Since the beam & support poles are out in the open in my shop I painted them. I first sanded/wire brushed them to remove the rust followed by wiping them down with thinner to remove the dust. Primed them with Rust-Oleum rusty metal primer then top coated with semi-gloss Rust-Oleum. It's been about 15 years since I did this & I have absolutely no peeling or flaking.

-Dave

thanks dave

There are numerous brands of 'rust conversion' coatings available.

They turn tight surface rust into a black stable base for paint.

Instead of trying to clean the surface rust to bare metal, you remove any loose rust, then just paint the conversion coating on.

Once it dries, apply paint.

Oh, I didn't get down to clean bare metal everywhere. There was some light surface rust left, hence my choice in primer.

If the relative humidity in the basement is kept at 50% or less ( I do not recommend anything less than 50%), rusting will be extremely slow. Most any paint will be adequate. But the conversion coating will be the deluxe solution.