Dec 2014, AutoPIPE V8i 09.06.01.10
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?
Create your piping layout as needed with the piping connected to the nozzle is not on the global axis and that the nozzle connection is modeled as an anchor point, apply the movements as Thermal Anchor movement Dx, Dy, Dz, Rx, Ry, & Rz.
To make life easier, copy the nozzle connection and a small section of the connected piping to a different part of the model and paste as a new segment. Now rotate the nozzle and piping so it is align with one of the global Axis (remember this rotated value XX=22.5 deg). Open the Anchor dialog and enter the correct displacement and rotational values for the nozzle due to the bulging vessel, example:
Select this copied segment and rotate it back to the correct orientation at the start of this procedure (i.e. XX=-22.5), AutoPIPE V8i 09.06.00.19 and higher has a new rotate command that prints out a report of the rotated objects.
Use the results from this report or open the rotated anchor dialog to see the updated values:
Transfer these values back to the original nozzle for the correct global coordinates on an off axis location. Final step, delete the extra segment and anchor before running an analysis.
Modeling Vessel / Nozzles