A fuel tank on a barge has been certified by a marine chemist as being "Safe for Men" and "Safe for fire." This condition may change if___________.

Correct Answer: Option D — all of the above

A Marine Chemist's certificate is valid only under the conditions present at the time of testing. Changes in ambient temperature can release trapped vapors from sludge, and leaks from adjacent tanks can re-introduce hazards. Continuous monitoring is required to maintain safety in any space previously containing hazardous cargo.