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Reply To: | adaptive re-use is from the department of repetitive redundancy division < [log in to unmask]> |
Date: | Sat, 8 Dec 2007 07:40:55 -0500 |
Content-Type: | text/plain |
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c,
> I just cannot figure out why such an apparatus would so drastically
> fail, especially after two guys were involved. But then there were
> plenty of engineers who went over the Titanic designs.
As Eric mentioned there is a difference between a permanent rig and a
temporary rig. A permanent rig I am used to calling a house rig. A
permanent rig is kind of incorporated into the building system. Usually
it was installed when the building was built. There are lot of different
configurations.
What I am used to seeing is on the roof to the inside of the parapet
there will be a rail that runs above the roof and that at intervals will
be supported on steel posts that go into the roof that I assume are
anchored to the building structure. You will then have posts that roll
around on the rail that support outriggers that support the scaffold
itself. It is usually designed in such a way that you can swing the rig
out over the parapet, or swing it in and move it around to another
location on the roof. There will be wires going to the house rig. Should
be different sorts of safety controls.
Window washers do not maintain these rigs. The rigs are maintained by
elevator service companies. In order to operate a rig you need to be
certified by the mechanics that work for the elevator company. That
process takes like a half hour on the site. So you can easily imagine
that the window washers might now have much of a clue about the
condition of the equipment. For those who work on temporary rigs they
are more apt to be intimate with the system as they assemble and
maintain their equipment on a regular basis. A temporary rig may also be
a bit less complicated of a system than a house rig and easier to
understand by a user.
The reason a house rig would fail is probably not that it was
particularly poorly engineered to begin with, though it could have been,
but likely has more to do with if it was stored in a manner to keep it
intact, or if it was maintained properly. Such things as cutting off
wires and leaving them dangling the guy from the elevator company may
feel just fine about that but it does not mean that it is safe. If you
do not understand the system and you are told by some guy that it is
safe the tendency is to believe them. Knowledge in this case is life.
Though the building owner may claim no responsibility it also has to do
with if they were willing to pay for an elevator maintenance company
that that was not into going the cheap way... at least when a wire is
cut that could be a safety override tape up the end of it and tie it off
so that it does not swing around in the air. As I recall, and I can be
corrected on this, there is not an independent inspection of house rigs
in the way that there is an inspection of elevators. I believe, if I am
not incorrect, that the elevator maintenance folks are supposed to look
at them once a year. A house rig can be forgot to be checked. I tends to
be up to the building engineer (maintenance) to keep track of these
maintenance issues. Though the building staff may not directly be
responsible for the hands-on maintenance they are responsible to make
sure the inspection schedule is kept up.
Though from Ralph's Xmas Party conversation it sounds like it may have
been a swing stage (temporary rig).
Later,
][<en
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