ASTM G91 - 11

    Standard Practice for Monitoring Atmospheric SO2 Deposition Rate for Atmospheric Corrosivity Evaluation

    Active Standard ASTM G91 | Developed by Subcommittee: G01.04

    Book of Standards Volume: 03.02


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    Significance and Use

    Atmospheric corrosion of metallic materials is a function of many weather and atmospheric variables. The effect of specific corrodants, such as sulfur dioxide, can accelerate the atmospheric corrosion of metals significantly. The sulfation plate method provides a simple technique to independently monitor the level of SO2 in the atmosphere to yield a weighted average result.

    Sulfation plate results may be used to characterize atmospheric corrosion test sites regarding the effective average level of SO2 in the atmosphere at these locations.

    Sulfation plate testing is useful in determining microclimate, seasonal, and long term variations in the effective average level of SO2.

    The results of sulfation plate tests may be used in correlations of atmospheric corrosion rates with atmospheric data to determine the sensitivity of the corrosion rate to SO2 level.

    The sulfation plate method may also be used with other methods to characterize the atmosphere at sites where buildings or other construction is planned in order to determine the extent of protective measures required for metallic materials.

    1. Scope

    1.1 This practice covers a weighted average effective SO2 level for a 30-day interval through the use of the sulfation plate method, a technique for estimating the effective SO2 content of the atmosphere, and especially with regard to the atmospheric corrosion of stationary structures or panels. This practice is aimed at determining SO2 levels rather than sulfuric acid aerosol or acid precipitation.

    1.2 The results of this practice correlate approximately with volumetric SO2 concentrations, although the presence of dew or condensed moisture tends to enhance the capture of SO2 into the plate.

    1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.


    2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    ASTM Standards

    D516 Test Method for Sulfate Ion in Water

    D1193 Specification for Reagent Water

    D2010/D2010M Test Methods for Evaluation of Total Sulfation Activity in the Atmosphere by the Lead Dioxide Technique

    G16 Guide for Applying Statistics to Analysis of Corrosion Data

    G84 Practice for Measurement of Time-of-Wetness on Surfaces Exposed to Wetting Conditions as in Atmospheric Corrosion Testing

    G140 Test Method for Determining Atmospheric Chloride Deposition Rate by Wet Candle Method

    ISO Standards

    ISO9225 Corrosion of metals and alloys- Corrosivity of atmospheres - Measurement of environmental parameters affecting corrosivity of atmospheres


    ICS Code

    ICS Number Code 13.040.20 (Ambient atmospheres)

    UNSPSC Code

    UNSPSC Code 41114604(Corrosion testers)


    DOI: 10.1520/G0091-11

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