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Which is better - fixed or floating tires?


Which is better - fixed or floating tires?



If the process is such that the temperature difference (delta T) between the shell and the tire at normal operating conditions is less than 40degC(~100degF)then a fixed tire is best. A fixed tire by shrink fit (3mm on the diameter) gives superior service compared to any other method or combination of methods of fixing such as welding, keying, pinning, wedging, etc. When the delta T is higher then a floating or migrating tire is suggested particularly when the process requires a refractory lining inside the tire supported shell. As a rule of thumb when shells are refractory lined migrating tires are used. When no refractory is necessary fixed tires should be used. Migrating or floating tires come with a severe penalty in terms of the comparitively high maintenance that ensues. So unless the process dictates that protection of the refractory is mandated by leaving room for shell expansion within the always less expanding tire, a fixed tire arrangement should be the preference. The ultimate solution for high delta T applications is a splined tire. This configuration leaves room for expansion but also locks the tire from rotating on the shell, hence mechanical maintenance and wear are greatly reduced. The illustration is from a Polysius patent of 1969.



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