ASTM D7155 - 20

    Standard Practice for Evaluating Compatibility of Mixtures of Turbine Lubricating Oils

    Active Standard ASTM D7155 | Developed by Subcommittee: D02.C0.01

    Book of Standards Volume: 05.04


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    Significance and Use

    5.1 The compatibility of oils can be important for users of oil-lubricated equipment. Mixing of two oils can produce a substance markedly inferior to either of its constituent materials. One or more of the following can occur:

    5.1.1 A mixture of incompatible oils most often forms a precipitate. The precipitate will form unwanted deposits in the lubrication system, plug filters, and oil passageways.

    5.1.2 A mixture of incompatible oils will sometimes exhibit degradation of certain performance parameters like demulsibility, foam inhibition oxidation stability, rust protection ability, or antiwear protection ability.

    5.1.3 A mixture of incompatible oils will sometimes exhibit non-miscibility of the base oils with each other.

    5.1.4 Such incompatibilities can lead to catastrophic equipment failures.

    5.2 To minimize the chances of these problems occurring, lubricant suppliers recommend evaluating compatibility of lubricating oil of different formulations and sources prior to mixing. Equipment users most often do not have the resources to evaluate oil compatibility and must rely on their suppliers. Mixing of oils without first determining the compatibility is a highly imprudent practice.

    5.3 Although new turbine oils may be compatible, in-service oil of the same type may be degraded or contaminated to such an extent that the new oil added may not be compatible with the system oil. In-service oil compatibility with new oil additions should be evaluated on a case-by-case basis.

    5.4 The oxidation resistance of different oils of the same type can vary widely, and compatibility does not imply equivalent performance without oxidation performance testing.

    1. Scope

    1.1 This practice covers the compatibility of mixtures of turbine lubricating oils as defined by Specification D4304. The methods compare properties of specific mixtures with those of the neat oils after storage at specified conditions.

    1.2 The methods are grouped into four tiers of testing types:

    1.2.1 Tier 1—Visual appearance

    1.2.2 Tier 2—Interfacial properties

    1.2.3 Tier 3—Physical and chemical properties

    1.2.4 Tier 4—Specific performance properties

    1.3 The methods can be used to evaluate new (unused) lubricant compatibility or the effects of adding new (unused) lubricant to in-service lubricant in the system.

    1.4 This practice does not evaluate the wear prevention characteristics, load carrying capacity, or the mechanical shear stability of lubricants mixtures while in service. If anti-wear (AW), extreme pressure (EP), or shear stability are to be evaluated, further testing of these parameters may be required.

    1.5 Mixtures of the two constituent oils are evaluated using the Tier 1 and Tier 2 testing protocol. Sequential or concurrent testing is continued by applying tests from Tier 3 or Tier 4 until the test requestor or user is satisfied that the intent of this practice has been met. If any mixture fails the methods, the oils are considered incompatible by that method. If all mixtures pass the methods, the oils are considered compatible by those methods. It is recommended that passing only Tier 1 does not adequately test for fluid compatibility.

    1.6 If the mixture passes Tier 1, it shows two oils are visually compatible only. If the mixture passes Tier 1 and 2, it shows two oils are visually and interfacially compatible. If the mixture passes Tier 1, 2 and 3, it shows two oils are visually, interfacially, physically, and chemically compatible. If the mixture passes Tier 1, 2, 3, 4, it shows two oils are compatible with the highest confidence level. Testing each tier level is giving the user more confidence that the two fluids are compatible.

    1.7 This practice applies only to lubricating oils having characteristics suitable for evaluation by the suggested test methods. If the scope of a specific test method limits testing to those oils within a specified range of properties, oils outside that range cannot be tested for compatibility by that test method.

    1.8 This practice may be used to evaluate the compatibility of different types and grades of oil. However, it is not intended to evaluate such mixtures for lubrication performance. The user is advised to consult with suppliers in these situations.

    1.9 This practice does not purport to cover all test methods that could be employed.

    1.10 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard.

    1.11 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

    1.12 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.


    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

    D130 Test Method for Corrosiveness to Copper from Petroleum Products by Copper Strip Test

    D445 Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)

    D611 Test Methods for Aniline Point and Mixed Aniline Point of Petroleum Products and Hydrocarbon Solvents

    D664 Test Method for Acid Number of Petroleum Products by Potentiometric Titration

    D665 Test Method for Rust-Preventing Characteristics of Inhibited Mineral Oil in the Presence of Water

    D892 Test Method for Foaming Characteristics of Lubricating Oils

    D893 Test Method for Insolubles in Used Lubricating Oils

    D974 Test Method for Acid and Base Number by Color-Indicator Titration

    D1401 Test Method for Water Separability of Petroleum Oils and Synthetic Fluids

    D1500 Test Method for ASTM Color of Petroleum Products (ASTM Color Scale)

    D2270 Practice for Calculating Viscosity Index from Kinematic Viscosity at 40C and 100C

    D2272 Test Method for Oxidation Stability of Steam Turbine Oils by Rotating Pressure Vessel

    D3120 Test Method for Trace Quantities of Sulfur in Light Liquid Petroleum Hydrocarbons by Oxidative Microcoulometry

    D3427 Test Method for Air Release Properties of Hydrocarbon Based Oils

    D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants

    D4304 Specification for Mineral and Synthetic Lubricating Oil Used in Steam or Gas Turbines

    D4310 Test Method for Determination of Sludging and Corrosion Tendencies of Inhibited Mineral Oils

    D4629 Test Method for Trace Nitrogen in Liquid Hydrocarbons by Syringe/Inlet Oxidative Combustion and Chemiluminescence Detection

    D5185 Test Method for Multielement Determination of Used and Unused Lubricating Oils and Base Oils by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES)

    D5762 Test Method for Nitrogen in Liquid Hydrocarbons, Petroleum and Petroleum Products by Boat-Inlet Chemiluminescence

    D5846 Test Method for Universal Oxidation Test for Hydraulic and Turbine Oils Using the Universal Oxidation Test Apparatus

    D6186 Test Method for Oxidation Induction Time of Lubricating Oils by Pressure Differential Scanning Calorimetry (PDSC)

    D6304 Test Method for Determination of Water in Petroleum Products, Lubricating Oils, and Additives by Coulometric Karl Fischer Titration

    D6514 Test Method for High Temperature Universal Oxidation Test for Turbine Oils

    D7042 Test Method for Dynamic Viscosity and Density of Liquids by Stabinger Viscometer (and the Calculation of Kinematic Viscosity)

    D7843 Test Method for Measurement of Lubricant Generated Insoluble Color Bodies in In-Service Turbine Oils using Membrane Patch Colorimetry

    D7873 Test Method for Determination of Oxidation Stability and Insolubles Formation of Inhibited Turbine Oils at 120C Without the Inclusion of Water (Dry TOST Method)

    D8148 Test Method for Spectroscopic Determination of Haze in Fuels


    ICS Code

    ICS Number Code 75.100 (Lubricants, industrial oils and related products)

    UNSPSC Code

    UNSPSC Code 15121527(Turbine oil)


    Referencing This Standard
    Link Here
    Link to Active (This link will always route to the current Active version of the standard.)

    DOI: 10.1520/D7155-20

    Citation Format

    ASTM D7155-20, Standard Practice for Evaluating Compatibility of Mixtures of Turbine Lubricating Oils, ASTM International, West Conshohocken, PA, 2020, www.astm.org

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