ASTM E608/E608M-00(2004)
(Specification)Standard Specification for Mineral-Insulated, Metal-Sheathed Base Metal Thermocouples
Standard Specification for Mineral-Insulated, Metal-Sheathed Base Metal Thermocouples
SCOPE
1.1 This specification covers the requirements for mineral-insulated, metal-sheathed base metal thermocouples for industrial or high-reliability applications. It applies specifically to thermocouples fabricated from sheathed thermocouple material in accordance with Specification E 585/E 585M. Provisions are made for selecting thermoelements, insulation, and sheath material, and measuring junction configuration, thermocouple assembly length, and the type of transition or termination.
1.2 This specification also includes provisions for quality assurance or verification program requirements, or both, as a purchaser's option.
1.3 The values stated in SI (metric) units or inch-pound units may be regarded separately as the standard. The values stated in each system are not the exact equivalents, and each system shall be used independently of the other.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
Designation: E 608/E 608M – 00 (Reapproved 2004)
Standard Specification for
Mineral-Insulated, Metal-Sheathed Base Metal
Thermocouples
This standard is issued under the fixed designation E 608/E 608M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year 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. Scope E 220 Test Method for Calibration of Thermocouples by
Comparison Techniques
1.1 This specification covers the requirements for mineral-
E 230 Specification and Temperature-Electromotive Force
insulated, metal-sheathed base metal thermocouples for indus-
(EMF) Tables for Standardized Thermocouples
trial or high-reliability applications. It applies specifically to
E 344 Terminology Relating to Thermometry and Hydrom-
thermocouples fabricated from sheathed thermocouple mate-
etry
rial in accordance with Specification E 585/E 585M. Provi-
E 585/E 585M Specification for Compacted Mineral-
sions are made for selecting thermoelements, insulation, and
Insulated, Metal-Sheathed, Base Metal Thermocouple
sheath material, and measuring junction configuration, thermo-
Cable
couple assembly length, and the type of transition or termina-
E 780 Test Method for Measuring the Insulation Resistance
tion.
of Sheathed Thermocouple Material at Room Temperature
1.2 This specification also includes provisions for quality
E 839 Test Methods for Sheathed Thermocouples and
assurance or verification program requirements, or both, as a
Sheathed Thermocouple Material
purchaser’s option.
2.2 AWS Standards:
1.3 The values stated in SI (metric) units or inch-pound
A5.9 Specification for Corrosion-Resisting Chromium and
units may be regarded separately as the standard. The values
Chromium-Nickel Steel Welding Rods and Bare Elec-
stated in each system are not the exact equivalents, and each
trodes
system shall be used independently of the other.
A5.14 Specification for Nickel and Nickel-Alloy Bare
1.4 This standard does not purport to address all of the
Welding Rods and Electrodes
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
3. Terminology
priate safety and health practices and determine the applica-
3.1 Definitions—The definitions given in Terminology
bility of regulatory limitations prior to use.
E 344 shall apply to this specification.
2. Referenced Documents 3.2 Definitions of Terms Specific to This Standard:
3.2.1 common ungrounded junction, n—measuring junc-
2.1 ASTM Standards:
tions within the same multi-pair thermocouple that are electri-
E 94 Guide for Radiographic Examination
callyisolatedfromthesheathbutelectricallyconnectedtoeach
E 142 Method for Controlling Quality of Radiographic
3 other.
Testing
3.2.2 isolated ungrounded junction, n—measuringjunctions
E 165 Test Method for Liquid Penetrant Examination
within the same multi-pair thermocouple that are electrically
isolated from the sheath and electrically isolated from each
This specification is under the jurisdiction of ASTM Committee E20 on other.
Temperature Measurement and is the direct responsibility of Subcommittee E20.04
3.2.3 lot, n—a quantity of thermocouples manufactured
on Thermocouples.
from the same continuous length of mineral-insulated, metal-
Current edition approved May 1, 2004. Published June 2004. Originally
sheathed thermocouple cable.
approved in 1977. Last previous edition approved in 2000 as E 608/E 608M - 00.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. Available from The American Welding Society (AWS), 550 NW LeJeune Rd.,
Withdrawn. Miami, FL 33126.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
E 608/E 608M – 00 (2004)
TABLE 1 Suggested Upper Temperature Limits for Sheathed Thermocouples
NOTE 1—This table gives the suggested upper temperature limits for the various thermocouples in several common sheath sizes. It does not take into
account environmental temperature limitations of the sheath material itself, nor does it address compatibility considerations between the thermoelement
materials and the sheath containing them. The actual maximum practical temperature in a particular situation will generally be limited to the lowest
temperature among the several factors involved. The purchaser should consult ASTM Manual 12 and other literature sources for further applications
information.
NOTE 2—The temperature limits given here are intended only as a guide to the purchaser and should not be taken as absolute values nor as guarantees
ofsatisfactorylifeorperformance.Thesetypesandsizesaresometimesusedattemperaturesabovethegivenlimits,butusuallyattheexpenseofstability
or life, or both. 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 [°F]
Nominal Sheath Diameter Thermocouple Type
mm in. T J E K, N
0.5 0.020 260 (500) 260 (500) 300 (570) 700 (1290)
. . . 0.032 260 (500) 260 (500) 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 (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)
3.2.4 sheathed thermocouple material, n—a combination of recommended. Instead, in situ calibration by comparison to a
two or more continuous thermoelements embedded in ceramic similarthermocoupleknowntobegoodisoftenrecommended.
insulation compacted within a metal protecting sheath.
5. Ordering Information
4. Significance and Use
5.1 The purchase documents shall specify the following
4.1 Thisspecificationdescribesthephysicalrequirementsof
options:
mineral-insulated, metal-sheathed base metal thermocouples
5.1.1 The type and quantity of thermoelement pairs, and the
and establishes suitable test criteria for them.
tolerances, if other than standard (see 6.4 and 6.5).
4.2 Standardized dimensional requirements, including ac-
5.2 The nominal sheath diameter. See Table 1 or Specifica-
ceptable allowances for manufacturing variations, are given.
tion E 585/E 585M for preferred nominal diameters.
4.3 Asetofstandardteststobeappliedtoallthermocouples
5.3 The type of ceramic insulation (MgO or Al O ). See
2 3
covered by this specification are described together with a
Specification E 585/E 585M.
group of optional tests from which applicable additional
5.4 Thetypeofsheathmaterial.SeeTable2orSpecification
requirements may be selected.
E 585/E 585M.
4.4 Warning—Users should be aware that certain charac-
5.5 The type of measuring junction, Class 1 (grounded) or
teristics of thermocouples might change with time and use. If
Class 2 (ungrounded). See Figs. 1 and 2. If more than one pair
a thermocouple’s designed shipping, storage, installation, or
of thermoelements is specified, Class 2 is further subdivided
operating temperature has been exceeded, the thermocouple’s
into Class 2A (common ungrounded) and Class 2B (isolated
moisture seal may have been compromised and may no longer
ungrounded). Do not specify Class 1 grounded junctions with
adequately prevent the deleterious intrusion of water vapor.
Type T thermoelements (see 6.3.2).
Consequently, the thermocouple’s condition established by test
5.6 The quantity, length, and length tolerance of each
at time of manufacture may not apply later during an extended
thermocouple. See Figs. 3-6 for examples.
periodofuse,andretestingmaybecomenecessary.Inaddition,
5.7 The type and configuration of connection head, connec-
inhomogeneities can develop in thermoelements because of
tor, transition piece, or termination, and moisture seal required
exposure to temperature, even in cases where maximum
on the end opposite the measuring junction. See Figs. 3-6 for
exposure temperatures have been lower than the suggested
examples. The minimum and maximum intended operating
uppertemperaturelimitsofTable1.Forthisreason,calibration
temperature of the connection head, transition, or termination,
of thermocouples destined for delivery to a customer is not
and moisture seal should be specified (6.6). For thermocouples
recommended (see S6.1). Because the EMF indication of any
with insulated wire attached (Fig. 6) and Class 2 junctions,
thermocouple depends upon the condition of the thermoele-
state the minimum acceptable insulation resistance (6.7).
ments along their entire length, as well as the temperature
5.8 Optional supplementary testing requirements and test
profile pattern in the region of any inhomogeneity, the EMF
sample rate (8.2).
outputofausedthermocouplewillbeuniquetoitsinstallation.
Because temperature profiles in calibration equipment are 5.9 The quality assurance or verification program require-
unlikelytoduplicatethoseoftheinstallation,removalofaused ments, or both, including material traceability if required. See
thermocouple to a separate apparatus for calibration is not Appendix X1.
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
E 608/E 608M – 00 (2004)
TABLE 2 Weld Closure Filler Metal
sheathed material. All transitional wire connections shall be
AWS brazed or welded. The moisture seal and termination (see Figs.
Weld Rod AWS
Sheath Material Specifica-
3-6) shall be compatible with their intended installation and
Type
tion
operating conditions (see 5.7).
Austenitic Stainless Steels
6.7 Room Temperature Insulation Resistance (Class 2
TP 304 ER 308 A5.9
Junctions)—The minimum room temperature electrical insula-
TP 304L ER 308L A5.9
TP 310 ER 310 A5.9
tion resistance between the thermoelement pairs and the sheath
TP 316 ER 316 A5.9
for sheathed thermocouples with Class 2 junctions shall be as
TP 316L ER 316L A5.9
specified in Table 4 for the dc test voltage noted. In addition,
TP 317 ER 317 A5.9
TP 321 ER 347 A5.9
for Class 2B (isolated ungrounded) junctions, the minimum
TP 347 ER 347 A5.9
electrical insulation specified in Table 4 shall also apply
TP 348 ER 348 A5.9
Nickel-chromium-iron alloy ER NiCrFe-5 A5.14 between thermoelement pairs. The minimum insulation value
shall be negotiated between the purchaser and the producer for
Fig. 6 assemblies with purchaser-specified insulated thermo-
couple extension wire or other devices attached. For Fig. 5
5.10 Any deviations from this specification or the refer-
assemblies, the minimum insulation resistance values of Table
enced specifications.
4 shall be imposed before the thermocouple is terminated
5.11 Shipping method and straightness criteria, if required
(when it is like Fig. 4).The insulation resistance shall be tested
(see 10.2).
in accordance with Test Method E 780.
5.12 The minimum and maximum intended operating tem-
6.8 Sheath Condition—The surface of the completed ther-
peratures of the thermocouple (see S6.1).
mocouples shall be visually clean, dry, and oxide-free.
6. General Requirements
6.9 The tests specified in 8.1 are required to determine if the
specification requirements have been met. Additional optional
6.1 Tagging—During fabrication, each thermocouple shall
requirements are listed in the Supplementary Requirements
be tagged with a unique identification number to keep trace-
section, and may be included in the purchase order require-
ability to materials and test data. The producer’s standard
ments, as desired by the purchaser.
tagging method may be used.
6.10 All testing and inspection shall be performed in accor-
6.2 Welding Rod—Filler material used for welding or plug-
dance with Test Methods E 839 unless otherwise indicated.
ging the end closure shall comply with Table 2.
6.3 Measuring Junctions:
7. Measuring Junction Configuration
6.3.1 The end closure shall be impervious to gases and
7.1 The measuring junction configurations are shown in
liquids. There shall be no cracks, holes, or void defects that
cross section in Figs. 1 and 2. The tip shape is optional as long
penetrate through the metal wall. Any mineral oxide removed
as the dimensional requirements are maintained. The preferred
during fabrication of the measuring junction shall be replaced
nominal sheath diameters are listed in Table 1 or Specification
with dry oxide of the same type that is in accordance with the
E 585/E 585M. The measuring junction dimensional require-
purity requirements of Specification E 585/E 585M. Class 2
ments are as follows:
measuring junctions shall be fabricated by welding the ther-
7.1.1 Dimension A, End-Closure Diameter, Classes 1 and
moelements without filler metal or flux.
2—The end-closure maximum diameter shall be no larger than
6.3.2 The measuring junction end closures shall be seal
thenominalsheathdiameterplusaweldallowanceof0.05mm
welded. The use of plugs or filler metals is optional. Class 1
(0.002 in.) or 2 % of the nominal sheath diameter, whichever is
(grounded) measuring junctions on Type T thermocouples are
larger. Localized reduction of the end-closure diameter caused
excluded from this specification because of the problems
by weld shrinkage shall not exceed 0.05 mm (0.002 in.) or 2 %
associated with welding the copper thermoelement.
of the nominal sheath diameter, whichever is larger. This
6.4 Standard Tolerances—Sheathed thermocouples fabri-
expanded end-closure diametral tolerance shall apply from the
cated to this specification shall conform to the standard
tip of the end closure over a length not exceeding 23 the
tolerances (see Table 3) in accordance with Specification
nominal sheath diameter.
E 230, unless otherwise specified.
7.1.2 Dimensions Controlled by Supplementary Radio-
6.5 Special Tolerances—If specified in the purchase docu-
graphic Inspection (see Supplementary Requirement S1):
ment, the special tolerances (see Table 3) in accordance with
7.1.2.1 Dimension B, Measuring Junction Length—The
Specification E 230 shall apply.
measuring junction length on Class 2Aand Class 2B junctions
6.6 Termination—The sheathed thermocouples shall be ter-
shall be a minimum of one and a maxim
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