ASTM E235-88(1996)e1
(Specification)Standard Specification for Thermocouples, Sheathed, Type K, for Nuclear or for Other High-Reliability Applications
Standard Specification for Thermocouples, Sheathed, Type K, for Nuclear or for Other High-Reliability Applications
SCOPE
1.1 Intent- This specification presents the requirements for sheathed, Type K thermocouples for nuclear 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 specifically to detail requirements for using this type of sheathed thermocouple in nuclear environments. 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 intended use of a sheathed thermocouple in a specific 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. 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 for sheathing, magnesium oxide or aluminum oxide as insulation, and Type K thermocouple wires for thermoelements (see Note 2).
1.2 General Design- Nominal sizes of the finished thermocouples shall be 0.0400 in. (1.016 mm), 0.0625 in. (1.588 mm), 0.1875 in. (4.763 mm), 0.125 in. (3.175 mm), or 0.250 in. (6.350 mm). Sheath dimensions and tolerances for each nominal size shall be in accordance with Table 1. The classes of thermocouples covered by this specification are as follows:
1.2.1 Class 1- Measuring junction grounded to sheath, and
1.2.2 Class 2- Measuring junction not grounded to sheath (insulated junction).
1.2.3 See Figs. 1 and 2 and Table 1 for details. Note 1-The values stated in inch-pound units are to be regarded as the standard.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Please contact ASTM International (www.astm.org) for the latest information.
ϵ1
Designation: E 235 – 88 (Reapproved 1996)
Standard Specification for
Thermocouples, Sheathed, Type K, for Nuclear or for Other
High-Reliability Applications
This standard is issued under the fixed designation E 235; 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 (ϵ) indicates an editorial change since the last revision or reapproval.
ϵ NOTE—Keywords were added editorially in November 1996.
1. Scope 1.3 The values stated in inch-pound units are to be regarded
as the standard. The values given in parentheses are for
1.1 This specification covers the requirements for sheathed,
information only.
Type K thermocouples for nuclear service. Depending on size,
these thermocouples are normally suitable for operating tem-
2. Referenced Documents
peratures to 1652°F (900°C); special conditions of environ-
2.1 ASTM Standards:
ment and life expectancy may permit their use at temperatures
A 262 Practices for Detecting Susceptibility to Intergranu-
in excess of 2012°F (1100°C). This specification was prepared
lar Attack in Austenitic Stainless Steels
specifically to detail requirements for using this type of
A 632 Specification for Seamless and Welded Austenitic
sheathed thermocouple in nuclear environments. This specifi-
Stainless Steel Tubing (Small Diameter) for General Ser-
cation can be used for sheathed thermocouples which are
vice
required for laboratory or general commercial applications
E2 Methods of Preparation of Micrographs of Metals and
where the environmental conditions exceed normal service
Alloys (Including Recommended Practice for Photography
requirements. The intended use of a sheathed thermocouple in
as Applied to Metallography)
a specific nuclear application will require evaluation, by the
E3 Methods of Preparation of Metallographic Specimens
purchaser, of the compatibility of the thermocouple, including
E45 Test Methods for Determining the Inclusion Content
the effect of the temperature, atmosphere, and integrated
of Steel
neutron flux on the materials and accuracy of the thermoele-
E94 Guide for Radiographic Testing
ments in the proposed application. This specification does not
E112 Test Methods for Determining the Average Grain
attempt to include all possible specifications, standards, etc.,
Size
for materials that may be used as sheathing, insulation, and
E 142 Method for Controlling Quality of Radiographic
thermocouple wires for sheathed-type construction. The re-
Testing
quirements of this specification include only the austenitic
E 165 Test Method for Liquid Penetrant Examination
stainless steels for sheathing, magnesium oxide or aluminum
E 220 Test Method for Calibration of Thermocouples by
oxide as insulation, and Type K thermocouple wires for
Comparison Techniques
thermoelements (see Note 2).
E 230 Specification for Temperature-Electromotive Force
1.2 General Design—Nominal sizes of the finished thermo-
(EMF) Tables for Standardized Thermocouples
couplesshallbe0.0400in.(1.016mm),0.0625in.(1.588mm),
E 344 Terminology Relating to Thermometry and Hydrom-
0.1875 in. (4.763 mm), 0.125 in. (3.175 mm), or 0.250 in.
etry
(6.350 mm). Sheath dimensions and tolerances for each nomi-
E 839 Test Methods for Sheathed Thermocouples and
nal size shall be in accordance with Table 1. The classes of
Sheathed Thermocouple Material
thermocouples covered by this specification are as follows:
2.2 ANSI Standard:
1.2.1 Class 1—Measuring junction grounded to sheath, and
B46.1 Surface Texture
1.2.2 Class 2—Measuring junction not grounded to sheath
(insulated junction).
1.2.3 See Figs. 1 and 2 and Tables 1-3 for details.
Annual Book of ASTM Standards, Vol 01.03.
Annual Book of ASTM Standards, Vol 01.01.
Discontinued, see 1982 Annual Book of ASTM Standards, Part 11.
1 5
This specification is under the jurisdiction of ASTM Committee E-20 on Annual Book of ASTM Standards, Vol 03.01.
Temperature Measurement and is the direct responsibility of Subcommittee E20.04 Annual Book of ASTM Standards, Vol 03.03.
on Thermocouples. Annual Book of ASTM Standards, Vol 14.03.
Current edition approved Aug. 19, 1988. Published October 1988. Originally Available from American National Standards Institute, 11 W. 42nd St., 13th
published as E 235 – 64 T. Last previous edition E 235 – 82. Floor, New York, NY 10036.
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.
Please contact ASTM International (www.astm.org) for the latest information.
ϵ1
E 235 – 88 (1996)
TABLE 1 Dimensions for Class 1 and 2 Measuring Junctions
Sheath Outside Diameter, A Minimum Minimum Minimum E, Tolerance F, Tolerance
Sheath Insulation Wire
Tolerance min max min max
Wall, Thickness, Diameter,
Nominal
B C D
min max
Inches
0.0400 0.0390 0.0415 0.006 0.004 0.005 0.006 0.020 0.004 0.021
0.0625 0.0615 0.0640 0.009 0.005 0.010 0.009 0.032 0.005 0.032
0.1250 0.1240 0.1265 0.012 0.012 0.020 0.012 0.062 0.012 0.063
0.1875 0.1865 0.1890 0.020 0.022 0.031 0.020 0.093 0.022 0.095
0.2500 0.2480 0.2520 0.030 0.024 0.040 0.030 0.125 0.024 0.125
Millimetres
1.016 0.991 1.054 0.15 0.10 0.13 0.15 0.51 0.10 0.53
1.588 1.562 1.626 0.23 0.13 0.25 0.23 0.81 0.13 0.81
3.175 3.150 3.213 0.30 0.30 0.51 0.30 1.57 0.30 1.60
4.763 4.737 4.801 0.51 0.56 0.79 0.51 2.36 0.56 2.41
6.350 6.299 6.401 0.76 0.61 1.02 0.76 3.18 0.61 3.18
4.1.3 The type of ceramic insulation required, either alu-
mina (Al O ) or magnesia (MgO),
2 3
4.1.4 The type of tubing material and other information
required (see 5.1.1),
4.1.5 The class of thermocouple measuring junction,
4.1.6 The type of dye-penetrant inspection procedure to be
used, and
4.1.7 Any deviations from this specification or the refer-
enced specifications.
FIG. 1 Grounded Measuring Junction, Class 1
5. Materials and Manufacture
5.1 All materials used shall be in accordance with the
following requirements:
5.1.1 Sheath Materials, Austenitic Stainless Steels—
Austenitic stainless-steel tubing used for thermocouple sheath
material shall conform to the requirements given in Specifica-
tion A 632A 632. The purchaser of the thermocouples shall
specify only the name of the material (seamless or welded),
grade, optional requirements, test report required, and ASTM
FIG. 2 Insulated (Ungrounded) Measuring Junction, Class 2
designation. The manufacturer of the thermocouples shall
specify all other options including the supplementary require-
2.3 American Welding Society Standard:
ments listed in Specification A 632A 632, except that alcohol
A59 Specification for Corrosion-Resisting Chromium and
shall be used as the cleaning solvent. (See Section 2 of
Chromium-Nickel Steel-Welding Rods and Bare Elec-
Specification A 632A 632 for ordering requirements.) In addi-
trodes
tion to the requirements of Specification A 632A 632, the
following requirements must be met:
3. Terminology
5.1.1.1 Theinclusionlevelofthetubingshallbedetermined
3.1 The definitions given in Terminology E 344E 344 shall
by mounting a 1-in. minimum length of a longitudinal section
apply to this specification.
of the tubing using Test Methods E 45E45, Microscopical
Method A, for examination. The inclusion level shall be less
4. Ordering Information and Basis of Purchase
than 3 A through D, thin or heavy.
4.1 The purchase order documents shall specify the follow-
5.1.1.2 The grain size of the tubing shall be determined by
ing information:
a specimen taken in accordance with Test Methods
4.1.1 The quantity, length, and nominal size of the sheathed
E112E112. Grain size shall not exceed the maximum speci-
thermocouple,
fied in Table 3 of this standard specification, as determined by
4.1.2 The initial calibration tolerance to be used to replace
the Comparison Procedure of Test Methods E 112E112.
limits of error if other than standard limits (see Specification
5.1.1.3 Each lot of tubing used shall be sampled using
E 230E 230),
Practices A 262A 262 as follows. Samples shall be tested by
Practice A, and further tested as outlined by Table 1, where
screening tests so indicate. Acceptance levels for these tests
AvailablefromtheAmericanWeldingSociety,2501NorthWest7thSt.,Miami,
Fla. 33125. shall be agreed upon between the purchaser and the producer.
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Please contact ASTM International (www.astm.org) for the latest information.
ϵ1
E 235 – 88 (1996)
TABLE 2 Insulation Resistance
Applied D-C Voltage Required Minimum
Sheath Outside Diameter, in. (mm) (Both Direct and Insulation Resistance at
Reversed Polarity) Room Temperature, MΩ
0.040 to 0.058 (1.0 to 1.48) 50 V dc (min) 1000
0.059 to 0.250 (1.49 to 6.35) 500 V dc 5000
TABLE 3 Maximum Grain Sizes
5.2.2 Annealing—The sheath of the finished thermocouple
Sheath Outside Diameter, in. (mm) Maximum shall be solution annealed and shall not be sensitized.
0.0400 (1.016) 6
6. Inspection and Test Methods
0.0625 (1.588) 5
0.1250 (3.175) 6.1 General Procedure—Inspect and approve all thermo-
0.1875 (4.763)
couples in accordance with the sampling procedures specified
0.2500 (6.35)
in this section and with inspection requirements stated herein
and in referenced specifications. Acceptance of the sample
inspection results does not relieve the thermocouple manufac-
5.1.2 Thermocouple Wires—Thermocouple wires referred turer of the responsibility that all thermocouples shall conform
to in this specification shall be Type K with standard initial to all requirements of this specification and the latest issue of
calibration tolerance to be used to replace limits of error. the referenced specifications.
6.1.1 Acceptance of thermocouples manufactured in accor-
NOTE 1—The purchaser may specify an alternative type of thermo-
dance with this specification requires the satisfactory comple-
couple wire as designated in Specification E 230E 230 by indicating this
tionofthegeneraltestsspecifiedforallthermocouplesandtwo
deviation in the ordering documents.
additional tests on selected sample thermocouples.
5.1.3 Insulation—The insulating material shall be either
6.1.2 Select a sample thermocouple at random from each“
magnesia (MgO) or alumina (Al O ) and shall comply with
2 3
lot” of thermocouples.A“lot” of thermocouples is defined as a
the following requirements as to composition:
group of 15 thermocouples or fraction thereof, manufactured
5.1.3.1 The magnesia shall be electrically fused with a 99.4
from the same materials in the same production run. Use a
percent minimum content of magnesia and with a maximum
section of the sample thermocouple for the tests required in 6.7
content of boron plus cadmium of 30 ppm. All impurities
and 6.10.2. For the test in 6.10.2, fabricate a measuring
includingboronandcadmiumshallbelessthan6000ppm.The
junction of the same class as that in the original “lot.”
sulfur content shall be less than 50 ppm and the carbon content
Inspection and testing of this measuring junction, such as that
less than 300 ppm.
in 6.3, is not required.
5.1.3.2 Thealuminashallbealphaaluminawithaminimum
6.2 Insulation Resistance—The electrical resistance be-
contentof99.5 %alumina.Themaximumboronpluscadmium
tween conducting wires and between each conducting wire and
content shall be 30 ppm. Sulfur shall not exceed 50 ppm while
the sheath shall be in accordance withTable 2, with the applied
carbonshallnotexceed300ppm.Allimpuritiesinthealumina,
voltage specified (both direct and reversed polarity) before
including the boron and cadmium, shall be no more than 5000
closures on both Class 1 and Class 2 thermocouples for a
ppm.
thermocouple length not exceeding 50 ft (15 m). This section
5.1.3.3 A certified analysis of the composition of the insu-
also applies to completed Class 1 thermocouples in the respect
lating material as supplied to the thermocouple manufacturer
thatthepurchasermayselectasamplethermocouplefromeach
shall be furnished to the purchaser. The thermocouple manu-
lot and remove the measuring junction to perform the test and
facturer shall be responsible for maintaining the purity within
exercise due caution to prevent moisture pickup. If the ther-
the specified limits in the finished product.
mocouple fails this test, reject the“ lot” of thermocouples. This
5.1.4 Welding Rod—Filler rod material used for welding on
section also applies to completed Class 2 thermocouples with
the sheath or thermocouple closures shall comply with the
respect to the insulation resistance between wires and sheath;
requirements of AWS Specification A 59 for the tubing mate-
in this case the purchaser may accept or reject thermocouples
rial specified on the ordering documents.
individually.
5.2 Processing:
6.3 Radiographic Inspection:
5.2.1 Cleanliness—The surface of the completed thermo-
6.3.1 Examine a length of the fabricated thermocouple
couples at the time of delivery shall be free of residues
extending a minimum of 4 in. (102 mm) from the measuring
containing nuclear poisons, such as boron and cadmium
junction, including the weld closure, by radiography to deter-
compounds, or foreign substances, such as chlorine com-
mine that the dimensions are in conformance with Table 1 and
pounds, strong acids, bases, oils, greases, or dust that could
that any defects do not exceed the requirements in 6.3.1.1 and
become the source of corrosion or chemistry changes in a
6.3.1.2:
primary coolant or heat-transfer medium. The use of com-
pounds containing halogens is prohibited for final cleaning. 6.3.1.1 Cracks, voids, or inclusions in the sheath wall
Alcohol, or methyl isobutyl ketone may be used unless greater than 15 % of the sheath wall thickness, or 0.002 in.
otherwise specified. (0.05 mm), whichever is greater,
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Please contact ASTM International (www.astm.org) for the latest information.
ϵ1
E 235 – 88 (1996)
6.3.1.2 Cracks, voids, inclusions, discontinuities, or local dance with Methods E 3E3. The sheath material at the
reductionoftheconductors,insulation,orsheathdiameterinor mounted specimen shall not contain evidence of cracks or
near the thermal junction greater than 0.002 in. (0.05 mm). localized wall thinning when longitudinally sectioned and
6.3.2 Radiograph the thermocouple in two directions 90° examinedbynormalmetallographicpracticeatamagnification
of 200 to 5003 in accordance with Methods E 2E2.
apart and perpendicular to the thermocouple axi
...
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