Sea going vessels with aluminum superstructures and welded-on-deck vertical
aluminum channels (think channel iron but aluminum instead) for mounting
tuners and or antennas with stainless steel fasteners connecting tinned
copper crimp terminals when exposed to the environment for a few months show
the following:
1. Corrosion/pitting of the aluminum channel near (within 1/2 inch or so)
the drilled hole where the stainless fasteners secure the terminals.
2. Corrosion of the ID of the hole with the stainless machine screw
through it.
3. Corrosion of the exposed coax braid. Braid turns to mush totally
disintegrating.
Well du-uh... given the dissimilar metals in contact with each other and the
salt water for electrolyte you have a galvanic cell which eats away at the
less noble of the two galvanic cell plates, especially without the
protection of a product such as coax seal.
So the marine radio equipment installer whose prime motivation is to make
things look neat as he finishes the job, uses his "UNIVERSAL FIX" which is
to apply some silicone rubber (RTV - room temperature vulcanizing) to all
metal near or touching any of his handiwork. This slows the corrosive
destruction by several days or maybe a few weeks or if luck id with you,
several months..
I have seen coax cables terminated with PL-259 (properly installed) for
connecting to a SO-259 female UHF connector (bulkhead mount style) with
ample Silicone rubber over everything but with the mounting flange of the
bulkhead mounted connector being eaten away by galvanic corrosion due to
dissimilar metals in contact with an electrolyte present. The mounting holes
were essentially gone from the connector and the holes in the aluminum
substrate (channel) were eaten out considerably oversized.
If you install antennas, feedlines, etc. in conditions including significant
quantities of airborne salt then you may experience some of the above
undesired results.
Perhaps some of the more experienced and knowledgeable members of this
august gathering can set forth a prescriptive methodology for preventing the
above mentioned deleterious effects.
Patrick AF5CK
-----Original Message-----
From: Jon Pearl - W4ABC
Sent: Tuesday, September 10, 2013 9:50 AM
To: john@kk9a.com
Cc: towertalk@contesting.com ; jwfisher@alumni.princeton.edu
Subject: Re: [TowerTalk] Force 12 hardware and aluminum treatment for
corrosion resistance
Hi Jim,
For the past few years I've used a product called Never-Seez Regular
Grade with great success on all of my outdoors fasteners. I'm surrounded
by water. I've got the Gulf of Mexico to the west and Tampa Bay to the
east.
REGULAR GRADE
The original anti-seize compound and extreme pressure lubricant
formulated with copper, graphite, aluminum and other ingredients to
protect metal parts against rust, corrosion and seizure up to 1800:F.
Specified by BMW, Mercedes, GE D6Y28A1, Garrett Engine Division PCS5724,
Pratt & Whitney PWA 36053-2 and tested to MIL-A-907.
http://www.bostik-us.com/market-products/product-assembly/mro/products/#regulargr
http://www.bostik-us.com/sites/default/files/NSRegular.pdf
It's available online at Amazon, etc., for less than $15 U.S. per 8 oz
brush top container.
73,
Jon Pearl - W4ABC
www.w4abc.com
On 9/10/2013 9:19 AM, john@kk9a.com wrote:
What an awesome QTH! I also use stainless steel hardware however I have
seen severe salt spray corrosion to aluminum where the S.S. is in contact.
What do you do to protect the tower system from corrosion?
John KK9A
To: towertalk <towertalk@contesting.com>
Subject: [TowerTalk] Force 12 hardware and aluminum treatment for
corrosion resistance
From: Jim and Hannelore Fisher <jwfisher@alumni.princeton.edu>
Date: Tue, 10 Sep 2013 12:36:46 +0000
I live in a salt-air environment and have replaced just about all U-bolts
and
other such hardware with stainless steel. Be sure to coat bolts with an
appropriate compound before installing nuts--if you are not familiar with
this,
ask your SS supplier.
Also, per advice from F12 many years ago, I assembled elements and then
painted
them with XIM400, which has protected them nicely. At some points, I have
had
over 50 F12 elements up at the edge of a cliff with saltwater to the
horizon
and little fluffy balls of salty foam flying up and over.
73,
Jim, VE1JF
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