Mu value, the stresses in the pipe do not change, which makes me believe I am not modeling the system correctly. My lower tank has a rigid weight of 120,000 pounds. Any help on this situation will be appreciated.

Thanks,
Devin

EDIT: I did search and read all posts found when "slide plate" was queried as well as other keywords.

Send your model to techsupport@coade.com and I will have a look.

This response is for anyone searching the site for this particular question...

I had friction coefficients for all horizontal restraints, as that is the way the friction force will act. I did not have any coefficient of friction for the vertical direction. Turns out this vertical direction is the key direction to apply the friction coefficient, as CAESAR then uses this to limit the horizontal movements. Pretty simple, just me not knowing how the program works exactly. Thanks Loren for the help.

Hi Devin
I am not sure whether I got your question correctly or not ?
In my understanding your situation is like that
1) Big Tank (16000 gallon capacity) supported from ground external structure.
2) Small tank ( 8000 gallon capacity) placed over big tank with relative anchor supported from big tank.
3) 12” schedule 10 piping connection between top & bottom tank.


If my above assumption is true, Now

a) By hand calculation you are putting Dx, Dy & Dz value at piping connection interface .At the same time you have to put Rx, Ry & Rz zero value. Can not leave rotation field blank. Then I think Caesar rigid equipment modelling & manual displacement modelling result will be very close in terms of stress & nozzle load.

b) If you change any thing for big tank support there will not be change in piping portion . Because relative nozzle interface remain the same.

c) If you can make any change in top tank support then your load & stress value will come down. Because in this case relative piping interface become more flexible than before.