Determining the Corrosivity of Atmospheres, through the Weight Loss Method, According to ISO 9223

Abstract

ISO 9223 can be used to categorize the corrosivity of atmospheres through either corrosion loss measurements or the use of environmental data. Although both methods are expected to give the same result, discrepancies have been found to occur. The present paper analyses this aspect of ISO 9223, focusing on the effects of metal composition, when using carbon steel, in corrosivity categorisation. Low and medium carbon steel were, therefore, exposed outdoors at one site in Mauritius to determine its atmospheric corrosivity. It was found that for medium carbon steel, the corrosivity obtained from corrosion loss results, through the weight loss method, was not in conformance with that obtained through the environmental data. This was not the case with low carbon steel. Taking into consideration the various factors affecting atmospheric corrosion, it was concluded that the carbon content of carbon steel is an important parameter that should be considered in ISO 9223 for more reliable determination of the corrosivity of atmospheres.