ASTM D7112-05a

Automatic determination of stability parameters using a light back-scattering technique improves accuracy and removes human errors. In manual testing, operators have to visually compare oil stains on pieces of filter paper to determine if asphaltenes have been precipitated.

Refinery thermal and hydrocracking processes can be run closer to their severity limits if stability parameters can be calculated more accurately. This gives increased yield and profitability.

Results from the test method could be used to set a standard specification for stability parameters for fuel oils.

The compatibility parameters of crude oils can be used in crude oil blending in refineries to determine, in advance, which crude oil blends will be compatible and thus can be used to minimize plugging problems, unit shut downs, and maintenance costs. Determination of crude oil compatibility parameters also enables refineries to select crude oil mixtures more economically.

This test method can measure stability and compatibility parameters, and determine stability reserve on different blends for particular applications to optimize the blending, storage, and use of heavy fuel oils

Note 1—Users of this test method would normally use stability and compatibility parameters to determine stability reserve of residual products, fuel blends and crude oils. However, the interpretation of stability, stability reserve and compatibility is heavily ‘use dependent,’ and is beyond the scope of this test method.

1.1 This test method covers an automated procedure involving titration and optical detection of precipitated asphaltenes for determining the stability and compatibility parameters of refinery residual streams, residual fuel oils, and crude oils. Stability in this context is the ability to maintain asphaltenes in a peptized or dissolved state and not undergo flocculation or precipitation. Similarly, compatibility relates to the property of mixing two or more oils without precipitation or flocculation of asphaltenes.

1.2 This test method is applicable to residual products from atmospheric and vacuum distillation, from thermal, catalytic, and hydrocracking processes, to products typical of Specifications D 396, Grades No. 5L, 5H, and 6, and D 2880, Grades No. 3-GT and 4-GT, and to crude oils, providing these products contain 0.05 mass % or greater concentration of asphaltenes.

1.3 This test method is not relevant to oils that contain less than 0.05 % asphaltenes, and would be pointless to apply to unstable oils that already contain flocculated asphaltenes.

1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

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.