Steel sheet piles are widely used in permanent earth retaining and structural foundation works. In the majority of circumstances, they can be used in an unprotected condition, such conditions are when the steel piles does not required any coating or cathodic protection system to be protected and depends solely on the corrosion allowance calculations The degree of corrosion and whether protection is required depends upon the working environment - which can vary even within the same project location.
In general, marine environments are the most corrosive and unpredictable. In the few meters of vertical zoning which most structures encompass, parts of the sheet piles are in contact with soil, and exposed to seawater immersion, inter-tidal, splash and marine atmospheric environments.