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 vs. 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) | |
| sawed or original surface as tensile face during MOR testing | |
| bar thickness | 0....... |