Probably it was the stainless alloy that was used. Sailboat standing
rigging can last 10 years, sitting 4 ft from salt water, and it is under
a lot of tension.
Yes, the oxygen deprivation is a problem with many SS alloys. 316 is the
most resistant 300 series alloy. Nitronic 50, used for rod rigging is
very resistant but a bit pricey. Keel bolts thru fiberglass hulls into
lead keels were falling off due to this problem until builders switched
to 316L or monel. I believe there is a bronze alloy that is stronger
than 300 series stainless and completely free of the problem, but have
forgotten the name.
see http://www.westmarine.com/WestAdvisor/Stainless-Steel-Rigging
Grant KZ1W
On 6/21/2016 8:22 AM, Patrick Greenlee wrote:
There is a process called oxygen deprivation corrosion that can in
some instances rapidly corrode stainless steel. Not claiming that to
be the culprit in this case, just offering up one suspect for the lineup.
Patrick NJ5G
On 6/21/2016 9:05 AM, Jim Thomson wrote:
Date: Tue, 21 Jun 2016 07:42:12 -0400
From: Herbert Schoenbohm <herbert.schoenbohm@gmail.com>
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Tower Incidents
I know of an incident in St. Thomas where a fall protection system
actually failed. My son a Comtrain certified instructor where preparing
for a 225 foot climb and the owner of the tower, the biggest owner of
towers across the country, required that any climber must use the fall
protection system installed on it. His co-worker was up first at 100
feet and took a short rest with his weight, about 200 lbs, on the
cable. Than bang the cable broke at the fitting at the top and down he
came. Fortunately a microwave dish at 40 feet broke his fall but he was
still badly injured with many broken bones when he finally hit the
ground. What added insult to injury was the cable came down on top of
him as well. My son called for help while removing the tangle mess and
stabilizing the victim. The co--worker survived after several months in
the hospital. Ironically while my son was visiting in the hospital
there were five lawyers waiting outside to handle the case. The
settlement was close to a million dollars. The tower had also been
inspected by a mainland company only a month before the incident.
Everybody lawyer-ed up and was litigating against each other before it
was all over. But here is a case were the very component designed to
save a life nearly cy caused the loss of one.
The problem was eventually traced to internal cable corrosion where the
cable connected at the top of the tower. Apart from replacing
everything every 5 years the internal rot on stainless fittings is
nearly impossible to detect. The hook and unhook with two fall arrest
cords IMHO the best way to climb. It takes more time but it is safer.
## so whats the difference between the safety cable..and any portion
of a guy wire system ?? Both use EHS guy cable..and both use pre-form
dead ends. Both use thimbles. The safety cable setup doesnt require any
egg insulators, and also uses .375 inch EHS...but that is about it.
How do you..rot SS ?? One huge forged eye bolt, and double nutted
at top of tower,
and a thimble and .375 ehs cable, and a pre-form dead end is about
all you need at the
top of a tower.
Jim VE7RF
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|