How To Restore A 25G Tower

[flintstone mop]

Hello All,
I was able to acquire, in the true sense of Amateur Radio, a few sections and a top section of 25G tower.
Rusting in certain areas and someone liked blue. The blue paint if chipping off. The top section is lightly rusted. No severe rust that would become a safety hazard.
What are ways to bring it back to life and protect what's left??
This will be for my 6M station.
I do not have $400 to hire a crane to instal another antenna that would be inaccessible on my bad idea utility pole.

Thanks for any guidance
Fred

[DMOD]

Hi Fred,

I would be more concerned with what I can't see.

Is any chance you could borescope the hollow tube legs to see what corrosion might be inside?

Phil - AC0OB

[W7TFO]

Rohn sections are galvanized inside as well.  Corrosion is almost always the result of physical damage like scratching or rubbing off the zinc, seldom found in the inside. 

Since the sections fit together telescopically and are open from end to end, there is no way for water to build up or set inside.

The pros will wire brush the rust off and spray what is called "ColdGalv" on the areas.

Kinda like a thick spray paint, it stops the rust.  It isn't permanent, but it lasts a long time.

73DG

[Pete, WA2CWA]

[W7TFO]

The ZRC product is what my crew uses.

73DG

[Jim, W5JO]

Do be careful with used 25G.  If water stands for long periods of time it can breach the galvanize.  I have seen several towers fall because water collected near ground level inside the legs then freezing causing the weakened leg to split.

Most old tower climbers I have known were very careful about climbing old installations if they climbed them at all.

[KL7OF]

Fred ..do a visual inspection and give any suspect areas the "tap test" ..sound the tubes with a small hammer and listen....

[k4kyv]

The pros will wire brush the rust off and spray what is called "ColdGalv" on the areas.

Kinda like a thick spray paint, it stops the rust.  It isn't permanent, but it lasts a long time.

My experience witth "ColdGalv" was not so spectacular.  I used it on an air conditioning unit, and rust started to peek through within a year or two.  OTOH, oil-based aluminium paint is almost as good as hot-dipped galvanising. I first used some ancient stuff that my father gave me. Later on, I used Rustoleum. It lasts for 1-2 decades before rust starts coming through. 

The base insulator for my tower was made by some off-brand company in Atlanta called the Radio Tower Company of Atlanta.  The end bells are bare cast steel.  When I acquired the insulator, which was removed from an old broadcast tower installation, the goop that filled in between the casting and the ceramic insulator had deteriorated, so I removed it, had the interior of the castings turned on a lathe at a machine shop, and reconstructed the insulator using a professional grade epoxy for the filler. I painted the exterior of the castings with aluminium paint, and covered the epoxy filler with a coat of roofing tar to prevent UV damage.  After about 15 years, I noticed a few splotches of rust, so I repainted the castings, which now still have very little rust.  In the meantime, the hot-dipped galvanising on the tower itself is showing quite a bit of rust.  Some sections have lost their silver-like sheen and are completely red.

A guy I talked to from the (original) Rohn tower co. told me not to worry about the rust that appears on the tower sections.  He said that even when the sections take on a ruddy complexion, there is still active zinc on the surface protecting the steel. I have become more concerned about the rusty guy cables, but so far, it looks like surface rest; I don't see evidence of pitting, at  least what is observable at the ground level.  I need to climb the tower and inspect the upper levels to make sure there is no pitting there, either.

It would cost more just to re-guy the tower now than the whole tower, hardware, base insulator and ground system cost me in 1980.

[flintstone mop]

Thank you all.
I'll give some tap tests and I think I'm ok on this. Apparently I did not pick up on the bottom section. These were all above ground.

Fred

[KM1H]

Ive seen many with severe internal rust from poor installations with almost no drainage and as mentioned several others with freeze splits. Some of the garage level 2 way shops are worse than hams for slipshod installs.

There was a time I could have them acid dipped and regalvanized in Boston all for about a third of new. The EPA screwed that up too. My last re-gal was up in Montreal with 200' in the back of the 1T Dodge van at 12mpg. Havent been back in about 10 years.

[k4kyv]

Ive seen many with severe internal rust from poor installations with almost no drainage and as mentioned several others with freeze splits. Some of the garage level 2 way shops are worse than hams for slipshod installs.

I suspect all of those were the Hammy Hambone method of burying the bottom section in concrete.  You won't have that problem with a guyed tower using the base plate/pier-pin method. If the tower is short enough for self-support, drain holes should be drilled right above the concrete level, and proper drainage per the Rohn manual should be incorporated in the initial installation. If, for some reason, I had to bury a bottom  section in  concrete, I would  use a short section just long enough for the legs to extend above the concrete, or cut a regular section to length, then fill the hollow legs with muck made from a mixture of sand and cement, up to the bolt holes, making sure there were no voids in the cement mixture from trapped air. I would let that mixture harden before attempting to install the tower section and pour the concrete. That would keep standing water from accumulating and corroding the interior of the section below grade, something especially dangerous if the tower is self-supporting. Even if proper drainage provisions are mode at the bottom of the hole, if your soil has extended periods with the water table rising near the surface, that means the hollow legs will be filled with standing water at least part of the year.

One of the stupidest Hammy Hambone abortions I ever heard described was when a local ham club was given by the new landowner a set of Rohn 25G towers from a directional broadcast array gone dark, for taking the towers down.  They salvaged several 25TG tapered base sections, designed for a base insulator or the pier pin method.  When I put up my tower 30 years ago, those sections sold for about double the cost of a regular section.  Now, they are several times the cost of a  regular section. Those idiots couldn't figure out how to properly use the tapered base sections, so they buried the tapered base parts in concrete and used them in the normal Hammy Hambone manner, probably without any provision for proper drainage. At least they sold the base insulators at a hamfest (I purchased one for $25, which I keep as a spare), but the guy told me they managed to break one while dismantling the tower.

[Bill, KD0HG]

If the tower is short enough for self-support, drain holes should be drilled right above the concrete level, and proper drainage per the Rohn manual should be incorporated in the initial installation. If, for some reason, I had to bury a bottom  section in  concrete, I would  use a short section just long enough for the legs to extend above the concrete, or cut a regular section to length, then fill the hollow legs with muck made from a mixture of sand and cement, up to the bolt holes, making sure there were no voids in the cement mixture from trapped air.

I might add- if not using a Rohn top section, permanently seal the pipes at the top of the tower so rain doesn't enter. Don't leave the top section open.

Bill

[W7TFO]

The Rohn installation guide shows direct implant of a section into concrete as a base for service other than an insulated base.

That is indeed why you see it a lot.

73DG

[k4kyv]

But that is intended for relatively short towers, up to 60 ft. or so, self-supporters or house bracketed towers, which of course comprises more than 90% of ham installations.  For anything taller they recommend the flat base plate that sits right on the concrete, with the pier pin holding it in place laterally. That piece is enormously cheaper than the tapered base section, which is primarily designed for the insulator, but the inexpensive base plate still allows the tower to have some "give" so that it can rock and sway in the presence of severe winds, and thus put less stress on the welds in the tower sections.

Another reason to use the base plate/pier pin method is that it gives some vertical leeway. A rigidly planted tower needs to be exactly plumb.  That is less important for a short tower with just a  few sections, but once you start going up 100' or more, even a minute vertical error at the base (almost unavoidable) becomes significant, but the unattached base plate allows the tower to tilt on the base ever so slightly, instead of placing undue stress on the tower.

You never see a large TV or communications tower planted directly in the concrete base.  They just about always use the same tapered base section (with pier pin), that is used on AM towers with the base insulator, so that the base acts as a pivot/bearing assembly.

[K1ZJH]

I believe the "planted" sections are allowed to drain into gravel beneath the
concrete. Most hammy hambones seal the ends in concrete, and the water
just builds up in the legs until it rusts through or freezes and splits.

I used a silver paint that is used by the railroads to paint their metal CP
buildings and telephone boxes.  It is a commercial grade "Rustoleum like"
product. They paint right over rust and it holds for years.  I painted my
used Rohn 25 with it before the tower went up, and it still looks new 10 years
later.

Pete

[The Slab Bacon]

The Rohn installation guide shows direct implant of a section into concrete as a base for service other than an insulated base.
That is indeed why you see it a lot.
73DG

They actually sold a half (short) section specifically for that purpose. That is the way mine is done, and it has been up for 20 years now with no problems (or splits).

When I took it down, it had brown rust stains all over the legs. They were actually rusty looking. This was from the rusty non-stainless hardware that the previous owner had used with / on it. After being up 20 years now, all of the brown rust stains have weathered off and it looks really good for as old as it is.

[KM1H]

Rohn didnt use stainless hardware. Initially it was galvanied and later just zinc plated.

Some years ago I bought a couple of unused sections that were stored outside standing up. The hardware packed in the plastic tubes stuffed in a leg was full of water and completely rusted hardware.

Stainless is actually not a good choice for a tower leg unless you absolutely know what you are buying. Hardware store stuff is junk.

Here is a thread on the subject.

http://forums.qrz.com/showthread.php?201310-Rohn-25G-Tower-Replacement-Bolts

[K1JJ]

The ZRC zinc product that Pete posted above (in the gallon can) is the best stuff to use. Buy a fluffy "painting mitt" at a paint store and rub it on by hand.   I've done all of my towers with it over the years. Only one application 10 years ago and still FB.  Use clothes and a climbing belt that you can sacrifice - expect to get ZRC on you.  Climb to the top and work your way down.  The gallon can weighs maybe 25lbs+ ? cuz it is a dense zinc mixture of  paste.  Use an electric drill with a 1" wood bit to mix it up for at least 20 minutes or else the zinc will sit on the bottom. The mixture  should look all silver when finished.  The ZRC paint spray cans are just "OK" cuz the coating is really too thin compared to the paste coating when using the gallon can and a mitt to apply. But the spray is good for quick touch up jobs.


As for the Rohn tower base.... yes, a pier pin is the cheapest and best approach. The thang is, with a locked-in concrete base, even if we get the alignment perfect, over time the tower guy wires stretch from the strain in the wind, guy anchors can migrate slightly and a host of other effects can put pressure to lean the tower. The whole tower then acts like a huge lever at the base, IF it is anchored in concrete. With a ROCKING base, the tower can easily compensate for storms, expansion, contraction, etc, by slightly rocking at the base.

What to do if we already have a hammy bone tower section stuck in concrete? As Don said, a short tower will probably be OK, but once the tower gets bigger than say, 80', we are axing for trouble with a solid concrete base.  Back in 1987 I put up my first 150' Rohn 45 guyed tower.  Like a dummy, I put the base in concrete, as suggested by the salesman at a very popular ham store.  It survived, but when I realized what a ticking bomb I had, I decided to add a pier pin instead.  It required loosening the guys until the whole 150' tower was moving around a little, but still standing erect. I cut the base of the tower legs with a saws-all and grinded down the leg stubs sticking out of the concrete. I then clamped two sets of U-bolts attached to a steel beam to the loose base tower legs and used two  3 ton hydraulic jacks to raise the tower base a foot or so.  I slipped in the pier pin and base plate, slid on the 150' tower and all set.  Yes, I proved to myself that it CAN be done without taking down the tower.  (** Actually, before cutting the tower legs, I took the weight off using the jack first -  this whole thang can be a dangerous operation, so be careful and think it out first)

BTW, I made my own pier pin base plate using a 1/8" sheet of steel and a 12" piece of old Rohn 45 tower welded to it.  The base plate does not have to be very thick, since it can then flex slightly if it needs to when sitting on the "flat" concete base.  For water leakage, I drilled a 3/8" hole in the sheet base plate directly under EACH leg so it could drain onto the concrete.  The pin itself can be a 3/8" steel rod that fits in a hole drilled into the concrete.

This 150' tower has been up for 25 years now and still looks and functions FB using the original guys, hardware and a coat of ZRC ten years ago.

The other critical addition I added was a 5/16" stainless cable going up the side of the tower used as the safety arrest system when climbing. All five towers here use them.  I just turned 60 and would not even think of climbing without this safety system clipped to my full body harness.  The days of free climbing to 190' are as crazy as using that tower section in concrete years ago...  


BTW, Carl, about the stainless steel bolts. Yes, SS is not as strong as the high grade steel bolts. I've actually broken off a SS bolt when a high grade bolt held up on the next try. However, I use SS fasteners for all antenna work, other than the tower bolts. We just need to use a size bigger than usual to be sure.  SS sure is FB when climbing up there 10 years later and seeing shiny fasteners. In contrast, I occasionally see the zinc bolts that got mixed into the batch at the hardware store by mistake and they are usually rusted toast.

T

[k4kyv]

I don't have any climbing gear right now.  I trashed my old WWII era leather signal corps belt.  Even though it was reinforced with nylon webbing, I felt like the thing was a death trap. I have been surfing the web looking for climbing gear. This looks like the best amongst all the things I have found so far, but haven't seen any reviews or heard from anyone who has actually used one.  I am always kind of leery of buying something sight unseen except for the ads and what's listed in the catalogue. Would be curious if anyone has any experience with this.

http://www.aikencolon.com/SafeWaze-7552-Elavation-Safety-Harness_p_663.html

One thing I like is that they give a chart for height and weight to determine your size (small, medium, large, extra  large) along with waist size.  Some of the others I looked at only gave waist size, which can be deceiving, since waist size is not always uniformly proportional to  the rest of the body.

I don't do that much climbing on mine, so I don't think I would bother with the option of the permanent fall arrest cable.  I would use two lanyards, and a clamp-on fall arrest cable that you fasten to a horizontal rung above your head while working. I always used the pair of lanyards for passing by a guying section, because I never felt comfortable free-climbing over the point where the guys are fastened to the tower.

[KM1H]

BTW, Carl, about the stainless steel bolts. Yes, SS is not as strong as the high grade steel bolts. I've actually broken off a SS bolt when a high grade bolt held up on the next try. However, I use SS fasteners for all antenna work, other than the tower bolts.

Ive broken more stainless over the decades than steel. The damn stuff galls and SNAP.

OTOH when I took down the HB stacks that were all put together with Dorman muffler clamps that I bought a large quantity direct I only snapped one piece for all 16 monobanders. Between 2 QTH's some had been up over 30 years. I dipped everything in aluminum paint first and used a spray can to touch up as I went along during the build and installation..

For the towers Ive been using Zero Rust gray spray cans and touching up as needed since there was a lot of climbing going on, side mounts for myself and commercial antennas that come and go on the 180'. On top of that the open hilltop has given the SW to NW a good acid rain blasting that I got a good start on spraying last year. This year I have to replace some guy sections that are completely rusted in just 22 years. Luckily its 1/4" EHS and not that wimpy 3/16
stuff.

I helped a 2 way friend take down 120' of 25G last year that had been up since 79. The rust was so bad on legs and guys that we simply cut the legs and let it fall into the trees as I wasnt about to climb it. I salvaged all the good sections below the tree line and the trees cushioned it all and those slid right apart. The Sawzall took care of the rest. A couple of hand bends snapped the guy wires as I showed Dave why I wasnt climbing!

[flintstone mop]

Thanks Tom
I definitely remember seeing ZRC around somewhere. That will be a better approach. And ouch!! $157.00 for a gallon can!!! Looks like the Rustoleum will have to do for now.
This small tower will be on the BPH25G base that allows "foldover". There is a Ham in 8 land who makes a copy of the Rohn product.
I'll have to get busy and start digging a hole for the base.
Some interesting stories about towers and rust.
Tom you are a dare-devil, with your modification on an existing tower.
A tower company replaced or patched a portion of a bottom leg of a 120 foot self supporting tower, loaded with 8 foot microwave dishes, and there was some serious machinery around.
Fred

[Pete, WA2CWA]

Thanks Tom
I definitely remember seeing ZRC around somewhere. That will be a better approach. And ouch!! $157.00 for a gallon can!!! Looks like the Rustoleum will have to do for now.
This small tower will be on the BPH25G base that allows "foldover". There is a Ham in 8 land who makes a copy of the Rohn product.
I'll have to get busy and start digging a hole for the base.
Some interesting stories about towers and rust.
Tom you are a dare-devil, with your modification on an existing tower.
A tower company replaced or patched a portion of a bottom leg of a 120 foot self supporting tower, loaded with 8 foot microwave dishes, and there was some serious machinery around.
Fred

Rustoleum use to offer it in a gallon can. Bought it from Grainger. Cost was somewhere around $140 to $150. Doesn't look like they offer it anymore.

[flintstone mop]

Thanks Tom
I definitely remember seeing ZRC around somewhere. That will be a better approach. And ouch!! $157.00 for a gallon can!!! Looks like the Rustoleum will have to do for now.
This small tower will be on the BPH25G base that allows "foldover". There is a Ham in 8 land who makes a copy of the Rohn product.
I'll have to get busy and start digging a hole for the base.
Some interesting stories about towers and rust.
Tom you are a dare-devil, with your modification on an existing tower.
A tower company replaced or patched a portion of a bottom leg of a 120 foot self supporting tower, loaded with 8 foot microwave dishes, and there was some serious machinery around.
Fred

Rustoleum use to offer it in a gallon can. Bought it from Grainger. Cost was somewhere around $140 to $150. Doesn't look like they offer it anymore.

Thanks Pete,
Probably could not compare to the quality of ZRC. Supposed to be a tight secret formula for the zinc and how it is mixed in with the other chemicals.

[Pete, WA2CWA]

Thanks Pete,
Probably could not compare to the quality of ZRC. Supposed to be a tight secret formula for the zinc and how it is mixed in with the other chemicals.

Not really. I've used both over the years and couldn't tell the difference. Aging seem to be the same. The Rustoleum product was always easier to find when I needed some. Grainger always has it in stock. From what I remember, there was only one or two authorized dealers in NJ and no where near my location.

[KM1H]

Likely just a private label.

Some years ago I watched a tower company replace the lower two 20' sections of Rohn 65 on a 500' tower on the hill next to me. It was overloaded and the sections developed stress cracks. They made it all look so easy.