I do know that if your talking about the acetylene bottles(Deep red colour)that they have to be treated as unexploded bombs if damaged.I believe this is to do with the make up of the bottle.It has a "honeycomb" type interior and that the acetylene is disolved in acetone.If the bottle becomes damaged the honeycomb comes away from the shell and in turn leaves a gap for the acetylene/acetone mix to settle in.Not sure how the honeycomb keeps the parts mixed but if the parts separate,which they do in an open space,the acetylene will explode,not sure why this is either but I believe it becomes unstable at approx 1bar pressure(A normal Acetylene bottle is in the region of 200bar)