ASTM C1113-C1113M Testing the Thermal Conductivity of Refractory Materials by Hot Wire Method (Platinum Resistance Thermometer Technique)

ASTM C1113/C1113M Testing the Thermal Conductivity of Refractory Materials by Hot Wire Method (Platinum Resistance Thermometer Technique)

The ASTM C1113/C1113M standard, developed by the American Society for Testing and Materials (ASTM), describes a test method for determining the thermal conductivity of carbon-free, dielectric refractories.

Applicable refractories include refractory bricks, refractory casting materials, plastic refractories, compression mixes, powder materials, granular materials, and refractory fibers.

Thermal conductivity values ​​can be specified from room temperature up to 1500 degrees, or up to the maximum service limit of the refractory or the temperature at which the refractory is no longer a dielectric.

This test method is valid for refractories with values ​​lower than 15 W/m·K.

In general, accurate measurements of anisotropic materials, especially those containing fibers, are difficult, and the use of this test method for such materials should be agreed upon between the relevant parties.

The ASTM C1113/C1113M standard, a widely recognized international standard, provides a standardized procedure for measuring the thermal conductivity of carbon-free, dielectric refractories using the transient hot-wire method with a platinum resistance thermometer.

This standard applies to a wide range of refractory and insulation materials, including:

• Refractory bricks
• Refractory castings and monolithic refractories
• Plastic refractories and compression mixtures
• Powder, granular and fibrous materials
• Sheet materials (in some applications)

This standard is generally suitable for materials with thermal conductivity values ​​below 15 W/m·K. Measurements can be taken from room temperature up to 1500 degrees or up to the maximum operating temperature of the material or the point at which it loses its dielectric properties. Unless the parties agree on its use, this standard is generally not ideal for highly anisotropic materials (e.g., those with oriented fibers).

The hot-wire technique is a transient, intermittent isothermal method (unlike steady-state methods such as water-cooled calorimetry approaches described in ASTM C201 or ASTM C182 standards).

The working principle is as follows:

• A thin platinum wire (which also serves as a resistance thermometer) is placed between two identically prepared samples (usually two approximately 23 cm bricks of the same density).
• A constant current is passed through the wire, generating heat.
• Heat radiates to surrounding material at a rate dependent on the thermal conductivity of the material.
• The temperature increase in the wire (measured through the change in electrical resistance) is recorded over time.
• Thermal conductivity is calculated from the temperature-time relationship, usually by using the slope of the logarithm of the temperature with respect to time on the linear portion of the curve.

This method allows for temperature measurements to be taken instead of averaging temperature values ​​along large gradients.

Industries that rely heavily on high-temperature insulation and refractories use this standard extensively. These include:

• Steel and metal production
• Cement and glass production
• Petrochemical and energy production
• Ceramics and kiln making

Advanced testing laboratories offer standard-compliant testing services for product development, quality control, and material certification.

The ASTM C1113/C1113M standard is essential because it provides a standardized method for evaluating the thermal performance of liquid thermal insulation materials, particularly coatings or paints, that are marketed as energy-saving or heat-reducing products. More specifically, this standard helps with the following:

• Establishing a consistent testing method: Without a common standard, manufacturers may test insulation coatings under different conditions and report results that are difficult or impossible to compare. This standard defines how thermal conductivity or thermal resistance should be measured, making results more consistent across laboratories and products.
• Verifying insulation claims: Many liquid-applied insulation products claim to reduce heat transfer, increase energy efficiency, or lower heating, ventilation, and air conditioning (HVAC) costs. This standard provides an objective way to test whether these claims are supported by measurable thermal properties.
• Supporting product certification and regulatory acceptance: Construction materials often require documented performance data to be accepted by building codes, architects, contractors, and certification bodies. This standard provides recognized test data that can be used in technical documentation and compliance filings.
• Helping with material comparison: Engineers and buyers need to compare different insulation materials such as conventional insulation, foams, blankets, or coatings. A standardized testing method allows for a fair comparison of thermal resistance values.
• Improving quality control: Manufacturers can use this standard during production to ensure batch consistency. If there are deviations in thermal properties, the test helps identify production or formulation problems.
• Risk reduction in construction and industrial applications: In pipelines, tanks, HVAC systems, and building facades, improper thermal performance can lead to condensation, energy loss, overheating, or inefficient operation. This standard helps ensure materials perform as expected before installation.

In short, the ASTM C1113/C1113M standard is important because it transforms thermal insulation performance from a marketing claim into measurable engineering data.

In conclusion, this testing method remains a critical tool for engineers and manufacturers working with high-temperature insulation, helping to optimize energy efficiency and thermal performance in challenging industrial environments.

For many years, our organization, with its competent and experienced team, has been understanding the needs of its clients, providing the advanced testing services they require, and assisting them in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services in accordance with the ASTM C1113/C1113M standard.