Page 182 - Challenges in Corrosion Costs Causes Consequences and Control(2015)

160 CORROSION CAUSES

In the case of towers in salty environments:

1. Check the condition of the tower structure.
2. Wash regularly the tower structure, in the absence of rains sufficient to wash
the tower free of salt.

3.17 MOTOR VEHICLES

American consumers, businesses, and government organizations own more than 200
million registered vehicles. Assuming a value of $5000 for each vehicle allows an
estimate that Americans have more than $1 trillion invested in their motor vehicles,
making automobiles one of the largest investments collectively among Americans.

3.17.1 Corrosion Causes

Several factors lead to various types of corrosion in motor vehicles, specifically the
design process, the manufacturing process, and operating conditions.

3.17.1.1 The Design Process Motor vehicle designers make a multitude of
choices that influence how susceptible a vehicle may be to corrosion. During the
design of the vehicle, engineers should strive to reduce dissimilar metal contacts,
crevices, stresses, poor drainage, and locations where salt and dirt can build up.
The choice of materials in the design will also dramatically affect the corrosion
performance of vehicles. The use of corrosion-resistant metals, coated steels, and
polymers, as well as avoidance of dissimilar metal contacts, will allow vehicles to
operate for many years without significant corrosion problems. One of the most
critical considerations in the design process that affects corrosion performance
involves the choice of primers, paints, and sealers. The use of corrosion-resistant
primers over the entire body and special chip-resistant coatings for the wheel and the
lower surface of the car has become standard in the industry to reduce the initiation
of corrosion.
Several elements of corrosion protection added in the design phase can be rendered
useless if the quality of manufacturing is below standard or low. A few elements of
the manufacturing process are of specific importance. First, the quality of welding
will affect the presence of crevices where corrosion can occur. Secondly, the surface
pretreatment must be done properly to ensure good adhesion of the primer and the
final coating. Finally, several of the special coatings, such as chip-resistant coatings
and the body sealants, are applied manually by hand, and the quality of this work is
very much dependent on the skill and the attention paid by the applicator.
The corrosivity of the local environment will strongly affect the corrosion perfor-
mance of the vehicle (19, 20). In locations where corrosive environments are possible
because of acid rain, deicing salts, or marine environments, personal driving habits
and diligent maintenance of the vehicle, such as regular washing and replacement of
fluids, can have a significant effect on the reduction of corrosion.