STP767

    Evaluation of the Effects of Microclimate Differences on Corrosion

    Published: Jan 1982


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    Abstract

    Analytical and statistical analyses of data obtained from a contracted exposure study performed by Rockwell International in St. Louis, Mo. reveal that many microclimate differences can account for observed differences in corrosion behavior within a geographic region. Data from Mansfeld's Atmospheric Corrosion Monitors (ACM's) were evaluated with data from the Regional Air Monitoring System (RAMS). Relative humidity, temperature, wind speed, and levels of total sulfur gases such as sulfur dioxide and oxides of nitrogen were found to be statistically significant variables. Problems of covariance were avoided by partitioning the large data set into subsets.

    Relative humidity was found to be the most important but least accurate variable. Because it is seldom measured at exposure sites, an equation was developed to relate site-to-site relative humidity differences to temperature differences. With average relative humidity and another empirical equation, time-of-wetness can be estimated. The results are in good agreement with time-of-wetness from the ACM's.

    Keywords:

    atmospheric corrosion, climate, pollution, measurement, statistical analysis, zinc, steel, wind speed, temperature, relative humidity, time-of-wetness, sulfur dioxide, nitrogen oxide


    Author Information:

    Haynie, FH
    Rockwell International Science Center, Creve Coeur, Mo.


    Paper ID: STP33200S

    Committee/Subcommittee: G01.04

    DOI: 10.1520/STP33200S


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