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Re: [TowerTalk] Rigid Steel Conduit as Mast?

To: John Kemker <>
Subject: Re: [TowerTalk] Rigid Steel Conduit as Mast?
From: "Roger (K8RI)" <>
Date: Fri, 05 Jun 2009 21:43:30 -0400
List-post: <">>

John Kemker wrote:
> So, for those of us who are in the process of tower-planning, what 
> should we order from the local "metals supermarket" type of supplier to 
> use for a 20 ft. mast to hold an HF tribander and a 6m beam?
> (Calculated wind load is 6 ft^2 for the tribander and 3 ft^2 for the 6m 
> for 9 ft^2 total wind load from the antennas ONLY.)
> DeKalb County, Georgia is a 90mph county and I've specced everything out 
> so far to 110mph ratings for the tower.
> I've found seamless steel tubing, 1/8" walls, non-galvanized, but am 
> concerned with how to protect the interior from corrosion if it's not 
> hot-dip galvanized?  I can "cold-galvanize" the outside, but the 
> interior is a different matter.

After a thorough cleaning, I cap the one end (often with nothing more 
than sheet plastic and tape) , pour in about a pint to a quart of 
Rustoleum., cap the other end and then roll it while tipping the ends up 
and down to thoroughly coat the inside.  It's still working after 6 
years, OTOH it's no where near as good as hot dipped galvanizing, nor 
will it last as long..

If the metal is thoroughly cleaned and etched I'd prefer a two part 
Acrylic or Epoxy paint to the Rustoleum.


Roger (K8RI)
> Jim Brown wrote:
>> On Fri, 05 Jun 2009 18:52:50 -0400, Roger (K8RI) wrote:
>>> There are two types of rigid steel conduit. The one is like schedule 40 
>>> pipe and the other (EMT) is thin wall.
>> Clarification: Actually, there are three thicknesses of steel conduit 
>> commonly used in North America. In the trade, they are designated "Rigid 
>> Steel Conduit," "Intermediate Metal Conduit," and Electrical Metallic 
>> Tubing.  Wall thicknesses varies with conduit size, and for these 1.5-inch 
>> nominal conduits are are 0.138 in, 0.09 in, and 0.065 in respectively. I'm 
>> talking about using a 10 ft length of "Rigid Steel Conduit," which is 1.9 
>> inch o.d., with only a 3-el SteppIR at the top (which is relatively small 
>> and light weight). 
>> 73,
>> Jim K9YC

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