Jeff Liebermann wrote in
:

Much is not in the text
books, such as some types of stainless steel are galvanically
incompatible with themselves.

Fortunately Bristol is far enough away from the coast for me not to have to
worry much. I did read a bit about galvanic corrosion though, and my
methods basically make sure that when almunium meets 304L stainless, there is
enough of it to withstand it with no significant loss for a very long time. I
use 316 in smaller peices for critical parts, but it seems ok with 304 in a
city envirnment. If anything, I expect the 304 to do the corroding, and
that's the bulk of it so no harm results overall.

Simple principles, such as NEVER design
in a horizontal surface, which will puddle water, are only learned
after a problem appears. Some of these lessons border on heresy, such
as hermetically sealed enclosures never really stay sealed (unless
welded shut).

I also avoid horizontal (or at least significantly flat) surfaces. About
seals, I agree there. Changes of pressure due to heat will always win if
there is any way through at all, it could be smaller than a hypodermic bore,
or a bit of microporosity (a bane of thick acetal sheet plastic), and fatigue
in the material will make this worse rapidly. I read somewhere that a small
cylindrical bore with enough length to hold all the possible expanded gas
with an inch or more to spare, then filling that bore with grease, might be
better than trying for a 'perfect seal'. I suspect it would be weatherproof
too, though there may well be things that would try to eat it, or clear it
out while trying to make a home.