ASTM E235/E235M-12
(Specification)Standard Specification for Type K and Type N Mineral-Insulated, Metal-Sheathed Thermocouples for Nuclear or for Other High-Reliability Applications
Standard Specification for Type K and Type N Mineral-Insulated, Metal-Sheathed Thermocouples for Nuclear or for Other High-Reliability Applications
ABSTRACT
This specification covers the requirements for sheathed, Type K and N thermocouples for nuclear service. This specification can be used for sheathed thermocouples which are required for laboratory or general commercial applications where the environmental conditions exceed normal service requirements. The measuring junction styles for thermocouples are as follows: Style G2 (grounded) in which measuring junction is electrically connected to conductive sheaths and Style U2 (ungrounded) in which measuring junctions are electrically isolated from conductive sheaths and from reference ground. Different properties of the sheath such as integrity, cracks, voids, inclusions, surface finish, surface defect, and metallurgical structure shall be determined by performing different tests. Insulation resistance between thermoelements and the sheath shall be measured as well.
SCOPE
1.1 This specification covers the requirements for simplex, compacted mineral-insulated, metal-sheathed (MIMS), Type K and N thermocouples for nuclear or other high reliability service. Depending on size, these thermocouples are normally suitable for operating temperatures to 1652°F [900°C]; special conditions of environment and life expectancy may permit their use at temperatures in excess of 2012°F [1100°C]. This specification was prepared to detail requirements for this type of MIMS thermocouple for use in nuclear environments, but they can also be used for laboratory or general commercial applications where the environmental conditions exceed normal service requirements. The intended use of a MIMS thermocouple in a specific nuclear application will require evaluation of the compatibility of the thermocouple, including the effect of the temperature, atmosphere, and integrated neutron flux on the materials and accuracy of the thermoelements in the proposed application by the purchaser.
1.2 This specification does not attempt to include all possible specifications, standards, etc., for materials that may be used as sheathing, insulation, and thermocouple wires for sheathed-type construction. The requirements of this specification include only the austenitic stainless steels and other alloys as allowed by Specification E585/E585M for sheathing, magnesium oxide or aluminum oxide as insulation, and Type K and N thermocouple wires for thermoelements (see Note 1).
1.3 General Design—Nominal sizes of the finished thermocouples shall be 0.0400 in., 0.0625 in., 0.125 in., 0.1875 in., or 0.250 in. [1.000 mm, 1.500 mm, 3.000 mm, 4.500 mm, or 6.000 mm]. Sheath dimensions and tolerances for each nominal size shall be in accordance with Table 1 and Figs. 1 and 2. The measuring junction styles for thermocouples covered by this specification are as follows:
1.3.1 Style G (grounded)—The measuring junction is electrically connected to its conductive sheath, and
1.3.2 Style U (ungrounded)—The measuring junction is electrically isolated from its conductive sheath and from reference ground.
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 are not exact equivalents or conversions; 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.
TABLE 1 Dimensions for Style G and U Measuring Junctions Sheath Outside Diameter, AMinimum
Sheath
Wall,
BMinimum
Insulation
Thickness,
CMinimum
Wire
Diameter,
DE, ToleranceF, Tolerance NominalToleranceminmaxminmax minmax Inches 0.04000.03900.04150.0060.0040.0050.0060.0200.0040.021 0.06250.06150.06400.0090.0050.0100.0090.0320.0050....
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Designation:E235/E235M −12
Standard Specification for
Type K and Type N Mineral-Insulated, Metal-Sheathed
Thermocouples for Nuclear or for Other High-Reliability
1
Applications
This standard is issued under the fixed designation E235/E235M; 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.
2
1. Scope 1.3.1 Style G (grounded)—The measuring junction is elec-
trically connected to its conductive sheath, and
1.1 This specification covers the requirements for simplex,
2
1.3.2 Style U (ungrounded)—The measuring junction is
compacted mineral-insulated, metal-sheathed (MIMS), Type K
electrically isolated from its conductive sheath and from
and N thermocouples for nuclear or other high reliability
reference ground.
service. Depending on size, these thermocouples are normally
1.4 The values stated in either SI units or inch-pound units
suitable for operating temperatures to 1652°F [900°C]; special
are to be regarded separately as standard. The values stated in
conditions of environment and life expectancy may permit
each system are not exact equivalents or conversions;
their use at temperatures in excess of 2012°F [1100°C]. This
specification was prepared to detail requirements for this type therefore,eachsystemshallbeusedindependentlyoftheother.
Combining values from the two systems may result in non-
of MIMS thermocouple for use in nuclear environments, but
they can also be used for laboratory or general commercial conformance with the standard.
applications where the environmental conditions exceed nor-
1.5 This standard does not purport to address all of the
mal service requirements. The intended use of a MIMS
safety concerns, if any, associated with its use. It is the
thermocouple in a specific nuclear application will require
responsibility of the user of this standard to establish appro-
evaluation of the compatibility of the thermocouple, including
priate safety and health practices and determine the applica-
the effect of the temperature, atmosphere, and integrated
bility of regulatory limitations prior to use.
neutron flux on the materials and accuracy of the thermoele-
1.6 This international standard was developed in accor-
ments in the proposed application by the purchaser.
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
1.2 This specification does not attempt to include all
Development of International Standards, Guides and Recom-
possible specifications, standards, etc., for materials that may
mendations issued by the World Trade Organization Technical
be used as sheathing, insulation, and thermocouple wires for
Barriers to Trade (TBT) Committee.
sheathed-type construction. The requirements of this specifi-
cation include only the austenitic stainless steels and other
2. Referenced Documents
alloys as allowed by Specification E585/E585M for sheathing,
3
magnesiumoxideoraluminumoxideasinsulation,andTypeK 2.1 ASTM Standards:
and N thermocouple wires for thermoelements (see Note 1). A262 Practices for Detecting Susceptibility to Intergranular
Attack in Austenitic Stainless Steels
1.3 General Design—Nominal sizes of the finished thermo-
E3 Guide for Preparation of Metallographic Specimens
couples shall be 0.0400 in., 0.0625 in., 0.125 in., 0.1875 in., or
E45 Test Methods for Determining the Inclusion Content of
0.250 in. [1.000 mm, 1.500 mm, 3.000 mm, 4.500 mm, or
Steel
6.000mm].Sheathdimensionsandtolerancesforeachnominal
E112 Test Methods for Determining Average Grain Size
size shall be in accordance with Table 1 and Figs. 1 and 2. The
E165 Practice for Liquid Penetrant Examination for General
measuring junction styles for thermocouples covered by this
Industry
specification are as follows:
E220 Test Method for Calibration of Thermocouples By
1 2
This specification is under the jurisdiction of ASTM Committee E20 on Style G and Style U measuring junctions were previously termed Class 1 and
Temperature Measurement and is the direct responsibility of Subcommittee E20.12 Class 2 measuring junctions respectively.
3
on Thermocouples - Specifications. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved May 1, 2012. Published August 2012. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1964. Last previous edition approved in 2006 as E235 – 06. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/E0235-12. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-
...
This document is not anASTM standard and is intended only to provide the user of anASTM 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:E235–06 Designation: E235/E235M – 12
Standard Specification for
Thermocouples, Sheathed, Type K and Type N Mineral-
Insulated, Metal-Sheathed Thermocouples for Nuclear or for
1
Other High-Reliability Applications
This standard is issued under the fixed designation E235/E235M; 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 specification covers the requirements for simplex, compacted mineral-insulated, metal-sheathed (MIMS), Type K and
N thermocouples for nuclear or other high reliability service. Depending on size, these thermocouples are normally suitable for
operating temperatures to 1652 °F (900 °C); 1652°F [900°C]; special conditions of environment and life expectancy may permit
their use at temperatures in excess of 2012 °F (1100 °C). 2012°F [1100°C]. This specification was prepared specifically to detail
requirements for using this type of sheathedMIMS thermocouple for use in nuclear environments.This specificationenvironments,
but they can also be used for sheathed thermocouples which are required for laboratory or general commercial applications where
theenvironmentalconditionsexceednormalservicerequirements.TheintendeduseofasheathedMIMSthermocoupleinaspecific
nuclear application will require evaluation by the purchaser of the compatibility of the thermocouple, including the effect of the
temperature, atmosphere, and integrated neutron flux on the materials and accuracy of the thermoelements in the proposed
application by the purchaser.
1.2 This specification does not attempt to include all possible specifications, standards, etc., for materials that may be used as
sheathing, insulation, and thermocouple wires for sheathed-type construction. The requirements of this specification include only
the austenitic stainless steels and other alloys as allowed withby Specification E585/E585M for sheathing, magnesium oxide or
aluminum oxide as insulation, and Type K and N thermocouple wires for thermoelements (see Note 1).
1.2
1.3 General Design—Nominalsizesofthefinishedthermocouplesshallbe0.0400in.(1.016mm),0.0625in.(1.588mm),0.125
in. (3.175 mm), 0.1875 in. (4.763 mm), or 0.250 in. (6.350 mm). Sheath dimensions and tolerances for each nominal size shall
be in accordance with —Nominal sizes of the finished thermocouples shall be 0.0400 in., 0.0625 in., 0.125 in., 0.1875 in., or 0.250
in. [1.000 mm, 1.500 mm, 3.000 mm, 4.500 mm, or 6.000 mm]. Sheath dimensions and tolerances for each nominal size shall be
in accordance with Table 1 and Figs. 1 and 2. The measuring junction styles for thermocouples covered by this specification are
as follows:
1.2.1
2
1.3.1 Style G (grounded)—Measuring junction electrically connected to conductive sheaths, and
1.2.2—The measuring junction is electrically connected to its conductive sheath, and
2
1.3.2 Style U (ungrounded)—Measuringjunctionsareelectricallyisolatedfromconductivesheathsandfromreferenceground.
1.3The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information
only.
1.4—The measuring junction is electrically isolated from its conductive sheath and from reference ground.
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
systemarenotexactequivalentsorconversions;therefore,eachsystemshallbeusedindependentlyoftheother.Combiningvalues
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.
1
This specification is 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.May 1, 2006.2012. Published November 2006.August 2012. Originally approved in 1964. Last previous edition approved in 20032006 as
E235 – 036. DOI: 10.1520/E0235-06.10.1520/E0235-12.
2
Style G and Style U measuring junctions were previously termed Class 1 and Class 2 measuring junctions respectively.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box
...
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