[TowerTalk] Fwd: Anchoring

[Lux, Jim]

On 11/17/22 9:51 PM, KD7JYK DM09 wrote:
> On 11/17/2022 18:33, Hans Hammarquist via TowerTalk wrote:
> I used the same type as the utility companies. They are a lot cheaper 
> if you buy them from a utility supply house. Anyhow I put them in with 
> the hep of a sledgehammer and a break-iron. We were two to do it. You 
> turn the helix anchor as far as you can. then you hit it a few times 
> with the sledgehammer and continue turning. The idea is that the 
> screw-anchor should be set in "undisturbed soil" to get maximum strength.
>
> I looked at those when I was buying the utility pole thimble eyes.
>
> My concern was, despite that big elaborate screw, depending on the 
> model, there was a few tack welds, or one relative short weld around 
> the shaft to hold it.
>
> Crack that, and the anchor slips out, leaving the screw in the hole, 
> and tower on the ground. 


All the screw in anchors I've seen (several dozen, 30 years ago) had a 
continuous weld for the entire helix. I would say that a "tack weld + 
short weld" is a unit that was mis-manufactured (i.e. shipped before the 
final welds were done).  As you say, if the weld were to fail it would 
be a problem.


I guess it's possible that as long as the total weld area is sufficient 
(greater than the shaft cross section), the screw might deform, but 
still stay attached and mostly embedded (the helix pitch might get 
longer or it might unscrew a bit (sliding along the helix length), but 
that seems unlikely, since the soil is holding it in place. It's all one 
piece of metal (if the weld was done properly). A good weld won't be 
more brittle than the parent metal.

They do actually test these things - Ask the mfr if that's their 
standard practice.