1、Designation: D 668 99 (Reapproved 2004)An American National StandardStandard Test Methods ofMeasuring Dimensions of Rigid Rods and Tubes Used forElectrical Insulation1This standard is issued under the fixed designation D 668; the number immediately following the designation indicates the year oforig
2、inal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods cover the measurement of thedimensions of a
3、ll rigid rods and tubes used as electricalinsulation, the limitations imposed being those of the sizerange of the more common forms of measuring instrumentsused.1.2 Where the number of tests to be made or the specifica-tions covering the rod or tube justify its use, an accuratelycalibrated “go-and-n
4、o-go” ring gage of suitable size may beused.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulat
5、ory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 374 Test Methods for Thickness of Solid Electrical Insu-lationD 1711 Terminology Relating to Electrical Insulation3. Terminology3.1 DefinitionsFor definitions of terms used in these testmethods refer to Terminology D 1711.4. S
6、ignificance and Use4.1 These test methods are used to measure the dimensionsof the rod or tube to determine conformance with specificationson full lengths or cut lengths. The measurements can also beused for manufacturing control, determination of uniformity,dimensional stability, and physical and e
7、lectrical properties ofthe rods and tubes.5. Conditioning5.1 Condition specimens prior to testing for at least 48 h at23 6 1 C and 50 6 2 % relative humidity. Perform tests in aircontrolled at that temperature and humidity.6. Method of Measurement6.1 Make all diameter and wall thickness measurements
8、 forspecimens with dimensions 300 mm (12 in.) and under inaccordance with the procedure described in Test MethodsD 374 as applicable. Close the micrometer or vernier caliperslowly on the specimen until contact is made without appre-ciable distortion of the specimen. The criterion of contact is thein
9、itial development of frictional resistance to movement of thespecimen between the micrometer or caliper surfaces. Use asteel tape or steel scale for measurement of length and diametergreater than 300 mm (12 in.).7. Length of Rods or Tubes 300 mm (12 in.) and Underin Length7.1 ApparatusA machinists m
10、icrometer or vernier cali-per of suitable size reading to 0.02 mm or 0.001 in.7.2 Test SpecimensSpecimens shall consist of rods ortubes 300 mm (12 in.) or shorter.7.3 ProcedureMeasure the length of the specimen to thenearest 0.02 mm or 0.001 in. Size permitting, make fourmeasurements at points 90 ap
11、art around the circumference ofthe specimen.7.4 ReportReport the average of the measurements takenas the length of the rod or tube.8. Length of Rod or Tubes Over 300 mm (12 in.) inLength8.1 ApparatusSteel tape or steel scale of suitable lengthgraduated in 0.5 mm or164 in.8.2 Test SpecimensSpecimens
12、shall consist of rods ortubes over 300 mm (12 in.) in length, including full lengths.8.3 ProcedureMeasure the length of the specimen to thenearest 0.5 mm or164 in. Size permitting, make four measure-ments at points 90 apart around the circumference of thespecimen.1These test methods are under the ju
13、risdiction of ASTM Committee D09 onElectrical and Electronic Insulating Materials and are the direct responsibility ofSubcommittee D09.07 on Flexible and Rigid Insulating Materials.Current edition approved Oct. 10, 1999. Published November 1999. Originallyapproved in 1942. Last previous edition appr
14、oved in 1989 as D 668 89.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 B
15、arr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.8.4 ReportReport the average of the measurements as thelength of the rod or tube.9. Diameter of Rods or Outside Diameter of Tubes 300mm (12 in.) and Under in Outside Diameter9.1 ApparatusA machinists micrometer or vernier
16、 cali-per reading to 0.02 mm or 0.001 in.9.2 Test SpecimensSpecimens shall consist of tubes 300mm (12 in.) and under in outside diameter or rods of anydiameter.9.3 ProcedureMeasure the outside diameter of the speci-men to the nearest 0.02 mm or 0.001 in. Make four measure-ments at points 45 apart ar
17、ound the circumference at each endand at the middle of the specimen.9.4 ReportReport the average of the twelve measure-ments as the outside diameter of the tube or the diameter of therod.9.4.1 In the case of tubes, report the variation in outsidediameter as the difference between the maximum and min
18、i-mum individual outside diameter readings, together with allmeasurements made.NOTE 1Rods having a diameter greater than 300 mm are generallycommercially available and no standard test procedures have beendeveloped for measuring dimensions of such rods.10. Outside Diameter of Tubes Over 300 mm (12 i
19、n.) inOutside Diameter10.1 ApparatusA flat steel tape graduated in steps of 0.5mm or164 in.10.2 Test SpecimenSpecimens shall consist of tubes over300 mm (12 in.) in outside diameter.10.3 ProcedurePlace the steel tape tightly around theoutside of the tube at a right angle to the long axis, and measur
20、ethe circumference to the nearest 0.5 mm or164 in. Calculate theoutside diameter by the following equation:D 5 tape reading/p! 2 2t (1)where:D = average outside diameter of tube, mm or in., andt = thickness of tape, mm or in.Make at least three measurements at three different locationson the tube.10
21、.4 ReportReport the average of all measurements as theoutside diameter of the tube.11. Inside Diameter of Tubes 300 mm (12 in.) and Underin Inside Diameter11.1 ApparatusA machinists inside micrometer or ver-nier caliper of suitable size reading to 0.02 mm or 0.001 in.preferably shall be used, althou
22、gh a combination of telescopinggage and standard machinists outside micrometer may be used(see 1.2).11.2 Test SpecimenSpecimen shall consist of tubes whoseinside diameter is not over 300 mm (12 in.) nor under 3 mm (18in.).11.3 ProcedureMeasure the inside diameter of the speci-men to the nearest 0.02
23、 mm or 0.001 in. Make four measure-ments at points 45 apart around the circumference at each endof the specimen.11.4 ReportReport the average of the measurements takenas the inside diameter of the tube.12. Inside Diameter of Tubes Over 300 mm (12 in.) inInside Diameter12.1 ProcedureDetermine the ave
24、rage inside diameter bysubtracting twice the average wall thickness from the averageoutside diameter. Determine the average wall thickness froman average of at least six measurements in accordance withSection 13.13. Wall Thickness of Tubes13.1 ApparatusA ball foot micrometer or suitable verniercalip
25、er reading to 0.02 mm or 0.001 in. shall be used for themeasurement of tubes 8 mm (516 in.) and over in insidediameter. A dial micrometer reading to 0.02 mm or 0.001 in.shall be used for the measurement of tubes under 8 mm (516in.) in inside diameter.13.2 Test SpecimensSpecimens shall consist of tub
26、es ofany length or diameter.13.3 ProcedureMeasure the wall thickness to the nearest0.02 mm or 0.001 in. For tubes 8 mm (516 in.) and over ininside diameter, take four measurements at points 90 apartaround the circumference at each end of the specimen. Fortubes under 8 mm (516 in.) in inside diameter
27、, measure the wallthickness by placing the specimen over a mandrel of slightlysmaller diameter which is fixed in position at right anglesrelative to the spindle of the dial micrometer. Note a zerosetting with the spindle against the pin. Then place thespecimen over the pin and take readings at vario
28、us pointsaround the circumference of the specimen. Take at least fourreadings.13.4 ReportReport the average of the measurementstaken as the wall thickness of the tube.14. Variation in Wall Thickness of Tubes14.1 Apparatussee 13.1.14.2 Test SpecimensSpecimens shall consist of tubes ofany length or di
29、ameter.14.3 ProcedureMeasure the wall thickness to the nearest0.02 mm or 0.001 in. For tubes 8 mm (516 in.) and over ininside diameter, make a series of measurements around eachend of the specimen. For tubes under 8 mm (516 in.) in insidediameter, measure the variation in wall thickness by rotatingt
30、he specimen around the mandrel and following the generalprocedure in accordance with 13.3 for tubes of this size.14.4 ReportReport the difference between the maximumand minimum values as the variation in wall thickness. Also,report all measurements taken.15. Warp15.1 ApparatusA horizontal flat surfa
31、ce and a rigid barwith plane surface firmly fixed at right angles to the flatsurface, both being at least as long as the specimen. The heightof the bar shall exceed half the diameter of the tube. Feelergages of suitable thicknesses will also be required.15.2 Test SpecimensSpecimens shall consist of
32、rods ortubes of any length or diameter.D 668 99 (2004)215.3 ProcedurePlace the specimen in the fixture. With theaid of feeler gages, measure the maximum distance betweenthe rod or tube and the plane surface, rotating the specimen asnecessary to locate the maximum. Measure to the nearest 0.02mm or 0.
33、001 in.15.4 ReportReport warp or lack of straightness as themaximum distance measured in accordance with 15.3.15.5 CalculationCalculate the percentage warp based ona 1-m or 36-in. length as follows:Wm5 1D/L2! 3 100 or W365 36D/L2! 3 100 (2)where:Wm= percentage warp calculated to a 1-m length,D = max
34、imum deviation of the rod or tube from thestraight edge, m or in.,L = actual length of the rod or tube as determined inaccordance with the procedure described in Section7 or 8, m or in., andW36= percentage warp calculated in a 36-in. length.When it is desired to compare the actual deviation for anyl
35、ength with the permissible deviation for that length, one of thefollowing equations may be used:Dxm/Dm5 Lxm2/1!2or Dx/D365 Lx2/36!2(3)where:Dxm= permissible deviation from the straight edge for thegiven length, m,Dm= permissible deviation for a 1-m length,Lxm= given length, m,Dx= permissible deviati
36、on from the straight edge for thegiven length, in.,D36= permissible deviation for a 36-in. length, andLx= given length, in.NOTE 2These requirements do not apply to cut pieces but only to rodor tube lengths as manufactured, unless otherwise agreed upon betweenthe manufacturer and the purchaser.16. Pr
37、ecision and Bias16.1 These tests have been in use for many years, but noinformation has been presented to ASTM upon which to basea statement of precision. No activity has been planned todevelop such information.16.2 These test methods have no bias because the values forthese measurements are determi
38、ned solely in terms of these testmethods themselves.17. Keywords17.1 dimensions; rigid rods; rigid tubes; wall thickness;warpASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are ex
39、pressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revi
40、sed, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you ma
41、y attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D 668 99 (2004)3
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