| Applies To | |||
| Product(s): | AutoPIPE, | ||
| Version(s): | All | ||
| Area: | Modeling | ||
| Original Author: | Bentley Technical Support Group |
Dec 2014, AutoPIPE V8i 09.06.01.10
Problem:
How to model a nozzle that is rotating due to hydrostatic bulging at the base of a large storage tank that is not on the global axis?
Large storage tanks start to bulge at the base as the liquid level rises, see exaggerated image below:
Sometimes these bulges occur at the same level as a nozzle connections to the tank. The image on the left show a nozzle that is horizontal when the tank liquid level is low. However as the liquid level increase the base of the tank begins to bulge cause the nozzle to rotate, image on the right.
How do I model this without doing a lot of hand calculation for values to be used as input?
Solution:
In a new model, insert piping layout as needed. The location where the nozzle connects to the tank should be modeled as an anchor point. Account for the nozzle rotation by applying either a. Thermal anchor movement, or b. Imposed support displacements. The advantage of using support imposed support displacement over thermal anchor movements, is that imposed support displacement can be assigned to most load cases, ex. U1, Gr, etc.. where Thermal anchor movement can only be assigned to the given Thermal case.
With regards to the original problem description above, modeling off global axis. For situations like this, one solution
a. Model the Tank nozzle connection with a little of the system piping on a global axis.
b. Insert / open the Anchor dialog and enter both the correct displacement and rotational values for the nozzle due to the bulging vessel, example:
c. Select the nozzle anchor and local piping currently on the global axis, using the Rotate command, rotate the piping to the correct orientation as needed (ex. rotate about the vertical axis -22.5 Deg..)
d. Use the results from this report or open the rotated anchor dialog to see the updated values:
e. Finish this modeling approach by continuing to model the piping system or connect the exiting piping system to the newly rotated pipe.
Done..