Popped some dents today. Pipe was pretty well stuffed in one spot, couple of other minor imperfections around the rest of the pipe. Bought a 7/8" and 1 7/8" expansion plug and a long valve stem. Shaved 5mm off the smaller plug and installed the valve stem. Since the plugs were too small I wrapped them with electrical tape, then proceeded to launch them across the garage. Nice dent in the door, no one was hurt. Bodged together a safety wire contraption for the small plug, then went to work. Popped the big plug. Called it a day. Decided that I wasn't going to let a simple inanimate pipe get the better of me, so I made a couple of mechanical brackets to hold the plugs in place, then went to town.
First step was to heat the area to red hot, then inflate pipe to 60 psi. The dent doesn't "pop" so much as "expand" to its original shape, mostly. Worked on some smaller dents, then attacked the large one. I snapped the first pic after realizing "hey, this might work!" Also, I wanted a little legacy (and evidence), you know, just in case. "So, Ma'am, you say he was using a torch to smoke out of a large pipe?"
Anyway, the big dent started to unfold, so I snapped a quick pic. This is about halfway "fixed," still pretty deep.