1、Designation: D348 07D348 13 An American National StandardStandard Test Methods forRigid Tubes Used for Electrical Insulation1This standard is issued under the fixed designation D348; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () 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
3、 the testing of rigid tubes used in electrical insulation. These tubes include many types made fromfibrous sheets of basic materials, such as cellulose, glass, or nylon, in the form of paper, woven fabrics, or mats, bonded togetherby natural or synthetic resins or by adhesives. Such tubes include vu
4、lcanized fiber and thermosetting laminates, as well as tubesmade from cast, molded, or extruded natural or synthetic resins, with or without fillers or reinforcing materials.1.2 Tubes tested by these test methods are most commonly circular in cross section; however, noncircular shapes are also incom
5、mercial use. To the extent that the individual methods are compatible with a particular noncircular shape, these test methodsare applicable to these other shapes. For tests on noncircular tubes, appropriate comments shouldshall be included in the test report,including details of orientation of test
6、specimens with respect 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 E4Conditioning. 4 .Density 20 to 24 .Dielectric Strength 25 to 32 D149Dimensional Measurements 5 D
7、668Dissipation Factor and Permittivity 33 to 35 D150Tensile Strength 6 to 11 E4Water Absorption 18 to 19 D5701.4 The values stated in inch-pound units are to be regarded as the standard. SI units in parentheses are for information only.1.5 This standard does not purport to address all of the safety
8、concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. For a specific hazard statement, see 27.1.1.2. Referenced Documents2.1 ASTM Stan
9、dards:2D149 Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials atCommercial Power FrequenciesD150 Test Methods for AC Loss Characteristics and Permittivity (Dielectric Constant) of Solid Electrical InsulationD570 Test Method for Water Absorp
10、tion of PlasticsD668 Test Methods of Measuring Dimensions of Rigid Rods and Tubes Used for Electrical InsulationD1711 Terminology Relating to Electrical InsulationE4 Practices for Force Verification of Testing Machines3. Terminology3.1 DefinitionsFor definitions of terms used in these test methods,
11、refer to Terminology D1711.1 These test methods are under the jurisdiction ofASTM Committee D09 on Electrical and Electronic Insulating Materials and are the direct responsibility of SubcommitteeD09.07 on Flexible and Rigid Insulating Materials.Current edition approved Feb. 1, 2007Nov. 1, 2013. Publ
12、ished February 2007November 2013. Originally approved in 1932. Last previous edition approved in 20002007as D348 00.D348 07. DOI: 10.1520/D0348-07.10.1520/D0348-13.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book
13、 of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technic
14、ally possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this st
15、andardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14. Conditioning4.1 In order to eliminate the effects of previous history of humidity exposure and to obtain reproducible results (Note 1), thetest specimens in all cases of dispute
16、, shall be given a conditioning treatment for physical tests (Note 2) as follows:4.1.1 Tensile Strength, Compressive Strength (Axial and Diametral), and DensityCondition the machined specimens prior totest by drying in an air-circulating oven for 48 h at 50 6 3 C, followed by cooling to room tempera
17、ture in a desiccator. In eithercase, all specimens shall be tested at room temperature maintained at 23 6 2 C, 50 % relative humidity.NOTE 1Conditioning of specimens may be undertaken: The following are potential reasons to undertake conditioning of specimens: (a) for thepurpose of bringing the mate
18、rial into equilibrium with standard laboratory atmospheric conditions of 23 C and 50 % relative humidity; (b) simply toobtain reproducible results, irrespective of previous history of exposure; or (c) to subject the material to abnormal conditions of temperature or humidityin order to predict its se
19、rvice behavior.The conditions given here to obtain reproducible results maywill give physical values which could be somewhat higher or somewhat lower than valuesunder equilibrium at normal conditions, depending upon the particular material and test. To ensure substantial equilibrium under normal con
20、ditions ofhumidity and temperature, however, will require from 20 to 100 days or more depending upon thickness and type of material and its previous history.Consequently, conditioning for reproducibility must of necessity be used for general purchase specifications and product control tests.NOTE 2Co
21、nditioning of specimens for electrical tests is also necessary to obtain consistent results. In order to secure comparative results, specimensshould be conditioned at the same temperature and humidity.4.1.2 Conditioning of specimens for electrical tests is also necessary to obtain consistent results
22、. In order to secure comparativeresults, specimens shall be conditioned at the same temperature and humidity.5. Dimensional Measurements5.1 Dimensional measurements of tube shall be made in accordance with Test Methods D668.TENSILE STRENGTH6. Significance and Use6.1 Tension tests, properly interpret
23、ed, provide information with regard to the tensile properties of rigid tubing, when employedunder conditions approximating those under which the tests are made. The It is possible that the tensile strength values maywillvary with the size of the tube and with the temperature and atmospheric conditio
24、ns. Tension tests may provide data potentiallyuseful for research and development and for engineering design, and are useful for quality control purposes.7. Apparatus7.1 Any universal testing machine may be used is acceptable for use provided it is accurate to 1 % of the lowest breaking loadto be ap
25、plied. Jaws that tighten under load, such as wedge-grip jaws, shall be used with the specimen properly aligned.7.2 The machine shall be verified in accordance with Practices E4.8. Test Specimens8.1 The test specimens shall be as shown in Fig. 1. The length, L, shall be as shown in Table 1. A groove
26、shall be machinedaround the outside of the specimen at the center of its length so that the wall section after machining shall be 60 % of the originalnominal wall thickness. This groove shall consist of a straight section 2.25 in. (57 mm) in length with a radius of 3 in. (76 mm)at each end joining i
27、t to the outside diameter. Steel or brass plugs having diameters such that they will fit snugly inside the tube,and having a length equal to the full jaw length plus 1 in. (25 mm) shall be placed in the ends of the specimen to prevent crushing.They can be located in the tube conveniently by separati
28、ng and supporting them on a threaded metal rod. Details of plugs and testassembly are shown in Fig. 1.9. Procedure9.1 Test five specimens. Measure the average inside and outside diameters, determined from at least two measurements 90apart, at the groove to the nearest 0.001 in. (0.03 mm) and calcula
29、te the cross-sectional area from these dimensions. Assemble themetal plugs with the tube as shown in Fig. 1. Grasp this assembly in the V-notched jaws of the testing machine.9.2 Speed of TestingThe crosshead speed of the testing machine shall be such that the load can be accurately weighed, butshall
30、 not exceed 0.05 in./min (1.3 mm/min) when the machine is running idle.10. Report10.1 Report the following information:10.1.1 The average inside and outside diameters of the specimen expressed to the nearest 0.001 in. (0.03 mm), each determinedfrom at least two measurements 90 apart,10.1.2 The avera
31、ge outside diameter of the reduced section expressed 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.2 or mm2,D348 13210.1.5 The breaking load of each specimen, lbf or N,10.1.6 The tensile strength of each specimen, psi or
32、 MPa, and10.1.7 The room temperature.11. Precision and Bias11.1 PrecisionThis test method has been in use for many years, but no information has been presented to ASTM upon whichto base a statement of precision. No activity has been planned to develop such information.11.2 BiasThis test method has n
33、o bias because the value for tensile strength is determined solely in terms of this test method.COMPRESSIVE STRENGTH (AXIAL AND DIAMETRAL)12. Significance and Use12.1 Compressive tests, properly interpreted, provide information with regard to the compressive properties of rigid tubingwhen employed u
34、nder conditions approximating those under which the tests are made. The compressive Compressive strengthvalues may have the potential to vary with the size of the tube, and with temperature and atmospheric conditions. Compressiontests may provide data which could be useful for research and developme
35、nt, engineering design, quality control, and acceptanceor rejection under specifications.13. Apparatus13.1 Any universal testing machine may be used is acceptable for use provided it is accurate to 1 % of the lowest breaking loadto be applied, in accordance with Practices E4. One end of the specimen
36、 for axial loading or the side of the specimen for diametralloading shall 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 2Off-center loading of the diametral compressi
37、ve test may has the potential to cause the tube to push to one side.14. Test Specimens14.1 Unless otherwise specified, the material shall be tested in the as-received condition.14.2 Test specimens shall consist of 1-in. (25-mm) long sections of the tubing.14.3 When cutting the test specimens for the
38、 axial tests, take care to have the ends of the specimens cut accurately and smoothlyat right angles to the axis of the tube.FIG. 1 Diagram Showing Location of Tube Tension Test Specimen in Testing MachineD348 13314.4 Care shall be taken in cutting the test specimens for the axial tests, to have the
39、 ends of the specimens cut accurately If thetubing is too large in diameter, or is too high in breaking strength to be tested with the available testing equipment, it is acceptableto substitute a segment of the test specimen specified in 14.2 and smoothly14.3 at right angles to the axis of the tube.
40、for axial tests.Such segments shall not be used for testing tubes less than 2 in. (51 mm) in outside diameter. Unless otherwise specified, usesegments having a circumferential length of 2 in. (51 mm).NOTE 4If the tubing is too large in diameter, or is too high in breaking strength to be tested with
41、the available testing equipment, a segment of thetest specimen specified in 14.2 and 14.3 may be substituted for axial tests. Such segments should not be used for testing tubes less than 2 in. (51 mm)in outside diameter. Unless otherwise specified, use segments having a circumferential length of 2 i
42、n. (51 mm).15. Procedure15.1 Test five specimens axially, with the load applied perpendicular to the faces or ends of the specimen, or test five specimensdiametrically, with the load applied perpendicular to the tangent at point of application.15.2 Discard specimens that break at some obvious fortui
43、tous flaw and retest, unless such flaws constitute a variable, the effectof which it is desired to study.15.3 Retain results (on specimens) that deviate markedly from the mean value of all tests unless 15.2 applies. In this case runadditional tests, the exact number to be fixed by the desired (stati
44、stical) significance level.15.4 Speed of TestingThe crosshead speed of the testing machine shall be 0.050 in./min (1.3 mm/min) when the machine isrunning idle. In cases of diametral loading of certain tubing, especially the larger diameter tubes, it may be necessary will benecessary, in some cases,
45、to operate the crosshead at a speed of loading greater than 0.050 in./min. In this event the speedshouldshall be stated in the report.16. Report16.1 Report the following information:16.1.1 The average inside and outside diameters of the specimen expressed to the nearest 0.001 in. (0.03 mm), each det
46、erminedfrom at least two measurements 90 apart,16.1.2 The average wall thickness of the specimen expressed to the nearest 0.001 in. (0.03 mm),16.1.3 The segment length, if segmental specimens are used for axial tests,16.1.4 The direction of application of the load,16.1.5 The load on each specimen at
47、 the first sign of rupture, lbf or N, and16.1.6 The ultimate compressive strength in force per unit area for axial loading and force for diametral loading.17. Precision and Bias17.1 PrecisionSame as 11.1.17.2 BiasSame as 11.2 except for the property of compressive strength.WATER ABSORPTION18. Signif
48、icance and Use18.1 The moisture content of a rigid tube has a definite influence on the electrical properties, as well as on mechanical strength,dimensional stability, and appearance. The effect upon these properties of changes in moisture content, due to water absorption,depends largely upon the in
49、herent properties of the rigid tube. The It is possible that the rate of water absorption maywill be widelyTABLE 1 Dimensions of Tension Specimens, in. (mm)Nominal Wall Thickness Length of Radial Sections, 2R.S. Total Calculated Minimum Length ofSpecimen Standard Length, L, of Specimen tobe Used 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)3
