ASTM D668-12

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D668 − 12
Standard Test Methods of
Measuring Dimensions of Rigid Rods and Tubes Used for
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Electrical Insulation
This standard is issued under the fixed designation D668; 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* used for manufacturing control, determination of uniformity,
dimensional stability, and physical and electrical properties of
1.1 These test methods cover the measurement of the
the rods and tubes.
dimensions of all rigid rods and tubes used as electrical
insulation, the limitations imposed being those of the size
5. Conditioning
range of the more common forms of measuring instruments
used.
5.1 Condition specimens prior to testing for at least 48 h at
23 6 1 °C and 50 6 2 % relative humidity. Perform tests in air
1.2 Where the number of tests to be made or the specifica-
controlled at that temperature and humidity.
tions covering the rod or tube justify its use, it is acceptable to
use an accurately calibrated “go-and-no-go” ring gage of
6. Method of Measurement
suitable size.
6.1 Make all diameter and wall thickness measurements for
1.3 This standard does not purport to address all of the
specimens with dimensions 300 mm (12 in.) and under in
safety concerns, if any, associated with its use. It is the
accordance with the procedure described in Test Methods
responsibility of the user of this standard to establish appro-
D374 as applicable. Close the micrometer or vernier caliper
priate safety and health practices and determine the applica-
slowly on the specimen until contact is made without appre-
bility of regulatory limitations prior to use.
ciable distortion of the specimen.The criterion of contact is the
initial development of frictional resistance to movement of the
2. Referenced Documents
2 specimen between the micrometer or caliper surfaces. Use a
2.1 ASTM Standards:
steeltapeorsteelscaleformeasurementoflengthanddiameter
D374 Test Methods for Thickness of Solid Electrical Insu-
3 greater than 300 mm (12 in.).
lation (Withdrawn 2013)
D1711 Terminology Relating to Electrical Insulation
7. Length of Rods or Tubes 300 mm (12 in.) and Under
in Length
3. Terminology
7.1 Apparatus—Amachinist’s micrometer or vernier caliper
3.1 Definitions— For definitions of terms used in these test
of suitable size reading to 0.02 mm or 0.001 in.
methods refer to Terminology D1711.
7.2 Test Specimens—Specimens shall consist of rods or
4. Significance and Use
tubes 300 mm (12 in.) or shorter.
4.1 These test methods are used to measure the dimensions
7.3 Procedure—Measure the length of the specimen to the
oftherodortubetodetermineconformancewithspecifications
nearest 0.02 mm or 0.001 in. Size permitting, make four
on full lengths or cut lengths. The measurements can also be
measurements at points 90° apart around the circumference of
the specimen.
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7.4 Report—Report the average of the measurements taken
These test methods are under the jurisdiction of ASTM Committee D09 on
Electrical and Electronic Insulating Materials and are the direct responsibility of
as the length of the rod or tube.
Subcommittee D09.07 on Flexible and Rigid Insulating Materials.
Current edition approved Nov. 1, 2012. Published November 2012. Originally
8. Length of Rod or Tubes Over 300 mm (12 in.) in
approved in 1942. Last previous edition approved in 2004 as D668 – 99(2004).
DOI: 10.1520/D0668-12. Length
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For referenced ASTM standards, visit the ASTM website, www.astm.org, or
8.1 Apparatus—Steel tape or steel scale of suitable length
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
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Standards volume information, refer to the standard’s Document Summary page on graduated in 0.5 mm or ⁄64 in.
the ASTM website.
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8.2 Test Specimens—Specimens shall consist of rods or
The last approved version of this historical standard is referenced on
www.astm.org. tubes over 300 mm (12 in.) in length, including full lengths.
*A Summary of Changes section appears at the end of this standard
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D668 − 12
8.3 Procedure—Measure the length of the specimen to the 11.2 Test Specimen—Specimen shall consist of tubes whose
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nearest 0.5 mm or ⁄64 in. Size permitting, make four measure- insidediameterisnotover300mm(12in.)norunder3mm( ⁄8
ments at points 90° apart around the circumference of the in.).
specimen.
11.3 Procedure—Measure the inside diameter of the speci-
8.4 Report—Report the average of the measurements as the men to the near
...