ASTM D349-99(2004)
(Test Method)Standard Test Methods for Laminated Round Rods Used for Electrical Insulation
Standard Test Methods for Laminated Round Rods Used for Electrical Insulation
SCOPE
1.1 These test methods cover the procedures for testing rigid round rods used in electrical insulation. These round rods include many types made from fibrous sheets of basic materials, such as cellulose, asbestos, glass, or nylon in the form of paper, woven fabrics, or mats, bonded together by natural or synthetic resins, or by adhesives. Such round rods include vulcanized fiber and thermosetting laminates as well as round rods made from cast, molded, or extruded natural or synthetic resins, with or without fillers or reinforcing materials.
1.2 The procedures appear in the following sections:SectionCompressive strength (axial)DensityDielectric strengthFlexural strengthTensile strengthWater absorption-
1.3 The values stated in inch-pound units are to be regarded as the standard.
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. For a specific warning statement see .
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An American National Standard
Designation:D349–99 (Reapproved 2004)
Standard Test Methods for
Laminated Round Rods Used for Electrical Insulation
This standard is issued under the fixed designation D 349; 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 D 668 Test Methods of Measuring Dimensions of Rigid
Rods and Tubes Used for Electrical Insulation
1.1 Thesetestmethodscovertheproceduresfortestingrigid
D 792 TestMethodsforDensityandSpecificGravity(Rela-
round rods used in electrical insulation. These round rods
tive Density) of Plastics by Displacement
include many types made from fibrous sheets of basic materi-
D 1711 Terminology Relating to Electrical Insulation
als, such as cellulose, asbestos, glass, or nylon in the form of
D 6054 Practice for Conditioning Electrical Insulating Ma-
paper, woven fabrics, or mats, bonded together by natural or
terials for Testing
synthetic resins, or by adhesives. Such round rods include
vulcanized fiber and thermosetting laminates as well as round
3. Terminology
rods made from cast, molded, or extruded natural or synthetic
3.1 Definitions—Use Terminology D 1711 for definitions of
resins, with or without fillers or reinforcing materials.
terms used in these test methods and associated with electrical
1.2 The procedures appear in the following sections:
or electronic insulation materials.
Section
Compressive strength (axial) 20-25
4. Selection of Test Specimens
Density 28-30
Dielectric strength 31-39
4.1 Specimens for tests shall be selected from portions of
Flexural strength 13-19
material that are free of obvious defects unless the purpose of
Tensile strength 7-12
Water absorption 26-27
the test is to evaluate the effect of these defects.
1.3 The values stated in inch-pound units are to be regarded
5. Conditioning
as the standard.
5.1 In order to eliminate the effects of previous history of
1.4 This standard does not purport to address all of the
humidity exposure and to obtain reproducible results (Note 1),
safety concerns, if any, associated with its use. It is the
in all cases of dispute give the test specimens of laminated rods
responsibility of the user of this standard to establish appro-
a conditioning treatment for physical test as follows:
priate safety and health practices and determine the applica-
5.1.1 Tensile, Flexural, and Compressive Strengths, and
bility of regulatory limitations prior to use. For a specific
Density—Prior to test, condition the machined specimens in
warning statement see 36.2.
accordance with Procedure B of Practice D 6054. All speci-
2. Referenced Documents mens shall be tested at room temperature maintained at 23 6
2 5 °C.
2.1 ASTM Standards:
D 149 Test Method for Dielectric Breakdown Voltage and
NOTE 1—Conditioning of specimens may be undertaken: (a) for the
Dielectric Strength of Solid Electrical Insulating Materials purpose of bringing the material into equilibrium with normal or average
room conditions of 23 °C and 50 % relative humidity; (b) simply to obtain
at Commercial Power Frequencies
reproducible results, irrespective of previous history of exposure; or (c)to
D 570 Test Method for Water Absorption of Plastics
subject the material to abnormal conditions of temperature or humidity in
order to predict its service behavior.
1 The conditions given here to obtain reproducible results may give
These test methods are under the jurisdiction of ASTM Committee D09 on
physical values somewhat higher or somewhat lower than values under
Electrical and Electronic Insulating Materials and are the direct responsibility of
equilibrium at normal conditions, depending upon the particular material
Subcommittee D09.07 on Flexible and Rigid Insulating Materials.
Current edition approved April 10, 1999. Published June 1999. Originally and test. To ensure substantial equilibrium under normal conditions of
approved in 1932. Last previous edition approved in 1997 as D 349 – 92 (1997).
humidity and temperature, however, will require from 20 to 100 days or
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
more depending upon thickness and type of material and its previous
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
history. Consequently, conditioning for reproducibility must of necessity
Standards volume information, refer to the standard’s Document Summary page on
be used for general purchase specifications and product control tests.
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D349–99 (2004)
6. Dimensional Measurements L, is as shown in Table 1. Machine a groove around the
specimen at the center of its length so that the diameter of the
6.1 Make dimensional measurements of rods in accordance
machined portion is 60 % of the original nominal diameter.
with Test Methods D 668.
This groove consists of a straight section 2 ⁄4 in. (57 mm) in
TENSILE STRENGTH length with a radius of 3 in. (76 mm) at each end joining it to
the outside diameter.
7. Significance and Use
10. Procedure
7.1 This test method is designed to provide data for the
control and specification of materials and for characterization
10.1 Adjust the crosshead speed of the testing machine not
purposes in research and development of new materials.
to exceed 0.050 in. (1.27 mm)/min when running idle and test
Tensile properties may vary with the size of specimens and the
five specimens.
speed of testing. Consequently, these factors along with others
noted herein must be controlled where precise comparative
11. Report
results are desired.
11.1 Report the following information:
11.1.1 The average diameter of the specimen, expressed to
8. Apparatus
the nearest 0.001 in. (0.0254 mm), determined from at least
8.1 Any testing machine may be used provided it is accurate
two measurements 90° apart,
to 1 % of the lowest breaking force to be applied. Use jaws
11.1.2 The average diameter of the reduced section, ex-
which tighten under load, such as wedge grip jaws, with the
pressed to the nearest 0.001 in. (0.025 mm), determined from
specimen properly aligned.
at least two measurements 90° apart,
11.1.3 Crosshead speed in inches per minute (or millime-
9. Test Specimens
tres).
9.1 PreparethetestspecimenasshowninFig.1.Thelength,
11.1.4 The breaking load of each specimen in pounds-force
(or newtons),
11.1.5 The tensile strength of each specimen in pounds-
force per square inch, (or pascals), and
11.1.6 The room temperature in degrees Celsius.
12. Precision and Bias
12.1 Precision—This test method has been in use for many
years, but no statement of precision has been available and no
activity is planned to develop such a statement.
12.2 Bias—A statement of bias is not applicable in view of
the lack of a standard reference material for this property.
FLEXURAL STRENGTH
13. Significance and Use
13.1 Flexural strength data are useful for the control and
specification of materials and to provide guidance in the design
of electrical equipment. Flexural properties may vary with the
size of the specimens and the speed of testing. Consequently,
these factors, together with others noted herein, must be
controlled where precise comparative results are desired.
14. Apparatus
14.1 Any testing machine may be used provided it is
accurate to 1 % of the lowest breaking force to be applied.
15. Test Specimens
15.1 Prepare the test specimen with a diameter equal to that
Metric Equivalents
of the rod and a length eight times the diameter, plus 1 in. (25.4
in. mm
mm) for rods under ⁄2 in. (12.7 mm) in diameter. For rods over
2 50.8
⁄2 in. and up to 2 in. (50.8 mm) in diameter, machine
2 ⁄4 57.1
specimens to a diameter of ⁄2 in. and cut to a length of 6 in.
3 76.2
3 ⁄2 88.9
(152.4 mm).
15.2 When the rod being tested is not circumferentially
FIG. 1 Diagram Showing Location of Rod Tension Test
Specimen in Testing Machine isotropic, prepare specimens for testing in both of the principal
D349–99 (2004)
TABLE 1 Dimensions of Rod Specimens
Total Calculated Minimum Standard Length, L, of Speci-
Nominal Diameter, Length of Radial Sections
Length of Specimen, men to be Used for 3 ⁄2 in.
in. (mm) 2 RS, in. (mm)
A
in. (mm) (88.9 mm) Jaws
⁄8 (3.2) 0.773 (19.63) 14.02 (35.61) 15 (381.0)
⁄16 (4.8) 0.946 (24.03) 14.20 (36.06) 15 (381.0)
⁄4 (6.4) 1.091 (27.71) 14.34 (36.42) 15 (381.0)
⁄8 (9.5) 1.333 (33.86) 14.58 (37.03) 15 (381.0)
⁄2 (12.7) 1.563 (38.01) 14.79 (37.56) 15.75 (400.0)
⁄8 (15.9) 1.714 (43.56) 14.96 (37.99) 15.75 (400.0)
⁄4 (19.0) 1.813 (46.05) 15.12 (38.40) 15.75 (400.0)
⁄8 (22.1) 2.019 (51.28) 15.27 (38.78) 15.75 (400.0)
1 (25.4) 2.154 (54.71) 15.40 (39.11) 16.5 (414.0)
1 ⁄4 (31.8) 2.398 (60.90) 15.65 (39.75) 16.5 (414.0)
1 ⁄2 (38.0) 2.615 (66.42) 15.87 (40.31) 16.5 (414.0)
1 ⁄4 (44.5) 2.812 (70.41) 16.06 (40.79) 16.5 (414.0)
2 (50.8) 2.993 (76.02) 16.24 (41.25) 17 (432.0)
A 1
Forotherjawsgreaterthan3 ⁄2in.(88.9mm),thestandardlengthshallbeincreasedbytwicethelengthofthejawminus7in.(177.8mm).Thestandardlengthpermits
1 1
a slippage of approximately ⁄4 to ⁄2 in. (6.35 to 12.7 mm) in each jaw while maintaining maximum length of jaw grip.
directions, and identify them as to directionality. This particu- 19.2 Bias—A statement of bias is not applicable in view of
larly includes rods machined from stripmolded or sheet stock. the lack of a standard reference material for this property.
16. Procedure
COMPRESSIVESTRENGTH(AXIAL)
16.1 Test five specimens for each laminate orientation, each
asasimplebeamloadedatthecenter.Thedistancebetweenthe
20. Significance and Use
supports shall be eight times the diameter of the rod. The
20.1 Compression tests, properly interpreted, provide rea-
supports shall have contact edges rounded to a radius of ⁄8 in.
sonably accurate information with regard to the compressive
(3.2 mm). Adjust the crosshead speed of the testing machine
propertiesofrigidroundrodswhenemployedunderconditions
nottoexceedanidlespeedof0.050in./min(1.27mm/min)and
approximating those under which the tests are made. The
apply the load through a steel block having a semi-circular
compressive strength values may vary with the size of the rigid
contact edge of the same radius as the rod, with edges rounded
round rod, and with temperature and atmospheric conditions.
to a radius of ⁄8 in. (3.2 mm).
Compression tests may provide data for research and develop-
17. Calculation ment, engineering design, quality control, and acceptance or
rejection under specifications.
17.1 Calculate the maximum fiber stress, S, as follows:
S 5 8 WL/pd (1)
21. Apparatus
21.1 Any testing machine may be used provided it is
where:
accurate to 1 % of the lowest breaking force to be applied. One
W = breaking load, lbf (N),
end of the specimen shall bear upon an accurately centered
L = distance between supports, in. (mm), and
spherical bearing block, located, whenever practicable, at the
d = diameter, in (mm).
top. The metal bearing plates shall be directly in contact with
the ends of the test specimen.
18. Report
18.1 Report the following information:
22. Test Specimens
18.1.1 The diameter of the specimen expressed to the
nearest 0.001 in. (0.0254 mm), determined from at least two
22.1 Unless otherwise specified in the test method or
measurements 90° apart,
specification for that material, test the samples as received. For
18.1.2 Crosshead speed in inches per minute (or millime-
rods ⁄8 to 1 in. (3.2 to 25.4 mm) in diameter, prepare the test
tres),
specimen with a diameter equal to the diameter of the rod, and
18.1.3 The breaking load of each specimen in pounds-force
length conforming to the following requirements:
(or newtons),
Length, in. Slenderness
Diameter, in. (mm) (mm) Ratio
18.1.4 The maximum fiber stress S, in pounds-force per
1 1 1
⁄8 to ⁄4 (3.2 to 6.4) incl ⁄2 (12.7) 16 to 8
square inch (pascals), and
1 1
Over ⁄4 to ⁄2 (6.4 to 12.7) incl 1 (25.4) 16 to 8
18.1.5 The direction of loading relative to the direction of 1
Over ⁄2 to 1 (12.7 to 25.4) incl 2 (50.8) 16 to 8
the laminate if the rods are ground from strip-molded stock,
22.2 For rods over 1 in. (25.4 mm) in diameter, specimens
sheet stock, and vulcanized fiber.
1 1
are standard ⁄2 by ⁄2 by 1-in. (12.7 by 12.7 by 25.4-mm) right
19. Precision and Bias
parallelepiped, cut from the rods so as to be representative of
their cross sections both at the center and near the edges.
19.1 Precision—This test method has been in use for many
years, but no statement of precision has been available and no 22.3 Accurately cut or grind the ends of each specimen
activity is planned to develop such a statement. parallel to each other.
D349–99 (2004)
23. Procedure 29. Procedure
23.1 Adjust the crosshead speed of the testing machine not 29.1 Determine the density in accordance with MethodAof
to exceed an idle speed of 0.050 in./min (1.27 mm/min), and Test Methods D 792.
test five specimens with the load applied perpendicular to the
30. Report
faces or ends of the specimen.
23.2 Discardspecimensthatbreakatsomeobviousflawand
30.1 Report the following information:
make retests unless such flaws constitute a variable, the effect
30.1.1 Complete identification of the material tested, and
of which it is desired to study.
30.1.2 Average density in grams per cubic centimetre.
24. Report
DIELECTRIC STRENGTH
24.1 Report the following information:
31. Significance and Use
24.1.1 The diameter of the specimen expressed to the
nearest 0.001 in. (0.0254 mm), determined from at least two
31.1 The dielectric strength of a rigid round rod will depend
measurements 90° apart, upon a number of factors such as rod diameter, which deter-
24.1.2 The load on each specimen in pounds at the first sign
mines the electrode diameter to be used in the test; direction of
of rupture, and applied dielectric stress, whether transverse or parallel to the
24.1.3 The compressive strength in pounds-force per square
axis; rate of application and the frequency of the voltage;
inch (or pascals) calculated from the data obtained on the
temperature, and surrounding atmospheric humidity. The test
application of the load perpendicular to the face of the
values for dielectric strength determined by standard proce-
specimen.
dure, which stresses a rod section ⁄16 in. (1.6 mm) in a
direction parallel to the axis, may not necessarily indicate the
25. Precision and Bias
safe operation in service. In actual service, the voltage may
...
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