How to Fix the Damage (Defect) of Oil Transformer Fin (No Leakage)

With the small amount of bending at that fin, it probably doesn't affect oil flow enough to show much of a measurable difference. Even if there were a little less cooling in that fin, sinc the oil flow is by convection the other fins would probably make up the difference. Unless the transformer is heavily loaded, you could walk up and touch the fins and not notice much of a temp difference from ambient.

As SolarEagle says, trying to correct the bend will probably fatigue the metal more at the bend and cause it to crack, or crush the tubes so that oil flow reduces even more. I would just leave it alone if it doesn't leak, and check regularly for future leaking.

Do nothing.

I would agree - do nothing to the transformer. You may want to consider some physical protection to prevent this happening again though?

If you try to straighten it, the odds are very good that you'll break it.

Do nothing.

I have to ask.

Is this cooler in service, or new? In other words, do you intend to sell it or use it?

I too suggest not to do anything, as long as there is no leakage. Then check for any temperature rise and condition monitoring.

Well there you have it. Leave it alone. Let sleeping dogs lie. If it aint broke, don't fix it. If people have issues with the fin, explain to them that small blemishes like this add great character and improves it's resale value.

Check for loose paint and clean off. Apply a new coat of paint anyway just to be sure. Do not bend it anymore.

I agree with the others, do nothing as trying to correct this minor defect has a high probability of creating a stress fracture & giving you a headache trying to stop it from leaking when it cracks.

The old saying is if it isn't broke don't fix it. Even if it doesn't leak straight away there is always a chance that a fracture will develop in the future because of expansion & contraction due to heating & cooling & possibly any vibration from the transformer while under load.

By the pictures it doesn't look like it will have any noticeable restriction in the flow, the view from under the fin may show a different story but we cannot see that