Rust Remoal From Plumbing Pipe

I'm curious why the rust on the outside of the pipe is an issue. Would it work to paint it? There are different colored tapes similar to the duct tape most are familiar with. Could you slit a piece of plastic tubing or hose lenthwise then put it over the pipe?

Maybe something like this would cover the rusty pipe.

Phosphoric acid, but it would be messy. That's the primary ingredient in products like Naval Jelly, but they provide the gel form. It still would be messy since you have to hose it off. Phosphoric has the advantage of reacting with rust but not the sound metal. I've used it to clean the inside of rusty motorcycle tanks, or for items I could put into a container but I don't have a good idea on how to use it on rusty pipes in place.

If it's for cosmetic reasons, Rust-Oleum Rust Reformer sprays on and turns black. It's meant to be painted over but if you like black...

If this is a water pipe size, they have those gray foam insulation tubes at HD. If gray isn't acceptable, could get a can of spray paint for plastic and paint it first. Or just wire brush it and paint it.

Should have added, if painting the pipe, put on rustoleum primer for rusty metal first.

The first choice is unworkable because of the location of the pipe.

I know of Rust-Oleum. That might be the choice. Color doesn't matter since the pipe is in the basement rafters.

You're the 2nd one to recommend Rust-Oleum. I guess I'll try that.

I had some olympic size weight plates stored in a shed and found they rusted fast. I tried WD-40 hoping for some protection but it was worthless. I did a little wire brush, then used Rustoleum spray rusty metal primer and Rustoleum gloss spray paint. They look great and are no longer rusting. In your application you'd probably want to go with flat rather than gloss.