If you are lucky the nut will turn, and the whole bolt will not turn. Oh YA! you may want to use rubber gloves. (remember all those times you missed) That's why the bolts may not turn. So don't Get Pissed off. (pardon the pun) if the nut will not come off the bolt, just get a 1/4" or a 3/8" drill bit and drill right through the center of the top of the bolt that is in the tank. The bolt will just drop out.