1、Designation: D 348 07An American National StandardStandard Test Methods forRigid Tubes Used for Electrical Insulation1This standard is issued under the fixed designation D 348; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the ye
2、ar 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.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 These test methods cover the
3、testing of rigid tubes usedin electrical insulation. These tubes include many types madefrom fibrous sheets of basic materials, such as cellulose, glass,or nylon, in the form of paper, woven fabrics, or mats, bondedtogether by natural or synthetic resins or by adhesives. Suchtubes include vulcanized
4、 fiber and thermosetting laminates, aswell as tubes made from cast, molded, or extruded natural orsynthetic resins, with or without fillers or reinforcing materials.1.2 Tubes tested by these test methods are most commonlycircular in cross section; however, noncircular shapes are alsoin commercial us
5、e. To the extent that the individual methodsare compatible with a particular noncircular shape, these testmethods are applicable to these other shapes. For tests onnoncircular tubes, appropriate comments should be included inthe test report, including details of orientation of test specimenswith res
6、pect to the cross section of the tube.1.3 The procedures appear in the following sections:Procedure SectionsASTM TestMethodReferenceCompressive Strength (Axial and Diametral) 12 to 17 E 4Conditioning. 4 .Density 20 to 24 .Dielectric Strength 25 to 32 D 149Dimensional Measurements 5 D 668Dissipation
7、Factor and Permittivity 33 to 35 D 150Tensile Strength 6 to 11 E 4Water Absorption 18 to 19 D 5701.4 The values stated in inch-pound units are to be regardedas the standard. SI units in parentheses are for informationonly.1.5 This standard does not purport to address all of thesafety concerns, if an
8、y, 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. For a specifichazard statement, see 27.1.1.2. Referenced Documents2.1 ASTM Standards:2D 149
9、Test Method for Dielectric Breakdown Voltage andDielectric Strength of Solid Electrical Insulating Materialsat Commercial Power FrequenciesD 150 Test Methods for AC Loss Characteristics and Per-mittivity (Dielectric Constant) of Solid Electrical Insula-tionD 570 Test Method for Water Absorption of P
10、lasticsD 668 Test Methods of Measuring Dimensions of RigidRods and Tubes Used for Electrical InsulationD 1711 Terminology Relating to Electrical InsulationE4 Practices for Force Verification of Testing Machines3. Terminology3.1 Definitions For definitions of terms used in these testmethods, refer to
11、 Terminology D 1711.4. Conditioning4.1 In order to eliminate the effects of previous history ofhumidity exposure and to obtain reproducible results (Note 1),the test specimens in all cases of dispute, shall be given aconditioning treatment for physical tests (Note 2) as follows:4.1.1 Tensile Strengt
12、h, Compressive Strength (Axial andDiametral), and DensityCondition the machined specimensprior to test by drying in an air-circulating oven for 48 h at 506 3 C, followed by cooling to room temperature in adesiccator. In either case, all specimens shall be tested at roomtemperature maintained at 23 6
13、 2 C, 50 % relative humidity.NOTE 1Conditioning of specimens may be undertaken: (a) for thepurpose of bringing the material into equilibrium with standard laboratoryatmospheric conditions of 23 C and 50 % relative humidity; (b) simply toobtain reproducible results, irrespective of previous history o
14、f exposure;or (c) to subject the material to abnormal conditions of temperature orhumidity in order to predict its service behavior.The conditions given here to obtain reproducible results may givephysical values somewhat higher or somewhat lower than values underequilibrium at normal conditions, de
15、pending upon the particular materialand test. To ensure substantial equilibrium under normal conditions of1These 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 Rigi
16、d Insulating Materials.Current edition approved Feb. 1, 2007. Published February 2007. Originallyapproved in 1932. Last previous edition approved in 2000 as D 348 00.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual B
17、ook of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.humidity and t
18、emperature, however, will require from 20 to 100 days ormore depending upon thickness and type of material and its previoushistory. Consequently, conditioning for reproducibility must of necessitybe used for general purchase specifications and product control tests.NOTE 2Conditioning of specimens fo
19、r electrical tests is also neces-sary to obtain consistent results. In order to secure comparative results,specimens should be conditioned at the same temperature and humidity.5. Dimensional Measurements5.1 Dimensional measurements of tube shall be made inaccordance with Test Methods D 668.TENSILE S
20、TRENGTH6. Significance and Use6.1 Tension tests, properly interpreted, provide informationwith regard to the tensile properties of rigid tubing, whenemployed under conditions approximating those under whichthe tests are made. The tensile strength values may vary withthe size of the tube and with the
21、 temperature and atmosphericconditions. Tension tests may provide data for research anddevelopment and for engineering design, and are useful forquality control purposes.7. Apparatus7.1 Any universal testing machine may be used provided itis accurate to 1 % of the lowest breaking load to be applied.
22、Jaws that tighten under load, such as wedge-grip jaws, shall beused with the specimen properly aligned.7.2 The machine shall be verified in accordance withPractices E4.8. Test Specimens8.1 The test specimens shall be as shown in Fig. 1. Thelength, L, shall be as shown in Table 1. A groove shall bema
23、chined around the outside of the specimen at the center of itslength so that the wall section after machining shall be 60 % ofthe original nominal wall thickness. This groove shall consistof a straight section 2.25 in. (57 mm) in length with a radius of3 in. (76 mm) at each end joining it to the out
24、side diameter.Steel or brass plugs having diameters such that they will fitsnugly inside the tube, and having a length equal to the full jawlength plus 1 in. (25 mm) shall be placed in the ends of thespecimen to prevent crushing. They can be located in the tubeconveniently by separating and supporti
25、ng them on a threadedmetal rod. Details of plugs and test assembly are shown in Fig.1.9. Procedure9.1 Test five specimens. Measure the average inside andoutside diameters, determined from at least two measurements90 apart, at the groove to the nearest 0.001 in. (0.03 mm) andcalculate the cross-secti
26、onal area from these dimensions. As-semble the metal plugs with the tube as shown in Fig. 1. Graspthis assembly in the V-notched jaws of the testing machine.9.2 Speed of TestingThe crosshead speed of the testingmachine shall be such that the load can be accurately weighed,but shall not exceed 0.05 i
27、n./min (1.3 mm/min) when themachine is running idle.10. Report10.1 Report the following information:10.1.1 The average inside and outside diameters of thespecimen expressed to the nearest 0.001 in. (0.03 mm), eachdetermined from at least two measurements 90 apart,10.1.2 The average outside diameter
28、of the reduced sectionexpressed to the nearest 0.001 in. (0.03 mm),10.1.3 The full wall thickness of the specimen,10.1.4 The net area of the test section, in.2or mm2,10.1.5 The breaking load of each specimen, lbf or N,10.1.6 The tensile strength of each specimen, psi or MPa,and10.1.7 The room temper
29、ature.11. Precision and Bias11.1 PrecisionThis test method has been in use for manyyears, but no information has been presented to ASTM uponwhich to base a statement of precision. No activity has beenplanned to develop such information.11.2 BiasThis test method has no bias because the valuefor tensi
30、le strength is determined solely in terms of this testmethod.COMPRESSIVE STRENGTH (AXIAL ANDDIAMETRAL)12. Significance and Use12.1 Compressive tests, properly interpreted, provide infor-mation with regard to the compressive properties of rigidtubing when employed under conditions approximating those
31、FIG. 1 Diagram Showing Location of Tube Tension TestSpecimen in Testing MachineD348072under which the tests are made. The compressive strengthvalues may vary with the size of the tube, and with temperatureand atmospheric conditions. Compression tests may providedata for research and development, eng
32、ineering design, qualitycontrol, and acceptance or rejection under specifications.13. Apparatus13.1 Any universal testing machine may be used provided itis accurate to 1 % of the lowest breaking load to be applied, inaccordance with Practices E4. One end of the specimen foraxial loading or the side
33、of the specimen for diametral loadingshall bear upon an accurately centered spherical bearing block,located whenever practicable at the top. The metal bearingplates shall be directly in contact with the test specimen.NOTE 3Off-center loading of the diametral compressive test maycause the tube to pus
34、h to one side.14. Test Specimens14.1 Unless otherwise specified, the material shall be testedin the as-received condition.14.2 Test specimens shall consist of 1-in. (25-mm) longsections of the tubing.14.3 Care shall be taken in cutting the test specimens for theaxial tests, to have the ends of the s
35、pecimens cut accurately andsmoothly at right angles to the axis of the tube.NOTE 4If the tubing is too large in diameter, or is too high in breakingstrength to be tested with the available testing equipment, a segment of thetest specimen specified in 14.2 and 14.3 may be substituted for axial tests.
36、Such segments should not be used for testing tubes less than 2 in. (51 mm)in outside diameter. Unless otherwise specified, use segments having acircumferential length of 2 in. (51 mm).15. Procedure15.1 Test five specimens axially, with the load appliedperpendicular to the faces or ends of the specim
37、en, or test fivespecimens diametrically, with the load applied perpendicular tothe tangent at point of application.15.2 Discard specimens that break at some obvious fortu-itous flaw and retest, unless such flaws constitute a variable, theeffect of which it is desired to study.15.3 Retain results (on
38、 specimens) that deviate markedlyfrom the mean value of all tests unless 15.2 applies. In this caserun additional tests, the exact number to be fixed by the desired(statistical) significance level.15.4 Speed of TestingThe crosshead speed of the testingmachine shall be 0.050 in./min (1.3 mm/min) when
39、 themachine is running idle. In cases of diametral loading ofcertain tubing, especially the larger diameter tubes, it may benecessary to operate the crosshead at a speed of loading greaterthan 0.050 in./min. In this event the speed should be stated inthe report.16. Report16.1 Report the following in
40、formation:16.1.1 The average inside and outside diameters of thespecimen expressed to the nearest 0.001 in. (0.03 mm), eachdetermined from at least two measurements 90 apart,16.1.2 The average wall thickness of the specimen ex-pressed to the nearest 0.001 in. (0.03 mm),16.1.3 The segment length, if
41、segmental specimens are usedfor axial tests,16.1.4 The direction of application of the load,16.1.5 The load on each specimen at the first sign of rupture,lbf or N, and16.1.6 The ultimate compressive strength in force per unitarea for axial loading and force for diametral loading.17. Precision and Bi
42、as17.1 PrecisionSame as 11.1.17.2 BiasSame as 11.2 except for the property of com-pressive strength.WATER ABSORPTION18. Significance and Use18.1 The moisture content of a rigid tube has a definiteinfluence on the electrical properties, as well as on mechanicalstrength, dimensional stability, and app
43、earance. The effectupon these properties of changes in moisture content, due towater absorption, depends largely upon the inherent propertiesof the rigid tube. The rate of water absorption may be widelydifferent through each edge and surface. A water absorptiondetermination will provide data useful
44、for research and devel-opment, engineering design, quality control, and acceptance orrejection under specifications.TABLE 1 Dimensions of Tension Specimens, in. (mm)Nominal Wall Thickness Length of Radial Sections, 2R.S.Total Calculated Minimum Length ofSpecimenStandard Length, L, of Specimen tobe U
45、sed for 312-in. (89-mm) JawsA132 (0.79) 0.547 (13.9) 13.80 (350.0) 15 (381.0)364 (1.2) 0.670 (17.0) 13.92 (354.0) 15 (381.0)116 (1.6) 0.773 (19.6) 14.02 (356.0) 15 (381.0)332 (2.4) 0.946 (24.0) 14.20 (361.0) 15 (381.0)18 (3.2) 1.091 (27.7) 14.34 (364.0) 15 (381.0)316 (4.8) 1.333 (33.9) 14.58 (370.0)
46、 15 (381.0)14 (6.4) 1.536 (39.0) 14.79 (376.0) 15.75 (400.0)516 (7.9) 1.714 (43.5) 14.96 (380.0) 15.75 (400.0)38 (9.5) 1.873 (47.6) 15.12 (384.0) 15.75 (400.0)716 (11.1) 2.019 (51.3) 15.27 (388.0) 15.75 (400.0)12 (12.7) 2.154 (54.7) 15.40 (391.0) 16.5 (419.0)AFor other jaws greater than 312 in. (89
47、mm), the standard length shall be increased by twice the length of the jaws minus 7 in. (178 mm). The standard length permitsa slippage of approximately14 to12 in. (6.4 to 12.7 mm) in each jaw while maintaining maximum length of jaw grip.D34807319. Procedure19.1 Determine and report the rate of wate
48、r absorption inaccordance with Test Method D 570, immersing specimens for24 h in distilled water at 23 C after preliminary conditioningfor1hat105C.19.2 For some types of materials, or for special applications,it may be desirable to employ longer periods of water immer-sion in order to evaluate perfo
49、rmance. In these cases, the reportshall indicate the exact conditioning procedure.DENSITY20. Significance and Use20.1 A density measurement will provide data useful forresearch and development, engineering design, quality control,and acceptance or rejection under specifications.21. Test Specimens21.1 Any suitable size specimen may be used. The specimen1 in. (25 mm) in length used for the water absorption test(Sections 18 and 19) will be found convenient.22. Procedure22.1 Test two specimens using any suitable hydrostaticdisplacement apparatus capable
