1、Designation:D66812Standard Test Methods ofMeasuring Dimensions of Rigid Rods and Tubes Used forElectrical Insulation1This standard is issued under the fixed designation D668;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of
2、 last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope*1.1 These test methods cover the measurement of thedimensions of all rigid rods and tubes used as electricalinsulation,the li
3、mitations 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,it is acceptable touse an accurately calibrated“go-and-no-go”ring gage ofsuitable size.1.3 Thi
4、s 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 regulatory limitations prior to use.2.Referenced Documents2.1
5、 ASTM Standards:2D374 Test Methods for Thickness of Solid Electrical Insu-lation(Withdrawn 2013)3D1711 Terminology Relating to Electrical Insulation3.Terminology3.1 Definitions For definitions of terms used in these testmethods refer to Terminology D1711.4.Significance and Use4.1 These test methods
6、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 electrical properties ofthe rods and tubes.5.C
7、onditioning5.1 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 forspecimens with dimensions 300 mm(12 in.)and un
8、der inaccordance with the procedure described in Test MethodsD374 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 theinitial development of frictional resistance to movement
9、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 ApparatusAmachinists micrometer or vernier caliperof suitable size reading to 0.02
10、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 apart around the circumference ofthe specimen.7.4 ReportReport the av
11、erage 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 or164in.8.2 Test SpecimensSpecimens shall consist of rods ortubes over 300 mm(12 in.)in length,including fu
12、ll lengths.1These test methods are under the jurisdiction 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 Nov.1,2012.Published November 2012.Originallyap
13、proved in 1942.Last previous edition approved in 2004 as D668 99(2004).DOI:10.1520/D0668-12.2For 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 Summar
14、y page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 8.3 ProcedureMe
15、asure the length of the specimen to thenearest 0.5 mm or164in.Size permitting,make four measure-ments at points 90 apart around the circumference of thespecimen.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 i
16、n.)and Under in Outside Diameter9.1 ApparatusAmachinists micrometer or vernier caliperreading 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 around the circumference at each endand at the middle of the specimen.9.4 ReportReport the average of the twelve measurementsas t