friends nowadays we have stopped our kiln due to redspots and radiations. our kiln length is 72m. we checked and found that refractory from 45m to 47.2m in poor conditions. in this area we use allumina refractory of 220mm so now how 2 designed and install refractory there becouse we noticed that some half pieces ring may also occured there. so upto how much size we can break the bricks to cover all the damaged portion.             Friends what is the maximum allowable shiming work in single ring.