[Towertalk] Coastal Corrosion

[Larry McDavid]

I grew up on an island--Galveston, Texas. Even galvanized steel rusts
there. Aluminum antennas were good for perhaps two years, after which
they typically fell apart. This makes the TV service folks happy since
the broadcast TV antennae are nearly 50 miles away so an outdoor antenna
is required. High humidity and blowing salt spray constitute an
atypical, tough environment.

In Galveston, about the only metal that lasted was Monel. That, one sees
commonly only on sailboats. Don't let anyone tell you that stainless
doesn't rust; the key word is corrosion *resistant* steel and that
resistance comes only from an allegedly self-healing, Angstrom-thick
film of chromium oxide.

Older and wiser, I now live in Los Angeles. We don't have rain or
lightning or even weather; snow we keep in the mountains, an hour's
drive away. The really tough environmental challenge is UV from the sun.
Watch out for those plastic antenna parts and for the cable jackets!

The moral of this story is: select materials and then design for the
intended service area. Don't expect the service life to be the same
everywhere!


> I can attest to the corrosive effects on aluminum at coastal areas... 
-- 
Best wishes,

Larry McDavid W6FUB
Anaheim, CA  (20 miles southeast of Los Angeles, near Disneyland)