ASTM D1458-96
(Test Method)Standard Test Methods for Fully Cured Silicone Rubber-Coated Glass Fabric and Tapes for Electrical Insulation
Standard Test Methods for Fully Cured Silicone Rubber-Coated Glass Fabric and Tapes for Electrical Insulation
SCOPE
1.1 These test methods cover procedures for testing fully cured silicone rubber-coated glass fabric and tapes to be used for electrical insulation.
1.2 The procedures appear in the following order:ProcedureSectionsASTM ReferencesBreaking Strength7 D 828 Breaking Strength After Creasing8...Conditioning5 ...Dielectric Breakdown Voltage9D 149, D 295,D 6054Dielectric Proof-Voltage10D 1389 Dissipation Factor and Relative Permittivity11D 150Sampling4 ...Thermal Endurance15 D 1830 Thickness6 D 374 Thread Count14 ...Volume Resistivity12 D 257Weight13 ...
1.3 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.
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. See 9.5.1 for a specific warning statement.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 1458 – 96 An American National Standard
Standard Test Methods for
Fully Cured Silicone Rubber-Coated Glass Fabric and Tapes
for Electrical Insulation
This standard is issued under the fixed designation D 1458; 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.
1. Scope Paper Used for Electrical Insulation
D 257 Test Methods for D-C Resistance or Conductance of
1.1 These test methods cover procedures for testing fully
Insulating Materials
cured silicone rubber-coated glass fabric and tapes to be used
D 295 Test Methods for Varnished Cotton Fabrics Used for
for electrical insulation.
Electrical Insulation
1.2 The procedures appear in the following order:
D 374 Test Methods for Thickness of Solid Electrical Insu-
ASTM Test Method
lation
Procedure Sections References
D 618 Practice for Conditioning Plastics and Electrical
Breaking Strength 6 D 828
Insulating Materials for Testing
Breaking Strength After Creasing 7 .
D 828 Test Method for Tensile Properties of Paper and
Conditioning 4 .
Dielectric Breakdown Voltage 8 D 149, D 295,
Paperboard Using Constant-Rate-of-Elongation Appara-
D 618
tus
Dielectric Proof-Voltage 9 D 1389
Dissipation Factor and Relative Permittivity 10 D 150 D 1389 Test Method for Proof-Voltage Testing of Thin
Sampling 3 .
Solid Electrical Insulating Materials
Thermal Endurance 14 D 1830
D 1830 Test Method for Thermal Endurance of Flexible
Thickness 5 D 374
Sheet Materials Used for Electrical Insulation by the
Thread Count 13 .
Volume Resistivity 11 D 257
Curved Electrode Method
Weight 12 .
D 5032 Practice for Maintaining Constant Relative Humid-
1.3 The values stated in inch-pound units are to be regarded
ity by Means of Aqueous Glycerin Solutions
as the standard. The values given in parentheses are for
E 104 Practice for Maintaining Constant Relative Humidity
information only.
by Means of Aqueous Solutions
1.4 This standard does not purport to address all of the
3. Sampling
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
3.1 Sample shipments of material as specified below, and
priate safety and health practices and determine the applica-
where possible take only one sample from any package.
bility of regulatory limitations prior to use. See 8.5.1 for a
3.1.1 Fabric—Over 3 in. (75 mm) in width.
specific warning statement.
3.1.1.1 Rolls—Select one roll from each ten rolls or fraction
thereof in a shipment of full-width fabric. Cut off not less than
2. Referenced Documents
two turns of fabric from each roll selected from sampling, and
2.1 ASTM Standards:
select sample material for the preparation of test specimens
D 149 Test Method for Dielectric Breakdown Voltage and
from the remaining layers of the roll.
Dielectric Strength of Solid Electrical Insulating Materials
3.1.1.2 Sheets—Select one sheet from each 50 sheets or
at Commercial Power Frequencies
fraction thereof in a shipment of sheeted fabric. Remove not
D 150 Test Methods for A-C Loss Characteristics and
less than six sheets from the outer layers of each package of
Permittivity (Dielectric Constant) of Solid Electrical Insu-
sheets selected from sampling, and then select sample material
lating Materials
for the preparation of test specimens from the remaining
D 202 Test Methods for Sampling and Testing Untreated
sheets.
3.1.2 Tapes and Strips—3 in. (75 mm) and less in width.
These test methods are under the jurisdiction of ASTM Committee D-9 on
Electrical and Electronic Insulating Materials and are the direct responsibility of
Subcommittee D09.07 on Flexible and Rigid Insulating Materials. Annual Book of ASTM Standards, Vol 08.01.
Current edition approved March 10, 1996. Published May 1996. Originally Annual Book of ASTM Standards, Vol 15.09.
published as D 1458 – 57 T. Last previous edition D 1458 – 91. Annual Book of ASTM Standards, Vol 10.02.
2 6
Annual Book of ASTM Standards, Vol 10.01. Annual Book of ASTM Standards, Vol 11.03.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 1458
3.1.2.1 Tapes—Cut off not less than six turns of tape from linear measure will be required.
each roll selected for sampling, and then select sample material 5.3 Conditioning—It is not necessary to condition the speci-
for the preparation of test specimens from the remaining layers mens for this test. Conduct tests at the Standard Laboratory
of the roll. Select rolls of tape in accordance with the following Temperature of 23 6 1°C (73.4 6 1.8°F).
schedule: 5.4 Procedure—Make ten measurements, equally spaced
along 36 in. (910 mm) of the specimen or specimens in
Minimum Number of Sample
Number of Rolls in Shipment Rolls
accordance with Method C of Test Methods D 374 modified as
follows:
Over 10 000 1 per 1000
5.4.1 Allow the presser foot to remain on the test specimen
5001 to 10 000 10
2001 to 5000 5
for 2 s, at the end of which read the dial gage.
Less than 2000 2
5.4.2 Use a presser foot 0.250 in. (6.35 mm) in diameter,
3.1.2.2 Strips—Select three strips from each 100 strips or
and an anvil surface upon which the specimen rests at least 2
fraction thereof in a shipment of strips. Remove not less than
in. (51 mm) in diameter. The force exerted on the specimen
six strips from the outer layers of each package of strips
shall be 3 ozf (85 g).
selected for sampling, and then select sample material for the
5.4.3 Method C is not considered interchangeable with
preparation of test specimens from the remaining strips.
Method A.
3.2 Prepare the test specimens from samples selected as
5.5 Report—Report the average, maximum, and minimum
specified in 3.1, and as provided for in the individual test
thickness to the nearest 0.0001 in. (0.003 mm).
methods.
6. Breaking Strength
4. Conditioning
6.1 Significance and Use—The breaking strength of fin-
4.1 Significance and Use—The properties of the material
ished fabric or tape is of importance as a measure of the tension
described in these test methods are affected by the temperature
it will withstand without failure while being applied in service.
and moisture content of the material to a greater or lesser
6.2 Apparatus—Use a power-driven tensile testing machine
extent, depending on the specific property.
meeting the requirements specified for Tensile Properties in
4.2 Conditioning—Unless otherwise specified in the indi-
Test Methods D 202, except that the means for determining
vidual test method, condition test specimens as described in
elongation and for recording applied load and elongation are
4.2.1 or 4.2.2, and in matters of dispute, consider 4.2.1 as the
not required. The machine shall be equipped with specimen-
referee method.
gripping devices as described in 6.2.1 or 6.2.2.
4.2.1 Condition the test specimens for 48 h in the Standard
6.2.1 Provide two flat-jawed clamps, in which case crocus
Laboratory Atmosphere of 50 6 2 % relative humidity at a
cloth will be required for holding specimens between the jaws,
temperature of 23 6 1°C (73.4 6 1.8°F), and conduct the tests
or
under these conditions.
6.2.2 Provide two gripping devices of the drum type as
4.2.2 Condition the test specimens for 48 h in the Standard
described in Fig. 1, in which case pins as indicated will be
Laboratory Atmosphere of 50 6 2 % relative humidity at a
required for securing specimens on the cylinders.
temperature of 23 6 1°C (73.4 6 1.8°F), and conduct the tests
6.3 Test Specimens—The test specimen shall be of sufficient
immediately upon removal of the specimens from the condi-
length to provide positive gripping in the jaws with a separa-
tioning room or chamber.
tion of approximately 6 in. (150 mm). In the case of the
flat-jawed clamps, this will require a minimum specimen
5. Thickness
length of 8 in. (200 mm) and a desirable length of 10 in. (250
5.1 Significance and Use:
mm). Where drum-type gripping devices are used, a specimen
5.1.1 The importance of space factor in the design of
no less than 20 in. (500 mm) long will be required. Prepare the
electrical equipment makes proper determination of thickness
specimens from each sample as follows:
essential.
6.3.1 Fabrics—Cut five specimens, 1 in. (25.4 mm) wide
5.1.2 Some properties, such as dielectric strength and di-
(Note 1), with sides parallel to the warp threads, and cut five
electric breakdown, vary with the thickness of the material, and
specimens of similar width with sides perpendicular to the
certain properties, such as thermal conductivity and dielectric
warp threads (Note 2).
constant, cannot be determined without a knowledge of thick-
NOTE 1—Where specimens 1 in. (25.4 mm) in width have ultimate
ness.
breaking loads exceeding the capacity of the machine, it is permissible to
5.2 Test Specimens—Cut specimens prepared from fabric
reduce the width of the specimen to not less than 0.5 in. (13 mm).
samples 1 in. (25 mm) wide across the entire width of the
NOTE 2—Frequently the fill threads of glass fabrics used to manufac-
fabric, while specimens prepared from tape and strip samples
ture silicone rubber-coated glass fabrics do not run in a straight line and
shall be the width of the sample and 36 in. (910 mm) long. are not perpendicular to the warp threads. Breaking strength from
specimens cut perpendicular to the warp threads may, therefore, be highly
Where the specimen is 36 in. or longer (full-width fabric 36 in.
variable.
or more in width, or where the length of a strip is 36 in. or
longer), only one specimen will be required unless otherwise 6.3.2 Tapes and Strips—Cut five specimens, 1 in. (25.4 mm)
specified. Where the specimen is less than 36 in. (full-width wide (see Note 2), from each sample. Where tapes or strips are
fabric less than 36 in. wide, or strips less than 36 in. long), as manufactured in widths less than 1 in. (25.4 mm), use the
many specimens as are needed to obtain the equivalent 36 in. specimen width as manufactured.
D 1458
specimens of the same sample. Since there is no accepted
reference material suitable for determining the bias for this test
method, no statement on bias is being made.
7. Breaking Strength After Creasing
7.1 Significance and Use—Creasing of silicone rubber-
coated glass fabric is accompanied by breaking of some of the
glass fibers at the crease and a consequent reduction in
breaking strength. The extent of this damage is related to the
thickness and weave of the glass fabric and the nature and
thickness of the silicone rubber coating. The creasing simulates
to a degree the pinching action resulting from several succes-
sive layers of tape moving relative to one another while in
confined position, such as in cables.
7.2 Apparatus:
7.2.1 Use a metal weight adjustable between 2.25 and 4.50
lbf (10 and 20 N). Mount it suitably through guides over a
metal horizontal plane so that the weight may be lowered at a
uniform speed perpendicular to the horizontal plane. The
bottom of the weight shall be parallel to the top surface of the
horizontal plane at all times. The creasing surface of the weight
is a rectangle of such dimensions that the side which is
perpendicular to the crease made on the specimen is 1.5 in. (40
mm). Suitable apparatus is shown in Fig. 2.
7.2.2 Provide suitable means for lowering the weight at a
FIG. 1 Drum-Type Gripping Devices uniform rate of 12 in. (300 mm)/min and of raising the weight
at the end of a 2-s dwell. This may be accomplished by
6.4 Conditioning—It is not necessary to condition speci- utilizing the breaking strength machine, described in 6.2, in
mens for this test. Conduct tests at the Standard Laboratory combination with a system of pulleys. It may also be achieved
Temperature of 23 6 1°C (73.4 6 1.8°F). by using a motor fitted with reducing gears and a cam, or by
6.5 Procedure: other devices that accomplish the purpose.
6.5.1 Clamp the ends of the specimen in the jaws between 7.3 Test Specimens—Prepare ten specimens as described in
two pieces of crocus cloth, the abrasive side of the cloth facing 6.3 except that specimens shall be taken from samples of tape
the metal jaws. Carefully align the specimen so that the or rolls of fabric only. In the case of fabric, cut the specimens
breaking force is parallel to the length of the specimen between in the warp direction only.
the jaws. Adjust the clearance between jaws to 6 in. (150 mm). 7.4 Conditioning:
6.5.2 Alternatively, loop the specimen around a binding pin 7.4.1 It is usually not necessary to condition specimens for
of suitable diameter so that the specimen fits neither too tightly this test. When specimens are not especially conditioned, test
nor too loosely in the hole provided. Insert the looped them at the Standard Laboratory Temperature of 23 6 1°C
specimen and pin in the hole provided in the drum-type (73.4 6 1.8°F).
gripping device. Carefully align the specimen so that the 7.4.2 Where it is desired to obtain the greatest degree of
breaking force will be parallel to the length of the specimen. reproducibility, condition specimens in accordance with 4.2.
Adjust the clearance between jaws to 6 in. (150 mm). 7.5 Procedure:
6.5.3 Adjust the speed of the machine in accordance with 7.5.1 Adjust the weight so that the specimens are creased by
the requirements for Tensile Properties in Test Methods D 202. a load of 4.5 lbf (20 N)/in. of width.
6.5.4 Disregard values for breaks in or at the jaws. In these 7.5.2 Fold the specimen without creasing, and insert the
cases, continue tests so that there are five reportable breaking looped end under the weight so that the crease will be formed
strength values per sample. under the center of the weight. Lower the weight at a uniform
6.6 Report: rate of 12 in. (300 mm)/min to crease the specimen.
6.6.1 Report the average, maximum, and minimum break- 7.5.3 Allow the creased specimen to support the weight for
ing strength in pounds per inch of width (or kilograms per a period of 2 s, at the end of which period lift the weight from
millimetre of width), together with the width and nominal the specimen.
7.5.4 Determine the breaking strength of the creased speci-
thickness.
6.6.2 In the case of fabrics, report the breaking strength in men in accordance with 6.5.
the warp and fill directions separately. 7.6 Report—Report the following information:
6.7 Precision and Bias—The precision (repeatability within 7.6.1 Average, maximum, and minimum breaking strengths
a single laborator
...
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