The industrial gas industry produces the elemental components of “air” (nitrogen, oxygen, and argon) that are used in other industries as part of their processes. Once separated from air, each element exists as an extremely cold cryogenic temperature liquid. Typical liquid temperatures are −185° C. Large, field-erected tanks are used to store these liquids, and these tanks range from 100,000 gallons to over 2,000,000 gallons in size. API-620/Appendix Q standards, or their equivalent, are the routine guiding design documents. These tanks are built as flat-bottom, domed-top tanks, typically with stainless steel inner containers, carbon-steel outer containers, and the top/side insulation space between these tanks filled with three to five feet (radial dimension) of granular perlite insulation. The inner tank sits on a sandwich structure of Foamglas® insulation and concrete. During cooldown and commissioning, these tanks need to be dried, inerted, and brought down to very cold temperatures to allow product to be introduced. If done incorrectly during cooldown, these tanks risk vacuum collapse. This article discusses the details surrounding one such occurrence.