on the roof of large storage
tanks is so common that the inspection
standard requires the roof be inspected for structural soundness and falling rafters before the tank can be entered. There have been statements made that condensation
in a diesel
tank is not possible, but the OP's question, industry standards, and the experience of EVERY API and UL tank inspector all support that condensation is common and serious. The "empty tank" test is not valid for a number of physical/chemical reasons.
(I am a licensed API tank inspector and have been in thousands of tanks).
The only way to prevent it is a silica gel filter (H2Out). These have been used in the refining industry for many, many decades. They work