Page 9 - Corrosion & Harsh Environment Protection

Corrosion & Harsh Environment Protection 9
Aluminum
Aluminum provides the advantages of high strength-to-weight ratio, superior resistance
to certain corrosive environments and ease of installation. Aluminum typically weighs about
50% less than steel and requires no maintenance after installation. It offers excellent
resistance to solvents and fuels, but is not recommended for exposure to other types
of chemicals, including salt, bleach, acid or chlorine.
In general, standard copper-free aluminum alloys such as A360 cannot be relied upon to
provide any appreciably longer lifespan than galvanized cast iron or steel in most corrosive
environments. However, certain specialty aluminum alloys have been developed to provide
a higher degree of corrosion protection. These include the Thomas & Betts CorroStall®
aluminum alloy, which offers excellent corrosion resistance as cast, without the need for
protective coating, and up to 300% longer life.
Other Options
In addition to PVC coating, other protective finishes and coatings have been developed
to give galvanized cast iron or steel superior protection against corrosion.
One example is the Thomas & Betts BlueKote® finish for cast iron alloy conduit bodies.
The BlueKote® finish starts with the electro-zinc plating with chromate finish that most
ferrous conduit bodies feature, but then adds a baked-on layer of powder-coated epoxy,
followed by another baked-on layer of epoxy paint. Last, the signature BlueKote® finish
is applied to and baked on the interior of the conduit body.
Salt Spray Hours
Metal Framing Channel Finish
Corrosion-Resistant Testing, ASTM B117
Industry
Enamel
Green
Epoxy
Green
Industry
Pre-Galvanized
G90
EG-
SilverGalv®
Trivalent
Galv-Krom®
1100
1000
900
800
700
600
500
400
300
200
100
0
The edge of an A360 aluminum
alloy conduit box after an
industry-standard salt spray test.
The edge of a CorroStall®
aluminum alloy conduit box after
the same salt spray test.
After a 500-hour 5% salt fog
test, the standard galvanized
iron conduit body has severe salt
adhesion and significant rusting.
The BlueKote® conduit body still has
a glossy sheen and no evidence of
salt adhesion or penetration after
the same salt fog test.
As another example, the Thomas & Betts Galv-Krom ® finish for Kindorf®
Modular Metal Framing is a gold trivalent finish applied over electro-galvanized
steel to provide superior corrosion resistance as compared to industry-standard
pre-galvanized G90 steel strut. The trivalent Galv-Krom ® finish is OSHA and
RoHS (Restriction of Hazardous Substances) compliant.