Stainless corrosion and maintenance - Page 6 - SailNet Community
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post #51 of 71 Old 11-04-2019
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Re: Stainless corrosion and maintenance

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Originally Posted by colemj View Post
Bad welds would be an example, but I wasn't addressing poor metal or fabrication in my suggestions. Those are a problem regardless.

Mark
Mark, that's exactly right. Normally stainless wouldn't be sensitized and a little acid will not harm it.


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post #52 of 71 Old 11-04-2019
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Re: Stainless corrosion and maintenance

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Originally Posted by jvlassak View Post
Rich, when you talk about "already oxidized grain boundaries", I assume you are talking about sensitized stainless steel, where acid could indeed quickly destroy your stainless by preferentially attacking the grain boundaries. That is not the result of oxidation, but occurs because the chromium at the grain boundaries is depleted. This happens because chromium reacts with carbon to form carbides at the grain boundaries when the stainless is heated in a range it shouldn't have been. If stainless is not sensitized, and none of the stainless on board should be, nitric or citric acid should be fine.
I agree. The problem with boats is that rain water, lake water, so-called fresh water is or can easily be as low as 5▒ pH (acidic) and which can additively over time begin to etch the exposed iron/ferrous/ferric components of the stainless.
Sea water, far from land drainage, is 'basic'
316 is the preseht choice due to its 2-3% molybdenum content. You can get in higher % on special order from the mom and pop shops of the orient ... or simply spec. an 'aquamet' type stainless at obscene costs. Most cosmetic stainless is probably simple '18-8' and with nil to no molybdenum to help protect against halide (iodine, chlorine, bromine, etc.) pitting nor acid attack.
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post #53 of 71 Old 11-04-2019
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Re: Stainless corrosion and maintenance

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I agree.
Wait, he just agreed with me that these commercial acid-based products won't harm the stainless on the boat, and you agree with him.

But you don't agree with me.

I've got to go back and refresh my memory on the transitive law.

But to spill that much vitriol, agreement doesn't work as a mechanism. That's OK - hope you are feeling better.

Now we still need to address just how much effort and time it takes to mirror-polish rusting stainless to the point that it guards against further rusting, particularly rigging and odd-shaped pieces - and also whether one would rather sail that year instead of polishing away full-time.

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post #54 of 71 Old 11-07-2019
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Way back in another world there used to be this thing called bronze. Yeah it turned green but it usually outlasted multiple owners and can often still be found in dusty corners of old boat shops, still usable.

Having spent my life on salt water, and having brought boats from the big inland ponds, corrosion is just something you deal with. Rigging and chainplates get inspected and replaced at regular intervals regardless of what you see with your eye. When things such as stanchions get unsightly, you replace them.

Rinsing your stuff as often as possible is a regular thing, as in normal, for people on the big water. It’s part of your maintenance schedule.

Research crevice corrosion if you really want to not sleep well at night. Many a rig have fallen down due to it.

We enjoy and use our equipment in the most corrosive environment on earth. It’s not a bumper sticker, it’s very true. Be religious in your inspections and do the best you can. We all deal with it. 🤙AA
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post #55 of 71 Old 11-07-2019
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Re: Stainless corrosion and maintenance

as a former great lakes sailor now in salt...
What do you do where we used to use rigging tape to protect from sharp edges? ie cotter pins? I have 2 on my backstay if not wrapped would snag you every time you get up from the helm.
Bob
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post #56 of 71 Old 11-07-2019
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Quote:
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as a former great lakes sailor now in salt...
What do you do where we used to use rigging tape to protect from sharp edges? ie cotter pins? I have 2 on my backstay if not wrapped would snag you every time you get up from the helm.
Bob
You remove it and rinse the metal from time to time. I use rigging tape. What I don’t use is pvc pipes or any other covering on anything. You want both air and fresh water to have access to all exposed metal. Also keep an eye on galvanic corrosion as it happens much faster in a salt environment. TGel or Lanocoat are your friends.
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post #57 of 71 Old 11-07-2019
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Quote:
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Quote:
Originally Posted by snokid View Post
as a former great lakes sailor now in salt...
What do you do where we used to use rigging tape to protect from sharp edges? ie cotter pins? I have 2 on my backstay if not wrapped would snag you every time you get up from the helm.
Bob
You remove it and rinse the metal from time to time. I use rigging tape. What I don’t use is pvc pipes or any other covering on anything. You want both air and fresh water to have access to all exposed metal. Also keep an eye on galvanic corrosion as it happens much faster in a salt environment. TGel or Lanocoat are your friends.
Oh and if you REALLY want to lose sleep at night, consider things like graphite impregnated flax on stainless steel prop shafts and how it’ll eat it, should you or should you not ground all underwater metals together. Ect ect.
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post #58 of 71 Old 11-07-2019
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Re: Stainless corrosion and maintenance

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Originally Posted by snokid View Post
as a former great lakes sailor now in salt...
What do you do where we used to use rigging tape to protect from sharp edges? ie cotter pins? I have 2 on my backstay if not wrapped would snag you every time you get up from the helm.
Bob
Look at cotter rings
No barbs to take blood samples
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post #59 of 71 Old 11-07-2019
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Quote:
Originally Posted by BillMoran View Post
Coming from the great lakes, I'm appalled at how fast the salt environment is attacking and corroding the stainless on my boat. I knew this would be a problem, but I'm shocked at how QUICKLY it's happening.

My question is a general request for advice on how to minimize and control the problem. I'm sure this has been discussed many times before but google is worthless because all it wants to do is recommend products to me.

I've already tried T9, but the stuff I've treated with T9 seems to be corroding just as fast as the untreated stuff. I have trouble believing that any competing product is going to be significantly better ... but if that's wrong, I'd love to hear about it.

Is it just a matter of monthly polishing to get rid of the corrosion? Of course, I can't polish the cables on my standing rigging, so is there anything I can do to slow the corrosion there?
Make damn sure that there isn't any plastic sheathing on any of your stainless, the lack of oxygen under that stuff will allow salt to eat even 316 sometimes, plus it inevitably looks like crap...
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post #60 of 71 Old 11-07-2019
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Re: Stainless corrosion and maintenance

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Look at cotter rings
No barbs to take blood samples
Glad I asked, Now I have something to do tomorrow! lol I have a jar of those rings already.
thank you!
Bob
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