19 June 2001
If dissimilar metals must be joined, the following preventive measures
should be taken:
Choose metals close together in the galvanic series.
Keep the cathodic area small in relation to the anode area; for
instance, bolts or screws of stainless steel for fastening aluminum
sheets, but not the reverse.
Provide a protective insulator between the two metals.
Use special coatings on the metals.
SYNTHETIC MATERIALS. Numerous synthetic materials are used in
waterfront facilities and components. They are extremely versatile in application
and serve as a structural material, coating material, or buoyancy material. In
general, these materials do not corrode in the marine environment, but
deteriorate due to other reasons, such as water absorption and swelling and
degradation by ultraviolet light. The common synthetic materials include:
Fiber-reinforced plastics (FRP)
Foams, rubbers, and elastomers
Plastic pile wraps and piping
increases with aging; plastics crack or separate, some become brittle; foams
crumble with age and lose resiliency; and elastomers stretch and deteriorate
from the effects of sun and exposure. In general, no preventive maintenance
measures are performed other than inspection. Certain materials and
components can be economically repaired when damaged.
Fiber-reinforced Plastics (FRP). FRP are used for applications
Pile jackets for steel, concrete, and timber piling to reduce
corrosion or erosion; for reinforcement; and to prevent marine borer
Lightweight, sandwich construction for small buildings and