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Old 26-02-2005, 07:44   #1
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Detecting Cracks In Hardware

I am trying to locate the dye kit used to detect cracks in chain plates but this old brain can't remember where I saw the kits. Can you point me in the right direction?

Thanks
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Old 26-02-2005, 10:51   #2
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Welding and tooling suppliers

Die test kit in spray cans. One red Penetrate dye and one Developer white power. Any dry solvent cleaner will work, like acetone or MEK. Each can should be about $6. A compleate kit ($72) has 2 cans each of penetrate, developer and cleaner. Way too much for a single sailboat, unless you check a lot. Most common brand name is Crown - Fault Finder

Preheat the parts to about 100 - 120º with a propane torch before spraying the red dye. The dye seeps into the cracks as it cools.

DON'T get the dye on your gelcoat!!!!! You should get instructions with the kit. If not ask, the salesperson.
................................._/)

BTW. The threads on the couplers may give you a faulse reading, so maybe the spray cleaner would be recommended for that area.
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Old 26-02-2005, 16:31   #3
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Quote:
Preheat the parts to about 100 - 120º with a propane torch before spraying the red dye. The dye seeps into the cracks as it cools.
Soo, ya have to take the chain plates of the boat to do the testing...?

The removal is usually the hardest part of the process, so ya might as well replace the plates if ya already got 'em out.

Replacing chain plates is part of normal sailboat maintenance anyway and should be done every 15 to 20 years as crevise corrosion in SS can be a silent killer.

To put my money where the mouth is, I replaced all 9 plates on my ship 2 years ago.
It was a bitch of a job, but the actuall expenses for having new plates made was not that great: $750.00 for all 9 plates pluss 3 backing plates, all 316 SS.
Also had 'em electro polished for another $120.00 or so,

All new shacles, pins, bolts, washers, nuts, caulking and misc came to another $300 or $400.

But the labor removing and re-installing was especially tasking.
Perhaps one of the disadvantages of the CSY 33: The chain plates are built in, and there is tight spaces..
Fortunately, it is a long time to the next round...
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Old 26-02-2005, 21:23   #4
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Chain plates

I would think that if there were any cracks they would be around the bolts or clevis eye.

You don't have to heat the parts, but it does work better that way. Just have to let it sit for a while to soak into the cracks before cleaning it off for the develpoer.

You can tape off around the plates to keep the dye from soaking in the paint or gelcoat. But you will not be able to see the back side and that's where you'll find the first cracks, most likely from the bolts pushing in on the plates.
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Old 05-03-2005, 14:39   #5
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try a local general aviation airport, the dye kits we use on aircraft do not require heating, but as stated before the dye is messy,
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Old 06-03-2005, 09:45   #6
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Roger,
the kit can be found @ aircraftspruce.com
listed as
met-l-chek penetrant inspection kits.
4 can kit @ 39.50
hope that helps
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Old 07-03-2005, 03:16   #7
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I have seen a yacht have its chain plates xrayed while the boat was still fully rigged and in the water.They taped film with a lead shield on the outside of the hull then xrayed them from the inside.Greg
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Old 24-05-2005, 03:46   #8
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Do a websearch for "magnaflux", then locate a local distributor. Most times if you are polite, etc. they might give you a 'sample' set. WorstMarine can special order; sometimes appears in the WM catalogue as 'dye penetrant'.

When looking for fatigue cracking, look for areas of dullness that look like 'fans' or a zone of dullness. Also especially look at any notches or areas of surface irregularities .... saw marks, mill scale, etc. Any area or surface that has changed 'texture' is suspect for fatigue, such zones may not show up with dye penetrant.
Polishing to a 'mirror' surface retards the fatigue process. But .... lets face it, most 'boat designers' design chainplates to 'tensile' values and NOT endurance/fatigue values; hence, the propensity of fatigued chainplates.
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