Re: [TowerTalk] Experience with Sacrificial Zinc?

[Grant Saviers <grants2@pacbell.net>]

Rich,

Galvanizing is so local (~1/4") for protecting bare/rusting steel that I 
don't think a zinc will help.  Since the PJ4 rust is apparently well 
developed there are some conversion + paint coatings which might be 
helpful, especially it the loose stuff can be brushed off before treatment.
https://www.rustoleum.com/product-catalog/consumer-brands/stops-rust/rust-reformer
https://www.forbes.com/wheels/accessories/best-rust-converters-and-inhibitors/#por-15-45404-rust-preventive-coating

I've been applying the rustoleum reformer to some wire brushed rusty 
parts but no long term experience.  Generally, I've had excellent 
results with Rustoleum paint. My process is two coats of primer, red on 
bare/clean steel, then grey to show complete coverage and then 2 or 
three coats of color.  From the can or a spray gun.  I've had tractor & 
forklift equipment stored outside for 17 years with no rust, but not in 
salt spray.
There are also spray on waxy coatings that last a couple of years
LPS-3 and CRC-06026.  Pretty hard to get off once on and can't paint 
over them, but it works for a while.  I squirt a bit on my Grade 8 
clamping bolts since they aren't hot dipped.
Grant KZ1W

On 8/8/2021 19:51, Richard Smith wrote:
>   Hi Grant,
> Thanks for your response. At our station in PJ4, the Hot Dipped Galvanizing is 
> holding up well, but some parts are Electro-Galvanized and are already 
> corroding. Part of the problem is erosion from trade winds, which seems to wear 
> down the Electro-Galvanizing, which then exposes the base metal to a corrosive 
> environment. Specifically, the Orion rotor drive plates and mast clamps seem 
> susceptible to the erosion and the subsequent corrosion.
> I was wondering if attaching a piece of zinc metal directly to those specific 
> parts would slow down the corrosion. The team is looking at changes to help 
> this situation in the future, but I'm also trying to find a quicker solution 
> for the parts that are already installed.
> The black tar coating followed by PVC tape sounds like a very good solution for 
> buried parts.
> 73, Rich, N6KT
>      On Sunday, August 8, 2021, 05:11:51 PM PDT, Grant Saviers 
> <grants2@pacbell.net> wrote:
>   
>   The MIL-HDBK-419A talks a little about this topic.  Adding Zn electrodes
> to a galvanized tower creates a parallel circuit, not clear which will
> go first IMO.  Impressed voltage systems are probably a better option.
> google it.
>
> I black tar coated my galvanized guy anchor rods and then wrapped them
> with 20mil 2" wide PVC tape for abrasion resistance to 2 feet above
> grade, same as done for black iron gas pipes that are buried.  Should
> last longer than me.
>
> Grant KZ1W
>
> On 8/8/2021 16:30, Richard Smith wrote:
> > Hi Tower Talkers,
> > It seems that sacrificial zinc is commonly used in boating to stop corrosion. The 
> > sacrificial zinc corrodes and "saves" the metal to which it is attached.
> > Does anyone in TowerTalk land have experience with using sacrificial zinc with 
> > towers and/or antennas?
> > 73, Rich, N6KT
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