Refractory brick or mix made mainly from kaolinitic clays, with roughly 25 to 45 percent alumina, the rest mostly silica. In US practice fireclay brick is graded low, medium, high and super duty by pyrometric cone equivalent, strength and reheat change, with super duty reaching at least cone 33. It is cheap, easy to install and resists thermal shock well, so it lines boilers, incinerators, stacks, blast furnace stacks and the cooler parts of many kilns.
Back-up course is super duty fireclay, the hot face is 70 percent alumina.
Also heard as
- firebrick
- fireclay brick
- super duty
- high duty
Related terms
High-alumina brick
Alumina-silica brick with more than 45 percent alumina, graded in steps such as 50, 60, 70, 80 and 90 percent.
Grog
Pre-fired clay or crushed brick added as aggregate to cut shrinkage and cracking in refractory bodies.
PCE
Pyrometric cone equivalent: a refractory's softening point expressed as the number of a matching standard cone.
Hard brick
Shop name for dense firebrick, as opposed to lightweight insulating soft brick.