ASTM E839-11(2016)
(Test Method)Standard Test Methods for Sheathed Thermocouples and Sheathed Thermocouple Cable
Standard Test Methods for Sheathed Thermocouples and Sheathed Thermocouple Cable
SIGNIFICANCE AND USE
5.1 This standard provides a description of test methods used in other ASTM specifications to establish certain acceptable limits for characteristics of thermocouple assemblies and thermocouple cable. These test methods define how those characteristics shall be determined.
5.2 The usefulness and purpose of the included tests are given for the category of tests.
5.3 Warning—Users should be aware that certain characteristics of thermocouples might change with time and use. If a thermocouple’s designed shipping, storage, installation, or operating temperature has been exceeded, that thermocouple’s moisture seal may have been compromised and may no longer adequately prevent the deleterious intrusion of water vapor. Consequently, the thermocouple’s condition established by test at the time of manufacture may not apply later. In addition, inhomogeneities can develop in thermoelements because of exposure to higher temperatures, even in cases where maximum exposure temperatures have been lower than the suggested upper use temperature limits specified in Table 1 of Specification E608/E608M. For this reason, calibration of thermocouples destined for delivery to a customer is not recommended. Because the EMF indication of any thermocouple depends upon the condition of the thermoelements along their entire length, as well as the temperature profile pattern in the region of any inhomogeneity, the EMF output of a used thermocouple will be unique to its installation. Because temperature profiles in calibration equipment are unlikely to duplicate those of the installation, removal of a used thermocouple to a separate apparatus for calibration is not recommended. Instead, in situ calibration by comparison to a similar thermocouple known to be good is often recommended.
SCOPE
1.1 This document lists methods for testing Mineral-Insulated, Metal-Sheathed (MIMS) thermocouple assemblies and thermocouple cable, but does not require that any of these tests be performed nor does it state criteria for acceptance. The acceptance criteria are given in other ASTM standard specifications that impose this testing for those thermocouples and cable. Examples from ASTM thermocouple specifications for acceptance criteria are given for many of the tests. These tabulated values are not necessarily those that would be required to meet these tests, but are included as examples only.
1.2 These tests are intended to support quality control and to evaluate the suitability of sheathed thermocouple cable or assemblies for specific applications. Some alternative test methods to obtain the same information are given, since in a given situation, an alternative test method may be more practical. Service conditions are widely variable, so it is unlikely that all the tests described will be appropriate for a given thermocouple application. A brief statement is made following each test description to indicate when it might be used.
1.3 The tests described herein include test methods to measure the following properties of sheathed thermocouple material and assemblies.
1.3.1 Insulation Properties:
1.3.1.1 Compaction—direct method, absorption method, and tension method.
1.3.1.2 Thickness.
1.3.1.3 Resistance—at room temperature and at elevated temperature.
1.3.2 Sheath Properties:
1.3.2.1 Integrity—two water test methods and mass spectrometer.
1.3.2.2 Dimensions—length, diameter, and roundness.
1.3.2.3 Wall thickness.
1.3.2.4 Surface—gross visual, finish, defect detection by dye penetrant, and cold-lap detection by tension test.
1.3.2.5 Metallurgical structure.
1.3.2.6 Ductility—bend test and tension test.
1.3.3 Thermoelement Properties:
1.3.3.1 Calibration.
1.3.3.2 Homogeneity.
1.3.3.3 Drift.
1.3.3.4 Thermoelement diameter, roundness, and surface appearance.
1.3.3.5 Thermoelement spacing.
1.3.3.6 Thermoelement ductility.
1.3.3.7 Metallurgical structure.
1.3.4 Thermocouple Assembly Prop...
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Designation: E839 − 11 (Reapproved 2016)
Standard Test Methods for
Sheathed Thermocouples and Sheathed Thermocouple
Cable
This standard is issued under the fixed designation E839; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.3.2.4 Surface—gross visual, finish, defect detection by
dye penetrant, and cold-lap detection by tension test.
1.1 This document lists methods for testing Mineral-
1.3.2.5 Metallurgical structure.
Insulated, Metal-Sheathed (MIMS) thermocouple assemblies
1.3.2.6 Ductility—bend test and tension test.
and thermocouple cable, but does not require that any of these
1.3.3 Thermoelement Properties:
testsbeperformednordoesitstatecriteriaforacceptance.The
1.3.3.1 Calibration.
acceptance criteria are given in other ASTM standard specifi-
1.3.3.2 Homogeneity.
cations that impose this testing for those thermocouples and
1.3.3.3 Drift.
cable. Examples from ASTM thermocouple specifications for
1.3.3.4 Thermoelement diameter, roundness, and surface
acceptance criteria are given for many of the tests. These
appearance.
tabulated values are not necessarily those that would be
1.3.3.5 Thermoelement spacing.
requiredtomeetthesetests,butareincludedasexamplesonly.
1.3.3.6 Thermoelement ductility.
1.2 Thesetestsareintendedtosupportqualitycontrolandto
1.3.3.7 Metallurgical structure.
evaluate the suitability of sheathed thermocouple cable or
1.3.4 Thermocouple Assembly Properties:
assemblies for specific applications. Some alternative test
1.3.4.1 Dimensions—length, diameter, and roundness.
methods to obtain the same information are given, since in a
1.3.4.2 Surface—gross visual, finish, reference junction end
given situation, an alternative test method may be more
moisture seal, and defect detection by dye penetrant.
practical. Service conditions are widely variable, so it is
1.3.4.3 Electrical—continuity, loop resistance, and connec-
unlikely that all the tests described will be appropriate for a
tor polarity.
given thermocouple application. A brief statement is made
1.3.4.4 Radiographic inspection.
following each test description to indicate when it might be
1.3.4.5 Thermoelement diameter.
used.
1.3.4.6 Thermal response time.
1.3.4.7 Thermal cycle.
1.3 The tests described herein include test methods to
measure the following properties of sheathed thermocouple
1.4 The values stated in either SI units or inch-pound units
material and assemblies.
are to be regarded separately as standard. The values stated in
1.3.1 Insulation Properties:
each system may not be exact equivalents; therefore, each
1.3.1.1 Compaction—direct method, absorption method,
system shall be used independently of the other. Combining
and tension method.
values from the two systems may result in non-conformance
1.3.1.2 Thickness.
with the standard.
1.3.1.3 Resistance—at room temperature and at elevated
1.5 This standard does not purport to address all of the
temperature.
safety concerns, if any, associated with its use. It is the
1.3.2 Sheath Properties:
responsibility of the user of this standard to establish appro-
1.3.2.1 Integrity—two water test methods and mass spec-
priate safety and health practices and determine the applica-
trometer.
bility of regulatory limitations prior to use.
1.3.2.2 Dimensions—length, diameter, and roundness.
1.3.2.3 Wall thickness.
2. Referenced Documents
2.1 ASTM Standards:
E3Guide for Preparation of Metallographic Specimens
These test methods are under the jurisdiction of ASTM Committee E20 on
Temperature Measurement and is the direct responsibility of Subcommittee E20.04
on Thermocouples. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Nov. 1, 2016. Published January 2016. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1989. Last previous edition approved in 2011 as E839–11. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/E0839-11R16. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E839 − 11 (2016)
E94Guide for Radiographic Examination 3.2 Definitions of Terms Specific to This Standard:
E112Test Methods for Determining Average Grain Size 3.2.1 bulk cable, n—a single length of thermocouple cable
E165Practice for Liquid Penetrant Examination for General
produced from the same raw material lots after completion of
Industry fabrication.
E177Practice for Use of the Terms Precision and Bias in
3.2.2 cable lot, n—a quantity of finished mineral–insulated,
ASTM Test Methods
metal-sheathed thermocouple cable manufactured from tubing
E207TestMethodforThermalEMFTestofSingleThermo-
or other sheath material from the same heat, wire from the
element Materials by Comparison with a Reference Ther-
same spool and heat, and insulation from the same batch, then
moelement of Similar EMF-Temperature Properties
assembled and processed together under controlled production
E220Test Method for Calibration of Thermocouples By
conditions to the required final outside diameter.
Comparison Techniques
3.2.3 cold-lap, n—sheath surface defect where the sheath
E230Specification and Temperature-Electromotive Force
surface has been galled and torn by a drawing die and the torn
(EMF) Tables for Standardized Thermocouples
surface smoothed by a subsequent diameter reduction.
E235Specification for Thermocouples, Sheathed, Type K
3.2.4 insulation compaction density, n—the density of a
and Type N, for Nuclear or for Other High-Reliability
Applications compacted powder is the combined density of the powder
particlesandthevoidsremainingafterthepowdercompaction.
E344Terminology Relating to Thermometry and Hydrom-
etry Sometimes the insulation compaction density is divided by the
theoretical density of the powder particles to obtain a dimen-
E585/E585M Specification for Compacted Mineral-
sionless fraction of theoretical density as a convenient method
Insulated, Metal-Sheathed, Base Metal Thermocouple
to express the relative compaction.
Cable
E608/E608MSpecification for Mineral-Insulated, Metal-
3.2.5 raw material, n—tubing or other sheath material,
Sheathed Base Metal Thermocouples
insulation and wires used in the fabrication of sheathed
E691Practice for Conducting an Interlaboratory Study to
thermocouple cable.
Determine the Precision of a Test Method
3.2.6 short range ordering, n—the reversible short-ranged,
E780Test Method for Measuring the Insulation Resistance
order-disorder transformation in which the nickel and chro-
of Mineral-Insulated, Metal-SheathedThermocouples and
mium atoms occupy specific (ordered) localized sites in the
Thermocouple Cable at Room Temperature
Type EP or Type KP thermoelement alloy crystal structure.
E1025 Practice for Design, Manufacture, and Material
3.2.7 thermal response time, n—the time required for a
Grouping Classification of Hole-Type Image Quality In-
sheathed thermocouple signal to attain the specified percent of
dicators (IQI) Used for Radiology
the total voltage change produced by a step change of
E1129/E1129MSpecification for Thermocouple Connectors
temperature at the sheath’s outer surface.
E1350GuideforTestingSheathedThermocouples,Thermo-
couples Assemblies, and Connecting Wires Prior to, and
4. Summary of Test Methods
After Installation or Service
E1684Specification for Miniature Thermocouple Connec-
4.1 Insulation Properties:
tors
4.1.1 Compaction—These tests ensure that the insulation is
E1751Guide for Temperature Electromotive Force (EMF)
compacted sufficiently (1) to prevent the insulation from
Tables for Non-Letter Designated Thermocouple Combi-
shifting during use with the possibility of the thermoelements
nations (Withdrawn 2009)
shorting to each other or to the sheath, and (2) to have good
E2181/E2181M Specification for Compacted Mineral-
heat transfer between the sheath and the thermoelements.
Insulated, Metal-Sheathed, Noble Metal Thermocouples
4.1.2 Insulation Resistance—The insulation shall be free of
and Thermocouple Cable
moisture and contaminants that would compromise the
2.2 ANSI Standard
voltage-temperature relationship or shorten the useful life of
B 46.1Surface Texture
the sheathed thermocouple. Measurement of insulation resis-
tance is a useful way to detect the presence of unacceptable
2.3 Other Standard
USAEC Division of Reactor Development and Technology levels of impurities in the insulation.
RDTStandardC2-1TDeterminationofInsulationCom-
4.2 Sheath Properties:
paction in Ceramic Insulated Conductors August 1970
4.2.1 Integrity—These tests ensure that (1) the sheath will
be impervious to moisture and gases so the insulation and
3. Terminology
thermoelements will be protected, (2) surface flaws and cracks
3.1 Definitions—ThedefinitionsgiveninTerminologyE344
that might develop into sheath leaks are detected, and (3) the
shall apply to these test methods.
sheath walls are as thick as specified.
4.2.2 Dimensions—Determination of length, diameter, and
sheath roundness are often necessary to assure proper dimen-
The last approved version of this historical standard is referenced on
sional fit.
www.astm.org.
4.2.3 Sheath Ductility—The sheath shall be ductile enough
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036. to bend the required amount without breaking or cracking.
E839 − 11 (2016)
4.3 Thermoelement Properties Service Life: Specification E608/E608M. For this reason, calibration of
4.3.1 Calibration—This test ensures that the temperature- thermocouples destined for delivery to a customer is not
recommended. Because the EMF indication of any thermo-
emf relationship initially corresponds to standardized toler-
ances. couple depends upon the condition of the thermoelements
along their entire length, as well as the temperature profile
4.3.2 Size—The thermocouple sheath and thermoelement
sizes are related to the service life and the thermoelement pattern in the region of any inhomogeneity, the EMF output of
a used thermocouple will be unique to its installation. Because
spacing is related to possible low insulation resistance or
shorting. temperature profiles in calibration equipment are unlikely to
duplicate those of the installation, removal of a used thermo-
4.3.3 Thermoelement Ductility—Ductility of the thermoele-
couple to a separate apparatus for calibration is not recom-
ments shall be sufficient to allow the assembly to be bent
mended. Instead, in situ calibration by comparison to a similar
during assembly or service without significant damage to the
thermoelements. thermocouple known to be good is often recommended.
4.4 Thermocouple Assembly Properties—The criteria listed
6. General Requirements
aboveshallapplytoboththermocoupleassembliesandtobulk
cable. In addition, the following tests are important for 6.1 All the inspection operations are to be performed under
clean conditions that will not degrade the insulation, sheath, or
thermocouple assemblies.
4.4.1 Continuity—The loop continuity test assures that the thermoelements.This includes the use of suitable gloves when
appropriate.
thermocouple assembly has a completed circuit.
4.4.2 Loop Resistance—The loop resistance test can detect
6.2 During all process steps in which insulation is exposed
shorted or damaged thermoelements.
to ambient atmosphere, the air shall be clean, with less than
4.4.3 Polarity—The connector polarity test indicates
50% relative humidity, and at a temperature between 20 and
whether the connector is correctly installed.
26°C (68 and 79°F).
4.4.4 Moisture Seal—The moisture seal at the reference
6.3 All samples which are tested shall be identified by
junction end of the thermocouple, if faulty, may allow con-
material code, and shall be traceable to a production run.
tamination of the insulation with moisture or gases.
4.4.5 Radiography—Radiographic examination of the junc-
7. Insulation Properties
tion and sheath closure weld can indicate faulty junctions and
sheath closures that will lead to early failure. Most internal 7.1 Insulation Compaction Density—The thermal conduc-
dimensions can also be measured from the radiograph.
tivityoftheinsulation,aswellastheabilityoftheinsulationto
4.4.6 Response Time—The thermal response time gives an lock the thermoelements into place, will be affected by the
indication of the quickness with which an installed thermo- insulation compaction density.
couple will signal a changing temperature under the test 7.1.1 Adirect method for measuring insulation compaction
conditions. density is applicable if a representative sample can be sec-
tioned so that the sample ends are perpendicular to the sample
4.4.7 Thermal Cycle—The thermal cycle test will offer
assurance that the thermocouple will not have early failure length and the sheath, thermoelements, and insulation form a
smooth surface free of burrs. The procedure is as follows:
because of strains imposed from temperature transients.
7.1.1.1 Weigh the sample section,
5. Significance and Use 7.1.1.2 Measure the sheath diameter and length with a
micrometer,
5.1 This standard provides a description of test methods
7.1.1.3 Separate the insulation from the thermoelement and
used in otherASTM specifications to establish certain accept-
sheath with the use of an air abrasive tool,
able limits for characteristics of thermocouple assemblies and
7.1.1.4 Weigh the thermoelements and sheath, and
thermocouple cable. These test methods define how those
7.1.1.5 Determine the sheath and thermoelements densities
characteristics shall be determined.
either by experiment or from references.
5.2 The usefulness and purpose of the included tests are
7.1.1.6 Determine the percentage of the maximum theoreti-
given for the category of tests.
cal insulation density ρ as follows:
5.3 Warning—Users should be aware that certain charac-
%ρ 5100 A 2 B / @0.785 C D 2 E/F1G/H #J (1)
~ ! $ ~ ! %
teristics of thermocouples might change with time and use. If
where:
a thermocouple’s designed shipping, storage, installation, or
operating temperature has been exceeded, that thermocouple’s A = total specimen mass, kg or lb,
B = sheath and wires mass, kg or lb,
moisture seal may have been compromised and may no longer
C = sheath diameter, m or in.,
adequately prevent the deleterious intrusion of water vapor.
D = specimen length, m or in.,
Consequently,thethermocouple’sconditionestablishedbytest
E = sheath mass, kg or lb,
at the time of manufacture may not apply l
...
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. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E839 − 11 E839 − 11 (Reapproved 2016)
Standard Test Methods for
Sheathed Thermocouples and Sheathed Thermocouple
Cable
This standard is issued under the fixed designation E839; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This document lists methods for testing Mineral-Insulated, Metal-Sheathed (MIMS) thermocouple assemblies and
thermocouple cable, but does not require that any of these tests be performed nor does it state criteria for acceptance. The
acceptance criteria are given in other ASTM standard specifications that impose this testing for those thermocouples and cable.
Examples from ASTM thermocouple specifications for acceptance criteria are given for many of the tests. These tabulated values
are not necessarily those that would be required to meet these tests, but are included as examples only.
1.2 These tests are intended to support quality control and to evaluate the suitability of sheathed thermocouple cable or
assemblies for specific applications. Some alternative test methods to obtain the same information are given, since in a given
situation, an alternative test method may be more practical. Service conditions are widely variable, so it is unlikely that all the tests
described will be appropriate for a given thermocouple application. A brief statement is made following each test description to
indicate when it might be used.
1.3 The tests described herein include test methods to measure the following properties of sheathed thermocouple material and
assemblies.
1.3.1 Insulation Properties:
1.3.1.1 Compaction—direct method, absorption method, and tension method.
1.3.1.2 Thickness. Thickness.
1.3.1.3 Resistance—atResistance—at room temperature and at elevated temperature.
1.3.2 Sheath PropertiesProperties::
1.3.2.1 Integrity—two water test methods and mass spectrometer.
1.3.2.2 Dimensions—length, diameter, and roundness.
1.3.2.3 Wall thickness. Wall thickness.
1.3.2.4 Surface—grossSurface—gross visual, finish, defect detection by dye penetrant, and cold-lap detection by tension test.
1.3.2.5 Metallurgical structure. Metallurgical structure.
1.3.2.6 Ductility—bendDuctility—bend test and tension test.
1.3.3 Thermoelement Properties:
1.3.3.1 Calibration. Calibration.
1.3.3.2 Homogeneity. Homogeneity.
1.3.3.3 Drift. Drift.
1.3.3.4 Thermoelement diameter, roundness, and surface appearance. Thermoelement diameter, roundness, and surface
appearance.
1.3.3.5 Thermoelement spacing. Thermoelement spacing.
1.3.3.6 Thermoelement ductility. Thermoelement ductility.
1.3.3.7 Metallurgical structure. Metallurgical structure.
1.3.4 Thermocouple Assembly Properties:
1.3.4.1 Dimensions—length, diameter, and roundness.
1.3.4.2 Surface—gross visual, finish, reference junction end moisture seal, and defect detection by dye penetrant.
1.3.4.3 Electrical—continuity, loop resistance, and connector polarity.
1.3.4.4 Radiographic inspection. Radiographic inspection.
These test methods are under the jurisdiction of ASTM Committee E20 on Temperature Measurement and is the direct responsibility of Subcommittee E20.04 on
Thermocouples.
Current edition approved Nov. 1, 2011Nov. 1, 2016. Published January 2012January 2016. Originally approved in 1989. Last previous edition approved in 20052011 as
E839 – 05.E839 – 11. DOI: 10.1520/E0839-11.10.1520/E0839-11R16.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E839 − 11 (2016)
1.3.4.5 Thermoelement diameter. Thermoelement diameter.
1.3.4.6 Thermal response time. Thermal response time.
1.3.4.7 Thermal cycle. Thermal cycle.
1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the
two systems may result in non-conformance with the standard.
1.5 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.
2. Referenced Documents
2.1 ASTM Standards:
E3 Guide for Preparation of Metallographic Specimens
E94 Guide for Radiographic Examination
E112 Test Methods for Determining Average Grain Size
E165 Practice for Liquid Penetrant Examination for General Industry
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E207 Test Method for Thermal EMF Test of Single Thermoelement Materials by Comparison with a Reference Thermoelement
of Similar EMF-Temperature Properties
E220 Test Method for Calibration of Thermocouples By Comparison Techniques
E230 Specification and Temperature-Electromotive Force (EMF) Tables for Standardized Thermocouples
E235 Specification for Thermocouples, Sheathed, Type K and Type N, for Nuclear or for Other High-Reliability Applications
E344 Terminology Relating to Thermometry and Hydrometry
E585/E585M Specification for Compacted Mineral-Insulated, Metal-Sheathed, Base Metal Thermocouple Cable
E608/E608M Specification for Mineral-Insulated, Metal-Sheathed Base Metal Thermocouples
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E780 Test Method for Measuring the Insulation Resistance of Mineral-Insulated, Metal-Sheathed Thermocouples and
Thermocouple Cable at Room Temperature
E1025 Practice for Design, Manufacture, and Material Grouping Classification of Hole-Type Image Quality Indicators (IQI)
Used for Radiology
E1129/E1129M Specification for Thermocouple Connectors
E1350 Guide for Testing Sheathed Thermocouples, Thermocouples Assemblies, and Connecting Wires Prior to, and After
Installation or Service
E1684 Specification for Miniature Thermocouple Connectors
E1751 Guide for Temperature Electromotive Force (EMF) Tables for Non-Letter Designated Thermocouple Combinations
(Withdrawn 2009)
E2181/E2181M Specification for Compacted Mineral-Insulated, Metal-Sheathed, Noble Metal Thermocouples and Thermo-
couple Cable
2.2 ANSI Standard
B 46.1 Surface Texture
2.3 Other Standard
USAEC Division of Reactor Development and Technology RDT Standard C 2-1T Determination of Insulation Compaction in
Ceramic Insulated Conductors August 1970
3. Terminology
3.1 Definitions—The definitions given in Terminology E344 shall apply to these test methods.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 bulk cable, n—a single length of thermocouple cable produced from the same raw material lots after completion of
fabrication.
3.2.2 cable lot, n—a quantity of finished mineral–insulated, metal-sheathed thermocouple cable manufactured from tubing or
other sheath material from the same heat, wire from the same spool and heat, and insulation from the same batch, then assembled
and processed together under controlled production conditions to the required final outside diameter.
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.
The last approved version of this historical standard is referenced on www.astm.org.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036.
E839 − 11 (2016)
3.2.3 cold-lap, n—sheath surface defect where the sheath surface has been galled and torn by a drawing die and the torn surface
smoothed by a subsequent diameter reduction.
3.2.4 insulation compaction density, n—the density of a compacted powder is the combined density of the powder particles and
the voids remaining after the powder compaction. Sometimes the insulation compaction density is divided by the theoretical
density of the powder particles to obtain a dimensionless fraction of theoretical density as a convenient method to express the
relative compaction.
3.2.5 raw material, n—tubing or other sheath material, insulation and wires used in the fabrication of sheathed thermocouple
cable.
3.2.6 short range ordering, n—the reversible short-ranged, order-disorder transformation in which the nickel and chromium
atoms occupy specific (ordered) localized sites in the Type EP or Type KP thermoelement alloy crystal structure.
3.2.7 thermal response time, n—the time required for a sheathed thermocouple signal to attain the specified percent of the total
voltage change produced by a step change of temperature at the sheath’s outer surface.
4. Summary of Test Methods
4.1 Insulation Properties:
4.1.1 Compaction—These tests ensure that the insulation is compacted sufficiently (1) to prevent the insulation from shifting
during use with the possibility of the thermoelements shorting to each other or to the sheath, and (2) to have good heat transfer
between the sheath and the thermoelements.
4.1.2 Insulation Resistance—The insulation shall be free of moisture and contaminants that would compromise the
voltage-temperature relationship or shorten the useful life of the sheathed thermocouple. Measurement of insulation resistance is
a useful way to detect the presence of unacceptable levels of impurities in the insulation.
4.2 Sheath Properties:
4.2.1 Integrity—These tests ensure that (1) the sheath will be impervious to moisture and gases so the insulation and
thermoelements will be protected, (2) surface flaws and cracks that might develop into sheath leaks are detected, and (3) the sheath
walls are as thick as specified.
4.2.2 Dimensions—Determination of length, diameter, and sheath roundness are often necessary to assure proper dimensional
fit.
4.2.3 Sheath Ductility—The sheath shall be ductile enough to bend the required amount without breaking or cracking.
4.3 Thermoelement Properties Service Life:
4.3.1 Calibration—This test ensures that the temperature-emf relationship initially corresponds to standardized tolerances.
4.3.2 Size—The thermocouple sheath and thermoelement sizes are related to the service life and the thermoelement spacing is
related to possible low insulation resistance or shorting.
4.3.3 Thermoelement Ductility—Ductility of the thermoelements shall be sufficient to allow the assembly to be bent during
assembly or service without significant damage to the thermoelements.
4.4 Thermocouple Assembly Properties—The criteria listed above shall apply to both thermocouple assemblies and to bulk
cable. In addition, the following tests are important for thermocouple assemblies.
4.4.1 Continuity—The loop continuity test assures that the thermocouple assembly has a completed circuit.
4.4.2 Loop Resistance—The loop resistance test can detect shorted or damaged thermoelements.
4.4.3 Polarity—The connector polarity test indicates whether the connector is correctly installed.
4.4.4 Moisture Seal—The moisture seal at the reference junction end of the thermocouple, if faulty, may allow contamination
of the insulation with moisture or gases.
4.4.5 Radiography—Radiographic examination of the junction and sheath closure weld can indicate faulty junctions and sheath
closures that will lead to early failure. Most internal dimensions can also be measured from the radiograph.
4.4.6 Response Time—The thermal response time gives an indication of the quickness with which an installed thermocouple will
signal a changing temperature under the test conditions.
4.4.7 Thermal Cycle—The thermal cycle test will offer assurance that the thermocouple will not have early failure because of
strains imposed from temperature transients.
5. Significance and Use
5.1 This standard provides a description of test methods used in other ASTM specifications to establish certain acceptable limits
for characteristics of thermocouple assemblies and thermocouple cable. These test methods define how those characteristics shall
be determined.
5.2 The usefulness and purpose of the included tests are given for the category of tests.
5.3 Warning—Users should be aware that certain characteristics of thermocouples might change with time and use. If a
thermocouple’s designed shipping, storage, installation, or operating temperature has been exceeded, that thermocouple’s moisture
seal may have been compromised and may no longer adequately prevent the deleterious intrusion of water vapor. Consequently,
E839 − 11 (2016)
the thermocouple’s condition established by test at the time of manufacture may not apply later. In addition, inhomogeneities can
develop in thermoelements because of exposure to higher temperatures, even in cases where maximum exposure temperatures have
been lower than the suggested upper use temperature limits specified in Table 1 of Specification E608/E608M. For this reason,
calibration of thermocouples destined for delivery to a customer is not recommended. Because the EMF indication of any
thermocouple depends upon the condition of the thermoelements along their entire length, as well as the temperature profile pattern
in the region of any inhomogeneity, the EMF output of a used thermocouple will be unique to its installation. Because temperature
profiles in calibration equipment are unlikely to duplicate those of the installation, removal of a used thermocouple to a separate
apparatus for calibration is not recommended. Instead, in situ calibration by comparison to a similar thermocouple known to be
good is often recommended.
6. General Requirements
6.1 All the inspection operations are to be performed under clean conditions that will not degrade the insulation, sheath, or
thermoelements. This includes the use of suitable gloves when appropriate.
6.2 During all process steps in which insulation is exposed to ambient atmosphere, the air shall be clean, with less than 50 %
relative humidity, and at a temperature between 20 and 26°C (68 and 79°F).
6.3 All samples which are tested shall be identified by material code, and shall be traceable to a production run.
7. Insulation Properties
7.1 Insulation Compaction Density—The thermal conductivity of the insulation, as well as the ability of the
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