ASTM WK48004

    New Test Method for Acid Number of Crude Oils and Petroleum Products by Catalytic Thermometric Titration

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    Developed by Subcommittee: D02.06 | Committee D02 | Contact Staff Manager


    1. Scope

    1.1 This test method covers the determination of acidic components in crude oil and petroleum products. It is applicable for the determination of acids or bases whose dissociation constants in water are larger than 109; extremely weak acids or bases whose dissociation constants are smaller than 109 do not interfere. The values obtained by this test method may not be numerically equivalent to other acid value measurements.


    crude oil; thermometric titration; acid number; naphthenic acids; corrosion


    An increase in the acidity of crude oil has been implicated in increased corrosion rates. Naphthenic acids and other components that are native to crude oil will react with base. Due to the difficulty in quantifying specific compounds in crude oil that are responsible for the acidity, a generic approach of representing everything that reacts with base per gram of sample is used. This approach is consistent with other methods that are used to quantify the acid number of a sample.

    Citing ASTM Standards
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    Work Item Status

    Date Initiated:

    Technical Contact:
    Peggy Broughton