You pose a very good arguement. I concur.
Black wrought iron is made by one of the processes to which you
refer. However, this may be a technique for the manufacuteres to readup on
again.
I have just finished reading an article about the WTC disaster. " ...the
steel beams in skyscrapers were commonly insulated with a 'wet' slugy spray
containing asbestos that had been devised by American inventor Herbert
Levine. But in the late 1960s research by Irving J Selikoff of the Mount
Sinai School of Medicine in NYC suggested that exposure to asbestos was
correlated with poor respitatory health and even death. ... Today,
however, the original Selikoff research is regarded as a case study in poor
statistical induction, since he failed to correct his numbers for tobacco
use... ..there is little evidence that workers in asbestos insulated
buildings suffer adverse health effects." Then is says, " ... what is
known is that when the initial switch was made, the asbestos insulation
reached no higher than the 64th floor. Mr Millory, in a column written for
Foxnews.com, wrote on September 14 that the asbestos spray inventor Levine
would often gesture toward the towers and say, 'Whenever I pass by there, I
worry. If a fire breaks out above the 64th floor, that building will fall
down.' " The replacement insulation was to protect the building from
collapse for four hours, one lasted 50 minutes the other about an
hour-and-a-half.
So the moral might be, Be very carefull when replacing the orginal
specification.
Chris opr VE7HCB
At 02:51 PM 2001-12-05 +0300, Eric Scace wrote:
> I am not a specialist in metal work. However, I would be nervous
> about heating metals. According to reference books, certain
>types of metals are produced through a combination of alloying and heat
>treatments during manufacture -- and the result has a
>different strength and resiliency. If the material is subsequently
>re-heated beyond a certain point, the structural properties of
>the metal can be altered -- changing the strength and resiliency, possibly
>in a way which we would not like for a structure like a
>tower.
>
> Since this tower was not installed in accordance with the K7LXC Prime
> Directive (i.e., the base was not poured as per
>manufacturer's instructions), if it was my station, I would correct the
>base to comply with the manufacturer's instructions. In
>this case, I would also check with a concrete specialist about how to pour
>an additional cap in such a way as to eliminate the
>boundary between the old concrete base and the new cap (which could allow
>water to seep in and continue the rusting process).
>
> In a previous life as a meteorologist, a group in my office at the
> National Weather Service was doing a post-hurricane damage
>review in North Carolina. Among the damaged sites, a number of high-rise
>apartment and hotel buildings along the shore had been
>swept off their foundations (pilings) and had to be condemned. These
>buildings were of modern construction and had been built
>compliant with the current code -- yet the pilings had sheared off
>cleanly. We were puzzled why this occurred -- especially since
>the hurricane was only mid-scale in strength and a modern structure should
>have been fine. Quite by accident, one of the team
>members was strolling along the beach during a lunch break and passed a
>location where a new building's foundation was being poured.
>The workers were also on lunch break... and the pouring of concrete had
>halted. Our team member noticed that the breeze had blown a
>fine layer of beach sand on top of the morning's concrete
>pour. Subsequent research showed that this layer of sand was sufficient
>to cause a discontinuity in the concrete column: a weak horizontal layer
>where the column would shear off relatively easily.
>Construction codes were subsequently changed to require a continuous pour
>without stopping to eliminate this failure mode.
>
> I gained a new respect for the importance of continuity in a block of
> concrete.
>
>-- Eric K3NA
>
>-----Original Message-----
>From: owner-towertalk@contesting.com
>[mailto:owner-towertalk@contesting.com]On Behalf Of Chris BONDE
>Sent: 2001 December 4 Tue 05:07
>To: Dave Sublette
>Cc: W9zr@aol.com; towertalk@contesting.com
>Subject: Re: [TowerTalk] Looking for Ideas for Preserving Tower Legs
>
>
>
>At 06:31 PM 2001-12-03 -0500, Dave Sublette wrote:
>Long time ago iron by the blacksmiths was protected and called black
>wrought iron. I think that the wat they protected the iron was to heat it
>to almost red then quench it in tar. It had to be coated now and then with
>molten tar. Now if you heated the legs with a propane tourch then put the
>roofing compound on the legs while hot, this might be a good method of
>protecting the legs.
>
>Chris opr VE7HCB
>
> >I coat the legs of my towers with roofing compound...black gooey stuff.
> >Your idea of treating the legs, then filling the concrete up to above
> >grade seems reasonable. I have actually removed a one yard base from the
> >ground using railroad jacks. It wasn't too hard.
> >
> >73,
> >
> >Dave, K4TO
> >
> >W9zr@aol.com wrote:
> >
> >>I am running into a problem with my tower legs starting to rust and I am
> >>looking for some ideas.
> >>
> >>Background:
>
>
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>
>
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