ASTM WK17124

    New Test Method for Test Method for Determination of Sludging Formation of Inhibited Oils Without the Inclusion of Water (Dry TOST Method)

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    Developed by Subcommittee: D02.09.0C | Committee D02 | Contact Staff Manager


    1. Scope

    This test method is used to evaluate the tendency of inhibited gas and steam turbine lubricants to form sludge during oxidation in the presence of oxygen and copper and iron metals at an elevated temperature. The test method can be used for testing circulating oils having a specific gravity less than that of water and containing rust and oxidation inhibitors.

    Varnish/deposit related issues in gas turbine oils is one of the most important lubricant end user issues. With the exception of Mitsubishi Heavy Industries (MHI), turbine OEMs do not have a specification method to evaluate Varnish/deposit formation of new oils. The MHI method (dry TOST) is currently an in-house method and it has not been standardized. The dry Tost method needs to be standardized so that turbine oil manufacturers can evaluate their existing products and develop new oils with low Varnish/deposit tendency. Users of this method will include independent, additive and lubricant supplier testing laboratories.


    TOST, insolubles, turbine oil, oxidation

    The title and scope are in draft form and are under development within this ASTM Committee.

    Citing ASTM Standards
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    Work Item Status

    Date Initiated:

    Technical Contact:
    Mark Okazaki

    Draft Under Development