Tank Bottom designed for vacuum

[MrTank]

Aside from maintaining a liquid level and making the tank bottom plate thicker, what other methods have been used to resist bottom vacuum on a vertical tank designed to API 650?

-MrTank

ôI have not failed. I've just found 10,000 ways that won't work.ö
-Thomas A. Edison

 

[LittleInch]

Please explain "bottom vacuum"

API 650 tanks have a very low negative pressure capability. About 4 inches wc from memory.

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[JStephen]

In Annex V of the current edition, external pressures up to 1 psi are addressed, and you also develop uplift on the bottom from an external flood condition.
In any event, in Roark's Formulas For Stress and Strain, he includes several cases for circular plates with "large" deflections, which can be useful.