Paul van der Eijk wrote:
> My tower was damaged by a truck delivering gravel (one guy and
> 2m antenna in the top.) Their insurance wants to prorate the years I
> owned the tower over the useful live of the installation. I'm not sure that
> this is acceptable, but if I have to make the choice, what would be the
> useful live of the installation?
> Tower is 90ft Rohn 45, guyed by a mix of phillystran and steel cable.
> 73 Paul KK4HD
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What they are doing is "depreciating" your installation. This is a
typical insurance procedure and is quite logical. You have already used
the portion the useful life prior to the accident and the company who
caused your installation to fail is responsible only for that portion of
the useful life AFTER the accident. At the end of the useful life you
will have to pay for improvements to extend the useful life. The
accident causer is not responsible for this either. That's the logic.
Now to your question. I obtained a chart depicting the useful life of
the galvanizing of a steel tower under various environmental conditions
(eg, urban, sea coast, residential, industrial, etc). That chart
identified the useful life in terms of the amount of galvanizing
remaining on the tower and defined end of life when there was 95% of the
galvanizing remaining, ie, 5% rust.
As I recall (I don't have the chart in front of me), in an urban,
non-corrosive environment, the useful life was 30-35 years.
The chart is probably available from the American Galvanizers
Association. Their web site is: http://usalink.net/aga/
Hope this helps.
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