ASTM E2181/E2181M-01

Standard Specification for Compacted Mineral-Insulated, Metal-Sheathed, Noble Metal Thermocouples and Thermocouple Cable

SCOPE
1.1 This specification establishes dimensional and material requirements for compacted, mineral-insulated, metal-sheathed, Type S (platinum-10 % rhodium versus platinum), Type R (platinum-13 % rhodium versus platinum), and Type B (platinum-30 % rhodium versus platinum-6 % rhodium) noble metal thermocouples. This specification also establishes dimensional and material requirements for compacted, mineral-insulated, metal-sheathed cable with at least one noble metal thermoelement pair.
1.2 This specification describes both the required processing and testing requirements and also the optional supplementary testing and quality assurance requirements.
1.3 Provisions are made for selecting the type of noble metal thermocouple or thermoelements, either magnesia (MgO) or alumina (Al 2O3) insulation, and a noble metal alloy or other alternate heat-resistant sheath material. Provisions are also made for selecting a thermocouple measuring junction configuration and for a transition or termination.
1.4 The values stated in inch-pound units or SI (metric) units may be regarded separately as standard. The values stated in each system are not the exact equivalents, and each system shall be used independently of the other.
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 requirements prior to use.

General Information

• Status: Historical
• Publication Date: 09-Dec-2001
• ICS: 29.060.20 - Cables
• ICS: 29.120.30 - Plugs, socket-outlets, couplers
• Technical Committee: E20 - Temperature Measurement

Relations

• Replaced By: ASTM E2181/E2181M-06 - Standard Specification for Compacted Mineral-Insulated, Metal-Sheathed, Noble Metal Thermocouples and Thermocouple Cable
• Effective Date: 01-May-2006
• Referred By: ASTM E2846-20 - Standard Guide for Thermocouple Verification
• Effective Date: 10-Dec-2001
• Referred By: ASTM E780-17(2021) - Standard Test Method for Measuring the Insulation Resistance of Mineral-Insulated, Metal-Sheathed Thermocouples and Mineral-Insulated, Metal-Sheathed Cable at Room Temperature
• Effective Date: 10-Dec-2001
• Referred By: ASTM E839-11(2016)e1 - Standard Test Methods for Sheathed Thermocouples and Sheathed Thermocouple Cable
• Effective Date: 10-Dec-2001
• Referred By: ASTM E1350-18(2023) - Standard Guide for Testing Sheathed Thermocouples, Thermocouple Assemblies, and Connecting Wires Prior to, and After Installation or Service
• Effective Date: 10-Dec-2001
• Referred By: ASTM E230/E230M-17 - Standard Specification for Temperature-Electromotive Force (emf) Tables for Standardized Thermocouples
• Effective Date: 10-Dec-2001
• Referred By: ASTM E1652-21 - Standard Specification for Magnesium Oxide and Aluminum Oxide Powder and Crushable Insulators Used in the Manufacture of Base Metal Thermocouples, Metal-Sheathed Platinum Resistance Thermometers, and Noble Metal Thermocouples
• Effective Date: 10-Dec-2001

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 2181/E 2181M – 01
Standard Specification for
Compacted Mineral-Insulated, Metal-Sheathed, Noble Metal
Thermocouples and Thermocouple Cable
This standard is issued under the fixed designation E 2181/E 2181M; 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 2.2 ASTM Standards:
A 213/A 213M Specification for Seamless Ferritic andAus-
1.1 This specification establishes dimensional and material
tenitic Alloy-Steel Boiler, Superheater, and Heat-
requirements for compacted, mineral-insulated, metal-
Exchanger Tubes
sheathed, Type S (platinum-10 % rhodium versus platinum),
A 249/A 249M Specification for Welded Austenitic Steel
Type R (platinum-13 % rhodium versus platinum), and Type B
Boiler, Superheater, Heat-Exchanger, and Condenser
(platinum-30 % rhodium versus platinum-6 % rhodium) noble
Tubes
metal thermocouples. This specification also establishes di-
A 269 Specification for Seamless and Welded Austenitic
mensional and material requirements for compacted, mineral-
Stainless Steel Tubing for General Service
insulated, metal-sheathed cable with at least one noble metal
A 632 Specification for Seamless and Welded Austenitic
thermoelement pair.
Stainless Steel Tubing (Small-Diameter) for General Ser-
1.2 Thisspecificationdescribesboththerequiredprocessing
vice
and testing requirements and also the optional supplementary
B 163 Specification for Seamless Nickel and Nickel Alloy
testing and quality assurance requirements.
Condenser and Heat-Exchanger Tubes
1.3 Provisions are made for selecting the type of noble
B 167 Specification for Nickel-Chromium-IronAlloy (UNS
metal thermocouple or thermoelements, either magnesia
N06600, N06601, and N06690) Seamless Pipe and Tube
(MgO) or alumina (Al O ) insulation, and a noble metal alloy
2 3
B 516 Specification for Welded Nickel-Chromium-Iron Al-
or other alternate heat-resistant sheath material. Provisions are
loy (UNS N06600, UNS N06603, UNS N06025, and UNS
also made for selecting a thermocouple measuring junction
N06045) Tubes
configuration and for a transition or termination.
E 165 Test Method for Liquid Penetrant Examination
1.4 The values stated in inch-pound units or SI (metric)
E 220 Method for Calibration of Thermocouples by Com-
units may be regarded separately as standard.The values stated
parison Techniques
in each system are not the exact equivalents, and each system
E 230 Specification for Temperature—Electromotive Force
shall be used independently of the other.
(EMF) Tables for Standardized Thermocouples
1.5 This standard does not purport to address all of the
E 344 Terminology Relating to Thermometry and Hydrom-
safety concerns, if any, associated with its use. It is the
etry
responsibility of the user of this standard to establish appro-
E 608/E 608M Specification for Mineral-Insulated, Metal-
priate safety and health practices and determine the applica-
Sheathed Base Metal Thermocouples
bility of regulatory requirements prior to use.
E 839 Test Methods for Sheathed Thermocouples and
2. Referenced Documents
Sheathed Thermocouple Material
E 1652 Specification for Magnesium Oxide and Aluminum
2.1 The following documents of the latest issue form a part
Oxide Powder and Crushable Insulators Used in the
of this specification to the extent specified herein. In the event
of a conflict between this specification and other specifications
referenced herein, this specification shall take precedence.
1 2
This specification is under the jurisdiction of ASTM Committee E20 on Annual Book of ASTM Standards, Vol 01.01.
Temperature Measurement and is the direct responsibility of Subcommittee E20.04 Annual Book of ASTM Standards, Vol 02.04.
on Thermocouples. Annual Book of ASTM Standards, Vol 03.03.
Current edition approved Dec. 10, 2001. Published February 2002. Annual Book of ASTM Standards, Vol 14.03.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E 2181/E 2181M
FIG. 2 Examples of Alternating Configurations
FIG. 1 Examples of Adjacent Configurations
Manufacture of Metal-Sheathed Platinum ResistanceTher-
3.2.5 lot, n—quantity of finished mineral-insulated, metal-
mometers, Base Metal Thermocouples, and Noble Metal
sheathed thermocouples, or length of thermocouple cable
Thermocouples
manufactured from tubing from the same heat, wire from the
E 1751 Guide for Temperature-Electromotive Force (EMF)
same spool and heat, and insulation from the same batch, then
Tables for Non-Letter Designated Thermocouple Combi-
assembled and processed together under controlled production
nations
conditions to the required final configuration.
2.3 ANSI Standard:
3.2.6 raw material, n—tubing, insulation, and wires used in
B46.1 Surface Texture
fabrication of the sheathed thermocouples or thermocouple
2.4 AWS Standard:
cable.
A5.14 Specification for Nickel and Nickel-Alloy Bare
Welding Rods and Electrodes
4. Significance and Use
4.1 Type S, R, and B noble metal thermocouples are
3. Terminology
generallyspecifiedforusewhentemperaturesexceedtheupper
3.1 Definitions—The definitions given in Terminology
recommended operating temperatures of base metal thermo-
E 344 shall apply to this specification.
couples (see Specification E 608/E 608M).
3.2 Definitions of Terms Specific to This Standard:
4.2 To optimize elevated temperature stability, Type S, R,
3.2.1 adjacent thermoelement configuration,
and B thermocouples should be supplied with noble metal
n—thermoelement configuration within a multi-pair thermo-
sheaths (see 6.3.1). Purchasers and users are cautioned that if
coupleorcablewheretwoormorepositivethermoelementsare
Type S, R, and B thermocouples are supplied with base metal
immediatelyadjacenttooneanotheraroundthecircularpattern
sheaths, such as 300 series stainless steels or other heat-
andtwoormorenegativethermoelementsarealsoimmediately
resistant nickel-chrome alloys, and are used at temperatures
adjacent to one another around the circular pattern as shown in
exceeding 600 °C [1100 °F], they will be more susceptible to
Fig. 1 (compare with alternating thermoelement configuration
drift and the development of inhomogeneity. The higher the
in Fig. 2).
temperature, the more pronounced the drift and the effects of
3.2.1.1 Discussion—By default, a multi-pair thermocouple
this inhomogeneity. In some cases, the elevated temperature
or cable with a thermoelement in the center must be considered
performance of a noble metal thermocouple with a base metal
an adjacent configuration.
sheath will be inferior to that of a base metal thermocouple
3.2.2 alternating thermoelement configuration,
with a base metal sheath.
n—thermoelement configuration within a multi-pair thermo-
couple or cable where positive thermoelements and negative
5. Ordering Information and Basis for Purchase
thermoelements alternate around the circular pattern as shown
in Fig. 2 (compare with adjacent thermoelement configuration 5.1 The purchasing documents shall specify the following
for both thermocouples and cable:
in Fig. 1).
5.1.1 The nominal outside diameter of the sheath (see Table
3.2.2.1 Discussion—In an alternating thermoelement pat-
1).
tern, there are never two or more positive thermoelements nor
5.1.2 The type and quantity of noble metal thermoelements
two or more negative thermoelements immediately adjacent to
(see 6.1). Note that non-letter designated noble metal thermo-
one another.
elements (that is, other than Types S, R, and B) may be used
3.2.3 common ungrounded junction, n—measuring junc-
upon purchaser and producer agreement.
tions within the same multi-pair thermocouple that are electri-
5.1.3 The kind of ceramic insulation (see 6.2). Note that
callyisolatedfromthesheathbutelectricallyconnectedtoeach
other insulation composition and impurity levels may be used
other.
with purchaser and producer agreement.
3.2.4 isolated ungrounded junction, n—measuringjunctions
within the same multi-pair thermocouple that are electrically 5.1.4 The kind of sheath material (see 6.3), and whether it
shall be seamless or welded and drawn. Note that other sheath
isolated from the sheath and electrically isolated from each
other. material may be used with purchaser and producer agreement.
5.1.5 The intended operating temperature range of the
thermocouple or cable (see 8.1.5).
Available from American National Standards Institute, 25 W. 43rd St., 4th
5.1.6 The tolerance of initial values of emf versus tempera-
Floor, New York, NY 10036.
ture if other than standard for Types S, R, and B thermo-
AvailablefromtheAmericanWeldingSociety(AWS),2501NorthWest7thSt.,
Miami, FL 33125. couples, or the emf versus temperature relationship and initial
E 2181/E 2181M
TABLE 1 Preferred Outside Diameters, A, for Thermocouples and
Cable in SI (Metric) and Inch-Pound Units
Diameter
millimetres inches
0.50 0.020
. . . 0.032
1.00 0.040
1.50 0.062
2.00 . . .
. . . 0.093 FIG. 3 Sheathed Thermocouple Cable
3.00 0.125
4.50 0.188
6.00 0.250
8.00 0.375
tolerance values if other than Type S, R, or B thermocouples
(see 8.1.5 and Guide E 1751).
5.1.7 Optional supplementary testing and test sample rates
or optional material requirements (see Supplementary Require-
ments).
5.1.8 Packagingmethodandstraightnesscriteria,ifrequired
FIG. 4 Sheathed Thermocouple with Exposed Thermoelements
(see 11.3).
5.1.9 The quality assurance and verification program re-
quirements (see Appendix X1).
5.1.10 Any deviations from this specification or its Refer-
enced Documents.
5.2 In addition, the purchasing documents shall specify the
following if purchasing thermocouples:
5.2.1 The type of measuring junction, Class 1 (grounded) or
Class 2 (ungrounded). See Figs. 8 and 9. If more than one pair
of thermoelements is specified, Class 2 is further subdivided
FIG. 5 Sheathed Thermocouple Assembly with Connector or
into Class 2A (common ungrounded) and Class 2B (isolated
Connection Head (any Type Specified)
ungrounded).
5.2.2 The quantity, sheath length, and sheath length toler-
ance of each thermocouple. See Figs. 3-6 for examples.
5.2.3 The type and configuration of connection head, con-
nector, transition piece, or termination, and moisture seal
required on the end opposite the measuring junction. See Figs.
3-6 for examples. The minimum and maximum intended
operating temperature of the connection head, transition, ter-
FIG. 6 Sheathed Thermocouple Assembly with Transition Piece
mination, or moisture seal should be specified (see 6.5). For
thermocouples with insulated wire attached (see Fig. 6) and
Class 2 junctions, state the minimum acceptable insulation
resistance (see 8.1.3.2).
5.3 In addition, the purchasing documents shall specify the
following if purchasing thermocouple cable:
5.3.1 The thermoelement configuration (see 3.2.1 and
3.2.2). Consult individual manufacturers for the available
number of thermoelements within a cable size.
FIG. 7 Sheathed Thermocouple Construction
5.3.2 The total length and tolerance of finished thermo-
couple cable, and the length and length tolerance of each piece
of finished thermocouple cable. 6.1.2 Thethermoelementsshallbesolidwire,roundincross
5.3.3 The kind of end seal applied to the open ends, prior to section. All wire used for fabrication shall meet the supple-
shipment (see 11.1). mental cleanliness requirements of SpecificationA 632, except
that acetone or any other solvents that might leave a harmful
6. Material and Manufacturing Requirements
residue shall not be used for final cleaning.
6.1 Thermoelements: 6.1.3 The initial emf versus temperature relationship for
6.1.1 The thermoelements shall only be noble metal, and Type S, R, and B thermoelements shall satisfy the standard
shall be of thermoelectric types S, R, or B unless otherwise tolerance specified by Specification E 230 unless otherwise
agreed upon between purchaser and producer. stated in the ordering information.
E 2181/E 2181M
FIG. 8 Grounded Measuring Junction, Class 1
FIG. 9 Ungrounded Measuring Junction, Class 2
6.2 Insulation: 6.3.3 Each piece of tubing shall meet the supplemental
6.2.1 The insulation shall only be magnesia (MgO) or cleanliness requirements of Specification A 632, except that
alumina (Al O ) conforming to Specification E 1652. Unless acetone or any other solvents that might leave a harmful
2 3
otherwise agreed upon between purchaser and producer, only residue may not be used for final cleaning.
Type 1 magnesia or Type 1 alumina shall be used. See 8.2.13
6.3.4 The sheath shall be free of visible surface contami-
and Supplementary Requirement S11.
nants and oxidation and shall be in the fully annealed state.
6.2.2 The minimum density of the compacted insulation
Tests for proving conformance are in Supplementary Require-
shall be 70 % of the maximum theoretical density which is
ment S7 or S12.
3 3 3
3580 kg/m [0.129 lb/in. ] for MgO, and 3970 kg/m [0.144
6.3.5 The sheath of the finished thermocouple or cable shall
3 8
lb/in. ]forAl O . See8.2.12andSupplementaryRequirement
2 3
exclude gases and liquids. There shall be no holes, cracks, or
S10.
other void defects that penetrate through the sheath wall. Tests
6.3 Sheath:
forprovingconformancetothisrequirementareinSupplemen-
6.3.1 The sheath material may be seamless or welded and
tary Requirements S2, S3, S4, and S5.
drawn tubing of platinum, platinum-10 % rhodium, platinum-
6.4 The end closure of thermocouples shall be seal welded
20 % rhodium, or platinum-30 % rhodium. The producer’s
and shall be impervious to gases and liquids. There shall be no
customary tubing specification may be used.
cracks, holes, or void defects that penetrate through the metal
6.3.2 Alternately, heat-resistant nickel-chrome alloy tubing
wall. Any mineral oxide removed during fabrication of the
per Specifications B 163, B 167, or B 516; or 310 or 321
measuring junction shall be replaced with dry oxide of the
stainless steel tubing per SpecificationsA 213/A 213M,A 249/
same type that conforms to the purity requirements of Speci-
A 249M,A 269, orA 632 may be supplied as sheath materials
ficationE 1652.Class2measuringjunctionsshallbefabricated
provided there is an agreement between purchaser and pro-
by welding the thermoelements together without filler metal or
ducer (see 4.2) and the annealing requirements imposed by
flux.The use of plugs or filler metals is optional, provided they
6.3.4 are satisfied. The producer’s customary tubing specifica-
are of the same nominal chemical composition as the sheath
...