Longer term answer for Rust in fridge burner

In 42 years as an RV tech, I only had to remove the orifice for cleaning less than 10 times in thousands of refers I worked on. I use compressed air to blow out the burner and flue. It is EXTREMELY hard for any debris to get inside the orifice hole from the outside. Doug

On my older rig I just vacuum or blow the burner clean a couple times a year without having to remove anything more than a small cover.

I HAVE NO IDEA IF THIS WOULD WORK! I'm just throwing it out there as something that occurred to me as I was reading this post.

What about ceramic coating like they do with automotive headers? Get a new chimney so it would be clean and full thickness (not rusted away) and get it coated.

Electric fridge = no more rust..

I do not know of any way to stop the chimney on propane fridges from rusting. The heat burns off the paint exposing the steel tubing to moisture in the air which creates iron oxide (IE rust).

I do not know if it is advisable to paint with a high temp paint as the paint can possibly interfere with heat transfer that is required making your fridge less efficient.

If one was to attempt to paint with a high temp paint, one needs to treat the rust, typically one would use a rust converter like Ospho which turns the rust into a black paintable surface.. However, I have never tried this on any high temperature surface like what is found on your fridge coils.