All good information and suggestions noted above...
I would like to add the fire protection considerations.
In the USA, we use the NFPA-30 code for installations where flamable liquid is stored. NFPA-30 only allowas certain design code. (namely API-650,620, ASME-VIII and others....)
If your stored liquid is flammable, the fire protectiuon code governing the installation location may govern the design.
Just a thought.....
regards,
MJC