ASTM D938-12(2017)

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: D938 − 12 (Reapproved 2017) British Standard 5088
Designation: 76/70(95)
Standard Test Method for
Congealing Point of Petroleum Waxes, Including
Petrolatum
This standard is issued under the fixed designation D938; 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 mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
1.1 This test method covers determination of the congealing
point of petroleum waxes, including petrolatum.
2. Referenced Documents
1.2 The values stated in SI units are to be regarded as the
2.1 ASTM Standards:
standard.
D127 Test Method for Drop Melting Point of Petroleum
1.2.1 Exception—The values given in parentheses are for
Wax, Including Petrolatum
information only.
E1 Specification for ASTM Liquid-in-Glass Thermometers
1.3 WARNING—Mercury has been designated by many
regulatory agencies as a hazardous material that can cause
3. Terminology
central nervous system, kidney and liver damage. Mercury, or
3.1 Definitions:
its vapor, may be hazardous to health and corrosive to
materials. Caution should be taken when handling mercury and
3.1.1 congealing point, n—of petroleum wax, that tempera-
mercury containing products. See the applicable product Ma- ture at which molten petroleum wax, when allowed to cool
terial Safety Data Sheet (MSDS) for details and EPA’s
under prescribed conditions, ceases to flow.
website—http://www.epa.gov/mercury/faq.htm—for addi-
3.1.2 thermometer, n—a device for determining temperature
tional information. Users should be aware that selling mercury
using one of a variety of different principles.
and/or mercury containing products into your state or country
3.1.2.1 Discussion—A thermometer has two important ele-
may be prohibited by law.
ments: the temperature sensor, within which some physical
1.4 This standard does not purport to address all of the
change occurs with temperature (for example, the bulb of a
safety concerns, if any, associated with its use. It is the
liquid-in-glass thermometer, or a thermistor in an electronic
responsibility of the user of this standard to establish appro-
thermometer), plus some means of converting this change into
priate safety and health practices and determine the applica-
a numerical value (for example, the scale on a liquid-in-glass
bility of regulatory limitations prior to use.
thermometer, or a digital readout in the case of an electronic
thermometer).
NOTE 1—This test method is an alternative to Test Method D127.
Results obtained are usually lower than the results obtained by Test
Method D127 – IP 133, the amount of the deviation varying with the
4. Summary of Test Method
nature of the petroleum wax.
4.1 A sample of wax is melted and a droplet is made to
1.5 This international standard was developed in accor-
adhere to the bulb of a thermometer. Using a prewarmed flask
dance with internationally recognized principles on standard-
as an air jacket, the droplet on the bulb is allowed to cool at a
ization established in the Decision on Principles for the
fixed rate until it congeals. The congealing point is observed as
Development of International Standards, Guides and Recom-
the temperature at which the droplet ceases to flow as the
thermometer is turned.
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
Subcommittee D02.10 on Properties of Petroleum Waxes and Alternative Wax-like
Materials. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved June 1, 2017. Published July 2017. Originally approved contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
in 1947. Last previous edition approved in 2012 as D938 – 12. DOI: 10.1520/ Standards volume information, refer to the standard’s Document Summary page on
D0938-12R17. the ASTM website.
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D938 − 12 (2017)
5. Significance and Use the thermometer in a horizontal position, firmly fit the ther-
mometer and stopper into the flask. Keep the assembly in a
5.1 Congealing point is a wax property that is of interest to
horizontal position.
many petroleum wax consumers. The procedure described here
measures the temperature at which a sample being cooled 7.6 While observing the drop on the thermometer bulb at an
develops a “set” or resistance to flow. At that temperature, the eye level position, rotate the thermometer and flask about a
wax may be at or close to the solid state, or it may be semisolid horizontal axis. Use a steady and even rate for each continuous
and quite unctuous, depending on the composition of the wax full revolution, and complete each revolution in not less than
or petrolatum being tested. In the case of petrolatums, congeal- 2 s, nor more than 3 s. Do not pause at the completion of each
ing property is associated with the formation of a gel structure revolution any longer than required to reindex the fingers for
as the sample cools. the next full and continuous rotation (Note 3). When the drop
is observed to rotate with the bulb, immediately read the
6. Apparatus
thermometer to the neares
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