Excellent question! Thanks for raising it. Typically folks only keep the problems AND baseline data on large equipment like OCB or transformers. But storage space is now pretty cheap and you may want to consider keeping 3-4 rounds of inspections until you are confident in your results and in the trends you are seeing (or not!).
Categorize them by equipment type, area or route, whatever works best for you when you want to retrieve them. Certainly there is value to permanently saving images of problems as they can be valuable in the future for reference images of similar equipment.
And, of course, you always want to get back to verify or qualify the repairs that are made as they all too often are not made properly the first time, even by the best maintenance teams!
Ease into it and don't make this task a full time job! I want you to stay out in the field doing good work. Would also love to see some of what you found. I've attached a good one of two OCB bushings we found a couple years ago. Thanks again for a great question.
Thermally Yours,
John
ASNT NDT Level III #48166
The Snell Group
www.thesnellgroup.com
www.thermalsolutions.org
800-636-9820