For storage tanks there are two types of surfaces, internal and external surfaces
For the external surface outline specifications can be found by using ISO 12944 and JGC has developed a selector for storage tanks external surfaces as well . It is identical to the bridge selector and it can be found by pressing here.
For the internal surfaces it all depend on which products are stored in the tank. The paint suppliers has carried out extensive studies and research, to determine which coatings are resistant to the various chemical products. It is highly advisable to consult the paint suppliers about coatings for the internal surfaces.
There are other special surfaces on some storage tanks. The so-called safety pits, which are basically a double hull construction. In the safety pits it is not necessary to apply topcoats and dry film thickness can be reduced.
Crude oil tanks are normally not coated internally because the crude oil is not corrosive.However, the flat bottom and about a meter up is normally coated to avoid corrosion damage from the reaction between sulfur components in the crude oil and condensing water to form sulfuric acid. Furthermore the underside of floating roofs are also not coated since it is floating on the crude oil.