During my spring cleaning, I found that my existing chimney pipe (metalbestos SS - class A) was corroded (documented here: https://www.hearth.com/econtent/index.php/forums/viewthread/37916/). After speaking with a few folks, I decided to try and replace the top 18" of pipe myself. I bought a new section of pipe, and a new storm collar, and went up to the roof today to give it a shot. I removed the caulking and the old storm collar, but couldn't get the old pipe out. I was able to twist it... even 360 degrees, but I wasn't able to pull it up and out. After looking through the pipe with a flash light, it looks like the pipe is connected to another piece of pipe beneath/within the roof flashing... I'm guessing there's something "locking" those two pieces of pipe together. My question for anyone who works with chimney pipe routinely.... first, does this sound accurate? second, is there an easy way to seperate the pipe so I can take the old piece off WITHOUT taking apart the flashing? If not, how big of a job is it to take the flashing off, and put it back (obviously, i'm not a roofer)? Thanks all!