Liquid-applied linings or coatings may be troweled on or spray applied. In

a lined tank there are usually four areas of contact with the stored material.

Each area has the potential of developing a different form of corrosive attack.

These areas are the bottom of the tank (where moisture and other contami-

nants of greater density may settle), the liquid phase (the area constantly

immersed), the interphase (the area where liquid phase meets the vapor

phase), and the vapor phase (the area above the liquid). Each of these areas

can be more severely attacked than the rest at one time or another. The type

of material contained, the nature of impurities that may be present, and the

amount of water and oxygen present are all factors affecting the attack.

In view of this, it is necessary to understand the corrosion resistance of the

lining material under each condition and not only the immersed condition.