ASTM C356-87(1997)
(Test Method)Standard Test Method for Linear Shrinkage of Preformed High-Temperature Thermal Insulation Subjected to Soaking Heat
Standard Test Method for Linear Shrinkage of Preformed High-Temperature Thermal Insulation Subjected to Soaking Heat
SCOPE
1.1 This test method covers the determination of the amount of linear shrinkage and other changes that occur when a preformed thermal insulating material is exposed to soaking heat. This test method is limited to preformed high-temperature insulation that is applicable to hot-side temperatures in excess of 200°F (93°C), with the exception of insulating fire brick which is covered by Test Method C210. At temperatures below 200°F, where humidity may also contribute to dimensional changes in a material, it should be tested in accordance with Test Method C548.
1.2 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are provided for information only.
1.3 This standard does not purport to address all of the safety problems, 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.
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Standards Content (Sample)
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Designation: C 356 – 87 (Reapproved 1997)
Standard Test Method for
Linear Shrinkage of Preformed High-Temperature Thermal
Insulation Subjected to Soaking Heat
This standard is issued under the fixed designation C 356; 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.
1. Scope 4. Significance and Use
1.1 This test method covers the determination of the amount 4.1 Linear shrinkage, as used in this test method, refers to
of linear shrinkage and other changes that occur when a the change in linear dimensions that has occurred in test
preformed thermal insulating material is exposed to soaking specimens after they have been subjected to soaking heat for a
heat. This test method is limited to preformed high-temperature period of 24 h and then cooled to room temperature.
insulation that is applicable to hot-side temperatures in excess 4.2 Most insulating materials will begin to shrink at some
of 200°F (93°C), with the exception of insulating fire brick definite temperature. Usually the amount of shrinkage in-
which is covered by Test Method C 210. At temperatures creases as the temperature of exposure becomes higher. Even-
below 200°F, where humidity may also contribute to dimen- tually a temperature will be reached at which the shrinkage
sional changes in a material, it should be tested in accordance becomes excessive. With excessive shrinkage, the insulating
with Test Method C 548. material has definitely exceeded its useful temperature limit.
1.2 The values stated in inch-pound units are to be regarded When an insulating material is applied to a hot surface, the
as the standard. The values given in parentheses are provided shrinkage will be greatest on the hot face. The differential
for information only. shrinkage which results between the hotter and the cooler
1.3 This standard does not purport to address all of the surfaces often introduces strains and may cause the insulation
safety concerns, if any, associated with its use. It is the to warp. High shrinkage may cause excessive warpage and
responsibility of the user of this standard to establish appro- thereby may induce cracking, both of which are undesirable.
priate safety and health practices and determine the applica- High shrinkage may also open gaps at the insulation joints to
bility of regulatory limitations prior to use. an excessive extent rendering the application less efficient and
more hazardous. In order to predict the limit of permissible
2. Referenced Documents
shrinkage in service, the degree of linear shrinkage to be
2.1 ASTM Standards: tolerated by specimens of an insulating material when sub-
C 154 Test Method for Warpage of Refractory Brick and
jected to soaking heat must be determined from experience.
Tile, or Deviation from a Plane Surface 4.3 It is recognized that a fixed relation between linear
C 168 Terminology Relating to Thermal Insulating Materi-
shrinkage under soaking heat and actual shrinkage in service
als cannot be established for different types of insulating materials.
C 210 Test Methods for Reheat Change of Insulating Fire- Generally the amount of shrinkage increases with time of
brick
exposure. The amount and rate of increase varies from one
C 548 Test Method for Dimensional Stability of Low- material to another. In addition, the various types of materials
Temperature Thermal Block and Pipe Insulation
may have different amounts of maximum permissible shrink-
age. Therefore, each product must define its own specific limits
3. Terminology
of linear shrinkage under soaking heat.
3.1 Definitions—Terminology C 168 shall apply to the
5. Apparatus
terms used in this test method.
5.1 Furnace—A gas-fired or electrically heated muffle fur-
nace, having a size sufficient to accommodate at least four test
This test method is under the jurisdiction of ASTM Committee C-16 on
1 1
specimens and two dummy specimens, 6 by 2 ⁄2 by 1 ⁄2 in.
Thermal Insulation and is the direct responsibility of Subcommittee C16.31 on
(152.4 by 63.5 by 38.1 mm) (Note 1), spaced so as to allow a
Chemical and Physical Properties.
Current edition approved Aug. 28, 1987. Published December 1987. Last
clearance of at least ⁄2 in. (12.7 mm) on all surfaces of every
previous edition C 356 – 60 (1980).
test specimen. The temperature of the furnace shall be con-
Discontinued; see 1986 Annual Book of ASTM Standards, Vol 15.01.
trolled throughout the volume occupied by the specimens to
Annual Book of ASTM Standards, Vol 04.06.
Annual Book of ASTM Standards, Vol 15.01.
Discontinued; see 1982 Annual Book of ASTM Standards, Vol 04.06.
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NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
C 356
within 6 1 % of the desired temperature. A furnace- if the sections are large enough. If the material is not
temperature indicator or recorder is required. homogeneous or the sections are not sufficiently large, then
curved or partly curved segments of a cylinder may be used. In
NOTE 1—If the structure is not homogeneous throughout its thickness,
this case, the specimens shall preferably be cut to an over-all
or if thinner materials are under test, the specimen should be tested
width of 2 ⁄2 in. (63.5 mm), with the sides cut parallel rather
without altering the original thickness. For smaller ovens, unable to
accommodate the required number of specimens, it will be necessary to than on a radius.
make several test batches in order to secure the minimum number of
7. Procedure
specimens required.
7.1 Select and prepare a minimum of four test specimens as
5.2 Oven—A controlled-temperature conditioning oven
prescribed in Section 6. Weigh the specimens in the as-received
with range up to at least 250°F (121°C).
condition and dry them to constant weight following applicable
5.3 Specimen-Measuring Apparatus—An instrument suit-
specifications for the material unless it has been shown that the
able for measuring a gage length up to 6 in. (152.4 mm), and
dimensional stability is not significantly affected by moisture
having an accuracy of measurement of 0.002 in. (0.05 mm) or
content. In the absence of such specifications the specimen
better. Care must be taken, by the use of proper measuring
should be dried in an oven or desiccator at a temperature of 215
techniques, to ensure reproduction of any measurement to
to 250°F (102 to 121°C) or at a suitable lower temperature if
within 0.01 in. (0.2 mm). It is particularly important to avoid
these temperatures would be destructive. If specimens are
crushing the ends of the specimens during measurement,
dried, they should be allowed to cool to room temperature and
especially in the case of soft materials.
if necessary held in a desiccator before testing. Other condi-
NOTE 2—A vernier caliper may be used. Reference points, such as pins,
tioning procedures may be used only where agreed upon
inserted near the ends of the specimen, serve to improve reproducibility
between manufacturer and purchaser. After conditioning and
without specimen damage; or metal strips may be inserted between the
before any changes in dimensions occur, determine the linear
specimen ends and the jaws of the caliper. Other instruments suggested are
dimensions. Make at least one measurement of length and two
dilatometers or comparators. One suitable type of comparator is equipped
with a fine adjustment. It has a long-range, continuous dial indicator. The
each of width and thickness at points marked so that remea-
dial is attached to a wide-face ( ⁄2-in. (12.7-mm) diameter flat) button
surements can be made at the same points after soaking heat.
point which is held against the specimen by internal spring pressure. When
7.2 Place the measured and weighed specimens in the
the point is lifted ⁄2 in. (12.7 mm), the pressure is about 50 g,
furnace, the temperature of which shall not exceed 250°F
corresponding to a bearing force of 0.6 psi (4.8 kPa), and suitable for very
(121°C). The specimens shall rest on their 6 by 1 ⁄2-in. (152.4
soft materials. For harder materials, an additional weight of 0.25 lb (0.114
1 by 38.1-mm) edges, supported by at least three supports (such
kg) may be applied, making the load of the specimen, at ⁄2 in. (12.7 mm)
compression of the spring, about 1.9 psi (13.1 kPa). Directly beneath the as small ceramic triangular bars, or cylindrical rods), which in
button point is another
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