ASTM D7873-13
(Test Method)Standard Test Method for Determination of Oxidation Stability and Insolubles Formation of Inhibited Turbine Oils at 120°C Without the Inclusion of Water (Dry TOST Method)
Standard Test Method for Determination of Oxidation Stability and Insolubles Formation of Inhibited Turbine Oils at 120°C Without the Inclusion of Water (Dry TOST Method)
SIGNIFICANCE AND USE
5.1 Insoluble material may form in oils that are subjected to oxidizing conditions.
5.2 Significant formation of oil insolubles or metal corrosion products, or both, during this test may indicate that the oil will form insolubles or corrode metals, or both, resulting in varnish formation during field service. The level of varnish formation in service will be dependent on many factors (turbine design, reservoir temperature, duty-cycle, for example. peaking, cycling, or base-load duty, maintenance, and so forth) and a direct correlation between results in this test and field varnish formation are yet to be established.
5.3 Oxidation condition at 120 °C under accelerated oxidation environment of Test Method D4310 and measurement of sludge and RPVOT value could reflect a practical oil quality in actual turbine operations. Results from this test should be used together with other key lubricant performance indicators (including other established oxidation and corrosion tests) to indicate suitability for service.
SCOPE
1.1 This test method is used to evaluate the sludging tendencies of steam and gas turbine lubricants during the oxidation process in the presence of oxygen and metal catalyst (copper and iron) at an elevated temperature. This test method may be used to evaluate industrial oils (for example, circulating oils and so forth).
1.2 This test method is a modification of Test Method D4310 where the sludging and corrosion tendencies of the same kinds of oils are determined after 1000 h at 95 °C in the presence of water. Water is omitted in this modification.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3.1 Exception—The values in parentheses in some of the figures are provided for information only for those using old equipment based on non-SI units.
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 WARNING—Mercury has been designated by many regulatory agencies as a hazardous material that can cause central nervous system, kidney and liver damage. Mercury, or its vapor, may be hazardous to health and corrosive to materials. Caution should be taken when handling mercury and mercury containing products. See the applicable product Material Safety Data Sheet (MSDS) for details and EPA’s website—http://www.epa.gov/mercury/faq.htm—for additional information. Users should be aware that selling mercury and/or mercury containing products into your state or country may be prohibited by law.
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D7873 − 13
StandardTest Method for
Determination of Oxidation Stability and Insolubles
Formation of Inhibited Turbine Oils at 120 °C Without the
Inclusion of Water (Dry TOST Method)
This standard is issued under the fixed designation D7873; 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.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This test method is used to evaluate the sludging
A510M Specification for General Requirements for Wire
tendencies of steam and gas turbine lubricants during the
Rods and Coarse Round Wire, Carbon Steel (Metric)
oxidation process in the presence of oxygen and metal catalyst
(Withdrawn 2011)
(copper and iron) at an elevated temperature. This test method
B1 Specification for Hard-Drawn Copper Wire
may be used to evaluate industrial oils (for example, circulat-
D943 Test Method for Oxidation Characteristics of Inhibited
ing oils and so forth).
Mineral Oils
1.2 This test method is a modification of Test Method
D1193 Specification for Reagent Water
D4310 where the sludging and corrosion tendencies of the
D2272 Test Method for Oxidation Stability of Steam Tur-
same kinds of oils are determined after 1000 h at 95 °C in the
bine Oils by Rotating Pressure Vessel
presence of water. Water is omitted in this modification.
D4057 Practice for Manual Sampling of Petroleum and
1.3 The values stated in SI units are to be regarded as Petroleum Products
D4310 Test Method for Determination of Sludging and
standard. No other units of measurement are included in this
standard. Corrosion Tendencies of Inhibited Mineral Oils
E1 Specification for ASTM Liquid-in-Glass Thermometers
1.3.1 Exception—The values in parentheses in some of the
E230 Specification and Temperature-Electromotive Force
figures are provided for information only for those using old
(EMF) Tables for Standardized Thermocouples
equipment based on non-SI units.
2.2 Other Standards:
1.4 This standard does not purport to address all of the
Specification for IP Standard Thermometers
safety concerns, if any, associated with its use. It is the
ISO 3696 Water for Analytical Laboratory Use—
responsibility of the user of this standard to establish appro-
Specification and Test Methods
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
3. Terminology
1.5 WARNING—Mercury has been designated by many
3.1 Definitions:
regulatory agencies as a hazardous material that can cause
3.1.1 sludge, n—a precipitate or sediment from oxidized
central nervous system, kidney and liver damage. Mercury, or
mineral oil that is insoluble in n-heptane. D943
its vapor, may be hazardous to health and corrosive to
materials.Cautionshouldbetakenwhenhandlingmercuryand
4. Summary of Test Method
mercury containing products. See the applicable product Ma-
4.1 Atotalofsixtoeighttubescontaining360mLofsample
terial Safety Data Sheet (MSDS) for details and EPA’s
each are heated at 120 °C with oxygen in the presence of an
website—http://www.epa.gov/mercury/faq.htm—for addi-
tional information. Users should be aware that selling mercury
and/or mercury containing products into your state or country
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
may be prohibited by law.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
The last approved version of this historical standard is referenced on
This test method is under the jurisdiction of ASTM Committee D02 on www.astm.org.
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR,
Subcommittee D02.09.0C on Oxidation of Turbine Oils. U.K., http://www.energyinst.org.
Current edition approved Dec. 1, 2013. Published January 2014. DOI: 10.1520/ Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
D7873-13. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7873 − 13
iron-copper catalyst. Each tube is removed over time and the includedinthedesign,thisviewingwindowshallbefittedwith
sample is analyzed by Test Method D2272 and the insolubles a suitable opaque cover and be kept closed when no observa-
are measured until the RPVOT residual ratio reaches below tion is being made.
25 % or an agreed-upon percentage or specified time. Test run
6.2.1.2 If glass heating baths are used, the bath shall be
for a specified time(s) may be run using a single tube or as
wrapped with aluminum foil or other opaque material.
many as specified by the requestor. The mass of insoluble
6.2.1.3 Bright light entering the test cell from directly
material of each oil sample is determined gravimetrically by
overhead can be eliminated by use of an opaque shield.
filtration of a 100 g oil sample through a membrane filter with
6.3 Flowmeter, with a flow capacity of at least 3 L of
pore size 1 µm. The insoluble mass (mg/kg oil) is plotted
oxygen/hour, and an accuracy of 60.1 L/h.
against RPVOT residual ratio. The insoluble mass in milli-
grams per kilogram oil at 25 % or an agreed-upon RPVOT
6.4 Heating Bath Thermometer,ASTMSolventsDistillation
residual ratio or specified time is reported.
Thermometer having a range from 98 °C to 152 °C and
conforming to the requirements for Thermometer 41C as
5. Significance and Use
prescribed in Specification E1, or for Thermometer 81C as
prescribed in Specifications for IP Standard Thermometers.
5.1 Insoluble material may form in oils that are subjected to
Alternatively,temperature-measuringdevicesofequalorbetter
oxidizing conditions.
accuracy and precision may be used.
5.2 Significant formation of oil insolubles or metal corro-
6.5 Oxidation Cell Thermometer, A 76 mm immersion LIG
sion products, or both, during this test may indicate that the oil
having a range of 110 °C to 130 °C, graduated in 0.1 °C, total
will form insolubles or corrode metals, or both, resulting in
lengthof300mm 65mm,andstemdiameterof6.0 mmto7.0
varnish formation during field service. The level of varnish
mm. Alternatively, temperature-measuring devices or DCT, of
formation in service will be dependent on many factors
equal or better accuracy and precision may be used. Tempera-
(turbinedesign,reservoirtemperature,duty-cycle,forexample.
ture of the sample shall be measured at 76 mm from the top of
peaking, cycling, or base-load duty, maintenance, and so forth)
the sample. See Fig. 2 and Fig. 3.
and a direct correlation between results in this test and field
NOTE 1—Temperature gradient within the sample may exist from the
varnish formation are yet to be established.
heating system and temperature control design.
5.3 Oxidation condition at 120 °C under accelerated oxida-
6.6 Wire Coiling Mandrel, as shown in Fig. 4.
tion environment of Test Method D4310 and measurement of
6.7 Thermometer Bracket, for holding the oxidation cell
sludge and RPVOTvalue could reflect a practical oil quality in
thermometer, of 18-8 stainless steel, having the dimensions
actual turbine operations. Results from this test should be used
shown in Fig. 5.The thermometer is held in the bracket by two
together with other key lubricant performance indicators (in-
fluoro-elastomer O-rings of approximately 5 mm inside diam-
cluding other established oxidation and corrosion tests) to
indicate suitability for service. eter. Alternatively, thin stainless steel wire may be used.
6.8 Abrasive Cloth, silicon carbide, 100 grit with cloth
6. Apparatus
backing.
6.1 Oxidation Cell, of borosilicate glass, as shown in Fig. 1,
6.9 Flexible Tubing, poly vinyl chloride approximately 6.4
consisting of a test tube, condenser, and oxygen delivery tube.
1 3
mm ( ⁄4 in.) inside diameter with a 2.4 mm ( ⁄32 in.) wall for
It is recommended to have a test tube with a calibration line at
delivery of oxygen to the oxidation cell.
360 mL(maximum error 1 mL). This calibration applies to the
6.10 Membrane Filters, white, plain, 47 mm in diameter,
test tube without inserts at 20 °C.
pore size 1 µm. The recommended membrane filters are PTFE
6.2 Heating Bath, thermostatically controlled, capable of
and cellulose acetate plus nitrocellulose material.
maintaining the oil sample in the oxidation cell at a tempera-
6.11 Filter Holder, 47 mm, consisting of a borosilicate glass
ture of 120 °C 6 0.5 °C, fitted with a suitable stirring device to
funnel and a funnel base with a coarse grade fritted-glass filter
provide a uniform temperature throughout the bath, and large
support with a length of 40 µm to 60 µm, or stainless steel
enoughtoholdthedesirednumberofoxidationcellsimmersed
screen support such that the filter can be clamped between the
in the heating bath to a depth of 355 mm 6 10 mm. Heated
ground-glass sealing surfaces of the funnel and its base by
metal block baths meeting the test method requirements may
means of a metal clamp.
also be used.
6.2.1 Studies have suggested that direct sunlight or artificial
6.12 Weighing Bottle, cylindrical body with ground-glass
light may adversely influence the results of this test. To
stopper; approximate inside diameter 65 mm, height of body
minimize effects of light exposure on the lubricant being
45 mm , capacity 60 mL.
tested, light shall be excluded from the lubricant by one or
6.13 Vacuum Source, to provide pressure reduction to
more of the following ways:
13.3 kPa 6 0.7 kPa (100 mm 6 5 mm Hg) absolute pressure.
6.2.1.1 Use of heated liquid baths that are designed and
constructed of metal, or combinations of metals and other 6.14 Cooling Vessel, A desiccator or other type of tightly
suitable opaque materials, that prevent light from entering the covered vessel for cooling the weighing vessels before weigh-
test cell from the sides is preferred. If a viewing window is ing. The use of a drying agent is not recommended.
D7873 − 13
NOTE 1—All dimensions are in millimetres (inches).
NOTE 2—The oxidation test tube has a calibration line at 360 mL. This calibration applies to the test tube alone at 20 °C.
NOTE 3—Open tube ends to be ground and fire-polished.
FIG. 1 Oxidation Cell
D7873 − 13
all reagents shall conform to the specifications of the commit-
tee onAnalytical Reagents of theAmerican Chemical Society,
where such specifications are available.
7.2 Reagent Water, Unless otherwise indicated, reference to
water shall be understood to mean distilled, deionized water as
defined by Type I or Type II in Specification D1193 or Grade
3 in ISO 3696.
7.3 Acetone, Reagent grade. (Warning—Health hazard,
flammable.)
7.4 Cleaning Reagent, cleaning by a 24 h soak at room
temperature in a free rinsing liquid acid cleaner with a pH of 2
to 4.5.
7.5 n-heptane, Reagent grade. (Warning—Flammable.
Harmful if inhaled.)
7.6 Isopropyl Alcohol, Reagent grade. (Warning—
Flammable.)
7.7 Catalyst Wires,
7.7.1 Low-Metalloid Steel Wire—1.59 mm (0.0625 in.) in
diameter (No. 16 Washburn and Moen Gage).
NOTE 2—Carbon steel wire, soft bright annealed and free from rust of
Grade 1008 as described in Specification A510M is satisfactory. Similar
wire conforming to Specification E230 is also satisfactory
7.8 Electrolytic Copper Wire, 1.63 mm (0.064 in.) in diam-
eter (No. 16 Imperial Standard Wire Gage or No. 14American
Wire Gage), 99.9 % purity, conforming to Specification B1.
NOTE 3—Alternatively, suitably prepared steel and copper catalyst coils
may be purchased from a supplier.
7.9 Detergent, free rinsing, water-soluble, anionic detergent
with a pH of 9.5 to 11.
7.10 Oxygen—(Warning—Oxygen vigorously accelerates
combustion.) 99.5 % minimum purity, with pressure regulation
FIG. 2 Oxidation Cell with Thermometer
adequate to maintain a constant flow of gas through the
apparatus. The use of a two-stage pressure regulator on tank
oxygen is recommended.
8. Sampling
8.1 Samples for this test can come from tanks, drums, small
containers, or even operating equipment. Therefore, use the
applicable apparatus and techniques described in Practice
D4057.
8.2 For one single determination at a specified time the
minimum required sample size is 360 mL. However, 6 to 8
tubes will be required to develop the data points to obtain the
sludge mass at 25 % or agreed-upon residual RPVOT ratio by
FIG. 3 76 mm Immersion LIG Thermometer
logarithmic interpolation. Therefore, approximately 2200 mL
to 2900 mL will be required for this test.
6.15 Drying Oven, capable of maintaining a temperature of
9. Preparation of Apparatus
70 °C 6 5 °C.
9.1 Cleaning Catalyst—Immediately prior to winding a
6.16 Forceps, having unserrated tips.
catalyst coil, clean a 3.00 m 6 0.01 m length of iron wire and
6.17 Rubber Policeman.
6.18 Pipette Bulb.
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
7. Reagents and Materials listed by the American Chemical Society, see Analar Standards for Laboratory
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
7.1 Purity of Reagents—Reagent grade chemicals shall be
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
used in all tests. Unless otherwise indicated, it is intended that MD.
D7873 − 13
FIG. 4 Mandrel for Winding Catalyst Coils
showninFig.4isdesignedtoproducesuchacoil.Usingthismandrel,the
an equal length of copper wire with wads of absorbent cotton
ironwireiswoundonathreadof14.98mm(0.590in.)diameter,whilethe
wet with n-heptane and follow by abrasion with abrasive cloth
copper wire is wound on a thread of 15.9 mm (0.625 in.) diameter. The
until a fresh metal surface is exposed. Then wipe with dry
smaller diameter is to allow for “springback” of the steel wire after
absorbent cotton until all loose particles of metal and abrasive
winding, so as to give 15.9 mm consistent inside diameter. Use of a very
have been removed. In subsequent operations, handle the softannealedsteelwiremayallowuseofidenticalthreaddiametersforthe
two wires.Any arrangement that leads to the coil configuration described
catalyst wires with clean gloves (cotton, rubber, or plastic) to
above is satisfactory.
prevent contact with the skin.
9.3 Catalyst Storage—The catalyst coil may be stored in a
9.2 Preparation of Catalyst Coil—
...
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