Rust Removel, old steel stairway

I'm working with a non-profit (little money) group the rust and repaint a 1.5 story steel stairway on their building. Hasn't been painted in ant least 30 years. We need to strip the rust before painting.
Our first thought was to sandblast it, but it turns out that none of the rental places rent sandblasters any more due to regulations requiring self contained breathing apparatus to sandblast. So, we're down to either hiring a commercial firm to come blast it (expensive and they're short on money) or trying something else. We could buy a sandblaster, but no one has a compressor with enough CFM to drive it hard, so we'd probably have lame results.
We can wire wheel the large supports, but the treads themselves are a grid like pattern of steel with too little space between the steel grid to even fit in a wire brush, let alone a grinder & wire wheel.
We've tossed around the idea of using a pressure washer. Opinions vary on whether or not a pressure washer would remove the rust, scale, and loose paint to a level where we could paint it or perhaps use some of that "extend" type sealant on it to convert the surface rust before painting.
Comments? Ideas?
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I rented a pressure washer once that mixed sand in with the pressureized water. You might ask the rental places about whether that would work.
Bob
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the compressor. Use ordinary sandbox sand, aka 'play sand', for the grit. I assume this is an outside stairway? If most of the old paint has already vanished, additional lead contamination should be minimal, but you probably want to spread tarps anyway. In a non-enclosed space, SCBA is probably overkill, but dust masks and bunny suits (or at least overalls) are definitely needed. (It is filthy work.) Rental place probably is confusing SCBA with a 'supplied air' system. Wearing an air bottle is tiring and expensive- dragging a hose linked to an air handler running upwind of work area is much less so.
Don't leave the metal bare, even overnight- the dew will restart the rust before you can paint. Do an area, use the compressor to blow all the grit and rust flakes away, and brush on some sort of anti-rust primer paint, like Rustoleum or tractor paint. Short of truck-mounted industrial-grade equipment, it'll take several days. Allow each painted spot to dry before starting to sandblast near there again.
I doubt a pressure washer will do much of anything, other than remove loose flakes and surface particles. It will also force water into any cracks and crevices, which will take days to dry out. If you paint over trapped water, it will cause the paint to bubble.
BTW, if this thing is a fire escape, their insurance company and possibly the local building inspector/fire department inspector will likely need to see it, before and after you work on it. Definitely want to call and ask. They may have no choice but to have a 'licensed professional' do the work. And if the rust has made any key parts of the metal too thin, those will have to be replaced or repaired.
aem sends....
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wrote:

Thanks... sounds like the route we may have to take.
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If the rust isn't too thick, you could try Naval Jelly.
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