Liquid Weight Calculations for Vertical Vessels on Legs, Lugs, or Rings

This is a conservative simplification that is only done for leg/lug/ring supported vessels. Any liquid depth automatically floods the bottom head for the operating cases. Because of this, you will see a sudden jump in weight and that weight will not adjust until the liquid elevation passes the bottom head to shell seam. At that point, the software will use the simple cylinder geometry to add only the liquid that actually exists in the cylinder. As the liquid elevation increases in the cylinder, you will see a linear increase in weight until gets above the top head/shell seam. At this point the top head will assume to be flooded as well.

Note the extra weight is typically more conservative. An exception would be a tensile stress in a wind case; but the empty condition with wind would likely govern that anyway.