This test method is primarily used to determine the resistance of the enamel layer of glass-lined flat specimens to sudden temperature changes. The core principle involves heating the sample to a specific temperature, then rapidly quenching it in cold water. The resistance to thermal shock is assessed by observing whether cracks, peeling, or other damage occurs in the glass-lined layer. Key instruments involved in the test include a constant-temperature furnace for precise heating and temperature control, as well as high-precision thermometers and thermocouple temperature measuring devices for temperature measurement. It should be noted that this standard has been abolished, and its technical content has been completely replaced and integrated into a new standard.