Pool Equipment room Panel

[arnettda]

I have a 3 phase sub panel in a Hotel pool equipment room. They replaced a air handler with a furnace in one portion of it and it went from208 to 120 volt. I was not able to get a single screw loose in the neutral bar so I put a cord on it and have it plugged into a general purpose outlet for now.
I believe the best option would be to replace the complete panel and all of its breakers. If the neutral Lugs are all rusted I would have to believe the bolt in breakers are rusted as well. The internal workings of the breakers have to be compromised in some way as well?
My question is do I put in another indoor rated 3 phase panel and let it corrode and have someone replace it again in 21 years. I believe the building was built in 2000.
Or is there other options, I do not see a good option of trying to relocate it.
The current maintenance person does a pretty good job of keeping the room room a lot dryer and the smell of the pool chemicals is not as bad as it has been in the past. As far as working clearance's go they are all good except when someone puts something i front of it.
Thank you

 

[dpcarls1598]

Where I work we have 2 pools. I‘ve gone the NEMA 3 route for other equipment but not the panels. I‘ve found that nothing I try prevents the corrosion. Since then, we have updated both pools from chlorine and acid to UV light systems. At the same time I replaced all panels and have yet to see any corrosion and the chlorine odor is totally gone too.
Back to your question, from what I figure, the chlorine and acid vapors will penetrate any enclosure. I have some building automation controls that are I a sealed non-metallic enclosure rated 4x and it still corroded to the point that it needed to be replaced about every 4-5 years before the UV. The vapors seem to penetrate via conduits, etc.