In rec.crafts.metalworking on 2010-12-21 Steve B wrote:
"Jim Wilkins" wrote ...
On Dec 20, 9:02 pm, "Steve B" wrote:
...It would take longer to make the
gin pole than to take down the structure.
Do you know any good tricks for erecting a gin pole or shear legs
without a crane?
[snip lots of good stuff]
One is the safe working load of the rope. Ours was a custom made 1" four
strand manila with a reverse lay. Usable life was calculated like drilling
cable. Drilling cable was calculated in ton miles, that being how many tons
had been lifted, and how many miles of the cable had been run through the
sheaves. IOW, wear. Wear could be accurately determined either in this
rope, or 1 1/8" drilling cable by caliper measurement and visual wear
inspection. Rope was not calipered, and just common sense and visible wear
was the criterion. Any broken strands made it a boat anchor rope. We used
custom lengths of over 9,000' to change antennas on a 3,000' high KATV TV
antenna located south of Kaplan Louisiana were made and used. Remember, you
have to go up, and down, and have a 3,000 tagline to hold back the load.
....
All those 3000' refs should be 2033' per fox16.com link below, or
2000', per at http://en.wikipedia.org/wiki/KATV_tower. The tallest
transmission tower in the world (2063') is 38 miles north of Fargo,
ND. It was built in 1963, a couple of years before the KATV tower.
http://en.wikipedia.org/wiki/KVLY-TV_mast says FCC and FAA have
since made it difficult to get permits for structures over 2000' feet
above ground level.
Now, your cathead and operator. It is a dirty oilfield heavy metal
operation that requires the touch of a surgeon. It takes ONE cathead
operator, and ONE person giving directions, so have a meeting ahead of time,
and assign a signal man, and instruct everyone else to either keep their
hands in their pockets or stuffed in their belt behind their backs, and
their mouths shut unless they see something clearly dangerous.
...
For example, " 'Apparently the top of the temporary jack cable we had
up top pulled out of the clamps at the anchor and let the top (of the
tower) bend over. That's what started the whole thing,' says President
of Structual Systems Technology Fred Purdy." -- from
http://www.fox16.com/news/local/story/2-000-Foot-Television-Tower-Collapses-One-Person/68WK3qaluUCutn6STJP2GA.cspx
Rigbuilding, diving, working on boats, high climbing, working with
explosives, oil well drilling, ............. it was like getting to
be a pirate.
--
jiw