In the case of storage tanks (like an oil AST), the H/D ratio is important if you have seismic considerations.
For steel tanks there is a rule of thumb table that is mentioned by Myers on his "Aboveground Storage Tanks" that is good for Seismic Zone 4 (and other assumptions) depending on the diameter. (This criteria is intended to follow API 650 seismic considerations)
Other criteria are less conservative (some would use HD to 0.75), or tries optimize the quantity of sheet needed to the build the tank in an economic way (the less area for a needed volume) and the less number of welds, etc. Hope this helps in your case.