Page 166 - Challenges in Corrosion Costs Causes Consequences and Control(2015)

144 CORROSION CAUSES

Figure 3.12 Example of a steel-reinforced concrete dam (7).

corrosion (16). Figure 3.13 shows the relative metal loss for steel piling after 5 years
of exposure to seawater at Kure Beach, North Carolina.
Atmospherically exposed submerged zones and splash zones typically experience
the most corrosion. The zones are found on piers and docks (ladders, railings,
cranes and steel support piles, bulkheads and retaining walls sheet steel piping,
steel-reinforced concrete elements, backside, and anchors on structures retaining
dredged fill), and mooring structures and dams (steel gates, hinges, intake/discharge
culverts, gates, and debris booms). Stationary navigational aids suffer from corrosion
of support piles and steel-reinforced concrete pile caps. Floating steel buoys are also
prone to corrosion.

3.9.2 Fresh Water
Airborne or splash zone attack is not normally a problem at freshwater facilities; how-
ever, air pollution can cause potential problems. Under certain flow conditions, such
as turbulent flow or cavitation, fresh water can cause severe corrosion to submerged
metallic elements. Ice damage also can limit the effectiveness of coatings on bulkhead
walls and support piling.
Piers and docks, bulkheads and retaining walls, locks, dams, and navigational aids
exposed to freshwater environment experience corrosion-related problems. The most
common areas of attack are submerged and splash zones on support piles (piers,
docks, and navigational aids) and steel sheet piling (bulkheads and retaining walls).
The zones are also found on locks (steel gates, hinges, intake/discharge culverts,
valves, and sheet pile walls), dams (steel gates, hinges, intake/discharge culverts,
grates, and debris booms), and navigational aids (anchorages).