Dye Penetrant vs X-ray Testing of Chainplates???

[Sharkbait Steve]

I intend to replace the standing rigging on my 1976 Ingrid 38. The chainplates are original. Seems like it would be a good idea to either inspect the chainplates or just replace them. Looking for input on dye penetrant vs. x-ray. DIY dye penetrant would be the least expensive way to go. I've found some dye penetrant test kits online: Magnaflux for about $270 and Dynaflux for about 1/3 that much. Anyone have experience with either of these? Would testing the chainplates while they are still bolted to the hull yield meaningful results? I haven't gotten a price yet for having the chainplates professionally inspected but I suspect that it will not be cost effective vs just replacing them. Any input/comments will be greatly appreciated!!!

[Tsuru]

This is not an expert opinion so don’t take it as such. On my boat if the chainplate were flat I’d be happy with dye penetrant testing procedures that utilize a developer. Removing the chainplate is important because you are not only testing for a crack. Corrosion can and will develop where the chainplate bonds to the hull or bulkhead.

Clean the chainplate prior to dye testing, use magnification, and if in doubt use additional more robust non destructive testing techniques.

If the chainplates have compound angles, welds, or anything wonky I’d go to X-ray or Magnetic particle. I’d Passivate the stainless chainplates after cleaning and or polishing, although probably not necessary.

Good luck,

[SailingHarmonie]

If you make new chainplates you know they are good.

Testing old ones is a good start, but not 100%.

You have to remove the old ones to do a half way decent inspection. The cost of new ones is not that high, the cost/hassle of removing them is high.

It seems silly to me to reuse old ones once you have gone to the trouble of removing them. That’s what I did.

[dlj]

Originally Posted by Sharkbait Steve

I intend to replace the standing rigging on my 1976 Ingrid 38. The chainplates are original. Seems like it would be a good idea to either inspect the chainplates or just replace them. Looking for input on dye penetrant vs. x-ray. DIY dye penetrant would be the least expensive way to go. I've found some dye penetrant test kits online: Magnaflux for about $270 and Dynaflux for about 1/3 that much. Anyone have experience with either of these? Would testing the chainplates while they are still bolted to the hull yield meaningful results? I haven't gotten a price yet for having the chainplates professionally inspected but I suspect that it will not be cost effective vs just replacing them. Any input/comments will be greatly appreciated!!!

The Ingred 38 has external chain plates IIRC, is that correct? So to remove them for inspection is a fairly straightforward task - is that also correct? If these are both correct, why not just remove and inspect?

I would not use Magnaflux - that is for magnetic materials, and your chain plates are not a magnetic material.

I'd use a liquid penetrant. If the Dynaflux is the liquid penetrant type - I'd use visible light type, not fluorescent type - that would be fine.

If you are doing this for insurance, you should use a certified NDE inspector, if it's just for your peace of mind, then it's really your choice. But I'd definitely recommend buying a copy of ASTM E1417 and read it. It gives a lot of information on how to do this kind of testing. Doesn't make you a NDE inspector, but at least it gives you a lot of helpful info...

dj

p.s. X-ray would require an NDE expert and it would likely not give you as good information as properly done dye penetrant inspection for this specific case. Unless, of course, you have welds in those plates.

[Sharkbait Steve]

Thanks guys for all the input and good ideas. I've checked the price for an x-ray inspection: $2,700. Hmmmm... I priced 316L stainless to make my own chainplates: $657 and I'll have quite a bit of material left over. My probable course of action will be to remove the chainplates and dye penetrant test them myself. They are mounted externally but pass through a narrow slot in the toerail. I expect that removing them without destroying the toerail will not be an easy job. If I need to, I'll use a product called "Debond" to help free the chainplates from any sealant used in the installation. Debond comes in an aerosol can and it's not cheap but I've been told that it works even with 5200. Anyway, I expect that in the end, I'll replace the chainplates. I have access to the machine shop here in the boatyard. Hopefully I'll be able to do most if not all the fabrication work myself. Wish me luck!!!

[Reefmagnet]

Dye penetrant. X-ray is more used for internal defects and wont detect fine cracks.

[The Yacht Rigger]

By the time you have removed all the original chainplates, you're better off just replacing them. 40+ year old stainless has done it's time.
I wouldn't waste time and money testing stainless that is that old. The peace of mind of new chainplates will be well worth it.

[dlj]

Originally Posted by The Yacht Rigger

By the time you have removed all the original chainplates, you're better off just replacing them. 40+ year old stainless has done it's time.
I wouldn't waste time and money testing stainless that is that old. The peace of mind of new chainplates will be well worth it.

That's a perspective. If it were my chain plates, I'd look carefully to see if there are signs of corrosion - minor corrosion I'd clean and then do penetrant inspection. Major visual corrosion and then I'd agree, no need to check, just replace.

Thing is, if there is no sign of a problem after cleaning and penetrant inspection, those chain plates should be good for another 40 years or more. One thing I'd do now however, is set up the mounting structure such that everytime you are going to replace your standing rigging, you can easily remove these chain plates each time you are changing that standing rigging. That way everytime standing rigging needs changing, an inspection of the chain plates can be done easily.

Unless there is an identified problem happening with those chain plates, there is no finite time limit for that material to require changing. Or said another way, this material does not require being changed every X number of years regardless of observed condition.

dj

[dlj]

Originally Posted by dlj

Or said another way, this material does not require being changed every X number of years regardless of observed condition.

dj

I was just rereading this, and that sentence doesn't make sense - I must have been thinking something else and that's what came out...

What I meant to say is: this material does not require being changed every X years just because it's been in use. You need to look at the condition to see if anything is changing, like stress cracks or corrosion or...

dj

[Wotname]

Originally Posted by Sharkbait Steve

........... They are mounted externally but pass through a narrow slot in the toerail. I expect that removing them without destroying the toerail will not be an easy job. ............

47 year old sealant will have partially failed decades ago, both at the toenail and between the hull and chainplate. These will be the two spots where crevice corrosion will occur. Crevice corrosion is not reliably observable by a surface inspection. In other words, you will not be able to determine if it exists or not.

The area where there is sealant (especially failed sealant) is a hostile environment which encourages mostly unseen crevice corrosion inside SS. Chainplates are a fundamental part of the standing rigging, any failure in any part of the rigging is a catastrophic event; IMO don't take the chance, replace them. You will much happier knowing the all the parts of the rigging are new next time you get caught out in a storm etc.

Anyway, I expect that in the end, I'll replace the chainplates. I have access to the machine shop here in the boatyard. Hopefully I'll be able to do most if not all the fabrication work myself. Wish me luck!!!

Yes, excellent idea and I wish you luck

[wsmurdoch]

The problem with my external chainplates was easily visible after cleaning and polishing the chainplates while they were in place. Chloride induced stress corrosion cracking. Most of the damage was on the front sides. The caulking on the backs was pristine as was the metal. I replaced all the 25 year old 304 plates with 316L. I also replaced the bolts with 316, but kept the backing plates.

This spot may have been the worst.

[dlj]

Originally Posted by Wotname

Crevice corrosion is not reliably observable by a surface inspection. In other words, you will not be able to determine if it exists or not.

The area where there is sealant (especially failed sealant) is a hostile environment which encourages mostly unseen crevice corrosion inside SS.

I've heard this before in a couple places, but I've never seen actual data or parts that exhibit what you are describing unless the penetrant testing has been done incorrectly.

The second part of the above statement "unseen crevice corrosion inside SS" is a unclear to me. Crevice corrosion always starts on the outside. It does not start inside. One of the reasons I typically suggest using someone qualified in NDE to do the penetrant inspection is so that the cleaning step of the test is done correctly. If that step is not done correctly, it can hide the surface indications.

dj

[Wotname]

Originally Posted by dlj

..................

The second part of the above statement "unseen crevice corrosion inside SS" is a unclear to me. Crevice corrosion always starts on the outside. It does not start inside. One of the reasons I typically suggest using someone qualified in NDE to do the penetrant inspection is so that the cleaning step of the test is done correctly. If that step is not done correctly, it can hide the surface indications.

dj

The above is true. Crevice corrosion always starts on the outside however having started on the outside, it progresses internally and leaves very little evidence of its presence on the outside of the material. Hence my previous statement was "mostly unseen crevice corrosion inside SS" rather than "unseen crevice corrosion inside SS". The adjective 'mostly' was to indicate the bulk of the corrosion is internal and therefore the bulk is not seen. The surface will always show the entry point but it is easy missed by the layman or DIY sailor.

I agree that a qualified NDT operator is the best person to preform the inspection.

[Searles]

40 plus years for S/S in a hostile environment,is a big ask ,of cause some one will know someone that has got away with it,it maybe not you ,if replacing for life ,only monel k 500 will do that job ,if S/S 2205 is your best option ,316 l ok if you inspect every 5 to 10 yrs or so ,but a lot of unknowns here ,while knowing the Ingrid class the size of the fitting is important for its service life ,the Ingrid that won the Hobart had galvanised steel chain plates . Or maybe iron ⚓️⛵️

[dlj]

Originally Posted by Searles

40 plus years for S/S in a hostile environment,is a big ask ,of cause some one will know someone that has got away with it,it maybe not you ,if replacing for life ,only monel k 500 will do that job ,if S/S 2205 is your best option ,316 l ok if you inspect every 5 to 10 yrs or so ,but a lot of unknowns here ,while knowing the Ingrid class the size of the fitting is important for its service life ,the Ingrid that won the Hobart had galvanised steel chain plates . Or maybe iron ⚓️⛵️

With all due respect, there are literally hundreds of thousands of sailboats, if not millions, that are surviving just fine.

I'd love to see the real numbers of sailboats that are running stainless steel chainplates, ages of those boats, and then look at the number of sailboats that have had chainplates break. While it is certainly a difficult and potentially dangerous event, - as well as highly visible - the percentage of sailboats suffering such breakages must be small in comparison. If indeed the material were a problem after a certain number of years, then boats everywhere would be dropping their masts within a certain number of years after manufacture. Doesn't seem to be the case.

Monel K500 is a great material. But certainly not the "only" one that could work as described.

dj