Analysis of piping connected to Tanks

I need clarifications on some aspect related to stress analysis of tank piping.

Refer image below, considering settlement of tank during operation, which is the correct node (40 or 61) where displacement for tank settlement should be entered?

You can simply model the both, and compare the result.
I'd input settlement displacement at Node 60.

If this is a large diameter, nearly atmospheric, vessel, you shouldn't even model nodes 50, 60, or 61, but instead use the "nozzle flex" calculations.

Pressure vessel modeling techniques are invalid for thin-walled vessels.

You also need to ensure that your piping is sufficiently flexible to allow the tank to move the pipe, and not the other way around.

Your tank settlement needs to be factored into the displacements calculated in the nozzle flex, and you should also pay special attention to whether settlement occurs every time the tank fills or if it's a one-time operation.

If this is a large diameter storage tank (od> 120 ft) you may wish to also include nozzle deflection and rotation due to tank bulging. These displacements will be additional to the tank settlement and vary with the liquid fill level.
For instance, a nozzle that is installed (about 30" above the tank bottom) on a 200 ft tank filled up to 40' and operating at 140, can expand axially about 1" and rotate downward about 0.5 degree.
For more detail, refer to API 650, Appx P.
For the large tanks, I don't model the tank, instead I define the displacements at the vessel node(40) that are cnoded to the nozzle node(30). Finally make sure that the load cases are correctly defined and they include proper displacements.

If you end you model at node 30 (ignoring 40-60) and specify API650 nozzle flexibilities, CAESAR II will also provide the API 650 full-tank bulge deflection and rotation, if you wish to use them.

Dave Diehl,

We a still using CII 2014 7.00.01.1600 (build 141003) due to project code of Record agreements.

The API 650 nozzle option does not appear to be applying the "full-tank bulge deflection and rotation" automatically into the CII model. The last time I used this option was about 10 years ago and I recall the bulging displacements and API 650 flex. were automatically used at the nozzle.

Was there a glitch in this version or do you always have to manually input these displacements?

I specified D9 as the displacement vector and added D9 to the load cases; tried many iterations with and without some parts of the tank and with and without the D9 BUT the tank rotation does not automatically get input into the system. I exaggerated the tank data to easily spot the large rotation but NO MAS.

Is there a special trick to get this to work?

Bob,

I'm looking into it. At the moment, I will ask that you continue with your work-around and explicitly specify the displacements reported in the error checker.

One note, to properly include tank bulge and growth (those reported displacements) for an API650 nozzle you cannot continue beyond the nozzle node. Remove the element 1011-1015.

More later...

Bob,

I defined an API650 nozzle in CII 2014 7.00.03.0100 (Build 150704) and the displacement set was properly loaded.

Hi Dave,

You have suggested to remove the node 1011-1015 in Bob's file. But in that case how we can count in the vertical thermal growth at nozzle junction?
Can please clarify?

I wouldn't expect much vertical thermal growth at a low tank nozzle at near-ambient temperature. But if you wish to include it, you can replace the zero defined as dy in the displacement with your calculated strain.

Is this problem resolved?
I'm using Caesar 2018 Version and still facing the same issue of tank radial growth and buldge rotation not appearing in the output.
I tried using D1 thru D9 and tweeked other parameters but nothing seems to work