Radiant tube is essential equipment for new heat-treatment furnace in steel rolling mill, such as normalizing furnace, etc. Sisic with its good physical property is an ideal radiant tube material (within 1380 centigrade degree). Sisic radiant tube (protective tube) advantages high corrosion resistance, oxidative resistance, and good creep property in high temperature, etc. Its thermal conductivity is about 4 to 6 times of high temperature metal. It is widely approved by heat-treatment industry for its long life cycle and high temperature flux capacity (reduce fuel consumption).