hkusq9- during meal breaks myself and others used to use 125psi to shoot 3/8" x 8" long pieces of steel through 1/2" birch and pine plywood from about 15' away. Volume of contained pressure and how it is released plays a role in the destruction and as others have mentioned it is dangerous to do what you did. Ask your ram providing superior officer what happens if you lose a thumb or an eye, at home, playing with chainsaw parts.
Next time dry the tank out completely, wash it out with soapy water at least 4 times, dry it out again completely and apply even low heat, then tap it apart with a wooden mallet and peg. It will take longer, but it is a safe and in terms of the parts being worked on it is a more controlled seperation. Do all of this in a well ventalated area using appropiate precautions.
Using pressure to break an epoxied seam is risky as the epoxy only needs to be slightly stronger than any other part being pressurized to produce a crack. The crack may not even show it's self until the part is reassembled and put back into use, vibrations make a tiny problem bigger.
In the grand scheme of things I would suggest that you treat rebuilding a chainsaw with the same reverance as rebuilding a firearm. The devil is in the details. If you do not know, ask, and wait for an answer. That flywheel you beat on with such abandon is spinning really really really fast, at CROTCH level. That tank you want to JBWeld is holding gas at CROTCH level, in front of a device that creates sparks and another that catches them.