Hello Richard,

After checking the thread, for me wasn't clear if the vertical displacement of the tank was considered or not by API 650 module.

I did some trial and error runs and did find out that during error check CAESAR only calculate the radial deflection and the longitudinal rotation and saw that after first Error Check, the input vector D1 reflect that writing dy=0.0 mm(vertical displ).

Also compare both methods:
1. Rigids to model the tank with Cnode at nozzle, inputting the displacement vector manually, D1 for deflections at the nozzle(radial deflection and rotation from API650 but vertical displacement "dy" blank to consider tank vertical expansion due to the expansion from the rigid that simulates the center of the tank) and D9 for settlement at the center of the tank.

2. Using API-650 and at the bottom of the input dialog in "drop list" selecting "D1" for the displacements in the input (at the specified node), but there is no vertical displacement calculated by CAESAR. And also input D9 for settlement at the nozzle node.

Why CEASAR discard the vertical expansion of the tank??
Which model you consider more accurate??

Thanks,