Steels continued soil corrosion

In order to form the patina a series of wet and dry periods is required. If the steel is installed in such a manner as to be sheltered from the rain, the dark patina does not form. Instead, a rust lighter in color forms that provides the same resistance. The corrosion rate of the weathering steels will be the same as the corrosion rate of unalloyed steel when it is continuously exposed to wetness such as in soil or water. 

Low resistivities and high chloride concentrations in the soil may lead to corrosion of buried steel pipehnes or structures. Cathodic protection should be considered for all buried steel pipehnes or structures. Where cathodic protection is not provided, corrosion monitoring equipment should be incorporated into the design to allow the operating staff to monitor the condition of the pipelines or structures. Nonwelded joints should be bonded for electrical continuity. In addition, coatings should also be considered. Coatings may be used alone or in con-jimction with cathodic protection. 

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