Roofing, Gutters and Waterproofing - Remove rust from furnace chimney flashing

The chimney fro my furnace has flashing up on the roof and it is began to rust. The rust is now running off and staining the shingles. Does anyone know how to remove the rust from the chimney/flashing. Where could I buy a new piece? It is not something that you could just pick up @ Home depot or something.

Wire brush or wire wheel on a drill..then paint with a galvanized coating type paint or a rust resistant paint.

You could also try a rust converter (available almost anywhere, Kleen-Strip and Navel Jelly are 2)..make sure its a converter not a remover. Then paint with a rust preventative paint.

Finally have it replaced with heavy gauge aluminum by a roofing or sheet metal company.

Naval jelly is a rust remover not a converter.there is a converter under the kleen-strip brand but that brand has other products so be sure it is the specific product.Rustoleum and permatex both have rust converters that are easily found at hardware stores and other retail.

If you choose to paint but not use a converter product prime first with a primer specifically for rusted metal then top coat with a quality oil based enamel.Rustoleum is the most well known brand for this however rustoleum is a brand for many many products so make sure you get the right one.

Ultimately replacement with aluminum is the best choice if possible.If you have steel flashing it's old and will continue to give you problems no matter what you do.Paint etc will just postpone the inevitable.