3.1 This test method indicates the ability of a refractory product to withstand the stress generated by sudden changes in temperature.

3.2 Because the recommended furnace temperature of this cycling test is 1200 °C (2190 °F), this test method may not indicate the ability of a refractory product to withstand cycling at higher or lower temperatures, especially if the existing morphology of the refractory product changes.

3.3 This test method is useful for research and development, as well as for comparing refractory products. The precision should be considered when using this test for specification purposes.

3.4 Ruggedness tests found the following variables to be rugged:

Temperature

+5 °C

Hot spacing

¹/₂ to ³/₄ in. (12.77 to 19 mm)

Cold spacing

¹/₂ to ³/₄ in. (12.77 to 19 mm)

Center versus end gripping of the bars

Hot hold time

10 to 15 min

Cold hold time

10 to 15 min

Operator air speed

0 to 2 mi/h (0 to 3.2 km/h)

Initially cold or heated samples

Last in, first out (LIFO); or first in, first out (FIFO)
 removal from the furnace

Sawed or original surface as tensile face during MOR testing

Bar thickness

0.96 to 1.04 in. (24.5 to 26.4 mm)

1.1 This test method is used for determining the strength loss or reduction in continuity, or both, of prism-shaped specimens which are cut from refractory brick or shapes and subjected to thermal cycling.

1.2 The strength loss is measured by the difference in modulus of rupture (MOR) between uncycled specimens and the specimens subjected to thermal cycling.

1.3 The reduction in structural continuity is estimated by the difference in sonic velocity before and after thermal cycling.

1.4 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.

1.5 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.6 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.