ASTM D128-98(2019)
(Test Method)Standard Test Methods for Analysis of Lubricating Grease
Standard Test Methods for Analysis of Lubricating Grease
SIGNIFICANCE AND USE
4.1 These test methods can be used to identify and estimate the amount of some of the constituents of lubricating greases. These test methods are applicable to many, but not all, greases.
4.2 Composition should not be considered as having any direct bearing on service performance unless such correlation is established.
Note 2: Details on other test methods for grease analysis can be found in other reference material.4,5,6
SCOPE
1.1 These test methods for analysis cover greases of the conventional type, which consist essentially of petroleum oil and soap. The constituents that can be determined are soap, unsaponifiable matter (petroleum oil, and so forth), water, free alkalinity, free fatty acid, fat, glycerin, and insolubles.
Note 1: Any of the test methods described herein are best used by an experienced grease analyst who may also be able to make appropriate adaptations of the techniques as occasion requires.
1.2 A supplementary test method is provided in Appendix X1. This test method is intended primarily for application to greases containing thickeners that are essentially insoluble in n-hexane, and to greases that cannot be analyzed by conventional methods because of the presence of such constituents as nonpetroleum fluids or nonsoap-type thickeners, or both. In some cases, these constituents can react with strong acid or alkaline solutions.
1.3 These test methods appear in the following order:
Sections
Ash Determination
7 – 11
Insolubles, Soap, Fat, Petroleum Oil,
and Unsaponifiable Matter
12 – 20
Free Alkali and Free Acid
21 – 23
Water
24
Glycerin (Quantitative)
25 – 29
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.6 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.
General Information
Relations
Standards Content (Sample)
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.
Designation: D128 − 98 (Reapproved 2019)
Standard Test Methods for
Analysis of Lubricating Grease
This standard is issued under the fixed designation D128; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
1.1 These test methods for analysis cover greases of the
Barriers to Trade (TBT) Committee.
conventional type, which consist essentially of petroleum oil
and soap. The constituents that can be determined are soap,
2. Referenced Documents
unsaponifiable matter (petroleum oil, and so forth), water, free
alkalinity, free fatty acid, fat, glycerin, and insolubles.
2.1 ASTM Standards:
D95 Test Method for Water in Petroleum Products and
NOTE 1—Any of the test methods described herein are best used by an
Bituminous Materials by Distillation
experienced grease analyst who may also be able to make appropriate
adaptations of the techniques as occasion requires. D156 Test Method for Saybolt Color of Petroleum Products
(Saybolt Chromometer Method)
1.2 A supplementary test method is provided in Appendix
D217 Test Methods for Cone Penetration of Lubricating
X1. This test method is intended primarily for application to
Grease
greases containing thickeners that are essentially insoluble in
D445 Test Method for Kinematic Viscosity of Transparent
n-hexane, and to greases that cannot be analyzed by conven-
and Opaque Liquids (and Calculation of Dynamic Viscos-
tional methods because of the presence of such constituents as
ity)
nonpetroleum fluids or nonsoap-type thickeners, or both. In
D473 Test Method for Sediment in Crude Oils and Fuel Oils
some cases, these constituents can react with strong acid or
by the Extraction Method
alkaline solutions.
D804 Terminology Relating to Pine Chemicals, Including
1.3 These test methods appear in the following order:
Tall Oil and Related Products
Sections
D1078 Test Method for Distillation Range of Volatile Or-
Ash Determination 7–11
ganic Liquids
Insolubles, Soap, Fat, Petroleum Oil, 12–20
and Unsaponifiable Matter D1193 Specification for Reagent Water
Free Alkali and Free Acid 21–23
D1353 Test Method for Nonvolatile Matter in Volatile Sol-
Water 24
vents for Use in Paint, Varnish, Lacquer, and Related
Glycerin (Quantitative) 25–29
Products
1.4 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
3. Terminology
standard.
3.1 Definitions:
1.5 This standard does not purport to address all of the
3.1.1 asphalt, n—a dark brown-to-black cementitious mate-
safety concerns, if any, associated with its use. It is the
rial in which the predominating constituents are bitumens.
responsibility of the user of this standard to establish appro-
3.1.1.1 Discussion—Asphalt can be a natural product or a
priate safety, health, and environmental practices and deter-
material obtained from petroleum processing.
mine the applicability of regulatory limitations prior to use.
1.6 This international standard was developed in accor-
3.1.2 candle pitch, n—a dark brown-to-black, tarry or solid,
dance with internationally recognized principles on standard-
by-product residue from soap and candle stock manufacture,
ization established in the Decision on Principles for the
refiningofvegetableoils,refiningofwoolgrease,orrefiningof
refuse animal fats.
These test methods are under the jurisdiction of ASTM Committee D02 on
Petroleum Products, Liquid Fuels, and Lubricants and are the direct responsibility
of Subcommittee D02.G0.01 on Chemical and General Laboratory Tests. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved July 1, 2019. Published August 2019. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
ɛ1
approved in 1922. Last previous edition approved in 2014 as D128 – 98 (2014) . Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D0128-98R19. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D128 − 98 (2019)
3.1.3 cup grease, n—any lubricating grease having physical 3.1.11 neutralization number, n—of petroleum oil, the quan-
properties, such as consistency and texture, suitable for its use tity of acid or base required to titrate to neutrality and
in spring-loaded or screw-type lubricating cups. expressed as equivalent milligrams of potassium hydroxide per
3.1.3.1 Discussion—Cup greases are predominantly NLGI gram of sample. D804
No. 3 or 4 calcium greases, but grease types other than calcium
3.1.12 NLGI, n—National Lubricating Grease Institute.
are also used.
3.1.13 NLGI number, n—a numerical scale for classifying
3.1.4 degras(woolfat,woolgrease,woolwax),n—afat-like
the consistency range of lubricating greases and based on the
material comprised primarily of sterols, other higher alcohols,
Test Methods D217 worked penetration.
and fatty acids, obtained from the solvent extraction of sheep’s
NLGI Lubricating Grease Guide
wool.
3.1.14 non-soap thickener (synthetic thickener, inorganic
3.1.5 free alkali, n— in lubricating grease, unreacted basic
thickener, organic thickener), n—in lubricating grease, any of
(alkaline) material present in the product.
several specially treated or synthetic materials, excepting
3.1.5.1 Discussion—Many greases are made with a slight
metallicsoaps,thatcanbethermallyormechanicallydispersed
excess of alkali to ensure complete saponification. Free alkali
in liquid lubricants to form the lubricating grease structure.
is determined by acidification of a solvent-thinned specimen
NLGI Lubricating Grease Guide
and back titration with standardized, alcoholic potassium
hydroxide. It is expressed in terms of the predominating alkali 3.1.15 residuum, n—a liquid or semi-liquid product ob-
and a mass % of the total grease composition (for example,
tained as residue from the distillation of petroleum and
mass % lithium hydroxide). consisting primarily of asphaltic hydrocarbons.
3.1.15.1 Discussion—Also known as asphaltic oil, asphal-
3.1.6 free fatty acid, n—in lubricating grease, unreacted
tum oil, liquid asphalt, black oil, petroleum tailings, and
carboxylic acid(s) present in the product.
residual oil.
3.1.6.1 Discussion—Some greases are made with a slight
excess of carboxylic acid to ensure a non-alkaline product.
3.1.16 rosin oil, n—a viscous, oily liquid obtained as a
Free fatty acid is determined by neutralization of a solvent-
condensate when the residue (rosin) from turpentine produc-
thinned specimen with standardized, alcoholic potassium hy-
tion is subjected to dry, destructive distillation.
droxide.Regardlessoftheactualcompositionofthecarboxylic
3.1.16.1 Discussion—Also used to describe specially com-
acid(s), it is expressed as free oleic acid and as a mass % of the
pounded oils having a rosin base.
total grease composition.
3.1.17 saponification, n—the interaction of fats, fatty acids,
3.1.7 insolubles, n—in lubricating greases analysis, the
or esters generally with an alkali to form the metallic salt,
material remaining after the acid hydrolysis, water extraction,
which is commonly called soap.
and solvent extraction of soap-thickened greases.
3.1.17.1 Discussion—Soap thickeners are most often made
3.1.7.1 Discussion—Consisting of such products as
by in situ saponification in the lubricating grease base oil.
graphite, molybdenum disulfide, insoluble polymers, and so
However, the use of pre-formed soaps is also common;
forth.
dispersion is effected by mechanical means and usually with
3.1.8 lubricating grease, n—a semi-fluid to solid product of
heat. NLGI Lubricating Grease Guide
a dispersion of a thickener in a liquid lubricant.
3.1.18 single base, adj— in lubricating grease, relating to a
3.1.8.1 Discussion—The qualifying term, lubricating,
thickener comprised of soaps of only one metal.
should always be used. The term, grease, used without the
qualifier refers to a different product, namely certain natural or
3.1.19 soap, n—in lubricating grease, a product formed in
processed animal fats, such as tallow, lard, and so forth.
the saponification (neutralization) of fats, fatty acids, or esters
3.1.9 mixed base, adj—in lubricating grease, the description by inorganic bases.
of a thickener system composed of soaps of two metals.
3.1.20 Soxhlet apparatus, n—a device, usually of glass,
3.1.9.1 Discussion—Although mixed-base grease can be
used to extract soluble material from a mixture of soluble and
made with soaps of more than two metals, in practice, such is
insoluble (generally solid) materials, by passing a volatile
rarely, if ever, encountered. All of the soaps need not be
solvent through the sample and recirculating the solvent by
thickeners, although the major soap constituent will be one
refluxing.
capable of forming a lubricating grease structure. Because the
3.1.21 tar, n—a brown or black, bituminous, liquid or
mixed soaps are seldom present in equal amounts. The pre-
semi-solid comprised primarily of bitumens condensed in the
dominant soap is referred to first.
processingofcoal,petroleum,oil-shale,wood,orotherorganic
NLGI Lubricating Grease Guide
materials.
3.1.10 montan wax, n—a wax-like material comprised pri-
3.1.22 thickener, n—in lubricating grease, a substance com-
marily of montanic acid and its ester, higher aliphatic alcohols,
posed of finely divided solid particles dispersed in a liquid
and resins obtained from the solvent extraction of lignite.
lubricant to form the product’s structure.
3.1.22.1 Discussion—The thickener can be fibers (such as
various metallic soaps) or plates or spheres (such as certain
Available from National Lubricating Grease Institute, 4635 Wyandotte St.,
Kansas City, MO 64112-1596; http://www.nlgi.org. non-soapthickeners),whichareinsolubleor,atmost,onlyvery
D128 − 98 (2019)
TABLE 1 Physical Requirements of n-hexane
slightly soluble in the liquid lubricant. The general require-
ments are that the solid particles be extremely small, uniformly Test Requirement ASTM
A
Designation
dispersed, and capable of forming a relatively stable, gel-like
Initial boiling point, min, °C 66.1 D1078
structure with the liquid lubricant. D217
Dry point, max, °C 68.9 D1078
3.1.23 thimble, n—in Soxhlet apparatus, a closed-end po- Nonvolatile matter, max, g/100 mL 0.001 D1353
Color, Saybolt, min + 30 D156
rous cylinder used to hold the material to be extracted, usually
A
Reaction with alkalies .
made of thick matted filter paper but sometimes made of
A
Boil 125 mL of n-hexane with 10 mL of 0.5 N alcoholic KOH solution and 50 mL
ceramic.
of neutral 50 % alcohol for 1 ⁄2 h on a hot plate. Use a glass tube about 7 mm in
inside diameter and 750 mm in length as a reflux condenser. After cooling, titrate
3.1.24 total fluid constituent, n—in lubricating grease
the solutions with 0.5 N HCl using phenolphthalein as the indicator. Not less than
analysis, the n-hexane-soluble material extracted from the
9.8 mL of 0.5 N HCl shall be required for neutralization. The amount of alkali
lubricating grease sample. consumed in this test shall be deducted as a blank correction in the fat
determination on Solution E.
3.1.24.1 Discussion—Typical materials include petroleum
oil, non-petroleum fluid, soluble fats, and soluble additives.
3.1.25 total n-hexane-insoluble material, n—in lubricating
grease analysis, that portion of grease (excluding free alkali)
5.2 Purity of Water—Unless otherwise indicated, references
that is essentially insoluble in n-hexane.
towatershallbeunderstoodtomeanreagentwaterconforming
3.1.25.1 Discussion—Typical materials include thickeners,
to Specification D1193, Type III.
fillers, inorganic salts, asphaltenes, or any combinations of
5.3 Acetone—American Chemical Society Reagent Grade
these(alsoincludesinsolublematerialsfoundintheanalysisof
Acetone.(Warning—Extremelyflammable.Vaporsmaycause
contaminated grease). Free alkali content is generally insignifi-
flash fires.)
cant.
5.4 Alcohol (50 %)—The alcohol shall be prepared from
3.1.26 unsaponifiable matter, n—in lubricating grease, or-
8,9
commercial 95 % ethanol or denatured alcohol (Warning—
ganic materials, either added or found with fatty materials,
Flammable.Denatured.Cannotbemadenontoxic)bydistilling
which do not react during saponification.
fromNaOHandneutralizingexactlywithNaOHorKOHusing
phenolphthalein as the indicator. (Warning—In addition to
4. Significance and Use
other precautions, avoid skin contact or ingestion.) Dilute with
4.1 These test methods can be used to identify and estimate
an equal volume of water.
the amount of some of the constituents of lubricating greases.
5.5 Ammonium Carbonate—(NH ) CO.(Warning—
4 2 3
These test methods are applicable to many, but not all, greases.
Harmful if swallowed.) (Warning—Harmful if swallowed.)
4.2 Composition should not be considered as having any
5.6 Butter Yellow Indicator (0.02 g⁄mL)—Toluene solution
direct bearing on service performance unless such correlation
(Warning—Flammable. Vapor harmful) of
is established.
p-dimethylaminoazobenzene. (Warning—Suspected carcino-
NOTE 2—Details on other test methods for grease analysis can be found
gen. In addition to other precautions, avoid inhalation or skin
4,5,6
in other reference material.
contact.)
5.7 t-Butyl Alcohol, melting point 24 °C to 25.5 °C
5. Reagents
(Warning—Flammable liquid; causes eye burns).
5.1 Purity of Reagents—Reagent grade chemicals shall be
5.8 Carbon Disulfide (CS ). (Warning—Extremely flam-
used in all tests. Unless otherwise indicated, it is intended that
mable. Poison. Vapor may cause flash fire. Vapor harmful.
all reagents shall conform to the specifications of the Commit-
Capable of self-ignition at 100 °C or above. Harmful or fatal if
tee onAnalytical Reagents of theAmerican Chemical Society,
swallowed. May be absorbed through the skin.)
where such specifications are available. Other grades may be
used, provided it is first ascertained that the reagent is of
5.9 EthylEther.(Warning—Extremelyflammable.Harmful
sufficiently high purity to permit its use without lessening the
if inhaled. May cause eye injury. Effects may be delayed. May
accuracy of the determinatio
...
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