ASTM D7157 - 12

    Standard Test Method for Determination of Intrinsic Stability of Asphaltene-Containing Residues, Heavy Fuel Oils, and Crude Oils (n-Heptane Phase Separation; Optical Detection)

    Active Standard ASTM D7157 | Developed by Subcommittee: D02.14

    Book of Standards Volume: 05.04


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    ASTM D7157

    Significance and Use

    5.1 This test method describes a sensitive method for estimating the intrinsic stability of an oil. The intrinsic stability is expressed as S-value. An oil with a low S-value is likely to undergo flocculation of asphaltenes when stressed (for example, extended heated storage) or blended with a range of other oils. Two oils each with a high S-value are likely to maintain asphaltenes in a peptized state and not lead to asphaltene flocculation when blended together.

    5.2 This test method can be used by petroleum refiners to control and optimize the refinery processes and by blenders and marketers to assess the intrinsic stability of blended asphaltene-containing heavy fuel oils.

    1. Scope

    1.1 This test method covers a procedure for quantifying the intrinsic stability of the asphaltenes in an oil by an automatic instrument using an optical device.

    1.2 This test method is applicable to residual products from thermal and hydrocracking processes, to products typical of Specifications D396 Grades No. 5L, 5H, and 6, and D2880 Grades No. 3-GT and 4-GT, and to crude oils, providing these products contain 0.5 mass% or greater concentration of asphaltenes (see Test Method D6560).

    1.3 This test method quantifies asphaltene stability in terms of state of peptization of the asphaltenes (S-value), intrinsic stability of the oily medium (So) and the solvency requirements of the peptized asphaltenes (Sa).

    1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

    1.5 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

    D396 Specification for Fuel Oils

    D2880 Specification for Gas Turbine Fuel Oils

    D4057 Practice for Manual Sampling of Petroleum and Petroleum Products

    D4175 Terminology Relating to Petroleum, Petroleum Products, and Lubricants

    D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products

    D4870 Test Method for Determination of Total Sediment in Residual Fuels

    D6560 Test Method for Determination of Asphaltenes (Heptane Insolubles) in Crude Petroleum and Petroleum Products

    D6792 Practice for Quality System in Petroleum Products and Lubricants Testing Laboratories


    ICS Code

    ICS Number Code 75.040 (Crude petroleum)

    UNSPSC Code

    UNSPSC Code 15101508(Crude oil); 15101700(Fuel Oils)


    DOI: 10.1520/D7157-12

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