Application of a Model for Prediction of Atmospheric Corrosion in Tropical Environments

Abstract

Based on analysis of data from field exposure programs within, e.g., UN ECE and ISO CORRAG a model describing atmospheric corrosion of common technical metals has been developed. The model uses environmental parameters that are easily available on different geographical scales. The combination of temperature and relative humidity can be used to express the time of wetness based on a probability model for the prediction of time of wetness from annual temperature and relative humidity data. The sulfur dioxide air concentration and the chloride deposition are included in different parts of the model and these two parts contain separate expressions for the combination of temperature and relative humidity (or temperature and time of wetness). This makes it possible to apply the model in marine areas with different deposition of chlorides and different pollution levels. The development of the model has contributed to a better understanding of the conditions for atmospheric corrosion, including tropical regions. The individual terms of the model have been adapted using physical and chemical principles. This makes the model useful for predictions also in regions outside those defining the original data set. Examples of independent data from field exposures not included in the model development are shown and discussed.