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Old 30-11-2013, 22:48   #31
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Re: through hole fittings

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Originally Posted by Gavala View Post
What a crock of crap. Let me say this before I exit this forum, crevice corrosion is a result of weld and not present on 'turned' fittings as stainless skin fittings are.

I was hoping you'd reply after googling this matter and mis interpreting the results.

As a chandlers supply manager up until last April I supplied many turned stainless fittings to high end customers, the most prevalent being Eric Claptons Vabene which is moored in Antigua.

He most likely didn't bother googling for the underwater properties of stainless steel and misinterpret wiki but took good advice from someone who is out there doing it rather than someone spending his days making 1.78 posts a day sat at a computer.

I bow out. You are almost laughable if I could surrender the energy.
During complete remastering on a 35 Chris craft I removed quite a number of stainless steel lumps that may have started as screws. Many different opinions at the marina but they were non magnetic so assumed to be of good quality. All the bronze screws could have been used again after 40 years the stainless were 8 years old and the reason for the refastening job in the first place.
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Old 30-11-2013, 22:49   #32
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Re: through hole fittings

That's supposed to be refastening
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Old 30-11-2013, 23:31   #33
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Re: through hole fittings

Ya I must have missed this thread when it first popped up, but the idea that crevice corrosion only occurs on welded stainless is so wrong I don't know where to start.

Stainless (of any grade even the 400 series) are subject to crevice corrosion as a result of the material properties of the steel. It's well documented, well understood, and there are thousands of articles that discuss it in one form or another.
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Old 01-12-2013, 17:53   #34
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Re: through hole fittings

I'm so glad this thread popped back up.....I needed a good laugh again about raping metals of their natural state!!
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Old 01-12-2013, 18:14   #35
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Originally Posted by Gavala View Post

No, but it took some time finding a random sight that has no weight when it relates to 300 stainless and not 316!!!!

Come on.

I'm really struggling here to get through. Crevice corrosion is due to weld and the site you linked is for 300 stainless. Please.
I think this guy is a troll, possibly david old jersey with a giant bag of popcorn!
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Old 01-12-2013, 18:34   #36
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Re: through hole fittings

I had to replace my prop shaft, turned and not welded stainless, due to corrosion. I had to replace my un-welded chain plates too, more crevice corrosion. I guess I'm really really stupid, I should have just told those chain plates and the prop shaft to stop faking it, shut the hell up, and get back to work.
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Old 01-12-2013, 19:57   #37
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Re: through hole fittings

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I think this guy is a troll, possibly david old jersey with a giant bag of popcorn!
LOL ^^
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Old 02-12-2013, 12:23   #38
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Re: through hole fittings

All 300 series stainless is very risky to use underwater. Even 316 used for drive shafts can have serious crevice corrosion issues where water is present but there is a lack of oxygen. This occurs in the area of the cutless bearing and inside the stuffing box. This is more common on boats that sit and are not used often. The only good choice for shafts is Aquamet 22 which has a much higher chromium content.

Welding stainless causes another issue - weld decay - which is caused when the wrong SS alloy is welded. Any stainless to be welded should be designated as 316L with the L meaning low carbon. If not you basically end up with steel along the welds, not stainless.

The best information I have seen recently about this is the article by Steve D'Antonio in the Dec/Jan 2014 issue of Professional Boatbuilder page 48.

Stainless through hulls are used on steel boats as bronze here is an issue.

Marelon is ABYC approved but wouldn't be my choice. It is nylon based Dupont Zytel. The handles are weak, especially on the smaller sizes. Another issue is the size hole required as the marelon through hulls need a larger hole through the hull for a given through hull size. This adds much complication if you wish to return to bronze in the future, involving re-glassing and then drilling the correct size hole for the bronze through hull. This thread, post 23 is informative: Seacocks... MARELON or BRONZE
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Old 08-12-2013, 08:42   #39
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Re: through hole fittings

The screws I removed from my Chris where non magnetic,slightly resembled screws and failed to hold the plank in place. I have never seen a welded screw these just failed due to lack of oxygen in their environment
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