Kiln and steel plant term for a hot spot that has gone far enough for the steel shell to glow dull red, which starts at roughly 500 C and up. On a cement kiln a red spot usually means the brick is gone in that area and the shell is at risk of permanent deformation, so most plants stop the kiln promptly. On a ladle or furnace it means the safety lining is exposed and the vessel comes out of service.
Red spot showing on the burning zone after dark, get the kiln down before the shell warps.
Also heard as
- red shell
- glowing shell
Related terms
Hot spot
Area of a vessel or kiln shell running hotter than normal because the lining behind it is thin or gone.
Breakout
Escape of molten metal or slag through a failed lining and shell, the most dangerous refractory failure.
Coating
Layer of clinker that sticks to the burning zone brick in a cement kiln and shields it from heat and wear.
Reline
Replacement of a worn refractory lining, in full or in zones, at the end of a campaign.