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Old 12-Nov-2015, 4:39 PM   #1
Ava&Jack
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How would you fix this tower?

Here's my first post, I found this forum while searching for some help, thank you in advance for any advice you can share!

We've got a small three leg 40' tower and I noticed that it was moving around more than I remembered. I started looking at it and I can see where the bolt holes have gotten egged out and allows it to move at the first joint about 6' off the ground.

How would you go about fixing it? I thought about drilling the holes out and putting bigger bolts in, but was worried this might make the pipe weaker with the bigger holes. I thought about putting a "sleeve" pipe over it and bolting it on. I've got a portable welder and all sorts of tools, but I hate to weld on the Galv. pipe.

Any help is appreciated!

I'll try to post a picture of it:
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Old 12-Nov-2015, 11:56 PM   #2
Flint Ridge
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Looks like non-standard bolts. Which section has been egged-out? Presume the base is solidly in concrete. This could be a serious safety concern (for climbing).

Is it just the first section? Can you tell if other section bolts are rusting also? If so the problem continues upward and I would not be interested in climbing that.

Sleeve might hold water and rust. Spot welding with protective finish and new bolts, might buy you time. Risky answer.

Might drill proper sized holes, protect for rust and install new bolts that are specifically designed for this. Looks like a Rohn 25, bots aren't cheap, but worth it to avoid your issue.

Official answer take it down and start over. Safest answer

Last edited by Flint Ridge; 12-Nov-2015 at 11:58 PM. Reason: Additional idea
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Old 13-Nov-2015, 1:12 AM   #3
Tower Guy
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Yes that looks like Rohn 25 to me too.

I'd drill the holes 1/16" bigger and install the next size larger bolts one bolt at a time. Make sure that your new bolts are high strength. Do not use standard grade 2 steel.

The original problem was due to the bolts installed loosely.

The tower will end up at 90-95 percent of the original strength so your tower location, wind zone and antenna loading should be reviewed. Perhaps you can install a house bracket.

To make the tower stronger you would clamshell the tower leg joint with a half round pipe one size larger than the existing leg and add extra bolt holes above and below the existing bolts. This would be in addition to larger bolts in the existing holes.
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Old 13-Nov-2015, 2:10 AM   #4
Flint Ridge
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This is what the bolts should have looked like. Nice shoulder on them fitting into the hole. Galvanized locking nuts, looks like one of the nuts is upside down. That was the original part #.

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Old 13-Nov-2015, 2:27 AM   #5
Tower Guy
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Those are grade 5 coarse threaded bolts. Note that older Rohn 25 was shipped with NF threads. The thread pitch doesn't change the strength.
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Old 13-Nov-2015, 3:11 AM   #6
Tower Guy
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Should you opt for the clamshell reinforcement, the normal way to protect the patch from water entry and possible ice damage is to seal the seams with silicone caulk.
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Old 13-Nov-2015, 1:38 PM   #7
tomfoolery
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I would suggest drilling them slightly larger in situ and using close fitting or even fitted bolts, though that's kind of hard on something like that. Those bolts are loaded in shear almost exclusively, and there's lots of material beyond the bolt to resist shear-out, so redrilling them isn't going to weaken it in any appreciable way. And larger bolts will have greater bearing area which in turn reduces the tendency to egg out again.

If you could sleeve the interior of the inner pipe with something like compression tubes or just a heavy wall, close fitting inner sleeve, you could use friction to your advantage, but that's a lot of work, and requires disassembling the tower.
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Old 13-Nov-2015, 7:23 PM   #8
Ava&Jack
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Thanks to all of you for the advice, I think I'll try to do a clam shell and oversized bolts. I'll take a picture of the final product!
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Old 14-Nov-2015, 10:30 PM   #9
Stereocraig
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I have used bar clamps to pull the two sections snug, before bolting them.
Hammering on the bracing to accomplish this, may not be a good idea.

Otherwise, all of the above work arounds, sound acceptable.
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Old 14-Nov-2015, 10:34 PM   #10
Ava&Jack
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Quote:
Originally Posted by Stereocraig View Post
I have used bar clamps to pull the two sections snug, before bolting them.
Hammering on the bracing to accomplish this, may not be a good idea.

Otherwise, all of the above work arounds, sound acceptable.
I've got 2" ratchet straps on there right now, they seemed to pull them together, I just haven't had time to make the clam shells yet.
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Old 15-Nov-2015, 11:14 AM   #11
Tower Guy
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If you can center the drill in the center of the egg shaped holes you'll end up with a better repair. The straps you have installed may get in the way of that goal.

I'd wait for a calm day and push the tower up one leg at a time using a jack and wooden supports.
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Old 19-Nov-2015, 5:13 PM   #12
Ava&Jack
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Here's what I ended up doing, I used grade 5 bolts that were long enough to get the shoulder all the way through. We've got 50 mph gusts here today and it looks like it's working very well.

Thank you again for all the advice!
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Old 19-Nov-2015, 11:27 PM   #13
Tower Guy
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Nice job. That's stronger than new. Don't forget to seal out the water.
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