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[TowerTalk] self-supporting steel tower questions

To: <>
Subject: [TowerTalk] self-supporting steel tower questions
From: (
Date: Mon, 2 Feb 1998 18:12:53 EST
In a message dated 98-02-02 15:49:15 EST, writes:

>  Tower was originally welded
>  together at swaged joints, and for removal the legs (and cross-members)
>  cut at three places (not the swaged joints) and the base, and the four
>  sections were removed with a sign crane. Lower sections use tubular steel
>  for the legs, about 2.5 inches at the base, and upper sections appear to be
>  solid steel. The tower is painted, with some light surface rust at spots
>  appears to be sound. The base was mounted using angle-steel welded to the
>  three legs, and bolted to three pieces of angle steel set in a concrete
>  that was about 6 feet square (depth unknown). The price is right (probably
>  less than scrap value), but.....
>  Questions: 
>  1) What would be the approximate weight of the whole tower?

    Who knows? How thick are the leg walls especially the bottom ones?

    140 foot Rohn RTP = 3348 pounds (70 MPH rated) 2.5" legs - 10.5' face
    140 foot Rohn RTP = 4080 pounds (90 MPH rated)    "                   "
    140 foot Rohn 55G with guys = around 2000 pounds
>  2) Likely manufacturer? Any markings to look for to determine this?
    There are literally dozens of tower manufacturers. I've never seen one
with welded leg joints. Probably a small manufacturer that you'll never find. 

>  3) Would it be feasible to weld the tower together at the places it has
>  cut, to put this into service again?
     Hmmm. Maybe. I'd grab a buddy who's a machinist, steel worker, engineer,
etc. who might be able to give you some perspective. 

     Would I put this thing up? Probably not. You've got to haul it to your
QTH using a boomtruck to load it on the freight truck and then unload it all.
Doesn't sound like you can put this in the back of your pickup.

    Then you've got to get a welder out to do the re-welding while it's being
held up with that boomtruck again. Now you've got to get a real crane in to
lift it up into place. 

     This will work with the following assumptions:

1.  The steel is okay.
2.  The tower is structurally straight and okay.
3.  You determine how big the base should be and install it.
4.  You determine what anchor bolts and fixture are suitable.
5.  You make an educated guess to what the capacity is and at what wind speed.
6.  You fabricate thrust bearing and rotator shelves.
7.  It gets welded back together so that it's true, safe and reliable.

     You're obviously not saving yourself any money or time with this project
so I would suggest sticking with a known quantity if you really want to put up
a new tower. 

     BTW, New Castle county is a 75 MPH wind speed zone but you're within 100
miles of hurricane oceanline so you probably want to use 80 or 90 MPH for a
system rating speed. 

73,  Steve  K7LXC

    TOWER TECH -- professional tower supplies and services for amateurs

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