Resuse 45 year old chainplates

[darc427]

Hello all, just pulled a chainplate off my 1977 45’ Fuji. I’m assuming it’s original because it has Japanese writing on it. So I’ll replace it because if it’s age. Then I thought, I’m going to polish it, put a load on it and inspect for micro fractures. If it looks perfect maybe I’ll just keep using them. Sure they’re are old, but IF no signs of corrosion then it’s obviously a quality piece of steel, and I would almost want to use that vs a new piece of steel that may or may not have the same quality to it. Crazy thought?

[letsgetsailing3]

I think that if I had gone that far, I'd just go ahead and replace it, so as not to have to worry about it.

[stormalong]

Crevasse corrosion is really hard to see. You would need a dye penetrant test kit to check it. You can find them at welders supply stores.

The kits contain three spray cans - a cleaner, a dye and a developer. Follow the instruction or get a pro to test it.

A long time ago I had a pro test mine. I couldn't see anything wrong. After showing me the traces of dye in the hairline crack he put the chainplate in a vice and easily bent it, revealing a rusty mess inside. All but one of my chainplates had similar hairline cracks. I had him replace them all and thanked my lucky stars that the hard 1000+ mile beat to get there didn't result in a dismasting.

[Alan Mighty]

Originally Posted by darc427

Hello all, just pulled a chainplate off my 1977 45’ Fuji. I’m assuming it’s original because it has Japanese writing on it. So I’ll replace it because if it’s age. Then I thought, I’m going to polish it, put a load on it and inspect for micro fractures. If it looks perfect maybe I’ll just keep using them. Sure they’re are old, but IF no signs of corrosion then it’s obviously a quality piece of steel, and I would almost want to use that vs a new piece of steel that may or may not have the same quality to it. Crazy thought?

Hmm ...

1. The kanji (the Nipponese name for Chinese characters) suggest that your photographed shroud is from the port side of your vessel with the writing on the outer face of chainplate No. 3.

2. Your photographed shroud certainly looks free of surface corrosion. Polishing and careful inspection should reveal any stress cracking.

3. Have you put a magnet to it? Do you have any documentation that might tell you the steel grade? Or give recommendations about its use cycle (such as when you should replace it)?

4. I'm not a structural engineer. Or a naval architect. So I can only offer layperson's advice:

Let's assume your vessel was designed and built in a capitalist economy. That means that profit is king and the ruling principle is that the buyer gets the level of engineering/strength/safety for which he/she pays. So over-engineering is avoided, but some level of adequate safety margin for the assumed lifetime/use cycle of the vessel is part of the specifications.

So the dimensions/scantlings of the chainplate were judged adequate for the expected stress of operation. That judgment would have involved calculating the engineering stress to which your chainplate might be subjected. And then considering the range of steel grades and choosing a grade which has a stress strain curve such that it would be at an appropriately low proportion of the level at which plastic deformation would take place.

But ....

let's assume your beautiful chainplate, which has been kept away from chloride ions all these 45 years, has been in use on your vessel.

If the steel is an austenitic stainless steel (very likely, I think), then it has been subject to work hardening.

The work hardening will have been a product of stress and strain. The amount of work hardening will have depended on whether your steel is austenitic, ferritic, duplex, or martensitic. If your chainplate was subject to low strain levels (10 - 15%) then the work hardening will be of a different magnitude compared to if the dimensions were skimpy and put to high strain.

I suggest you need to consult an expert. I'd be surprised to learn that 45 year old austenitic ss, if it's been subject to even just the ordinary sailing loads of 45 years, is still good to go.

[JC Reefer]

It’s off, it’s old. Get it replaced. There is a shelf life to SS. Back when I was rigging, I would not install an unused 50 year old part.

Call it cheap insurance.

[ItDepends]

Originally Posted by darc427

Hello all, just pulled a chainplate off my 1977 45’ Fuji. I’m assuming it’s original because it has Japanese writing on it. So I’ll replace it because if it’s age. Then I thought, I’m going to polish it, put a load on it and inspect for micro fractures. If it looks perfect maybe I’ll just keep using them. Sure they’re are old, but IF no signs of corrosion then it’s obviously a quality piece of steel, and I would almost want to use that vs a new piece of steel that may or may not have the same quality to it. Crazy thought?

Yes it is a crazy thought.

Just replace the damn thing. It's just a piece of old stainless steel. It is not mystical unobtainium metal sprinkled with the urine of virgins that give it magical properties and a forever life.

Today, just like 50 years ago, you can buy good stainless, and you can buy crap. The best stainless in the world doesn't last forever in a loaded marine environment. You have two options. Put this one back and continue to use it until it fails (whenever than might be), or start the clock over again with a new piece.

[Chotu]

I’m with everyone else. Why not replace it? It’s in your hand. Then you can have confidence.

[Cheechako]

Originally Posted by darc427

Hello all, just pulled a chainplate off my 1977 45’ Fuji. I’m assuming it’s original because it has Japanese writing on it. So I’ll replace it because if it’s age. Then I thought, I’m going to polish it, put a load on it and inspect for micro fractures. If it looks perfect maybe I’ll just keep using them. Sure they’re are old, but IF no signs of corrosion then it’s obviously a quality piece of steel, and I would almost want to use that vs a new piece of steel that may or may not have the same quality to it. Crazy thought?

Is that a weld up near the top? A repair?
I'd just replace them if you've gone to the work of removing them. You can clean it up and have it inspected, or buy the DyePen kit. But if that's a weld I would replace it.

BTW, work hardened Austenitic SS will be magnetic. The more work hardened, the more magnetic generally.

[darc427]

Ha ha great replies.
My intention is to just replace it, which I will…

[James S]

I'm also with the "replace the damn things" camp.. and when doing so you might have the opportunity to reassess their size.
I'm certainly no expert but chainplates are one of those elements that can't be to big..
That being said by the owner of a 20 ton 48 footer.. So im obviously not a high performance boat.
In any case hats off to you for being thorough in your refit!!

[WaldPinkler]

I have a 20 year old Asian built boat with very similar looking chainplates.

I've taken 3 out and polished them and they all look reasonable.

Experienced boat builder friends have said to just replace. Of course I had mental arguments against the cost and effort and it will be okay. After months of this I've just accepted to replace them. It's not worth going across an ocean and dropping the mast. That's what's called a catastrophe.

Now I have trouble finding anyone to do the waterjet or laser cutting. I've sent technical drawings for quotes and I don't hear back from companies. Such a backlog of any type of work here in Australia.

I have access to proper drill presses and band saws so now I'm leaning towards just buying the 1/2" flat bar and doing the work myself. I saw 4m of flatbar for AU$400. It's pretty cheap, though time consuming polishing with an angle grinder. I've bought 100 carriage bolts, nuts and mud guard washers. That was only $150. 5 mins on each polishing the heads, no problem.

Anyway, that's not much money but a fair bit of time.