Atmospheric corrosion in subtropical areas: influences of time of wetness and deficiency of the ISO 9223 norm

In this paper the first results of the study of the corrosion of exposed metals to the action of saline atmospheres in subtropical areas (Canary Islands, Spain) are presented. During three years, carbon steel, zinc and copper sheets have been exposed to the action of different atmospheres in 35 test sites distributed in the western islands of the Canarian Archipelago, located in front of the African continent, which are characterized by a soft climate and seasonal rains. Corrosion rates of the three metals have been obtained by lost of weight. Time of wetness and deposition rates of atmospheric pollutants (i.e. Cl− and SO2) have also been determined. Applying the standard ISO 9223 norm aggressiveness of the atmospheres corresponding to the different test sites has been determined. In the whole region it can be frequently found corrosion values that exceed those established by the Standard ISO 9223 norm. Therefore, the scale of the aggressiveness to the corrosion was enlarged in order to include coastal areas of the tropical and subtropical regions.