ASTM D128-98(2003)e1
(Test Method)Standard Test Methods for Analysis of Lubricating Grease
Standard Test Methods for Analysis of Lubricating Grease
SIGNIFICANCE AND USE
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.
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.6 ,7 ,8
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 Appencix 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: SectionsAsh Determination7-11Insolubles, Soap, Fat, Petroleum Oil,and Unsaponifiable Matter12-20Free Alkali and Free Acid21-23Water24Glycerin (Quantitative)25-29
1.4 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.
1.5 The values stated in SI units are to be regarded as the standard.
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An American National Standard
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Designation:D128–98 (Reapproved 2003)
Standard Test Methods for
Analysis of Lubricating Grease
This standard is issued under the fixed designation D 128; 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 (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
e NOTE—Warning notes were editorially moved into the standard text in July 2003.
1. Scope Bituminous Materials by Distillation
D 156 Test Method for Saybolt Color of Petroleum Prod-
1.1 These test methods for analysis cover greases of the
ucts (Saybolt Chromometer Method)
conventional type, which consist essentially of petroleum oil
D 217 Test Methods for Cone Penetration of Lubricating
and soap. The constituents that can be determined are soap,
Grease
unsaponifiable matter (petroleum oil, and so forth), water, free
D 445 Test Method for Kinematic Viscosity of Transparent
alkalinity, free fatty acid, fat, glycerin, and insolubles.
and Opaque Liquids (the Calculation of Dynamic Viscos-
NOTE 1—Any of the test methods described herein are best used by an 2
ity)
experienced grease analyst who may also be able to make appropriate
D 473 Test Method for Sediment in Crude Oils and Fuel
adaptations of the techniques as occasion requires.
Oils by the Extraction Method
1.2 A supplementary test method is provided in Appendix
D 1078 Test Method for Distillation Range of Volatile
X1. This test method is intended primarily for application to
Organic Liquids
greases containing thickeners that are essentially insoluble in
D 1193 Specification for Reagent Water
n-hexane, and to greases that cannot be analyzed by conven-
D 1353 Test Method for Nonvolatile Matter in Volatile
tional methods because of the presence of such constituents as
Solvents for Use in Paint, Varnish, Lacquer, and Related
nonpetroleum fluids or nonsoap-type thickeners, or both. In
Products
some cases, these constituents can react with strong acid or
alkaline solutions. 3. Terminology
1.3 These test methods appear in the following order:
3.1 Definitions:
Sections
3.1.1 asphalt, n—a dark brown-to-black cementitious ma-
Ash Determination 7-11
terial in which the predominating constituents are bitumens.
Insolubles, Soap, Fat, Petroleum Oil, 12-20
3.1.1.1 Discussion—Asphalt can be a natural product or a
and Unsaponifiable Matter
Free Alkali and Free Acid 21-23
material obtained from petroleum processing.
Water 24
3.1.2 candle pitch, n—a dark brown-to-black, tarry or solid,
Glycerin (Quantitative) 25-29
by-product residue from soap and candle stock manufacture,
1.4 This standard does not purport to address all of the
refiningofvegetableoils,refiningofwoolgrease,orrefiningof
safety concerns, if any, associated with its use. It is the
refuse animal fats.
responsibility of the user of this standard to establish appro-
3.1.3 cup grease, n—any lubricating grease having physical
priate safety and health practices, and determine the applica-
properties, such as consistency and texture, suitable for its use
bility of regulatory limitations prior to use.
in spring-loaded or screw-type lubricating cups.
1.5 The values stated in SI units are to be regarded as the
3.1.3.1 Discussion—Cup greases are predominantly NLGI
standard.
No. 3 or 4 calcium greases, but grease types other than calcium
are also used.
2. Referenced Documents
3.1.4 degras (wool fat, wool grease, wool wax), n—a
2.1 ASTM Standards:
fat-like material comprised primarily of sterols, other higher
D 95 Test Method for Water in Petroleum Products and
alcohols, and fatty acids, obtained from the solvent extraction
of sheep’s wool.
These test methods are under the jurisdiction of ASTM Committee D02 on
Petroleum Products and Lubricants and are the direct responsibility of Subcommit-
tee D02.G0 on Lubricating Grease. Annual Book of ASTM Standards, Vol 05.01.
Current edition approved May 10, 2003. Published July 2003. Originally Annual Book of ASTM Standards, Vol 06.04.
approved in 1922. Last previous edition approved in 1998 as D 128–98. Annual Book of ASTM Standards, Vol 11.01.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D128–98 (2003)
3.1.5 free alkali, n—in lubricating grease, unreacted basic in liquid lubricants to form the lubricating grease structure.
(alkaline) material present in the product. NLGI Lubricating Grease Guide
3.1.5.1 Discussion—Many greases are made with a slight
3.1.15 residuum, n—a liquid or semi-liquid product ob-
excess of alkali to ensure complete saponification. Free alkali
tained as residue from the distillation of petroleum and
is determined by acidification of a solvent-thinned specimen
consisting primarily of asphaltic hydrocarbons.
and back titration with standardized, alcoholic potassium
3.1.15.1 Discussion—Also known as asphaltic oil, asphal-
hydroxide. It is expressed in terms of the predominating alkali
tum oil, liquid asphalt, black oil, petroleum tailings, and
and a mass % of the total grease composition (for example,
residual oil.
mass % lithium hydroxide).
3.1.16 rosin oil, n—a viscous, oily liquid obtained as a
3.1.6 free fatty acid, n—in lubricating grease, unreacted
condensate when the residue (rosin) from turpentine produc-
carboxylic acid(s) present in the product.
tion is subjected to dry, destructive distillation.
3.1.6.1 Discussion—Some greases are made with a slight
3.1.16.1 Discussion—Also used to describe specially com-
excess of carboxylic acid to ensure a non-alkaline product.
pounded oils having a rosin base.
Free fatty acid is determined by neutralization of a solvent-
3.1.17 saponification, n—the interaction of fats, fatty acids,
thinned specimen with standardized, alcoholic potassium hy-
or esters generally with an alkali to form the metallic salt,
droxide.Regardlessoftheactualcompositionofthecarboxylic
which is commonly called soap.
acid(s), it is expressed as free oleic acid and as a mass % of the
3.1.17.1 Discussion—Soap thickeners are most often made
total grease composition.
by in situ saponification in the lubricating grease base oil.
3.1.7 insolubles, n—in lubricating greases analysis, the
However, the use of pre-formed soaps is also common;
material remaining after the acid hydrolysis, water extraction,
dispersion is effected by mechanical means and usually with
and solvent extraction of soap-thickened greases.
heat. NLGI Lubricating Grease Guide
3.1.7.1 Discussion—Consisting of such products as graph-
3.1.18 single base, adj— in lubricating grease, relating to a
ite, molybdenum disulfide, insoluble polymers, and so forth.
thickener comprised of soaps of only one metal.
3.1.8 lubricating grease, n—a semi-fluid to solid product of
3.1.19 soap, n—in lubricating grease, a product formed in
a dispersion of a thickener in a liquid lubricant.
the saponification (neutralization) of fats, fatty acids, or esters
3.1.8.1 Discussion—The qualifying term, lubricating,
by inorganic bases.
should always be used. The term, grease, used without the
qualifier refers to a different product, namely certain natural or 3.1.20 Soxhlet apparatus, n—a device, usually of glass,
processed animal fats, such as tallow, lard, and so forth. used to extract soluble material from a mixture of soluble and
3.1.9 mixed base, adj—inlubricatinggrease,thedescription insoluble (generally solid) materials, by passing a volatile
of a thickener system composed of soaps of two metals. solvent through the sample and recirculating the solvent by
3.1.9.1 Discussion—Although mixed-base grease can be refluxing.
made with soaps of more than two metals, in practice, such is
3.1.21 tar, n—a brown or black, bituminous, liquid or
rarely, if ever, encountered. All of the soaps need not be
semi-solid comprised primarily of bitumens condensed in the
thickeners, although the major soap constituent will be one
processingofcoal,petroleum,oil-shale,wood,orotherorganic
capable of forming a lubricating grease structure. Because the
materials.
mixed soaps are seldom present in equal amounts. The pre-
3.1.22 thickener, n—in lubricating grease, a substance
dominant soap is referred to first.
composed of finely divided solid particles dispersed in a liquid
NLGI Lubricating Grease Guide
lubricant to form the product’s structure.
3.1.10 montan wax, n—a wax-like material comprised pri-
3.1.22.1 Discussion—The thickener can be fibers (such as
marily of montanic acid and its ester, higher aliphatic alcohols,
various metallic soaps) or plates or spheres (such as certain
and resins obtained from the solvent extraction of lignite.
non-soapthickeners),whichareinsolubleor,atmost,onlyvery
3.1.11 neutralization number, n—of petroleum oil,the
slightly soluble in the liquid lubricant. The general require-
quantity of acid or base required to titrate to neutrality and
ments are that the solid particles be extremely small, uniformly
expressed as equivalent milligrams of potassium hydroxide per
dispersed, and capable of forming a relatively stable, gel-like
gram of sample. D804
structure with the liquid lubricant. D217
3.1.12 NLGI, n—National Lubricating Grease Institute.
3.1.23 thimble, n—in Soxhlet apparatus, a closed-end po-
3.1.13 NLGI number, n—a numerical scale for classifying
rous cylinder used to hold the material to be extracted, usually
the consistency range of lubricating greases and based on the
made of thick matted filter paper but sometimes made of
Test Methods D 217 worked penetration.
ceramic.
NLGI Lubricating Grease Guide
3.1.24 total fluid constituent, n—in lubricating grease
3.1.14 non-soap thickener (synthetic thickener, inorganic
analysis, the n-hexane-soluble material extracted from the
thickener, organic thickener), n—in lubricating grease, any of
lubricating grease sample.
several specially treated or synthetic materials, excepting
3.1.24.1 Discussion—Typical materials include petroleum
metallicsoaps,thatcanbethermallyormechanicallydispersed
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)
Available from National Lubricating Grease Institute, 4635 Wyandotte St.,
Kansas City, MO 64112-1596. that is essentially insoluble in n-hexane.
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D128–98 (2003)
TABLE 1 Physical Requirements of n-hexane
3.1.25.1 Discussion—Typical materials include thickeners,
fillers, inorganic salts, asphaltenes, or any combinations of Test Requirement ASTM
A
Designation
these (also includes insoluble materials found in the analysis of
Initial boiling point, min, °C 66.1 D 1078
contaminated grease). Free alkali content is generally insignifi-
Dry point, max, °C 68.9 D 1078
cant.
Nonvolatile matter, max, g/100 mL 0.001 D 1353
3.1.26 unsaponifiable matter, n—in lubricating grease, or-
Color, Saybolt, min + 30 D 156
A
Reaction with alkalies .
ganic materials, either added or found with fatty materials,
A
Boil125mLofn-hexanewith10mLof0.5NalcoholicKOHsolutionand50mL
which do not react during saponification.
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
4. Significance and Use
the solutions with 0.5 N HCl using phenolphthalein as the indicator. Not less than
9.8mLof0.5 N HCl shall be required for neutralization. The amount of alkali
4.1 These test methods can be used to identify and estimate
consumed in this test shall be deducted as a blank correction in the fat
the amount of some of the constituents of lubricating greases.
determination on Solution E.
These test methods are applicable to many, but not all, greases.
4.2 Composition should not be considered as having any
5.5 Ammonium Carbonate—(NH ) CO.(Warning—
4 2 3
direct bearing on service performance unless such correlation
Harmful if swallowed.) (Warning—Harmful if swallowed.)
is established.
5.6 Butter Yellow Indicator (0.02 g/mL)—Toluene solution
(Warning—Flammable. Vapor harmful) of
NOTE 2—Details on other test methods for grease analysis can be found
, ,
6 7 8
in other reference material.
p-dimethylaminoazobenzene. (Warning—Suspected carcino-
gen. In addition to other precautions, avoid inhalation or skin
5. Reagents
contact.)
5.1 Purity of Reagents—Reagent grade chemicals shall be
5.7 t-ButylAlcohol,meltingpoint24to25.5°C(Warning—
used in all tests. Unless otherwise indicated, it is intended that
Flammable liquid; causes eye burns).
all reagents shall conform to the specifications of the Commit-
5.8 Carbon Disulfide (CS ). (Warning—Extremely flam-
tee onAnalytical Reagents of theAmerican Chemical Society,
mable. Poison. Vapor may cause flash fire. Vapor harmful.
where such specifications are available. Other grades may be
Capable of self-ignition at 100°C or above. Harmful or fatal if
used, provided it is first ascertained that the reagent is of
swallowed. May be absorbed through the skin.)
sufficiently high purity to permit its use without lessening the
5.9 Ethyl Ether.(Warning—Extremely flammable. Harm-
accuracy of the determination.
ful if inhaled. May cause eye injury. Effects may be delayed.
5.2 Purity of Water—Unless otherwise indicated, references
May form explosive peroxides. Vapors may cause flash fire.
to water shall be understood to mean reagent water conforming
Moderately toxic. Irritating to skin.)
11,12
to Specification D 1193, Type III.
5.10 n-hexane, high-purity grade, conforming to the
5.3 Acetone—American Chemical Society Reagent Grade
requirements of Table 1. (Warning—Extremely flammable.
Acetone.(Warning—Extremelyflammable.Vaporsmaycause
Harmful if inhaled. May produce nerve cell damage. Vapors
flash fires.)
may cause flash fire.)
5.4 Alcohol (50 %)—The alcohol shall be prepared from
5.11 Hydrochloric Acid (37 %)—Concentrated acid (HCl).
,
10 11
commercial 95 % ethanol or denatured alcohol
(Warning—Poison. Corrosive. May be fatal if swallowed.
(Warning—Flammable. Denatured. Cannot be made non-
Liquid and vapor cause severe burns. Harmful if inhaled.)
toxic) by distilling from NaOH and neutralizing exactly with
5.12 Hydrochloric Acid, Standard Solution (0.5 N)—
NaOH or KOH using phenolphthalein as the indicator.
Prepare and standardize a 0.5 N solution of HCl.
(Warning—In addition to other precautions, avoid skin con-
5.13 Hydrochloric Acid (10 %), a solution containing 10 %
tact or ingestion.) Dilute with an equal volume of water.
by weight of concentrated HCl in water, with a permissible
variation of 0.5 %.
5.14
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