Kiln shell segments are a part of the tubular casing of a rotary kiln which is made from boiler quality graded steels. The plate of desired thickness is rolled into a cylindrical shape and then welded on the joint seam. The entire rotary kiln comprises of a number of kiln shell segments of varying lengths depending upon the total kiln length. Individual kiln shells are transported to the respective project site where they are methodically welded together. This is mainly due to the convenience in transportation as a complete rotary kiln is too large to be transported in assembled condition. The overall kiln is sized based on the process conditions, type of material processed and capacity requirements. These specifications determine the diameter, length and thickness of the kiln shells. The sections have alignment tabs welded inside the shell to hold and align the shell pieces until finally welded together after which the alignment tabs are removed. It is critical that the kiln shell be as straight as possible. It is also important that the drive components such as girth gear and kiln supporting components such as riding rings / kiln tyres and supporting rollers are to be within specified tolerances. If mismatch or misalignment occurs the life of refractory lining can be drastically reduced because of stress and deformity on the shell. If refractory lining is of insufficient thickness or missing excessive heat can cause damage to the kiln shells depending on the quantum of heat. Even under normal operation the heat released requires the kiln to stay continually rotating. If the kiln stops rotating, it can sag in between the support rollers. It is a common practice to replace kiln shell sections which are damaged beyond repair. This requires the existing shell to be supported while the section is replaced.