boiler scale

boiler scale

[′bȯil·ər ‚skāl] (chemistry) Deposits from silica and other contaminants in boiler water that form on the internal surfaces of heat-absorbing components, increase metal temperatures, and result in eventual failure of the pressure parts because of overheating. Also known as scale.

boiler scale

Metal from the inner surfaces of a boiler which decomposes and flakes off (in much the same manner as rust forms).