What type of stainless, please?
- Thread starter NealB
- Start date
Wansworth
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Is that like cross threading
Bouba
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No.....I think the little burrs left on thread after the manufacturing process....get super heated when being tightened and weld themselves (bolt thread to nut thread)
andsarkit
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vyv_cox
Well-known member
Not necessarily when being tightened. Pressure between the two surfaces, either static or dynamic, tends to squeeze out lubricants allowing metal to metal contact. At pressure they can then weld together.
Prevention, as with EP gear lubricants, is to form sulfides on the steel surface. Welding iron sulfides is far more difficult than welding iron. Hence the effectiveness of MoS2 in galling prevention, ZDTP (zinc di-thiophosphate) in lubricants.
NealB
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Sorry ...... pushing my luck, I know ........ but did you use any magical anti-gall potion, between the nuts and bolts when mounting your winches?
vyv_cox
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No I didn't. They have been in situ for two decades so they might well be galled. Doesn't matter as they are never coming off.
andsarkit
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At work we had trouble with stainless parts galling and resorted to using Silver Goop which seemed to work well. If you think marine stuff is expensive take a look here:
Silver Goop
Silver Goop
rogerthebodger
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When I was fitting out my boat I had some stainless-steel galling and I started to use wool fat that prevented any more galling
The bolts that had already galled could not be removed without cutting the bolt and replacing it with new
Bouba
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Loctite do one…so should be easy to source
https://www.hisco.com/loctite-anti-seize
https://www.hisco.com/loctite-anti-seize
thinwater
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The other important considerations re. galling and stainless are:
- Tighten VERY Slowly. A half turn then rest. No power driving and easy with the ratchet. The ability to run nuts up quickly with drivers has created an epidemic in some applications.
- Do not tighten under load, like a turnbuckle. Virtually ALL rigging screws have bronze bodies or inserts for this reason. If they are all stainless, they are NOT meant for tuning rigging. Stainless-to-stainless should be pulled up all but the last turn or two by some other means. Drawing a long distance with stainless is asking for galling. One trick is to use a bronze nut.
NealB
Well-known member
Thank you.
Just to be sure I understand you ......
Decades ago (in the late seventies), I used to crew on a seriously competitive quarter-tonner, and the skipper would keep winding up the windward rigging to remove any noticeable slack in the lee rigging. It seemed brutal to me (I kept surreptitiously checking that the sidedecks weren't lifting), but ......... it wasn't my boat, and the skipper was very successsful.
So with my own winches, I'll tighten the mounting bolts very slowly indeed, with the winch itself not doing any work, till my torque wrench clicks, thereafter the bolts should left be left in peace.
thinwater
Well-known member
The reason to not use bolts to pull something down a long distance, like a turnbuckle, as opposed to a few turns to snug a winch down, is the heat that several people mentioned. The longer you turn, the more heat. Also, the longer you turn under pressure, the more debris is generated, increasing friction.
I have some tiny container of some sort of thread lubricant in every tool bag. It saves a lot of aggravation. Even Chapstik in a pinch. Locktite makes a product in a Chapstik-type tube, but the one I had broke in a few days.
Zing
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In order of cost: A2 corrodes and stains a fair bit. A4 somewhat less. 2205 a bit less, nickel alu bronze almost nothing and titanium not at all. I’m moving to 2205 where possible. Good enough and interestingly is intrinsically cheaper than A4 due to its low nickel content. Just one half hour polishing away corrosion or dealing with an early failure and you have paid the premium a hundred times over in your time, so get a good grade. 304 is a false economy.
Just look what Jeanneau use and don’t use that.
Just look what Jeanneau use and don’t use that.
NealB
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Phew! They're out of stock.
Zing
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I thought all rigging screw fittings were bronze against stainless and vice versa because of the galling issue? They certainly are on my boat.
vyv_cox
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2205 has similar corrosion resistance to 304. It is called duplex because it contains ferrite and austenite. Its advantage is that ferrite can be heat treated for strength, unlike 300 series. But ferrite corrodes, as in carbon steel.
Graham_Wright
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I had an order for a replacement shaft for a chicken macerator (chicken processor, if the chicken is dead before it is killed, it is condemned for human consumption and is reduced to pulp).
A failed shaft was supplied to be copied (it stank to high heaven and required numerous attempts to accept it into the factory).
The new component was made from 316 50mm in diameter and had a ring nut (C spanner). The thread pitch was ~1mm. Trying the nut for size on the shaft, it welded itself up solid.
A part time employee (escaping the vacuum cleaner on a Saturday morning), was a highly qualified engineer from Lucas fuel systems.
He started tapping the nut radially around its periphery while rotating the shaft. Half an hour later, he removed it.
A valuable lesson.
Zing
Well-known member
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vyv_cox
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Those are all highly specialised conditions. I thought we were discussing marine fittings at ambient temperatures. See this paper for example but there are many others:
Stainless Steel Material In Sea Water
304L, LDX 2101® and 316L can all tolerate somewhat more corrosive conditions in systems which do not contain obvious crevices, provided all welds are of good quality and well cleaned.
•........
• 2205 or lower alloyed grades are usually not sufficiently corrosion resistant.