1、Designation: E 235 06Standard Specification forThermocouples, Sheathed, Type K and Type N, for Nuclearor for Other High-Reliability Applications1This standard is issued under the fixed designation E 235; the number immediately following the designation indicates the year oforiginal adoption or, in t
2、he 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 This specification covers the requirements for sheathed,Type K and N thermocouples f
3、or nuclear service. Dependingon size, these thermocouples are normally suitable for operat-ing temperatures to 1652 F (900 C); special conditions ofenvironment and life expectancy may permit their use attemperatures in excess of 2012 F (1100 C). This specificationwas prepared specifically to detail
4、requirements for using thistype of sheathed thermocouple in nuclear environments. Thisspecification can be used for sheathed thermocouples which arerequired for laboratory or general commercial applicationswhere the environmental conditions exceed normal servicerequirements. The intended use of a sh
5、eathed thermocouple ina specific nuclear application will require evaluation by thepurchaser of the compatibility of the thermocouple, includingthe effect of the temperature, atmosphere, and integratedneutron flux on the materials and accuracy of the thermoele-ments in the proposed application. This
6、 specification does notattempt to include all possible specifications, standards, etc.,for materials that may be used as sheathing, insulation, andthermocouple wires for sheathed-type construction. The re-quirements of this specification include only the austeniticstainless steels and other alloys a
7、s allowed with SpecificationE 585/E 585M for sheathing, magnesium oxide or aluminumoxide as insulation, and Type K and N thermocouple wires forthermoelements (see Note 1).1.2 General DesignNominal sizes of the finished thermo-couples shall be 0.0400 in. (1.016 mm), 0.0625 in. (1.588 mm),0.125 in. (3
8、.175 mm), 0.1875 in. (4.763 mm), or 0.250 in.(6.350 mm). Sheath dimensions and tolerances for each nomi-nal size shall be in accordance with Table 1 and Figs. 1 and 2.The measuring junction styles for thermocouples covered bythis specification are as follows:1.2.1 Style G2(grounded)Measuring junctio
9、n electricallyconnected to conductive sheaths, and1.2.2 Style U2(ungrounded)Measuring junctions are elec-trically isolated from conductive sheaths and from referenceground.1.3 The values stated in inch-pound units are to be regardedas the standard. The values given in parentheses are forinformation
10、only.1.4 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 regulatory limitations prior to use.2. Referen
11、ced Documents2.1 ASTM Standards:3A 262 Practices for Detecting Susceptibility to Intergranu-lar Attack in Austenitic Stainless SteelsE3 Guide for Preparation of Metallographic SpecimensE45 Test Methods for Determining the Inclusion Contentof SteelE94 Guide for Radiographic ExaminationE112 Test Metho
12、ds for Determining Average Grain SizeE 165 Test Method for Liquid Penetrant ExaminationE 220 Test Method for Calibration of Thermocouples ByComparison TechniquesE 230 Specification and Temperature-Electromotive Force(EMF) Tables for Standardized ThermocouplesE 344 Terminology Relating to Thermometry
13、 and Hydrom-etryE 585/E 585M Specification for Compacted Mineral-Insulated, Metal-Sheathed, Base Metal ThermocoupleCableE 780 Test Method for Measuring the Insulation Resistanceof Mineral-Insulated, Metal-Sheathed Thermocouples andThermocouple Cable at Room TemperatureE 839 Test Methods for Sheathed
14、 Thermocouples andSheathed Thermocouple MaterialE 883 Guide for ReflectedLight PhotomicrographyE 1652 Specification for Magnesium Oxide and Aluminum1This specification is under the jurisdiction of ASTM Committee E20 onTemperature Measurement and is the direct responsibility of Subcommittee E20.04on
15、Thermocouples.Current edition approved Nov. 1, 2006. Published November 2006. Originallyapproved in 1964. Last previous edition approved in 2003 as E 235 03.2Style G and Style U measuring junctions were previously termed Class 1 andClass 2 measuring junctions respectively.3For referenced ASTM standa
16、rds, 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 Barr Harbor Drive, PO Box C700, West Conshohocken, PA
17、 19428-2959, United States.Oxide Powder and Crushable Insulators Used in theManufacture of Metal-Sheathed Platinum Resistance Ther-mometers, Base Metal Thermocouples, and Noble MetalThermocouples2.2 ANSI Standard:B46.1 Surface Texture42.3 American Welding Society Standard:A5.9 Specification for Corr
18、osion-Resisting Chromium andChromium-Nickel Steel-Welding Rods and Bare Elec-trodes53. Terminology3.1 The definitions given in Terminology E 344 shall applyto this specification.4. Ordering Information and Basis of Purchase4.1 The purchase order documents shall specify the follow-ing information:4.1
19、.1 The quantity, length, and nominal diameter of thesheathed thermocouple,4.1.2 The thermocouple type and tolerance on initial valuesof emf versus temperature, if other than standard (see Speci-fication E 230),4.1.3 The type of ceramic insulation required, either alu-mina (Al2O3) or magnesia (MgO),4
20、.1.4 The type of sheath material and other informationrequired (see 5.1.1),4.1.5 The style of thermocouple measuring junction,4.1.6 The type of dye-penetrant inspection procedure to beused, and4.1.7 Any deviations from this specification or the refer-enced specifications.5. Materials and Manufacture
21、5.1 All materials used shall be in accordance with thefollowing requirements:5.1.1 Sheath MaterialsThe sheath material used for thethermocouples described in this specification must meet therequirements of Specification E 585/E 585M. The purchaser ofthe thermocouples shall specify only the name of t
22、he material(seamless or welded), grade, optional requirements, test reportrequired, and ASTM designation.5.1.1.1 The inclusion level of the tubing shall be determinedby mounting a 1-in. minimum length of a longitudinal sectionof the tubing using Test Methods E45, Microscopical MethodA, for examinati
23、on. The inclusion level shall be less than 3 Athrough D, thin or heavy.5.1.1.2 The grain size of the tubing shall be determined bya specimen taken in accordance with Test Methods E112.Grain size shall be as specified in Table 2, or finer, asdetermined by the Comparison Procedure of Test MethodsE112.
24、5.1.1.3 Each lot of tubing used shall be sampled usingPracticesA 262 as follows. Samples shall be tested by PracticeA, and further tested as outlined by Table 1 in PracticesA 262,4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ans
25、i.org.5Available from American Welding Society (AWS), 550 NW LeJeune Rd.,Miami, FL 33126, http:/www.aws.org.TABLE 1 Dimensions for Style G and U Measuring JunctionsSheath Outside Diameter, A MinimumSheathWall,BMinimumInsulationThickness,CMinimumWireDiameter,DE, Tolerance F, ToleranceNominalTolerance
26、 min max min maxmin maxInches0.0400 0.0390 0.0415 0.006 0.004 0.005 0.006 0.020 0.004 0.0210.0625 0.0615 0.0640 0.009 0.005 0.010 0.009 0.032 0.005 0.0320.1250 0.1240 0.1265 0.012 0.012 0.020 0.012 0.062 0.012 0.0630.1875 0.1865 0.1890 0.020 0.022 0.031 0.020 0.093 0.022 0.0950.2500 0.2480 0.2520 0.
27、030 0.024 0.040 0.030 0.125 0.024 0.125Millimetres1.016 0.991 1.054 0.15 0.10 0.13 0.15 0.51 0.10 0.531.588 1.562 1.626 0.23 0.13 0.25 0.23 0.81 0.13 0.813.175 3.150 3.213 0.30 0.30 0.51 0.30 1.57 0.30 1.604.763 4.737 4.801 0.51 0.56 0.79 0.51 2.36 0.56 2.416.350 6.299 6.401 0.76 0.61 1.02 0.76 3.18
28、 0.61 3.18FIG. 1 Grounded Measuring Junction, Style GFIG. 2 Ungrounded Measuring Junction, Style UE235062where screening tests so indicate. Acceptance levels for thesetests shall be agreed upon between the purchaser and theproducer.5.1.2 ThermoelementThermoelements referred to in thisspecification s
29、hall be Type K or Type N with a tolerance oninitial values of emf versus temperature specified if other thanstandard.NOTE 1The purchaser may specify an alternative type of thermoele-ment as designated in Specification E 230 by indicating this deviation inthe ordering documents.5.1.3 InsulationThe in
30、sulating material shall be eithermagnesia (MgO) or alumina (Al2O3) and shall comply withSpecification E 1652 Type 1 material requirements:5.1.3.1 A certified analysis of the composition of the insu-lating material as supplied to the thermocouple manufacturershall be furnished to the purchaser. The t
31、hermocouple manu-facturer shall be responsible for maintaining the purity withinthe specified limits in the finished product.5.1.4 Welding RodFiller rod material used for welding onthe sheath or thermocouple closures shall comply with therequirements of AWS Specification A5.9 for the tubing mate-ria
32、l specified on the ordering documents.5.2 Processing:5.2.1 CleanlinessThe surface of the completed thermo-couples at the time of delivery shall be free of residuescontaining nuclear poisons, such as boron and cadmiumcompounds, or foreign substances, such as chlorine com-pounds, strong acids, bases,
33、oils, greases, or dust that couldbecome the source of corrosion or chemistry changes in aprimary coolant or heat-transfer medium. The use of com-pounds containing halogens is prohibited for final cleaning.Alcohol, or methyl isobutyl ketone may be used unlessotherwise specified.5.2.2 AnnealingThe she
34、ath of the finished thermocoupleshall be solution annealed and shall not be sensitized.6. Inspection and Test Methods6.1 General ProcedureInspect and approve all thermo-couples in accordance with the sampling procedures specifiedin this section and with inspection requirements stated hereinand in re
35、ferenced specifications. Acceptance of the sampleinspection results does not relieve the thermocouple manufac-turer of the responsibility that all thermocouples shall conformto all requirements of this specification and the latest issue ofthe referenced specifications.6.1.1 Acceptance of thermocoupl
36、es manufactured in accor-dance with this specification requires the satisfactory comple-tion of the general tests specified for all thermocouples and twoadditional tests on selected sample thermocouples.6.1.2 Select a sample thermocouple at random from each“lot” of thermocouples. A “lot” of thermoco
37、uples is defined asa group of not more than 15 thermocouples, manufacturedfrom the same materials in the same production run. Use asection of the sample thermocouple for the tests required in 6.7and 6.10.2. For the test in 6.10.2, fabricate a measuringjunction of the same style as that in the origin
38、al “lot.”Inspection and testing of this measuring junction, such as thatin 6.3, is not required.6.2 Insulation ResistancePerform the insulation resis-tance test in accordance with Test Method E 780. The electricalresistance between thermoelements and the sheath shall be inaccordance with Table 3, wi
39、th the applied voltage specified(both direct and reversed polarity) before closures on bothStyle G and Style U thermocouples for a thermocouple lengthnot exceeding 50 ft (15 m). This section also applies tocompleted Style G thermocouples in the respect that thepurchaser may select a sample thermocou
40、ple from each lot andremove the measuring junction to perform the test and exercisedue caution to prevent moisture pickup. If the thermocouplefails this test, reject the “lot” of thermocouples. This sectionalso applies to completed Style U thermocouples with respectto the insulation resistance betwe
41、en wires and sheath; in thiscase the purchaser may accept or reject thermocouples indi-vidually.6.3 Radiographic Inspection:6.3.1 Examine a length of the fabricated thermocoupleextending a minimum of 4 in. (102 mm) from the measuringjunction, including the weld closure, by radiography to deter-mine
42、that the dimensions are in conformance with Table 1 andthat any defects do not exceed the requirements in 6.3.1.1 and6.3.1.2:6.3.1.1 Cracks, voids, or inclusions in the sheath wallgreater than 15 % of the sheath wall thickness, or 0.002 in.(0.05 mm), whichever is greater,6.3.1.2 Cracks, voids, inclu
43、sions, discontinuities, or localreduction of the conductors, insulation, or sheath diameter in ornear the thermal junction greater than 0.002 in. (0.05 mm).6.3.2 Radiograph the thermocouple in two directions 90apart and perpendicular to the thermocouple axis.6.3.3 Perform the radiography in accordan
44、ce with GuideE94, at a sensitivity level at 2-1T.TABLE 2 Maximum Grain SizesSheath Outside Diameter, in. (mm) Maximum0.0400 (1.016) 60.0625 (1.588)0.1250 (3.175)0.1875 (4.763)0.2500 (6.35)5TABLE 3 Insulation ResistanceSheath Outside Diameter, in. (mm)Applied D-C Voltage(Both Direct andReversed Polar
45、ity)Required MinimumInsulation Resistance atRoom Temperature, MV0.040 to 0.058 (1.0 to 1.48) 50 10000.059 to 0.250 (1.49 to 6.35) 500 5000E2350636.3.4 The use of nonfilm techniques is permitted.6.3.5 Supply the radiograph to the purchaser with appropri-ate means to identify the thermocouple with its
46、 radiograph.6.4 Sheath Integrity:6.4.1 Inspect in accordance with Test Methods E 839,Sheath Integrity-Mass Spectrometer Method.6.5 Surface FinishThe surface of the sheaths of allthermocouples in the completed condition shall have a brightappearance with a finish no rougher than 32 rms in. Make avisu
47、al comparison with roughness standards in accordancewith ANSI B46.1.6.6 Surface DefectsThere shall be no cracks, seams,holes, or other defects on the surface of the sheath of thefinished thermocouples when tested in accordance with Proce-dureA2 or B3 of Test Method E 165.Any indication of cracks,sea
48、ms, holes, or other defects shall be cause for rejection.6.7 Metallurgical Structure of the Sheath:6.7.1 Conduct tests on the austenitic stainless-steel sheathon a section of the sample thermocouple selected in accordancewith 6.1. Close wind the selected section of the sheath threefull turns on a ma
49、ndrel twice the sheath diameter. Cut thecenter turn from the section and mount for metallographicexamination. Prepare the metallographic specimen in accor-dance with Practice E3. The sheath material at the mountedspecimen shall not contain evidence of cracks or localized wallthinning when longitudinally sectioned and examined bynormal metallographicb practice at a magnification of 200 to500 3 in accordance with Guide E 883.6.7.2 Mount a transverse section from the sample thermo-couple, which has not been bent, and examine for grain size,defects, and grain bound
