ASTM C767-20

Standard Test Method for Thermal Conductivity of Carbon Refractories

SIGNIFICANCE AND USE
3.1 The thermal conductivity of carbon refractories is a property required for selecting their thermal transmission characteristics. Users select carbon refractories to provide specified conditions of heat loss and cold-face temperature without exceeding the temperature limitation of the carbon refractory. This test method establishes placement of thermocouples and positioning of test specimens in the calorimeter.  
3.2 This procedure must be used with Test Method C201 and requires a large thermal gradient and steady state conditions. The results are based upon a mean temperature.  
3.3 The data from this test method is suitable for specification acceptance, estimating heat loss and surface temperature, and the design of multi-layer refractory construction.  
3.4 The use of these data requires consideration of the actual application environment and conditions.
SCOPE
1.1 This test method supplements Test Method C201, and shall be used in conjunction with that test method to determine the thermal conductivity of carbon or carbon-bearing refractories. This test method is designed for refractories having a conductivity factor of not more than 200 Btu·in./h·ft2·°F (28.8 W/m·K).  
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.  
1.3 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Mar-2020
• ICS: 71.100.99 - Other products of the chemical industry
• ICS: 81.080 - Refractories
• Technical Committee: C08 - Refractories
• Drafting Committee: C08.02 - Thermal Properties

Relations

• Replaces: ASTM C767-93(2013) - Standard Test Method for Thermal Conductivity of Carbon Refractories
• Effective Date: 01-Apr-2020
• Refers: ASTM E220-13 - Standard Test Method for Calibration of Thermocouples By Comparison Techniques
• Effective Date: 01-Nov-2013
• Refers: ASTM C155-97(2013) - Standard Classification of Insulating Firebrick
• Effective Date: 01-Sep-2013
• Refers: ASTM C201-93(2013) - Standard Test Method for Thermal Conductivity of Refractories
• Effective Date: 01-Sep-2013
• Refers: ASTM C201-93(2009) - Standard Test Method for Thermal Conductivity of Refractories
• Effective Date: 01-Mar-2009
• Refers: ASTM E220-07a - Standard Test Method for Calibration of Thermocouples By Comparison Techniques
• Effective Date: 01-Nov-2007
• Refers: ASTM E220-07 - Standard Test Method for Calibration of Thermocouples By Comparison Techniques
• Effective Date: 01-May-2007
• Refers: ASTM E220-07e1 - Standard Test Method for Calibration of Thermocouples By Comparison Techniques
• Effective Date: 01-May-2007
• Refers: ASTM C155-97(2007) - Standard Classification of Insulating Firebrick
• Effective Date: 01-Mar-2007
• Refers: ASTM C201-93(2004) - Standard Test Method for Thermal Conductivity of Refractories
• Effective Date: 01-Sep-2004
• Refers: ASTM E220-02 - Standard Test Method for Calibration of Thermocouples By Comparison Techniques
• Effective Date: 10-May-2002
• Refers: ASTM C201-93(1998) - Standard Test Method for Thermal Conductivity of Refractories
• Effective Date: 10-Sep-1998
• Refers: ASTM C155-97 - Standard Classification of Insulating Firebrick
• Effective Date: 10-Feb-1997
• Refers: ASTM C155-97(2002) - Standard Classification of Insulating Firebrick
• Effective Date: 10-Feb-1997
• Refers: ASTM E220-86(1996)e1 - Standard Test Method for Calibration of Thermocouples By Comparison Techniques
• Effective Date: 10-Nov-1996

Overview

ASTM C767-20: Standard Test Method for Thermal Conductivity of Carbon Refractories is a key international standard developed by ASTM for assessing the thermal conductivity of carbon and carbon-bearing refractory materials. This method is essential for determining how carbon refractories transmit heat, making it critical for industries that require precise control over heat flow and temperature stability. ASTM C767-20 supplements ASTM C201 and is specifically designed for refractories with a conductivity factor not exceeding 200 Btu·in./h·ft²·°F (28.8 W/m·K).

Engineers, manufacturers, and buyers rely on this standard to evaluate refractory performance, ensure specification compliance, and inform advanced refractory design. By providing robust guidance on specimen preparation, thermocouple placement, and test conditions, ASTM C767-20 enhances the reliability and consistency of thermal conductivity results.

Key Topics

• Thermal Conductivity Measurements: Defines procedures to measure how efficiently carbon refractories conduct heat in controlled laboratory conditions.
• Test Setup and Specimen Preparation: Specifies placement of thermocouples, arrangement of insulation materials, and calorimeter assembly in conjunction with ASTM C201.
• Steady-State and Thermal Gradient Requirements: Outlines the need for a large thermal gradient and steady-state heat flow to obtain accurate results.
• Operational Environment: Emphasizes the importance of a nonoxidizing atmosphere (typically maintained with argon) and describes measures to prevent oxygen contamination during testing.
• Data Application and Limitations: Advises users to consider the actual service environment and conditions when applying test data for specification acceptance and refractory design.

Applications

The ASTM C767-20 test method supports a range of practical applications across various high-temperature industries, such as:

• Specification Acceptance: Enables manufacturers and purchasers to verify that carbon refractories meet the required thermal conductivity specifications before deployment in service.
• Heat Loss Estimation: Assists engineers in estimating heat loss and cold-face temperature, which is vital for energy-efficient furnace, kiln, and reactor design.
• Multi-layer Refractory Construction: Provides critical data for designing advanced, multi-layer refractory linings, ensuring optimal heat management and protection of underlying structures.
• Performance Benchmarking: Offers a standardized approach to compare different carbon-based refractory products, supporting procurement and quality assurance processes.

Related Standards

In order to perform accurate and standardized testing, ASTM C767-20 references several other standards, including:

• ASTM C201 - Standard Test Method for Thermal Conductivity of Refractories (required in conjunction with C767-20)
• ASTM C155 - Classification of Insulating Firebrick (referenced for insulation materials)
• ASTM E220 - Test Method for Calibration of Thermocouples By Comparison Techniques (for thermocouple calibration)

These related standards, together with ASTM C767-20, form a comprehensive framework for the thermal analysis of refractory materials.

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Keywords: ASTM C767-20, thermal conductivity, carbon refractories, refractory testing, specification acceptance, calorimeter, nonoxidizing atmosphere, high-temperature materials, thermal insulation, ASTM standards.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: C767 − 20
Standard Test Method for
Thermal Conductivity of Carbon Refractories
This standard is issued under the fixed designation C767; 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 characteristics. Users select carbon refractories to provide
specified conditions of heat loss and cold-face temperature
1.1 This test method supplements Test Method C201, and
without exceeding the temperature limitation of the carbon
shall be used in conjunction with that test method to determine
refractory. This test method establishes placement of thermo-
the thermal conductivity of carbon or carbon-bearing refracto-
couples and positioning of test specimens in the calorimeter.
ries. This test method is designed for refractories having a
conductivity factor of not more than 200 Btu·in./h·ft ·°F 3.2 This procedure must be used with Test Method C201
(28.8 W⁄m·K). and requires a large thermal gradient and steady state condi-
tions. The results are based upon a mean temperature.
1.2 The values stated in inch-pound units are to be regarded
as standard. The values given in parentheses are mathematical 3.3 The data from this test method is suitable for specifica-
conversions to SI units that are provided for information only tion acceptance, estimating heat loss and surface temperature,
and are not considered standard. and the design of multi-layer refractory construction.
1.3 This standard does not purport to address all of the
3.4 Theuseofthesedatarequiresconsiderationoftheactual
safety concerns, if any, associated with its use. It is the
application environment and conditions.
responsibility of the user of this standard to establish appro-
4. Apparatus
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
4.1 The apparatus shall consist of that described in Test
1.4 This international standard was developed in accor-
Method C201 with the addition of thermocouples, back-up
dance with internationally recognized principles on standard-
insulation, and refractory fiber paper as described in Section 5
ization established in the Decision on Principles for the
of this test method.
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical 5. Test Specimen and Preparation
Barriers to Trade (TBT) Committee.
5.1 Select the test specimen and prepare in accordance with
Test Method C201.
2. Referenced Documents
5.2 Thermocouples—Calibrated thermocouples shall be
2.1 ASTM Standards:
embedded in the test specimen at two points for measuring the
C155 Classification of Insulating Firebrick
temperature. Thermocouples sheathed with material having
C201 Test Method for Thermal Conductivity of Refractories
low reactivity with carbon must be used. Use the top thermo-
E220 Test Method for Calibration of Thermocouples By
couple for one test only.
Comparison Techniques
5.3 Installation of Thermocouples—The hot junction of the
3. Significance and Use thermocouplesshallbeplacedinthecenterofeach9by4 ⁄2-in.
(228 by 114-mm) face and just below the surface of the test
3.1 The thermal conductivity of carbon refractories is a
specimen. Grooves to receive the wire shall be cut in each 9 by
property required for selecting their thermal transmission
4 ⁄2-in. face of the brick to a depth necessary to embed the
thermocouple just beneath the surface by means of an abrasive
1 wheel. The layout for the grooves allows all of the cold-
This test method is under the jurisdiction of ASTM Committee C08 on
Refractories and is the direct responsibility of Subcommittee C08.02 on Thermal junction ends of the wires to extend from one end of the brick.
Properties. 1
Cut a groove in the center of each 9 by 4 ⁄2-in. face along the
Current edition approved April 1, 2020. Published April 2020. Originally
9-in. dimension and end ⁄4 in. (6 mm) beyond the center.
approved in 1973. Last previous edition approved in 2013 as C767 – 93 (2013).
DOI: 10.1520/C0767-20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Test Method E220 specifies calibration procedures for thermocouples.
Standards volume information, refer to the standard’s Document Summary page on Claud S. Gordon Co., 5710 Kenosha St., Richmond, IL 60071, ⁄16-in. (2-mm)
the ASTM website. sheathed Xactpak thermocouple, Cat. No. 401-2104 or equivalent.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C767 − 20
Before cementing the thermocouples in place, measurements calorimeter section on its 9 by 4 ⁄2-in. (228 by 114-mm) face,
shall be taken to obtain, within 60.01 in. (60.3 mm), the the guard brick placed at the sides of the test specimen so as to
eventual distance between the center lines of the thermocouple completely cover the calorimeter and inner guard area, and the
junctions.Thisshallbedonebymeasuringthe2 ⁄2-in.(64-mm) soap brick placed along the edges of the three brick so as to
dimension of the brick at the location for the hot junctions and completely cover the calorimeter assembly. The small space
deducting the distance between the center line of each junction between the furnace walls and the test brick assembly shall be
in its embedded position and the surface of the brick. filled with granulated insulating firebrick.
5.4 The calorimeter and inner and outer guards shall be
5.6 The silicon carbide slab shall be placed over the 9 by
covered with a 0.50-in. (12.7-mm) thick layer of Group 20
13 ⁄2-in. (228 by 342-mm) area of the t
...

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: C767 − 93 (Reapproved 2013) C767 − 20
Standard Test Method for
Thermal Conductivity of Carbon Refractories
This standard is issued under the fixed designation C767; 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 test method supplements Test Method C201, and shall be used in conjunction with that procedure test method to
determine the thermal conductivity of carbon or carbon-bearing refractories. This test method is designed for refractories having
a conductivity factor of not more than 200 Btu·in./h·ft ·°F (28.8 (28.8 W W/m·K).⁄m·K).
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.
1.3 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
C155 Classification of Insulating Firebrick
C201 Test Method for Thermal Conductivity of Refractories
E220 Test Method for Calibration of Thermocouples By Comparison Techniques
3. Significance and Use
3.1 The thermal conductivity of carbon refractories is a property required for selecting their thermal transmission characteristics.
Users select carbon refractories to provide specified conditions of heat loss and cold face temperature, cold-face temperature
without exceeding the temperature limitation of the carbon refractory. This test method establishes placement of thermocouples
and positioning of test specimens in the calorimeter.
3.2 This procedure must be used with Test Method C201 and requires a large thermal gradient and steady state conditions. The
results are based upon a mean temperature.
3.3 The data from this test method is suitable for specification acceptance, estimating heat loss and surface temperature, and the
design of multi-layer refractory construction.
3.4 The use of these data requires consideration of the actual application environment and conditions.
4. Apparatus
4.1 The apparatus shall be in accordance with consist of that described in Test Method C201 with the addition of thermocouples,
back-up insulation, and refractory fiber paper as described in Section 5 of this test method.
5. Test Specimen and Preparation
5.1 Select the test specimen and prepare in accordance with Test Method C201.
This test method is under the jurisdiction of ASTM Committee C08 on Refractories and is the direct responsibility of Subcommittee C08.02 on Thermal Properties.
Current edition approved Sept. 1, 2013April 1, 2020. Published September 2013April 2020. Originally approved in 1973. Last previous edition approved in 20092013 as
C767 – 93 (2009).(2013). DOI: 10.1520/C0767-93R13.10.1520/C0767-20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C767 − 20
5.2 Thermocouples—Embed calibrated Calibrated thermocouples shall be embedded in the test specimen at two points for
measuring the temperature. Thermocouples sheathed with material having low reactivity with carbon must be used. Use the top
thermocouple for one test only.
5.3 Installation of Thermocouples—Place the The hot junction of the thermocouples shall be placed in the center of each 9 by
4 ⁄2-in. (228 by 114-mm) face and just below the surface of the test specimen. Cut grooves Grooves to receive the wire shall be
cut in each 9 by 4 ⁄2-in. face of the brick to a depth necessary to embed the thermocouple just beneath the surface by means of
an abrasive wheel. The layout for the grooves allows all of the cold-junction ends of the wires to extend from one end of the brick.
1 1
Cut a groove in the center of each 9 by 4 ⁄2-in. face along the 9-in. dimension and end ⁄4 in. (6 mm) beyond the center. Before
cementing the thermocouples in place, take measurements measurements shall be taken to obtain, within 60.01 in. (60.3 mm),
the eventual distance between the center lines of the thermocouple junctions. Do this This shall be done by measuring the 2 ⁄2-in.
(64-mm) dimension of the brick at the location for the hot junctions and deducting the distance between the center line of each
junction in its embedded position and the surface of the brick.
5.4 Cover the The calorimeter and inner and outer guards shall be covered with a 0.50-in. (12.7-mm) thick layer of Group 20
insulating firebrick (see Classification C155) for the purpose of obtaining a higher mean temperature in the test sample than would
result by placing the sample directly over the calorimeter area. Cut and grind the back-up insulation The back-up insulation shall
be cut and ground so as to provide surfaces that are plane and do not vary from parallel by more than 60.01 in. (0.3 mm). Grind
the The sides of the pieces that are to be placed in contact shall be ground plane and at right angles to the horizontal faces. Make
the The joints between the pieces shall be tight without the use of any mortar.
1 1 1
5.5 Place two Two strips of refractory fiber paper 13 ⁄2 by ⁄2 by 0.02 in. (342 by 13 by 0.5 mm) shall be placed along the 13 ⁄2-in.
(343-mm) dimension of the inner guard at the outside edges. Place twelve Twelve strips of refractory fiber paper 2 by ⁄2 by 0.02
in. (51 by 13 by 0.5 mm) shall be placed on the outer guards at inte
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