Several factors must be considered to determine inspection intervals for storage tanks. These include, but are
not limited to, the following:
a) the nature of the product stored;
b) the results of visual maintenance checks;
c) corrosion allowances and corrosion rates;
d) corrosion prevention systems;
e) conditions at previous inspections;
f) the methods and materials of construction and repair;
g) the location of tanks, such as those in isolated or high risk areas;
h) the potential risk of air or water pollution;
i) leak detection systems;
j) change in operating mode (e.g. frequency of fill cycling, frequent grounding of floating roof support legs);
k) jurisdictional requirements;
l) changes in service (including changes in water bottoms);
m)the existence of a double bottom or a release prevention barrier.