... 91.00.8application of insulating firebricks: 1.Recommended for use as a primary hot face refractory lining2.as back- ... up insulation behind other refractory in furnace, kilns, flues, ... soaking pits, annealing furnace, catalyst case and similar high temperature industrial equipment. high strength series--Insulating firebricks (TJMC1,B6,C2,B7)