[TowerTalk] [Bulk] Re: Tower buried section legs -- Buried in Concrete orBelow the Concrete?

Fri Jan 29 14:12:06 EST 2016

FYI, Rohn 65 with 4 bolt 5/8" thick flanges on each leg has one 1/4" 
weep hole on each leg, at both ends right next to the flange.  The 
flanges are drilled to the leg od and welded outside and inside to the 
tube before galvanizing.  So there are redundant paths for water to 
escape.  My PE specified 1 foot of 3/4 gravel for the legs to be set 
into before the 4x4x2' base pad was poured.

I had ten 20' R65 sections regalvanized by Ace Galvanizing here in 
Seattle and they did a terrific job.

Having seen a few R25s with burst legs, I think it best to follow the 
Rohn instructions.  If the legs below the concrete rust, I wouldn't be 
concerned as they serve no structural purpose.  Once the leg is into the 
concrete enough to be inside the rebar cage, say a foot or so, more leg 
in the concrete below that probably doesn't have much structural 
contribution.

If the ground is corrosive enough to be a big concern then the 
galvanized guy anchors need good protection all along where they are in 
contact with the earth.  For peace of mind I used heavy asphalt paint 
for full coverage and then 50% overlap 20mil pipe tape for protection 
from the backfill (same tape as often required on buried black iron gas 
lines) to 1 foot above grade.

Grant KZ1W

On 1/29/2016 10:00 AM, Dan Cisson wrote:
> One of the problems with Rohn tower sections,, all of them-25G, 45G, and
> 55G, when the galvanizing was done at
> The plant,, galvanize would form inside the legs and create a "plug".  Thus
> the water would not drain thru the legs and out the bottom section.
> What I have done to ALL tower sections is slide an eight foot ground rod
> thru each leg to eliminate any
> Galvanize plugs. This alone helps prevent water freezing and splitting a
> leg.  And, I have drilled a weep hole also...I hate to
> Do that cause it is a weakness, not much at all, but slight.  I might say, I
> have not seen the galvanize plugs this day and time as much as 20 yrs ago..
> Dan N4GNR
>
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of
> Patrick Greenlee
> Sent: Friday, January 29, 2016 11:56 AM
> To: towertalk at contesting.com
> Subject: Re: [TowerTalk] Tower buried section legs -- Buried in Concrete
> orBelow the Concrete?
>
> What does the brain trust think about the idea of plugging the ID of
> tower legs slightly above the top of the concrete foundation and
> drilling a weep (drain) hole at the top of the plug.  It would require
> poking into that hole periodically to prevent insects or whatever from
> plugging the hole but should eliminate the need for any concern or
> proactive adding of pea gravel below the tower legs or acid soil eating
> on the bottom of the legs.
>
> Patrick        NJ5G
>
> On 1/29/2016 10:40 AM, Chris Wynn via TowerTalk wrote:
>> On my first Rohn 25 tower that I put up while in college, I had water get
> into a leg and actually busted outwardly.  It left about an inch and a half
> rip looking seam.  This occurred about 4 feet from the top of the concrete
> pad.  I could only imagine that there was some type of obstruction in the
> leg that allowed water to build at that point.  When it froze, the water
> expanded outwardly, busting the leg.Regardless, the tower lasted throughout
> my college career and until I later got married and moved out.  I would
> imagine that my father is still using that section to hold up one of his
> bird houses.I would add that pea gravel as a way to drain any moisture, just
> in case....
>> Good luck
>> Sent from Yahoo Mail on Android
>>    
>>     On Fri, Jan 29, 2016 at 8:51 AM, Larry<lknain at nc.rr.com> wrote:   I
> have always put the pea gravel in the bottom as spec'd by Rohn. The way
>> the legs are constructed and assembled on G sections I suspect there is
> very
>> little water that gets in the legs. Probably more of an issue if the top
>> section is just another straight section and the ends are not capped in
> some
>> way. But I could imagine a very small amount of seepage perhaps through
> the
>> bolt connections and perhaps over time rusting out the bottom of a leg
> that
>> is sealed in concrete.  Perhaps condensation in some environments could
> play
>> a role. The latter two seem awfully remote to me.
>>
>> 73, Larry  W6NWS
>>
>> -----Original Message-----
>> From: Larry Loen
>> Sent: Friday, January 29, 2016 7:17 AM
>> To: TowerTalk
>> Subject: [TowerTalk] Tower buried section legs -- Buried in Concrete
> orBelow
>> the Concrete?
>>
>> The Rohn spec calls for the legs of the bottom section to be buried a few
>> inches in pea gravel below the concrete.  My contractor suggests that as
>> long as the top is properly sealed, it's overkill and that overall, it's
>> better to encase the legs in concrete, protecting them from corrosion from
>> that rare day in Arizona that the water levels would reach the bottom of
>> the tower.  He suggests that the tower will be adequately sealed on top.
>> Soil here is acidic enough that I've been advised not to let the tower
>> sections touch the ground for even the short time they are stored here
>> awaiting erection.  Even if some got in over the years, rainwater is
>> presumably less acidic.
>>
>> I don't try to innovate in these matters, but I wonder who is right here.
>>
>> Thoughts?
>>
>>
>> Larry WO7R
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