“Matt started notching the flues and tubes and cut a couple at the fire box end in preparation for being driven out.  You notch the smoke box end to relieve the compression fit. This end is rolled which seals the tubes with a mechanical fit. The fire box ends are rolled and welded. So you cut the fire box end off just inside the tube sheet so you can get a tool on them to drive them loose. After that, you drag them out armstrong method. When this is done, you grind off the welds on the stubs in the firebox and knock them out with a hammer. We have to remove all the tubes which are around the edge right next to the boiler shell,  but  will not be removing all the flues which sit farther in. We will remove just enough to allow someone to crawl around inside the boiler for a visual inspection.” – Charles Harrison.