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316-L is about as good as it gets but also reflected in it's price.
Also make sure you use a stainless steel wire wheel or hand brush
and a grinding disc that says aluminum on it if you need to grind
it. You will impregnate the metal with bad stuff if you use a
grinding disc for steel.<span class="moz-smiley-s2"><span> :-( </span></span><br>
<br>
Rick <br>
<br>
<div class="moz-cite-prefix">On 1/9/2015 11:37 AM, Stephen Fordyce
via Personal_Submersibles wrote:<br>
</div>
<blockquote
cite="mid:CAAzgXiNUhGFxukT_hBzCcWkDr0jZK6a5aEtMwM7gbU2=LQb8vQ@mail.gmail.com"
type="cite">
<div dir="ltr">
<div>Hi Brian,</div>
<div>SS304 is the most common grade of stainless for general
use, but SS316 is the most common used in marine (and is
usually what people mean when they say "marine grade"). That
said, the difference in performance is mainly cosmetic for
intermittent salt water use (ie. some very light
"tea-staining" rust), and I've used various bits of SS304 on
my boat and dive gear that are absolutely fine years later,
although it all gets fresh water washed after use.</div>
<div><br>
</div>
<div>For continuous exposure to salt water, or with crevices
(ie. your thru hull seals) likely to trap and hold salt
water, SS304 is likely to eventually corrode enough that it
may eventually wear or cause the seals to develop leaks.</div>
<div><br>
</div>
<div>I know at least sometimes the prop & propshaft on
bigger boats is protected from corrosion with an anode, which
wouldn't be very practical on a thru hull. Possibly this
explains why the one you have is 304.</div>
<div><br>
</div>
<div>Another thing I see at work all the time is contamination
of any grade of SS pipe with carbon steel dust from grinders,
drill shavings, etc. A piece of SS you thought was clean left
in the rain will develop nasty rust spots overnight!
Important to store your SS away from carbon steel workshop
areas and/or cover it.</div>
<div><br>
</div>
<div>Cheers,</div>
<div>Steve</div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Fri, Jan 9, 2015 at 7:59 AM, Brian
Cox via Personal_Submersibles <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:personal_submersibles@psubs.org"
target="_blank">personal_submersibles@psubs.org</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div style="font-family:Arial,sans-serif;font-size:10pt">
<div>Hi All,</div>
<div> I was given a stainless steel prop shaft
which is about 1 1/2" in diameter, I have cut it up into
2" long pieces so they can be used as thru hull fittings
for some of my rotating shafts that I will be using. I
was always under the impression that the prop shafts
were a highly resistant alloy of stainless and would be
good for my application. I recently was able to have
someone do a spectral analysis of the metal and
it showed that the material is 304 stainless. I'm
wondering if that will be good enough to use as a
stainless fitting for a thru hull ?</div>
<span class="HOEnZb"><font color="#888888">
<div> </div>
<div>Brian </div>
</font></span></div>
<br>
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</blockquote>
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