ASTM E839-96
(Test Method)Standard Test Methods for Sheathed Thermocouples and Sheathed Thermocouple Material (Withdrawn 2005)
Standard Test Methods for Sheathed Thermocouples and Sheathed Thermocouple Material (Withdrawn 2005)
SCOPE
1.1 These are test methods for sheathed thermocouple material and assemblies.
1.2 The tests are intended to assure quality control and to evaluate the suitability of sheathed thermocouple material 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 and 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-absorption method and tension method,
1.3.1.2 Thickness, and
1.3.1.3 Resistance-room temperature and elevated temperature.
1.3.2 Sheath Properties:
1.3.2.1 Integrity-water test (two 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, and
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, and
1.3.3.7 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 end seal, and defect detection by dye penetrant,
1.3.4.3 Electrical-continuity, loop resistance, and connector polarity,
1.3.4.4 Insulation resistance-room temperature, and elevated temperature,
1.3.4.5 Radiographic inspection,
1.3.4.6 Thermoelement diameter,
1.3.4.7 Thermal response time, and
1.3.4.8 Thermal cycle.
WITHDRAWN RATIONALE
These are test methods for sheathed thermocouple material and assemblies.
Formerly under the jurisdiction of Committee E20 on Temperature Measurement, these test methods were withdrawn in August 2005 in accordance with section 10.5.3.1 of the Regulations Governing ASTM Technical Committees, which requires that standards shall be updated by the end of the eighth year since the last approval date.
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:E839–96
Standard Test Methods for
Sheathed Thermocouples and Sheathed Thermocouple
Material
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 (e) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Thermocouples are widely used in industry and they provide reliable service. However, if
thermocouples fail in service, the results can range from negligible to life threatening. Often a loss of
equipment, product, or operating time will result. The user should weigh the potential consequences
of thermocouple failure when considering what tests should be performed. No tests are required by
this document except those specifically ordered by the user. This document lists methods for testing
sheathed thermocouples and thermocouple material but does not state criteria for acceptance. The
acceptance criteria for the particular thermocouple, when subjected to the tests, are given in other
ASTM standard specifications for that thermocouple. Examples from ASTM thermocouple specifi-
cations 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 given here as examples only.
1. Scope 1.3.2.1 Integrity
water test (two test methods) and mass spectrometer,
1.1 These are test methods for sheathed thermocouple
1.3.2.2 Dimensions—length, diameter, and roundness,
material and assemblies.
1.3.2.3 Wall thickness,
1.2 The tests are intended to ensure quality control and to
1.3.2.4 Surface—gross visual, finish, defect detection by
evaluate the suitability of sheathed thermocouple material or
dye penetrant, and cold-lap detection by tension test,
assemblies for specific applications. Some alternative test
1.3.2.5 Metallurgical structure, and
methods to obtain the same information are given, since in a
1.3.2.6 Ductility—bend test and tension test.
given situation an alternative test method may be more
1.3.3 Thermoelement Properties:
practical. Service conditions are widely variable and so it is
1.3.3.1 Calibration,
unlikely that all the tests described will be appropriate for a
1.3.3.2 Homogeneity,
given thermocouple application. A brief statement is made
1.3.3.3 Drift,
following each test description to indicate when it might be
1.3.3.4 Thermoelement diameter, roundness, and surface
used.
appearance,
1.3 The tests described herein include test methods to
1.3.3.5 Thermoelement spacing,
measure the following properties of sheathed thermocouple
1.3.3.6 Thermoelement ductility, and
material and assemblies.
1.3.3.7 Metallurgical structure.
1.3.1 Insulation Properties:
1.3.4 Thermocouple Assembly Properties:
1.3.1.1 Compaction
1.3.4.1 Dimensions
absorption method and tension method,
length, diameter, and roundness,
1.3.1.2 Thickness, and
1.3.4.2 Surface—gross visual, finish, reference end seal,
1.3.1.3 Resistance—room temperature and elevated tem-
and defect detection by dye penetrant,
perature.
1.3.4.3 Electrical—continuity, loop resistance, and connec-
1.3.2 Sheath Properties:
tor polarity,
1.3.4.4 Insulation resistance—room temperature, and el-
These test methods are under the jurisdiction of Committee E-20 on Temper- evated temperature,
ature Measurement and are the direct responsibility of Subcommittee E20.04 on
1.3.4.5 Radiographic inspection,
Thermocouples.
1.3.4.6 Thermoelement diameter,
Current edition approved June 10, 1996. Published August 1996. Originally
1.3.4.7 Thermal response time, and
published as E839–89. Last previous edition E839–89.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E839–96
1.3.4.8 Thermal cycle. tion. Sometimes the insulation compaction density is divided
by the theoretical density of the powder particles to obtain a
2. Referenced Documents
dimensionless fraction of theoretical density as a convenient
2.1 ASTM Standards: method to express the relative compaction.
3.2.4 production run, n—thequantityofBMLs(producedat
D2771 Test Methods for Compaction Density of Electrical
Grade Magnesium Oxide one time and from the same material lot) that travel together
continuouslythroughthesameprocessingsteps,thatis,assem-
E3 Methods of Preparation of Metallographic Specimens
E94 Guide for Radiographic Testing bly, size reduction, annealing, etc.
3.2.5 raw material, n—material components (tubing, insu-
E112 Test Methods for Determining the Average Grain
Size lators, and thermoelements) as received, prior to any manufac-
turing procedures.
E142 Method for Controlling Quality of Radiographic
Testing 3.2.6 short range ordering, n—the reversible short-ranged,
order-disorder transformation in which the nickel and chro-
E165 Practice for Liquid Penetrant Examination
E207 Method of Thermal EMF Test of Single Thermoele- mium atoms occupy specific (ordered) localized sites in the
Type EP or Type KP thermoelement alloy crystal structure.
ment Materials by Comparison with a Secondary Standard
3.2.7 thermocouple assembly, n—thecut-to-length,finished
of Similar EMF-Temperature Properties
assembly consisting of thermocouple material with thermoele-
E220 Method for Calibration of Thermocouples by Com-
ments having one end joined in a measuring junction. The
parison Techniques
assembly has the sheath closed at the measuring end and has a
E230 Specification for Temperature-Electromotive Force
moisture seal at the reference junction end of the sheath. The
(EMF) Tables for Standardized Thermocouples
assemblydoesnotincludeareferencejunctionbutmayinclude
E235 Specification for Thermocouples, Sheathed, Type K,
a thermocouple connector, thermocouple extension, or com-
for Nuclear or for Other High-Reliability Applications
E344 Terminology Relating to Thermometry and Hydrom- pensating wire.
etry
4. Summary of Test Methods
E 585 Specification for Sheathed Base-Metal Thermo-
4.1 Insulation Properties:
couple Materials
4.1.1 Compaction—These tests ensure the insulation is
E608 Specification for Metal-Sheathed Base-Metal Ther-
compacted enough (1) to prevent the insulation from shifting
mocouples
during use with the possibility of the thermoelements shorting
E780 Test Method for Measuring the Insulation Resistance
toeachotherortothesheathand(2)tohavegoodheattransfer
ofSheathedThermocoupleMaterialatRoomTemperature
between the sheath and the thermoelements.
E988 Temperature-Electromotive Force (EMF) Tables for
4.1.2 Resistance—The insulation must be free of moisture
Tungsten-Rhenium Thermocouples
and contaminants that would compromise the voltage-
E1129/E1129M Specification for Thermocouple Connec-
temperature relation or shorten the useful life of the sheathed
tors
thermocouple.Measurementofinsulationresistanceisauseful
2.2 ANSI Standard
way to detect the presence of unacceptable levels of impurities
B 46.1 Surface Texture
in the insulation.
3. Terminology 4.2 Sheath Properties:
4.2.1 Integrity—These tests ensure (1) the sheath will be
3.1 Definitions—The definitions given in Terminology
impervious to moisture and gases so the insulation and
E344 shall apply to these test methods.
thermoelements will be protected, (2) surface flaws and cracks
3.2 Definitions of Terms Specific to This Standard:
that might develop into sheath leaks are detected, and (3) the
3.2.1 bulk material length (BML), n—a single length of
sheath walls are as thick as specified.
thermocouple material (produced from the same raw material
4.2.2 Dimensions—Ifthesheathmustfitinafixedspacethe
lot) after completion of fabrication resulting in sheathed
dimensions of length, diameter, and sheath roundness must be
thermocouple material.
determined.
3.2.2 cold-laps, n—sheath surface defects where the sheath
4.2.3 Ductility—If the sheath must be bent during installa-
surface has been galled and torn by a drawing die and the torn
tion or service, then the sheath must be ductile enough to bend
surfaces smoothed by a subsequent diameter reduction.
the required amount without breaking or cracking.
3.2.3 insulation compaction density, n—the density of a
4.3 Thermoelement Properties Service Life:
compacted powder is the combined density of the powder
4.3.1 Calibration—These tests ensure the temperature
particles and of the voids remaining after the powder compac-
(emf) relation corresponds to the standard values both initially
and after a short time of heating to service temperatures.
2 4.3.2 Size—The thermocouple sheath and thermoelement
Annual Book of ASTM Standards, Vol 10.01.
sizes are related to service life, and the thermoelement spacing
Annual Book of ASTM Standards, Vol 03.01.
Annual Book of ASTM Standards, Vol 03.03.
is related to possible low insulation resistance or shorting.
Annual Book of ASTM Standards, Vol 14.03.
4.3.3 Ductility—Thermoelementductilityisnecessaryifthe
Discontinued. See 1994 Annual Book of ASTM Standards, Vol 14.03.
thermocouple assembly must be bent during installation or
Available from American National Standards Institute, 11 W. 42nd St., 13th
Floor, New York, NY 10036. service.
E839–96
4.4 Thermocouple Assembly Properties—The criteria listed tioned so the sample ends are perpendicular to the sample
abovemustapplytoboththermocoupleassembliesandtobulk length and the sheath, thermoelements, and insulation form a
sheathed material, and in addition the following tests are smooth surface free of burrs. The test procedure is to:
important for thermocouple assemblies. 7.1.2.1 Weigh the sample section,
4.4.1 Continuity—The loop continuity test assures that the 7.1.2.2 Measure the sheath diameter and length with a
thermocouple assembly has, at least, a completed circuit. micrometer,
4.4.2 Resistance—The loop resistance test can detect 7.1.2.3 Separate wires, sheath, and insulation by use of an
shorted or damaged thermoelements. air abrasive tool (air-driven abrasive particles) to remove the
4.4.3 Polarity—The connector polarity test indicates insulation from the sample,
whether the connector is correctly installed. 7.1.2.4 Weigh the thermoelements and sheath, and
4.4.4 End Seal—Thereferenceendseal,iffaulty,mayallow 7.1.2.5 Determine the sheath and thermoelements densities
the contamination of the insulation with moisture or gases. either by experiment or from references.
4.4.5 Radiography—Radiographic examination of the junc- 7.1.3 The fraction of the maximum theoretical insulation
tion and sheath closure weld can indicate faulty junctions and density is determined as follows:
sheath closures that will lead to early failure. The internal
~A 2B!/$@0.785C D2~E/F 1G/H!#J% (1)
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 thermo- where:
A = total specimen mass, g or lb,
couple will signal a changing temperature under the test
B = sheath and wires mass, g or lb,
conditions.
C = sheath diameter, mm or in.,
4.4.7 Thermal Cycle—The thermal cycle test will offer
D = specimen length, mm or in.,
assurance that the thermocouple will not have early failure
E = sheath mass, g or lb,
because of strains imposed from temperature transients.
3 3
F = sheath density, kg/m or lb/in. ,
G = wires mass, g or lb,
5. Significance and Use
H = wires density (averaged density if applicable), kg/m
5.1 Thesetestsprovideadescriptionoftestmethodsforuse
or lb/in. , and
inASTM specifications that establish certain acceptable limits
J = maximum theoretical density of the insulation, kg/m
for characteristics of thermocouple assemblies and thermo- 3
or lb/in. .
couple materials.
7.2 Insulation Compaction, Tension Test Method—This is a
5.2 The intended use of these test methods is to define the
destructivetestonrepresentativesamplesthatdeterminesifthe
methods by which the characteristics shall be determined.
thermoelements are locked together with the sheath by the
5.3 The usefulness and purpose of the included tests are
compacted insulation, but the test does not measure the
given for the category of tests.
compaction density per se.This tension test is the complement
of the tests of 7.1 that measure the insulation compaction
6. General Requirements
density but does not establish that the thermoelements are
6.1 All the inspection operations are to be performed under
locked to the sheath (since there is no established minimum
clean conditions (that is, conditions that will not degrade the
compaction density where locking begins). This test can be
insulation, sheath, or thermoelements), including the use of
performed concurrently with the sheath ductility test (8.5.3).
suitable gloves when appropriate.
7.2.1 Cut a test sample about 0.5 m (20 in.) long from one
6.2 During all process steps in which insulation is exposed
end of a bulk material length and strip both ends of the sample
to ambient atmosphere, the air must be clean, with less than
to expose a minimum of 10 mm (0.4 in.) of the thermoele-
50% relative humidity, and at a temperature between 20 and
ments.
26°C (68 and 79°F).
7.2.2 Without sealing the exposed insulation, clean the
6.3 All samples which are tested shall be identified by
thermoelements(wires)ofinsulationtoprovidegoodelectrical
material code, and shall be traceable to a production run.
contact and twist the wires together on one end to form a
thermocouple loop (Fig. 1).
7. Insulation Properties
7.1 Insulation Compaction Density—The thermal conduc-
tivityoftheinsulation,aswellastheabilityoftheinsulationto
lock the thermoelements into place, will be affected by the
insulation compaction density.
7.1.1 Test Methods D2771 is a test on representative
samples to measure the compaction density of electrical grade
magnesium oxide. Two methods are used to find the density:
Test MethodAfor water displacement and Test Method B for
oil absorption. Both Test Methods A and B require precision
weighing and careful procedure.
7.1.2 A direct measurement test of insulation compaction
FIG. 1 Specimen of Sheathed Thermocouple Material Prepared
density is applicable if a representative sample can be sec- for Tension Testing
E839–96
7.2.3 Measure the electrical resistance of the thermocouple
loop to 6 0.01 V and measure the length of the thermocouple
loop to establish the electrical resistance per unit length.
7.2.4 Placethetestsampleinthetensiontestingmachineso
that(1)thegripsclamponlyonthesamplesheath,(2)theforce
will be applied longitudinally on the sheath, and (3) there is at
least a 0.25-m (10-in
...
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