"Chris" wrote in message
oups.com...

So how does this dye test work?


Chris - You don't seem to be getting an answer to your question. Cracks in
welds etc are often better seen after treatment with a dye penetrant. This
is sometimes sprayed on. have a look at this Magnaflux web site then do your
own search. http://www.magnaflux.com/index.asp

I worked as a yacht rigger for many years. I consulted with metallurgical
engineers who also happened to be sailors. They said that by the time a dye
penetrant would help, it was too late! The problem is that the cracks start
from inside the swage and work their way outwards. We confirmed this by
cutting through swages that shows small external cracks and making a
polished section - There were many more cracks that were not visible but
which we could see under a powerful microscope. The cracks start at a
crevice where the swage has not fully surrounded a wire strand. At this
point, the stainless steel is under stress from swaging and there are often
chlorides present and a lack of oxygen. Apparently these are ideal
conditions for Chloride Stress cracking to occur.

We found that the only way we could delay cracking, was to seal the fitting
when we made the swage. We sometimes did this by adding a small amount of
epoxy to the wire near the end of the swage. The heat from the swaging
process caused the epoxy to run and fill all the voids and also make a neat
bead at the end of the swage. Others have used bees wax, nail polish and
other materials to seal the swages so as to keep the salt atmosphere out.

So far as inspection is concerned, we would clean up the swages using fine
emery paper or synthetic cleaning pads. We would then look at the fitting
through a strong magnifying glass. In particular, look at the edges of the
swage where the wire enters - that is where cracks often start.

Since there is really no good way to inspect, best solution is to replace
rigging on a regular basis - In freshwater, this may not be necessary - the
wire likely will fail first due to fatigue. In salt water, about every 7 to
10 years depending on temperature of area should be OK.

I have been out of the business for some time, so if anyone knows better,
please feel free to correct the above!

Hope this helps!