Are we talking about pure aluminium or aluminium alloy? Remember that the entire fuselage is made of aluminium alloy
Yes mate, but the wall/frame of the AC might heat and cool a lot, and the only thing retarding its movement is the air around it.
The thermal conductivity of Al is about 120k (Btu per fDegree per square foot). For brass this figure is about 67k.
Thus the Al will cool quicker, and will shrink faster ( Al COE=24 as against Brass COE=19 ) around the regulator. Looking at the interface between the two there has to be considerable action/reaction at the joint. Think about how a soft little toadstool can push up through a bitumen road surface.
Now if the Al alloy used is purposely designed to contain a gas, then it could be quite different from one that only needs to behave well with a brass regulator. And I would expect the bottle alloy composition would be far removed from that used in an AC skin.
Boy, would I ever love to get the adjacent bottle and test cycle it -50C to +50C under pressure for another 1000 cycles. Thant said, I would LOVE for it to hold up and disprove my theory.