Page 362 - Corrosion Engineering Principles and Practice

330 C h a p t e r 9 A t m o s p h e r i c C o r r o s i o n 331

FIGURE 9.2 Bird damage to a 1931 bronze statue commemorating the 21st
Battalion battles in WW I. (Courtesy of Kingston Technical Software)

9.2.2 Marine
A marine atmosphere is laden with fine particles of sea mist carried
by the wind to settle on exposed surfaces as salt crystals. The quantity
of salt deposited may vary greatly with wind velocity and it may, in
extreme weather conditions, even form a very corrosive salt crust,
similar to what is experienced on a regular basis by sea patrolling
aircraft or helicopters [Figs. 9.3(a) and (b)].
The quantity of salt contamination decreases with distance from the
ocean, and is greatly affected by wind currents. The marine atmosphere
also includes the space above the sea surfaces where splashing and
heavy sea spray are encountered. The equipment exposed to these splash
zones are indeed subjected to the worst conditions of intermittent
immersion with wet and dry cycling of the corrosive agent (Fig. 9.4).

9.2.3 Rural
Rural atmospheres are typically the most benign and do not contain
strong chemical contaminants, that is unless one is close to a farm