So the black steel fittings I installed outdoors on my gas line a few weeks ago are already starting to rust... not the pipe which has some glossy coating, just the elbows. Yes Packy told me to paint them ASAP and now I see why.

Do I need to disassemble and replace these fittings, then paint? Or can I use a wire brush on a drill and try to shine them up a bit then paint them?

Also, am I allowed to paint prior to inspection?

from the internet...

Can I paint over rust?
Once done, you can paint over rust. ... The first step is to clean off loose rust and flaking paint and then apply a rust-inhibitive primer. You don't need to get down to bare, shiny metal—just clean off the flakes and powdery surface rust that prevent paint from adhering.

as for inspection...
around here we can't pass inspection of outdoor gas pipe unless it is painted.

Around here, outdoor gas pipe has to be galvanized so it doesn't rust.

I understand that galvanized pipe for a gas line is not a good idea because the zinc can flake off and get stuck in the appliance using the gas.