MIL-HDBK-1110
b)
Cathodic areas where the metal is protected
c)
An electrolyte (conductive medium such as soil or
water)
d)
A metallic path between the anode and cathode
In atmospheric corrosion, surface moisture and
contamination serve as the electrolyte. Dissimilar metals are
anodic and cathodic to each other; also, the same metal
components have anodic and cathodic areas because of slight
chemical or physical differences.
1.3.2
Deterioration of Wood. The chief causes of
deterioration of wood are effects of ultraviolet light, and
swelling and contracting. These adversely affect the physical
properties of the wood.
1.3.3
Deterioration of Concrete. The chief cause of concrete
deterioration is moisture and electrolyte penetration. This may
result in deterioration of the concrete itself or in corrosion of
reinforcing steel which causes spalling of the concrete.
1.3.4
Design Factors Affecting Deterioration. Poor design of
structures may accelerate their deterioration or interfere with
their protection by coatings. Examples of poor designs are
listed below:
a)
Water traps
b)
Crevices
c)
Rough and sharp surfaces
d)
Limited access
e)
Incompatible environment
f)
Contact of dissimilar metals
1.3.4.1
Water Traps. Since water greatly accelerates
deterioration, structures should be designed so that water is not
collected. For example, angle irons and other configurations
that can collect water should be oriented downward rather than
upward. Weep holes of sufficient size should be placed where
water collection cannot be otherwise avoided. Condensate water
from air conditioners should not be allowed to run or drip on
surfaces and steam or other vapors should not be allowed to
impinge on surfaces.
2
Previous Page
