My dad has an older CB...don't know the model, the biggest one they had short of going to a commercial unit. They have replaced the door on it several times over the years, I think the first time or two was under warranty...my brother said the last time (recent) it is now a steel door...he said they are having problems with the damper sticking closed now, which never happened before...said it is getting "creosoted shut"
I welded some shaker grates on my old Yukon wood/coal/oil furnace using 7018 rod back in 2012...preheated, then used a infrared thermometer to check temp since I wanted to let it cool very slowly, heat provided by oxy/acetylene torch for the cool down period...held up fine, still in one piece when I sold it recently...