With a period of almost 2 and 8 months operation, the refractory bricks installed at the front panel of our pusher type reheating furnace was collapsed (fell down). We suspect the problem was started at the arch bricks on the burner block. The thickness of the wall is 545mm, (230mm -70%Alumina Bricks, 115mm-50%Alumina Bricks, 115mm-Insulation Bricks and 75mm siliminite blocks/ceramic blanket). Our operation is only 5 days a week but we keep furnace temperature at 700degC during nonworking day. What is the probable cause of this problem.