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Frank, You're making the case for aluminum I think, at least
for my application. As far as coming in contact with cement that will not
be an issue since it will only be coming in contact with epoxy coated
cement. I'm looking at having numerous brackets, like "L" brackets, so the
easy thing for me would be to get some aluminum angle stock and cut it up and
drill it. Seems like a lot more issues if I tried to do that with
stainless. Stainless is impossible to
drill!
I will need a "T" shaped bracket as well, if I can't find
something like that's all ready made in aluminum I may have to have it
fabricated. All of the aluminum I have seen on boats is amazing
looking. I have a friend who had a whole entire boat which was
aluminum, it seemed impervious to the elements. He ran a dive charter out
of the Channel Islands Harbor. The entire hull was aluminum, maybe
it is a special grade?
Brian
It’s
my understanding that Stainless Steel after machining needs to be passivated.
This process removes any free iron on the surface and replaces it with
chromium or nickel oxide.
The
process consists of soaking in an acid bath of primarily nitric acid with some
chromic acid. I have used this on a number of objects used in the sea with
positive results.
Jim
what acid did you use in an your passivation process??
Ken
Martindale
From:
owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of
ShellyDalg@aol.com
Sent: Friday, May 07, 2010 4:08
PM
To: personal_submersibles@psubs.org
Subject: Re:
[PSUBS-MAILIST] stainless vs aluminum
In a
message dated 5/7/2010 6:45:34 A.M. Pacific Daylight Time,
jimrudholm@gmail.com writes:
The
first overnight outside and they had a thin rust film. The cure
was to
soak the parts in acid to remove embedded iron from steel tools
including
drills.
This
brings up a good point. When working with stainless, pieces get embedded from
tools. This is evident when using a wire wheel.......gotta use a stainless
wire wheel. It'll get crusty real quick. Heat control and restoring a "worked
part" back to clean solid SS is the only way to minimize corrosion. For small
parts like brackets it's best to use 316L-SS so the cost is kept low. Larger
pieces in 304 are OK but you must watch the seams, welds, and breaks ( folds )
for any corrosion and clean it right up before it gets to be a
problem.
Using
ZINC sacrificial anodes helps a lot too. They will cut your corrosion way
down.
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