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Do You Know Where Your Tower Came From?
Bob Turner (N2NFG)
on
July 10, 2003
View comments about this article!
Title.... Do you know where your tower sections have been?
A couple of weeks ago here in Warren County, NC, the local radio station, WARR had their tower fail. It was 150 feet of ROHN 25G that came down when a tractor mowing the field surrounding it snagged the guy wires at one of the anchor points. There were no injuries other than a scared tractor driver.
A few days ago I drove to the site to see if any of the sections that had fallen might be available to salvage. I was fortunate to get there just as the tower crew was finishing up with a brand new 150' 25G tower for WARR. I asked the owner of the tower company about the availability of the fallen tower, and he directed me to where they had stacked what was left. WOW! Lots of good straight section, big insulators. and probably some salvagable guy wire. I.m currently going up with 70' of 25G to support a 2 element tri-band quad. I already have those sections, but plans for the future include a 2 element 40 meter yagi at 70' and a 30' tower to support a Hustler 4BTV vertical. I was in heaven! I was quickly brought back to earth when the tower guy asked me what I intended to do with the sections. After explaining my plans to him, he stated that it would not be safe to go more than 30' high with any of the fallen sections. Why not? He explained that there was no way of telling how badly stressed each section was subject to during the collapse. Welds that look fine on the cross braaces could fail under additional stress. The tower could buckle at the joints under stress. This stress could be as mild as a normal wind or even the twisting of the tower by rotating a relatively light antenna. YIKES, do I know where my used tower sections at home had been? Do you know where your used sections came from? Fortunately, all of my sections with the exception of a top piece could be accounted for. But just to be safe, I'll take the following precautions:
1. Before repainting, I'll check all of the welds on each section. Remember that paint can hide small cracks, so examination before painting is a must.
2. Check for any kind of stress at the joints between sections.
3. The next time I buy used sections, I'll get a history of prior erection. Was it taken down, or did it fall down? I'll stay away from the ones that fell down, thank you.
I'm not trying to scare anyone away from buying used tower, there's plenty of good stuff out there. It's also the only way many of us can afford a tower at all. A little prudence and listening to the advice of a pro never hurts though!
This article has expired. No more comments may be added.
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Do You Know Where Your Tower Came From?
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by KA4KOE on July 10, 2003
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I'd forget it and buy new. A friend of mine was injured by a "used" tower. Fractured his pelvis and S1 and S2 as it fell with him on it.
Philip
KA4KOE
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RE: Do You Know Where Your Tower Came From?
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by KD7EZE on July 10, 2003
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Bob---
I suppose what the tower crew told you has some validity, but not in all occasions. One of my current towers (63' of 25G) suffered a fall, from its original owner. I got the sections for $10 each, and after close inspection, took them home. It's been erected and used for over 10 years, in two different states. It supports multiple quad beams, and has never given me any trouble. Sounds like the radio station should have fenced in the areas where the guy wires make contact with the earth. The commercial towers here all do that.
'73 de KD7EZE/5
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Do You Know Where Your Tower Came From?
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by WV8WC on July 10, 2003
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Yikes indeed! I'm sure going to take a good look at the used tower sections I have before putting them up. I got these from a co-worker who got them from a cell phone tower site. The installer was putting these four sections on when they dropped from the crane, bending the bottom one slightly. The guy just wrote them off and my co-worker picked them up. It's been hammered back out, but with this info not I'm not so sure I'd want to trust it.
Shane
WV8WC
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Do You Know Where Your Tower Came From?
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by VA3BJD on July 10, 2003
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I would forget it. Listen to the tower guy...he obviously speaks from experience. Most of the the stress points will be hidden under the surface. You cannot see them without cutting and examining the metal and welds under a microscope. It is not only the joints that come under stress.
You are gambling using this tower. Sometimes gambles pay off sometimes they don't.
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RE: Do You Know Where Your Tower Came From?
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by KE4SKY on July 10, 2003
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Unless you have the means to ultrasonic and xray inspect EVERY weld, you have no idea whether the welds are sound. Due to cost this isn't practical unless you are either "in the business" or know a cooperative ham who is.
I put up a "free" tower which was given to me, and had good results, but I knew exactly where it came from. The Rohn HDBX48 was located at the home of an SK whose estate wanted it removed to that the house could be sold. It was erected as a self-supporter, but we rigged temporary guys to enable it to be disassembled.
Because there was some surface rust due to weathering, individual tower sections were sandblasted at my brother's work QTH, which had a sandblast pit large enough to do truck bodies. Then we trucked the sections to a commercial shop for a hot acid dip, which efectively "disassembled" the sections by dissolving the aluminum rivets holding it together, as well as removing all oxides to bare metal to enable a close inspection. Any bent or questionable cross bracing was replaced with new pieces we fabricated in the shop. All pieces were then hot-dip galanized at a total cost of about $150, and the sections reassembled over the winter using approximately 450, 1/4-28 stainless steel aircraft grade 18-8 bolts, each coated with anti-sieze compound and torqued to AISI specs as each section was squared and plumbed. New structural grade bolts were used in the final assembly. We used a cone penetrometer to verify the soil bearing capacity of the footing, and had a fellow ham who is a PE verify and seal the calculations needed for a county building permit. The tower has been up eight years and has survived numerous wind and ice storms. It also serves as my Skywarn severe wind gage, as the 15 ft. Telex reinforced mast section in the rotor box "sings" like a fog horn during storms once the wind velocity hits 66 mph, measured.
This "free" tower was not cheap to put up right, but has proven safe and satisfactory, because we were cautious and I urge all others to weigh safety over cost.
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RE: Do You Know Where Your Tower Came From?
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by AC5E on July 10, 2003
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There's a LOT of good information here. Let me add that any used tower should be commercially re-galvanized before erection. Rust can and does set up inside the tower, and at the joints. Even a tiny pinhole in the original galvanizing can quickly become a hole in the tower.
The cost is comparatively small, and most of the small lot shops do as good and often a better job of galvanizing than the tower makers. So that job falls in the category of cheap insurance.
And - do go to the auto parts store and get some "stainless steel tape" or to an industrial supply for stainless steel shim stock. Anything that is not galvanized attached to the tower should have a layer of stainless steel between the clamp/block/or whatever and the tower itself. Some rain is as acid as lemonade and a dissimilar metal joint can quickly become a tower on the ground.
73 Pete Allen AC5E
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RE: Do You Know Where Your Tower Came From?
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by W9WHE on July 10, 2003
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The "tower guy" was right.
Its one thing to buy a used tower that has been hinged or taken down without excessive stress. Its an entirely different matter to use sections of a FAILED tower that FELL. Unless you magniflux and X-ray the entire section, you really don't know whether there are cracks or fatigue. Visual inspection is NOT adequate.
But hey, its just your life and that of your family & neighbors!
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Do You Know Where Your Tower Came From?
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by N3QT on July 10, 2003
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You DAWWG!!!
Old Irish Saying, "If you fell in a pile of @#$%, you'd come up with lump of gold".
Congratulations!!! Enjoy it.
73, John DE N3QT
p.s. What was the name of that lawn service? I will have to recommend them highly in my area...hi hi hi.
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RE: Do You Know Where Your Tower Came From?
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by W0FM on July 10, 2003
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The mother of all tractor-pulls and they didn't even sell a single ticket!
WØFM
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Do You Know Where Your Tower Came From?
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by AA6DX on July 10, 2003
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In the commercial business of 2-way for a while in my "careers" ... and a big no-no was including used towering for any purpose, even though the customer would have loved to save the $$$$. Just think of the liability risks! ON THE OTHER HAND .. for my own use, totally within my property (like, out in the country, like I used to was) ---- Hmmm .... 73 -- Mark
AA6DX
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RE: Do You Know Where Your Tower Came From?
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by W9HZ on July 10, 2003
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I've just got to respond to KD7EZEs comments.... You've been lucky that's all there is to it. You say you did "A close inspection", did that include ultrasonic or liquid penetrant or possibly a magnetic particle test on EACH and EVERY weld on every section of tower?? If your close inspection consisted of nothing more then a visual of each section, I'd say you have a lot to learn about welding and metalurgy. After 20 sometning years in the nuclear power business, I've seen more then enough welds that looked perfectly acceptable on visual, but upon closer examination turned out to be little more then a thin surface layer covering a void or crack. Every time you climb that tower, everytime the wind blows, you are subjecting yourself and possibly alot of other people to unecessary danger and possibly injury or death. Just because it hasnt come down yet, isn't an assurrance that the tower is in good shape.You are risking your life and the life of everybody around you by betting on an unknown.
KD7EZE.... please rethink your actions before somebody gets killed and you end up trying to explain your actions to a jury in a criminal trial.
I really don't think the excuse: Well ya see your Honor... I got it really cheap, will hold much water.
Mitch
W9HZ
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RE: Do You Know Where Your Tower Came From?
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by KO4BB on July 10, 2003
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I think Mitch is basically right, but maybe going a little overboard. After a tower fall, you are not trying to see if the tower is suitable for use in a nuclear plant. You are not trying to see if the solder joints were made right to begin with (I assume that Rohn's production test is sufficient and adequate to establish that the product they ship is suited to the purpose). You are only trying to determine if there was mechanical damage to the tower.
The kind of defect caused by mechanical stress is quite different from the type of defect caused by improper manufacturing process, and the inspection process is therefore somewhat different.
That is not to say that it is easy to do, but I do believe it should be possible.
I believe that fall damage will leave visible traces, as the stress will have been externally applied on "presumed" good solder joints (should I say "previously proven" good solder joints, assuming Rohn puts the tower sections through some sort of mechanical stress as part of their production testing). Evidence of stress may be on the solder joint themselves, or on other areas of the tower section.
Now, evidence of such stress may not be easy to spot, and this is something each ham who reuses tower sections for his own installation will have to wrestle with, as I am sure you will not find anyone able or willing to certify such hardware because of liability.
A safe guideline would be that any evidence of mechanical stress anywhere on the tower section would be sufficient to discard it. This does not necessarily include scrapes, but if the scrape is deep enough to expose the metal under the zinc plating, throw the section away.
In addition, you want to make sure you will not use the tower anywhere near its maximum ratings and guy it properly.
Didier/KO4BB
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RE: Do You Know Where Your Tower Came From?
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by K9VDD on July 11, 2003
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After reading the article I would offer the following: I have been involved with towers for over 30 yrs and have supervised the erection of over 100 cell towers. Having a failure like that HAS TO have caused serious internal stress failures to most all sections. You have no idea how much stress was put on those sections in such a short time span. I completely agree with the position of " If it fell, let it rest in peace in a junkyard," not a cemetery where a short sited inexperienced ham, or an innocent bystander might just end up as a result of a "good deal!!" Rohn 25 will not take much stress under those conditions to become unusable, so be safe, not sorry at an unnecessary funeral or court proceeding.
www.qsl.net/k9vdd
73, Ralph K9VDD
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RE: Do You Know Where Your Tower Came From?
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by K0BG on July 11, 2003
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What ever happened to the phrase "Safety First!"?
Buying used anything falls under the old adage "Caveat Emptor". Sometimes you get a good one, sometimes not. A used rig typically won't kill you, but a uses tower can and does. Personally, my life's worth more than saving a few bucks.
Alan, KØBG
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Do You Know Where Your Tower Came From?
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by NK7J on July 11, 2003
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IF you put up a tower that has previously failed you are just plain stupid. I am sorry but that is the way I see it. So far I have seen 4 tower failures (all rohn guyed towers by the way) and actually seen one go down (cat operator found guy wire) and if you could see the stress that these peices endure during a collapse there is no way you would want to use them! I disagree with the notion that there will be visible signs of fatique or failure. There MIGHT be but who wants to die for that chance? Think about the tourque and stress that occors in sharp spurts while that tower is coming down and stress the tower sections to thier limits.
In every case of tower failure there are pieces left that look good. Here is what I do with them, I get out the cutting torch and cut them into peices that no one will ever try and use as a tower and they get hauled off to the scrap iron pile.
Think Safety, not how cheap can I get by.
Jack
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RE: Do You Know Where Your Tower Came From?
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by KE4MOB on July 11, 2003
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150 feet of 25G? I'm surprised that there is anything left that isn't bent into a pretzel.
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RE: Do You Know Where Your Tower Came From?
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by KD7KOY on July 11, 2003
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My favorite "tower" is a 50 foot tree made by 'God Inc.'. It's been there for..er..about 80 years I think. Also there is a side benefit..Shady in the summer. ; )
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Do You Know Where Your Tower Came From?
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by KZ1X on July 11, 2003
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Bob
I'm in Chapel Hill.
I'm glad you got a good deal, and hope things work out well with the install. Take it from me, nothing beats having a nice tower and beams! Also glad that the radio station is back on the air. Community broadcast radio, our cousins on the air, is an important American institution.
I don't mind working on my tower, and it's an 80-footer.
But - I hope you won't mind if I decline to climb yours (if I was ever asked). I have some formal training in metallurgy. That bargain could turn into a liability, really quick. If YOU climb it, PLEASE be careful. Don't ever want to read about you getting anything but DXCC.
Steve
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Do You Know Where Your Tower Came From?
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by W4ROT on July 11, 2003
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Good read Bob....
First Maxwell, now Newton. How much is there to learn in this Hobby?
An antenna at 70 ft ain't worth dying for.
But what about 150?
Please, Nobody fall !!!!
Terry
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RE: Do You Know Where Your Tower Came From?
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by N1RWC on July 12, 2003
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First I would like to say that there is some validity to the replies earlier in this article. I am a former heavy steel fabricator and welding is a science that not everyone can master. Some guys mentioned UV Inspect and X-Rays...Here's my 2 cents worth.
First stop at a Welding Supply House and see if you can rent or purchase a small handheld Mag Particle Tester. It consists of an U shaped Electromagnet, and a bottle of Fine Red Powder. You place the magnet on the pieces in which the weld is connecting and sprinkle the powder on the weld. The powder will get in the cracks of the weld if present and mark any cracks or welds with the collection of red powder. If you are so Inclined, you can repair (Reweld) these cracked welds to make the tower salvagable.
As for the liability aspect. If it is for your own use and you feel confident that you can use it safely, then go for it. But if you have any thoughts of problems, rethink and reinspect before trying. use guy cables and grade 8 Bolts for everything on it, I have seen some free standing towers that the manufacturer claimed was free standing start to collapse but didn't because the owner guyed the tower in place.
I have a 40 foot free standing tower that I am looking to put up in my back yard, been saying that for the last 5 years now. The only thing stopping me is time and money. The tower is used, came from a ham in CT who did not put it up, and the price was right, namely "get it off my property". Hope this helps. 73 matt N1RWC
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RE: Do You Know Where Your Tower Came From?
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by KD7EZE on July 12, 2003
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W9HZ Mitch----
How is somebody going to be killed? No one has ever climbed my used tower, or any other tower I own, for that matter. I erect my towers, install my antennas, and perform service & maintenance, using my "bucket truck". Actually, it's a former firefighting snorkle truck, that will get me safely higher than any of my towers. I don't like to climb, and fortunately, I don't have to. I do think you went a little overboard in your inspection procedures statements. All that infrared, x-ray technical process is just unjustified. It's not like I'm erecting a massive radio station or TV transmitting apparatus. I, like many of the hams that I know, don't have bazillions of dollars laying around, to spend on the extravagant equipment or testing. I know a bargain when I see it, and the obvious junk can be easily spotted as well. If, in the unfortunate event, that any of my towers would come crashing down, the only damage would be to terra firma, my antennas, rotors, etc. and obviously some or all of the tower sections. As there are no buildings within the falling radius, with the exception of my concrete hamshack, only I would suffer any significant loss, i.e. the aforementioned equipment.
'73 de KD7EZE
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RE: Do You Know Where Your Tower Came From?
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by W9HZ on July 13, 2003
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KD7EZE...
Well, it's really nice that you have an old bucket truck to do your work from, you didn't mention that earlier though, and very few of us are as fontunate as you to have that. As far as liability goes, if a tower comes down and damages some ones property or injures them, you have a liability problem. In short a tower of questionable integrity is a liability and not an asset.
You may live where liability from damage isnt a problem but, alot, probably most hams, live where that is a concern. I don't want to have the legal or moral liability on my mind that my tower came down and injured someone or destroyed part of the home, because I could save a few bucks on a tower.
I was trying to make a point, you dont just put up a tower that has come down from a catastraphic failure. A tower that has fallen has been subjectted to unknown stresses. You don't know where the weak or broken parts are and a visual inspection just isn't good enough to say everything will be alright. There can be defects that won't be visible, small cracks that can propagate over time, slight deflections in the tubing so on and so forth... I'm not going to get into a discussion of ASME or AWS specifications, that is not my area, I have worked with enough welding and structural engineers over the years to know that a peice of metal may not be what it appears to be on the surface.
Did I go over board... No.... I just made a point that you can't assume everything is fine from a visual and you have to do something in excess of that to insure it's integrity. Your comments in your origianal post about being able to look at and see the bad sections is just plain wrong and could lead someone to commit a very serious mistake, which could cost them their life.
One responder to this thread used the term "solder" throughout his response. Soldering is a very different process then welding, it serves a very different purpose. Would you want them to inspect a fallen tower with you???
Mitch
W9HZ
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RE: Do You Know Where Your Tower Came From?
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by W9HZ on July 13, 2003
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Just in case someone might be interested....
Do a Google search on "tower failure" (put the words in quote marks) and see how many hits you get. You'll see some stuff about the World Trade Center towers and alot about antenna and mast failures. I found one set of picstures of a Rohn 25 tower that had come down. There wasn't much left that was even regognizable, kind of makes me think twice about trying to salvage anything.
Mitch
W9HZ
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Do You Know Where Your Tower Came From?
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by WW1Z on July 14, 2003
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I think it was Matt KC1XX of XX towers who told me that when they remove a tower for any reason he has each section cut in half. Really cuts down on liability concerns. Years ago I got 100 feet of Rohn 25. It had been used as for TV reception and the "pros" who installed it had under guyed it. One set of anchors. In a nasty wind storm one of the anchors pulled out of the ground. Tower was guyed at 4 places with some of that plastic coated stranded wire. None of which broke! The tower went into a tree at not to great of an angle. Another company came in and removed it from the tree with a crane, which they used to set the new one. A very nice new installation. I bought a straight and another top section and have had to 60 footers for 20 years. Still look good. I will note that both of them are rather unloaded by ham standards, sorrounded by much taller trees and worse am located at the bottom of the hill. Not exactly high stress installations!
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RE: Do You Know Where Your Tower Came From?
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by KE4MOB on July 14, 2003
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If it's so hard to tell good tower from bad...and if tower is so fragile that seeming good looking tower can be a deathtrap...
How do you know that "brand new" tower that you installed 10 years ago won't come down when you climb it the next time or the next windstorm comes along?
You don't.
I would hazard a guess and say more people have been killed falling off towers in perfect condition than have been killed riding one to the ground. I would go even further to guess that most "tower failures" aren't tower failures at all...they are actually failure of tower guy system (due to a doofus hooking the guy wire with the mower or improper anchoring or an antenna falling taking guy wires with it, etc).
Looking at it from a purely structural viewpoint, one could stack tower up as high as he wanted to until the bottom sections couldn't hold up the weight. As long as the wind didn't blow or there wasn't any uneven loading, the tower would stand. What kills towers is when a non symmetric loading occurs and the tower travels "out of column". It's not the tower itself, it's the guys. If improperly guyed, even a good tower will come down.
I would look it over...I'd reject any sections that are bent even in the slightest or have even minor dings on any of the tubes. Ditto for tubes that are split (often caused by an owner not keeping the weepholes cleaned out and water freezing inside and bursting the tube) or have crimped ends or obviously bent ends. I would probably even go so far as to check each of the tubes at midspan of each section for roundness by using a vernier calipers and reject any that were out of round. Then I wouldn't go over 40 or 50 feet and securely *and properly* guy it in at least 2 places.
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RE: Do You Know Where Your Tower Came From?
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by KE4MOB on July 14, 2003
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Oh, and by the way, here's a pic of what Rohn 25 is capable of handling...
http://www.ki4d.org/towerlean/
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RE: Do You Know Where Your Tower Came From?
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by N0TONE on July 15, 2003
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KD7EZE, most of us don't have the bazillions of dollars needed to rent a bucket truck.
Rohn 25G is pretty cheap stuff, really. Not built all that well. 50 feet of it would run about $400-$500 brand new. FAR LESS than what most of us would have to pay to rent that bucket truck that you're in the fortunate position of being able to use for free.
For any of us, it comes down to this: we get what we can as it's made available.
I have helped others put up used towers. The basic method has always been the same: since you can get fairly up-scale commercial A-frame towers for "free to whoever takes it" that's what the guys always use. No welds, these are usually all-bolted towers. If you're really picky, you replace all the hardware with grade 8 stuff - the strongest made. You borrow the best gin pole you can, use hard hats and have a good crew.
People get killed by towers in many ways other than climbing. Antennas can fall and kill. A guy working on a tower can drop a tool and kill. Thank God it's rare, but it has happened in recorded ham history. I have had the sad experience of sitting on a jury where the death being debated was caused by a guy wire snapping loose from a tower and impacting the victim.
Please consider safety and all of the ways that a tower can kill and make sure you have backups for all of it.
Merely not climbing it does NOT protect you from all possibilities.
Also, I've done the engineering calculations. Rohn 25, more than 70 feet, even with guy wires, scares me. If your antenna is not torque-balanced, the twisting force on the tower can put incredible forces on the welded joints. Even without torque, when the wind blows, the guy wires change the sideways force into downward force. Have you ever played the game where you stand on an empty Coke can? You can do it, until the slightest tap on the side of the can, and the can then collapses. Similarly, a tower can endure these massive downward forces (tons with a large antenna and 80 mile per hour winds), as long something hasn't weakened in one leg. One bad rust spot, and you have a problem, if you have chosen to use a minimal tower like Rohn 25G. Mind you, I like Rohn, but when you use the least tower you can get away with, and you don't carry out a commercial-grade inspection and maintenance program (annual regalvanizing, etc) you run a lot of risks. I don't actually know any ham who maintains the tower according to Rohn's specs.
On towers that fell, I'm actually not that spooked. In my many decades of metalwork, I have seen extremely few instances where a weld or joint was stressed to the weakening point, but did not fail at that time. It's actually hard to do if you think about it. The exception to this rule is aluminum, or any situation where you repeatedly stress and release metal. Steel does better than most in this case, too, though. I'm just spooked about how "on edge" many of the ham installations are to begin with.
For my own peace of mind, my antennas are all intalled in mother nature-provided trees, plus one light mast. If my mast fell, it could not kill anybody - I don't have that much weight on it.
So please, be careful. Tower safety is not a place for joke, or getting upset about what someone else said. It is a time for sober reflection, and careful consideration of everything that can go wrong.
AM
>>>W9HZ Mitch----
How is somebody going to be killed? No one has ever climbed my used tower, or any other tower I own, for that matter. I erect my towers, install my antennas, and perform service & maintenance, using my "bucket truck". Actually, it's a former firefighting snorkle truck, that will get me safely higher than any of my towers. I don't like to climb, and fortunately, I don't have to. I do think you went a little overboard in your inspection procedures statements. All that infrared, x-ray technical process is just unjustified. It's not like I'm erecting a massive radio station or TV transmitting apparatus. I, like many of the hams that I know, don't have bazillions of dollars laying around, to spend on the extravagant equipment or testing. I know a bargain when I see it, and the obvious junk can be easily spotted as well. If, in the unfortunate event, that any of my towers would come crashing down, the only damage would be to terra firma, my antennas, rotors, etc. and obviously some or all of the tower sections. As there are no buildings within the falling radius, with the exception of my concrete hamshack, only I would suffer any significant loss, i.e. the aforementioned equipment.
'73 de KD7EZE
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Do You Know Where Your Tower Came From?
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by KD2E on July 16, 2003
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Well, If it fell once, I don't think I would be climbing on it at any height.
But you mentioned a vertical at 40 feet??
Use it for that...perfect! You are probably going to walk it up anyway!
Even in that case, I'd wrap it here and there with a rubber mallet, and listen for the vibration characteristics. That will tell you real quick if a weld let go.
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RE: Do You Know Where Your Tower Came From?
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by KB5UVC on July 16, 2003
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You have a very good point. I had a 38ft. Rohn 25 which was on the property when I bought the house 12 years ago. (No telling how long it had been up) that sufferd a fall. When I inspected the tower I discovered that the nipple on the tilt over base plate were rusted and two of them were almost broken off. By the amount of new metal showing, this condition had apparently existed for some time. I had the welding shop next door reweld the breaks and they added gussets to reinforce it. They welded the top half of the base plate to the bottom tower section. I put the bottom 10 ft. setion back up for the TV antenna. It could be very possible that the inside of the rest of the sections is also bad.
If I put any of the old tower and other tower sections I have collected up it will only be for a short tower just to support the TV antenna. I don't think I want to trust my KT-34a beam to bad tower sections
Bottom line is INSPECT your TOWER FREQUENTLY including guy cables and insulators.
Ron Hughes KB5UVC
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RE: Do You Know Where Your Tower Came From?
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by K1YA on July 16, 2003
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Responding to "what rohn 25 can handle" on web page http://www.ki4d.org/towerlean/
First of all, I am not a tower expert but it doesn't seem like good engineering practice to hold up a 155 foot tower with screw-in guy anchors. Looking at the tower construction photos, the base concrete is not even sloped away, so water can sit and rust out the bottom section. And those tower sections look used, but I can't be certain. Yikes.
But in my estimation, after being subjected to the bending loads as shown on that web site, the tower sections (and bolts) are most likely damaged to some extent, and anyone who would climb that now should have their head examined. :)
Also interesting is that the web site has a link to "tower safety", but there is nothing there...... hmmmmmm.
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Do You Know Where Your Tower Came From?
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by K0KN on July 17, 2003
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Kind of off the subject, but it's closely related:
I am in need of some large bolts to build my tower base for a custom tubular tower.
Can anyone recommend a source for good, strong bolts? This tower is a crank-up design, and is about 40 feet at full height.
The original base bolts were 18" or so in length, 1/2" or 3/4" size.
Does anyone have any ideas? Please reply to
k0kn@qsl.net
Thanks!
Kyle
K0KN
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RE: Do You Know Where Your Tower Came From?
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by KE4DRN on July 18, 2003
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Interesting photos of the bowed tower.
Structural integrity has been exceeded !
Oh, and by the way, here's a pic of what Rohn 25 is capable of handling...
http://www.ki4d.org/towerlean/
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RE: Do You Know Where Your Tower Came From?
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by N4UE on July 24, 2003
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Very interesting article and responses.
One thing I haven't read is model of Rohn tower. I have a friend who was very proud of his purchase of a bunch of Rohn 25G. Looking it over, there were sections with 7 horizontal bars (20G) mixed in with the 25G, which has 8 horizontal bars per section. The thing is, that they mate perfectly. However, there is a MAJOR difference in the weight of the 2 models.
I understand that for economy of manufacture, Rohn probably uses the same fixtures for both. Yes, even the zig-zag braces are smaller guage in the 20G.
Imagine a 100' tower with a large array on top. Properly guyed, there would be tremendous vertical forces acting on the base. If the first section out of the ground was 20G, there could be a major problem.
I am in the process of putting up 2 90' towers. One bracketed to the shop at 30' and 3 tiers of guys from 5 locations. Yep, lots of guy wire. It is a 20G I got from my neighbor. It still has the 'warning' tags on it. It is only going to have a 6M and 432 antennas on it. The 25G is 80' feet away and will have the conventional 120 degree spacing of guys at 3 levels.
I am fortunate that these will NOT be able to fall on anyone's land but my own. However, I still have to get up and fown it!
It would be great if a welder from Rohn could make some comments here.
I have a good friend in Lexington, Ky that is a Certified Weldor for Link Belt. One time he had to travel to Oklahoma for 3 weeks to do field repairs. He took a week and a half of vacation at the end of his work trip. When he got back to the plant, he had to be recertified before he could weld.
The reason? He was out of the plant for more than 30 days at one time! Made no difference if he was welding for the company in the field. He was really sweatting it too. The test is brutal and if you have one joint fail, you go to a job at about 1/2 pay.
All the test welds are X-rayed and they have a huge hydraulic machine that pulls apart sections of tube steel that uou have to but weld together. If one weld breaks, you're done. All of his held and this machine actually pulls the tube to failure!
ron
N4UE
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RE: Do You Know Where Your Tower Came From?
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by KC8YFT on February 22, 2004
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imagine the liability of poor or faulty welds on a rollercoaster train...failure could be tragic and or fatal. any neglect or complacance to safety is unacceptable and intolerated.
so, guess what i do to generate money for my ham hobby....you guessed it, work on rollercoasters.
we involve a third party company to perform all of our non-destructive testing. using the aformentioned electromag and blue powder ( we don't like the red, it "stains" our rides ) they test the welds on various components. same concept here, paint hides too much, and we need to look deeper. as for a shop rate, i couldn't begin to tell you how much of the green stuff they get, but i'm sure a "house call" is not cheap. is inspecting the welds a guarantee against component failure??? absolutely not!! we all know what guarentees are good for, an undeserved element of comfort. there is no way to tell if steel is fatigued. testing only shows cracks, be they in welds or otherwise.
bottom lline---if non-destructive testing is good enough for rollercoasters, it's good enough for me.
if you don't feel confident about a used tower, sections of, or otherwise, have them tested or replaced. if you have no regard for your own life, please respect others, and make sure that anything you do doesn't impose any kind of hazard upon others.
you know, common sense stuff.....
73's jack
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