STP1000: Evaluation of an Atmospheric Damage Function for Galvanized Steel

    Haynie, FH
    Environmental engineer and chemist, U.S. Environmental Protection Agency, Research Triangle Park, NC

    Spence, JW
    Environmental engineer and chemist, U.S. Environmental Protection Agency, Research Triangle Park, NC

    Lipfert, FW
    Environmental engineer, Brookhaven National Laboratory, Upton, NY

    Cramer, SD
    Metallurgist, Bureau of Mines, Albany, OR

    McDonald, LG
    Metallurgist, Bureau of Mines, Albany, OR

    Pages: 16    Published: Jan 1990


    Abstract

    A model for corrosion of zinc based on competing mechanisms of the formation and dissolution of a protective film of basic zinc carbonate was evaluated. The model consists of a diffusivity term (ions through the film) which controls the buildup of a protective film and a solubilization term which controls the rate of dissolution of the film. The model was evaluated by using comprehensive data collected from field experiments designed to separate the effects of wet and dry acid deposition from normal weathering effects such as clean rain, temperature, wind speed, and relative humidity. These data were used primarily to evaluate the theoretically calculated components of the dissolution rate term because after about three years it becomes the rate upon which long-term corrosion behavior may be predicted. The model was also evaluated with respect to historical long-term data for different shapes and sizes of galvanized products.

    The field data used in this evaluation were found to be consistent with values predicted by the model. Thus, the model can be used with reasonable confidence to predict long-term corrosion behavior of different structures in real environments if those environments are properly described.

    Keywords:

    zinc corrosion, acid rain, sulfur dioxide, deposition velocity, corrosion products


    Paper ID: STP39192S

    Committee/Subcommittee: G01.04

    DOI: 10.1520/STP39192S


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