A castable built on lightweight aggregates such as expanded clay, perlite, vermiculite or bubble alumina, with densities roughly 0.5 to 1.6 g/cm3. It forms the backup layer of dual-layer linings in refinery heaters, ducts, FCC vessels and kilns, behind a dense hot-face castable. It is weak and absorbs water easily, so it needs protection during installation and a careful dry-out.
Dual-layer lining is 100 millimetres of insulating castable behind 50 of dense erosion mix.
Also heard as
- lightweight castable
- LWC
- insulating refractory concrete
Related terms
Castable
Dry refractory mix of aggregate, fines and binder that is mixed with water and poured or pumped like concrete.
Thermal conductivity
How readily a material conducts heat, the number used to size lining layers and predict shell temperature.
IFB
Insulating firebrick: light, porous brick rated by the maximum temperature it can face, such as group 23 or 26.
Dry-out
Controlled first heat-up of a new monolithic lining to drive off water without cracking or spalling.