You can probably solder the tube after washing it with acetone a few time and letting the vapors dissipate.  Soldering iron, not torch.  Use flux to clean and some steel wool before your acetone washes. The flux and solder will wick into the crack.  Just don't feed it too much solder...capillary action of the solder will wick it into the crack.  Getting entire tube hot will be challenge most likely.  60w or 100w iron will do the job...