When you do thermographic surveys, do you look for problems, or do you expect things to be OK? You can fix problems, but you can't fix what’s OK. Experts advise performing surveys under normal running conditions, because equipment that isn't running won't generate a very useful thermal signature (although some defects will still show up).
Problem: If you don't find defects under normal operating conditions, this doesn't mean they don't exist. Normal running conditions aren't the conditions under which the next failure is likely to happen.
Solution: Follow up with a stress mode survey. To the extent possible, run key equipment under maximum load, and repeat the thermographic survey. Look at the delta between the two surveys. Caution: Plan this out with operations first.