Re: [Paddlewise] Stainless Steel Types (was: Leaky cockpit - through hull bolts )

From: Dave Kruger <kdruger_at_pacifier.com>
Date: Mon, 09 Apr 2007 16:52:44 -0700
alex wrote:
> Stainless screws and other stainless items apparently are not all
> created equal.  I've seen traces of rust around different stainless
> fasteners in sea environment many times (not to mention my River Shorty
> knife, - allegedly stainless too).

Too true; Alex speaks from a wealth of experience.

Wikipedia has a good summary / comparison of the myriad grades of 
"stainless" steel, right here:
  http://en.wikipedia.org/wiki/Stainless_steel#Types_of_stainless_steel
An excerpt, denoting the two most common grades:  304 (not so good) and 316
(better; aka "marine grade stainless":

> Type 304the most common grade; the classic 18/8 stainless steel. [snip]
> Type 316the second most common grade (after 304); for food and
> surgical stainless steel uses; [snip]  It is also known as "marine
> grade" stainless steel due to its increased resistance to chloride
> corrosion compared to type 304

In my experience, 316 shows no rust even after long use on sea kayaks; 304 
shows rust within weeks of regular exposure to salt water; neither is a 
real safety hazard in our use, most likely.  Take a gander at the "crevice 
corrosion" section in the Wikipedia reference above to see what the real 
concern is for stainless in a marine environment.

-- 
Dave Kruger
Astoria, OR
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Received on Mon Apr 09 2007 - 16:52:40 PDT

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