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-   -   18-8/304/316/... SS fasteners? (http://www.sailnet.com/forums/gear-maintenance/69362-18-8-304-316-ss-fasteners.html)

micheck 10-25-2010 12:45 PM

18-8/304/316/... SS fasteners?
 
I am told that one should use 316 Stainless Steel in a saltwater environment - that other 'grades' will not stand up to the environment. I also see that places like West Marine and my local fastener superstore both carry extensive 18-8 stocks of fasteners but very few (and expensive) 316 fasteners. Thoughts?

Charles

mitiempo 10-25-2010 01:26 PM

Where are you using them? I would bet most of the bolts and screws on my boat are 304 and they look good after 33 years.

sailingdog 10-25-2010 01:44 PM

I'd point out that 304 is generally stronger than 316 as well.

tommays 10-25-2010 01:54 PM

18-8: 300 series stainless steel having approximately (not exactly) 18% chromium and 8% nickel. The term "18-8" is used interchangeably to characterize fittings made of 302, 302HQ, 303, 304, 305, 384, XM7, and other variables of these grades with close chemical compositions. There is little overall difference in corrosion resistance among the "18-8" types, but slight differences in chemical composition do make certain grades more resistant than others do against particular chemicals or atmospheres. "18-8" has superior corrosion resistance to 400 series stainless, is generally nonmagnetic, and is hardenable only by cold working.


18-8 is covers a bit to much ground BUT i have never seen many problems in above the water line use other than staining which is pretty easy to resolve these days with a product like spotless stainless

mitiempo 10-25-2010 01:58 PM

I agree, have rarely seen problems above waterline. Stainless really should not be used underwater anyway.

Bloke 11-20-2010 07:33 PM

Marine grade stainless steel is 316 or 316L - period.

Cliams like "built of high quality marine grade 304 stainless" are blatent lies.

Stainless steel is a very big subject and if you want to learn it, there are plenty of resources on the web to do so. But if you haven't got the time then take the advices of the SS manufacturers - every one of them identifies 316 as the Marine grade.

Parts manufacturers on the other hand are competing with other parts manufacturers who use claims like "built of high quality marine grade 304 stainless" and in a price driven market are using the cheaper SS to compete.
Boat manufacturers use 304 because it will last past their warranty period, beyond that they don't care, in fact they would prefer it to rust.

Easiest test to establish grade is to use a magnet - 304 is magnetic, 316 is not, (except where it has been welded)

A magnet is also useful when buying hose clamps - many have 316 bands but use 304 screws - a fact responsible for many failures and several sinkings...

sailingdog 11-21-2010 04:19 PM

You'd be a lot more credible if you knew what you were talking about. A lot of good marine hardware is made of 304 grade stainless steel, which is non-magnetic. The cheaper martenistic grades of stainless steel are magnetic, but the 300 series of austenitic stainless steels are not.

Quote:

Originally Posted by Bloke (Post 668803)
Marine grade stainless steel is 316 or 316L - period.

Cliams like "built of high quality marine grade 304 stainless" are blatent lies.

Stainless steel is a very big subject and if you want to learn it, there are plenty of resources on the web to do so. But if you haven't got the time then take the advices of the SS manufacturers - every one of them identifies 316 as the Marine grade.

Parts manufacturers on the other hand are competing with other parts manufacturers who use claims like "built of high quality marine grade 304 stainless" and in a price driven market are using the cheaper SS to compete.
Boat manufacturers use 304 because it will last past their warranty period, beyond that they don't care, in fact they would prefer it to rust.

Easiest test to establish grade is to use a magnet - 304 is magnetic, 316 is not, (except where it has been welded)

A magnet is also useful when buying hose clamps - many have 316 bands but use 304 screws - a fact responsible for many failures and several sinkings...


PorFin 11-21-2010 04:36 PM

Quote:

Originally Posted by sailingdog (Post 669017)
You'd be a lot more credible if you knew what you were talking about.

Boy, I just had a flashback -- my Dad used to say that to me a lot! :D :D

Other pearls were
o "You could probably see a lot better if you'd get your head out of your a$$."
o "How's the light up there, dimwit?"
and truly a classic -- "Any damn fool can break a shovel handle."

JiffyLube 11-21-2010 06:53 PM

I have this Harkin pad eye with a 3" base (heavy duty), that is 17-4 and magnetic. I read that 17-4 is suppose to be similar to 304, but I can safely say I don't know what I'm talking about on this subject. :D

Bloke 11-26-2010 05:02 PM

Quote:

Originally Posted by sailingdog (Post 669017)
You'd be a lot more credible if you knew what you were talking about. A lot of good marine hardware is made of 304 grade stainless steel, which is non-magnetic. The cheaper martenistic grades of stainless steel are magnetic, but the 300 series of austenitic stainless steels are not.

ha! :-)
I used to think that too, was taught it fact.
Experience has proven my teachers to be wrong in so many things. - like the idea that the 300 series is all non magnetic... try it, you'll be surprised too.

Like I said, SS is a big subject - but as general rule 316 is the most corosion resistant and the only one I would consider "Marine grade" (even though it will still rust - they all will).

"Good marine hardware made of 304"?
Just last week I had to throw away my boarding ladder - 304 and rusted out from the inside - Couldn't buy one in 316, so had to build one.

"If I knew what I was talking about"... cheap shot - You got shares in a chandlery or something?


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