Join our team! Watlow is hiring. No experience necessary, skilled training provided, great pay, full benefits and advancement opportunities. Click here to visit our career opportunities page and apply today.

Thermal System Prevents Stress Cracking in Refractory

Problem:

To prevent thermal stress cracking a refractory materials processor required pre-heating refractory materials to a minimum 1000°F (540°C) before processing. The heater had to fit inside an 8-inch (20 cm) wide by 54-inch (137 cm) deep refractory, and be capable of keeping the heating profile on a precalculated ramp to prevent thermal shock. A built-in thermocouple was needed to sense inside sheath temperatures.

Solution:

Watlow provided a thermal system solution HT FIREROD® cartridge heaters, a Series 920 ramp and soak temperature controller, a Series 140 high-limit temperature controller, mercury displacement relays, and a Type K thermocouple. The 10 W/in2 (1.5 W/cm2) heaters were spaced three inches (75 mm) center to center to avoid cross radiation. Using Watlow's thermal system kept the refractory heating profile within ±12°F (±6.6°C), eliminating thermal cracking of the refractory.