1、Designation: E 608/E 608M 06Standard Specification forMineral-Insulated, Metal-Sheathed Base MetalThermocouples1This standard is issued under the fixed designation E 608/E 608M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the y
2、ear of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification covers the requirements for mineral-insulated, metal-sheathed base metal thermocouples for
3、indus-trial or high-reliability applications. It applies specifically tothermocouples fabricated from sheathed thermocouple mate-rial in accordance with Specification E 585/E 585M. Provi-sions are made for selecting thermoelements, insulation, andsheath material, and measuring junction configuration
4、, thermo-couple assembly length, and the type of transition or termina-tion.1.2 This specification also includes provisions for qualityassurance or verification program requirements, or both, as apurchasers option.1.3 The values stated in SI (metric) units or inch-poundunits may be regarded separate
5、ly as the standard. The valuesstated in each system are not the exact equivalents, and eachsystem shall be used independently of the other.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
6、 establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E 165 Test Method for Liquid Penetrant ExaminationE 220 Test Method for Calibration of Thermocouples ByComparison TechniquesE 230 Spe
7、cification and Temperature-Electromotive Force(EMF) Tables for Standardized ThermocouplesE 344 Terminology Relating to Thermometry and Hydrom-etryE 585/E 585M Specification for Compacted Mineral-Insulated, Metal-Sheathed, Base Metal ThermocoupleCableE 780 Test Method for Measuring the Insulation Res
8、istanceof Mineral-Insulated, Metal-Sheathed Thermocouples andThermocouple Cable at Room TemperatureE 839 Test Methods for Sheathed Thermocouples andSheathed Thermocouple Material2.2 AWS Standards:3A5.9 Specification for Corrosion-Resisting Chromium andChromium-Nickel Steel Welding Rods and Bare Elec
9、-trodesA5.14 Specification for Nickel and Nickel-Alloy BareWelding Rods and Electrodes3. Terminology3.1 DefinitionsThe definitions given in TerminologyE 344 shall apply to this specification.3.2 Definitions of Terms Specific to This Standard:3.2.1 common ungrounded junction, nmeasuring junc-tions wi
10、thin the same multi-pair thermocouple that are electri-cally isolated from the sheath but electrically connected to eachother.3.2.2 isolated ungrounded junction, nmeasuring junctionswithin the same multi-pair thermocouple that are electricallyisolated from the sheath and electrically isolated from e
11、achother.3.2.3 lot, na quantity of thermocouples manufacturedfrom the same continuous length of mineral-insulated, metal-sheathed thermocouple cable.3.2.4 sheathed thermocouple material, na combination oftwo or more continuous thermoelements embedded in ceramicinsulation compacted within a metal pro
12、tecting sheath.4. Significance and Use4.1 This specification describes the physical requirements ofmineral-insulated, metal-sheathed base metal thermocouplesand establishes suitable test criteria for them.1This specification is under the jurisdiction of ASTM Committee E20 onTemperature Measurement a
13、nd is the direct responsibility of Subcommittee E20.04on Thermocouples.Current edition approved Nov. 1, 2006. Published November 2006. Originallyapproved in 1977. Last previous edition approved in 2004 as E 608/E 608M -00 (2004).2For referenced ASTM standards, visit the ASTM website, www.astm.org, o
14、rcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American Welding Society (AWS), 550 NW LeJeune Rd.,Miami, FL 33126, http:/www.aws.org.1Copyright ASTM International,
15、 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.2 Standardized dimensional requirements, including ac-ceptable allowances for manufacturing variations, are given.4.3 Aset of standard tests to be applied to all thermocouplescovered by this specification are desc
16、ribed together with agroup of optional tests from which applicable additionalrequirements may be selected.4.4 WarningUsers should be aware that certain charac-teristics of thermocouples might change with time and use. Ifa thermocouples designed shipping, storage, installation, oroperating temperatur
17、e has been exceeded, the thermocouplesmoisture seal may have been compromised and may no longeradequately prevent the deleterious intrusion of water vapor.Consequently, the thermocouples condition established by testat time of manufacture may not apply later during an extendedperiod of use, and rete
18、sting may become necessary. In addition,inhomogeneities can develop in thermoelements because ofexposure to temperature, even in cases where maximumexposure temperatures have been lower than the suggestedupper temperature limits of Table 1. For this reason, calibrationof thermocouples destined for d
19、elivery to a customer is notrecommended (see S6.1). Because the EMF indication of anythermocouple depends upon the condition of the thermoele-ments along their entire length, as well as the temperatureprofile pattern in the region of any inhomogeneity, the EMFoutput of a used thermocouple will be un
20、ique to its installation.Because temperature profiles in calibration equipment areunlikely to duplicate those of the installation, removal of a usedthermocouple to a separate apparatus for calibration is notrecommended. Instead, in situ calibration by comparison to asimilar thermocouple known to be
21、good is often recommended.5. Ordering Information5.1 The purchase documents shall specify the followingoptions:5.1.1 The type and quantity of thermoelement pairs, and thetolerances, if other than standard (see 6.4 and 6.5).5.2 The nominal sheath diameter. See Table 1 or Specifica-tion E 585/E 585M f
22、or preferred nominal diameters.5.3 The type of ceramic insulation (MgO or Al2O3). SeeSpecification E 585/E 585M.5.4 The type of sheath material. See Table 2 or SpecificationE 585/E 585M.5.5 The type of measuring junction, Style G (grounded) orStyle U (ungrounded). See Figs. 1 and 2. If more than one
23、 pairof thermoelements is specified, Style U is further subdividedinto Style CU (common ungrounded) and Style IU (isolatedungrounded).4Do not specify Style G grounded junctions withType T thermoelements (see 6.3.2).5.6 The quantity, length, and length tolerance of eachthermocouple. See Figs. 3-6 for
24、 examples.5.7 The type and configuration of connection head, connec-tor, transition piece, or termination, and moisture seal requiredon the end opposite the measuring junction. See Figs. 3-6 forexamples. The minimum and maximum intended operatingtemperature of the connection head, transition, or ter
25、mination,and moisture seal should be specified (6.6). For thermocoupleswith insulated wire attached (Fig. 6) and Style U junctions,state the minimum acceptable insulation resistance (6.7).5.8 Optional supplementary testing requirements and testsample rate (8.2).5.9 The quality assurance or verificat
26、ion program require-ments, or both, including material traceability if required. SeeAppendix X1.5.10 Any deviations from this specification or the refer-enced specifications.5.11 Shipping method and straightness criteria, if required(see 10.2).54Style G, Style U, Style CU, and Style IU measuring jun
27、ctions were previouslytermed Class 1, Class 2, Class 2A, and Class 2B measuring junctions respectively.5“Manual on the Use of Thermocouples in Temperature Measurement,” ASTMManual 12, ASTM International, 1993.TABLE 1 Suggested Upper Temperature Limits for Sheathed ThermocouplesNOTE 1This table gives
28、 the suggested upper temperature limits for the various thermocouples in several common sheath sizes. It does not take intoaccount environmental temperature limitations of the sheath material itself, nor does it address compatibility considerations between the thermoelementmaterials and the sheath c
29、ontaining them. The actual maximum practical temperature in a particular situation will generally be limited to the lowesttemperature among the several factors involved. The purchaser should consult ASTM Manual 125and other literature sources for further applicationsinformation.NOTE 2The temperature
30、 limits given here are intended only as a guide to the purchaser and should not be taken as absolute values nor as guaranteesof satisfactory life or performance. These types and sizes are sometimes used at temperatures above the given limits, but usually at the expense of stabilityor life, or both.
31、In other instances, it may be necessary to reduce the given limits in order to achieve adequate service.Upper Temperature Limit for Various Sheath Diameters C FNominal Sheath Diameter Thermocouple Typemm in. T J E K, N0.5 0.020 260 (500) 260 (500) 300 (570) 700 (1290). . . 0.032 260 (500) 260 (500)
32、300 (570) 700 (1290)1.0 0.040 260 (500) 260 (500) 300 (570) 700 (1290)1.5 0.062 260 (500) 440 (825) 510 (950) 920 (1690)2.0 . . . 260 (500) 440 (825) 510 (950) 920 (1690). . . 0.093 260 (500) 480 (900) 580 (1075) 1000 (1830)3.0 0.125 315 (600) 520 (970) 650 (1200) 1070 (1960)4.5 0.188 370 (700) 620
33、(1150) 730 (1350) 1150 (2100)6.0 0.250 370 (700) 720 (1330) 820 (1510) 1150 (2100)8.0 0.375 370 (700) 720 (1330) 820 (1510) 1150 (2100)E 608/E 608M 0625.12 The minimum and maximum intended operating tem-peratures of the thermocouple (see S6.1).6. General Requirements6.1 TaggingDuring fabrication, ea
34、ch thermocouple shallbe tagged with a unique identification number to keep trace-ability to materials and test data. The producers standardtagging method may be used.6.2 Welding RodFiller material used for welding or plug-ging the end closure shall comply with Table 2.6.3 Measuring Junctions:6.3.1 T
35、he end closure shall be impervious to gases andliquids. There shall be no cracks, holes, or void defects thatpenetrate through the metal wall. Any mineral oxide removedduring fabrication of the measuring junction shall be replacedwith dry oxide of the same type that is in accordance with thepurity r
36、equirements of Specification E 585/E 585M. Style Umeasuring junctions shall be fabricated by welding the ther-moelements without filler metal or flux.6.3.2 The measuring junction end closures shall be sealwelded. The use of plugs or filler metals is optional. Style G(grounded) measuring junctions on
37、 Type T thermocouples areexcluded from this specification because of the problemsassociated with welding the copper thermoelement.6.4 Standard TolerancesSheathed thermocouples fabri-cated to this specification shall conform to the standardtolerances (see Table 3) in accordance with SpecificationE 23
38、0, unless otherwise specified.6.5 Special TolerancesIf specified in the purchase docu-ment, the special tolerances (see Table 3) in accordance withSpecification E 230 shall apply.6.6 TerminationThe sheathed thermocouples shall be ter-minated at the end opposite the measuring junction in a mannerspec
39、ified by the purchaser. All exposed MgO or Al2O3shall besealed from moisture to keep the insulation dry.All connectors,connection heads, or transitions shall include a positive methodof preventing strain on the thermoelements emerging from thesheathed material. All transitional wire connections shal
40、l bebrazed or welded. The moisture seal and termination (see Figs.3-6) shall be compatible with their intended installation andoperating conditions (see 5.7).6.7 Room Temperature Insulation Resistance (Style UJunctions)The minimum room temperature electrical insula-tion resistance between the thermo
41、element pairs and the sheathfor sheathed thermocouples with Style U junctions shall be asspecified in Table 4 for the dc test voltage noted. In addition,for Style IU (isolated ungrounded) junctions, the minimumelectrical insulation specified in Table 4 shall also applybetween thermoelement pairs. Th
42、e minimum insulation valueshall be negotiated between the purchaser and the producer forFig. 6 assemblies with purchaser-specified insulated thermo-couple extension wire or other devices attached. For Fig. 5assemblies, the minimum insulation resistance values of Table4 shall be imposed before the th
43、ermocouple is terminated(when it is like Fig. 4). The insulation resistance shall be testedin accordance with Test Method E 780.6.8 Sheath ConditionThe surface of the completed ther-mocouples shall be visually clean, dry, and oxide-free.6.9 The tests specified in 8.1 are required to determine if the
44、specification requirements have been met. Additional optionalrequirements are listed in the Supplementary Requirementssection, and may be included in the purchase order require-ments, as desired by the purchaser.6.10 All testing and inspection shall be performed in accor-dance with Test Methods E 83
45、9 unless otherwise indicated.7. Measuring Junction Configuration7.1 The measuring junction configurations are shown incross section in Figs. 1 and 2. The tip shape is optional as longas the dimensional requirements are maintained. The preferrednominal sheath diameters are listed in Table 1 or Specif
46、icationE 585/E 585M. The measuring junction dimensional require-ments are as follows:7.1.1 Dimension A, End-Closure Diameter, Styles U andGThe end-closure maximum diameter shall be no larger thanthe nominal sheath diameter plus a weld allowance of 0.05 mm(0.002 in.) or 2 % of the nominal sheath diam
47、eter, whichever islarger. Localized reduction of the end-closure diameter causedby weld shrinkage shall not exceed 0.05 mm (0.002 in.) or 2 %of the nominal sheath diameter, whichever is larger. Thisexpanded end-closure diametral tolerance shall apply from thetip of the end closure over a length not
48、exceeding 23 thenominal sheath diameter.7.1.2 Dimensions Controlled by Supplementary Radio-graphic Inspection (see Supplementary Requirement S1):7.1.2.1 Dimension B, Measuring Junction LengthThemeasuring junction length on Style CU and Style IU junctionsshall be a minimum of one and a maximum of fou
49、r thermo-element diameters long.7.1.2.2 Dimension C, Minimum Measuring Junction Insula-tion Thickness, Radial DimensionThe minimum insulationthickness on Style CU and IU junctions, as measured from thejunction to the sheath in a radial direction, shall be 5 % of thenominal sheath diameter.7.1.2.3 Dimension D, Minimum Material Thickness, Style Gand Style U JunctionsThe thickness at any point of theend-closure weld interface shall be not less than 10 % of thenominal sheath diameter. Wall thinning caused by weldingshall be limited to the minimum material sheat
