We have the same black single wall stove pipe inside the house since 1990, about 7' of it. When I clean it I see surface rust on the inside of it but just use the wire brush on it, it gets some surface rust on the elbow and the small piece right above it, but I steel wool it off and apply paste stove polish to it, stick small cut pieces of gasket in the "gaps" that it has from factory where the pieces join, and just let it rip. But I am wondering, when should this be replaced? Obviously if there were any holes in it and it was leaking smoke then of course, but what kind of lifespan does this have? I never really thought about it much, but like I said it's 33 years old, should I replace it or just use it and keep an eye out for issues?
Thank you
Thank you