[TowerTalk] Tower Incidents

[Grant Saviers]

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 at gmail.com>
>> To: towertalk at 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
>>
>>
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