WHAT IS CORROSION?
Corrosion is the chemical reaction of a metal, in this case
aluminum, with its environment, which leads to the deterioration of the
properties of metals.
Corrosion accounts
for approximately 40% of all equipment failures in industrial facilities.
Facilities located in potentially corrosive outdoor environments such as seacoast,
heavily populated urban areas, industrial sites, some rural locations are
exposed to various threats of salt laden corrosive elements, various air borne
molecular contaminants (AMC) and water vapor (as a result of high relative humidity).
Few other environments such as laundry facilities, diesel-burning devices/exhaust
piping, sewer vents, traffic, pool areas, water treatment facilities and household
cleaning agents etc. can also produce corrosive atmospheres resulting in the
creation of electrolytes that facilitates the corrosion process. These
pollutants, in combination with other factors such as wind direction, humidity,
water, fog, temperature, proximity to pollutant source, and dust or particle
contamination, may result in the premature failure of equipment. Premature
corrosion of air conditioning heat exchangers, specifically condenser coils can
be a serious problem. Coils installed in these environments have been known to
fail in less than 1 year. The result is the costly replacement of the coil
and/or the entire unit. If these units are left unprotected, they can
experience rapid corrosion from exposure to aggressive elements.
ALUMINIUM AND CORROSION
Aluminum
is a very reactive metal, but it is also a passive metal. This contradictory
nature is explainable because aluminum reacts with oxygen or water and forms a
coherent surface oxide which impedes further reaction of aluminum with the
environment.
CAUSES OF CORROSION
· Temperature
· Gases such as hydrogen sulfide, sulfur oxides, chlorine, hydrogen
Fluoride (HF), nitrogen oxides and ammonia
Pre-coated Aluminum-Fin Coils
Pre-coat processes sheet aluminum
before it is manufactured into coils. Pre-coats are not a very good long-term
coating solution because the manufactured edges are not coated and are
therefore exposed to corrosive forces. This results in a rapid deterioration of
the coil. In addition, the application of a pre-coat prior to manufacture precludes
the effective application of any other type of coating to the coil. Pre-coating
offers protection in mildly corrosive coastal environments when compared to
standard uncoated coil, but is not recommended in severe industrial or coastal
environments.
Post-coated Aluminum-Fin Coils
There are two methods for applying
post-coat coatings: dipping or spraying. All coatings applied by a dip process
must be applied at a factory. Products are immersed into product baths a set
number of times and for specific durations, then either baked or allowed to
cure naturally. Spray processes can be done either at the factory or in the
field.
MERITS OF ALUMINIUM GUARD
· Suitable for ferrous & non – ferrous metals
· Resistant to UV and Chemical Reactions
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