I really wanted to ask about this basic question. I am "reassembling" some pipe (some new pieces and some old) and figure the best way is to use the twistlock by itself, but perhaps add some Rutland direct vent sealant to the joints after assembly. This squeeze-tube sealant is flat black in color and latex based so I can get it apart for cleaning/ or other in the future. In the past, I assembled pellet pipe with clear silicone hi- heat caulk at the joints and it is a pain to take apart. Also, when I deal with one of Simpson Dura Vents adjustable pipes (usually I use 1 foot section), do you caulk this adjustable section in particular because it is prone to leaking? Also, do you screw fasten it to the twist sections, or do you prefer to let it "float" more for ease of dissassembly-sealing it with caulk later after the height is set. In one forum, someone suggested putting HVAC foil tape on the joints. I like that idea, but wonder if the tape holds up to that much more heat. Also, I have been painting the pipes black in color. If I knew about the tape idea, I would have left them galvanized. The paint actually does stick to the galvanized, I dont think it comes out that bad.