The kiln shell is composed of rolling steel into a circular shape then welding the seam
The overall kiln is sized based off many proccess conditions. By these process specifications diameter and length are determined. The kiln sections are sized by what is practical to transport or capabilities of the shop. The sections are then welded together to form the long cylinder we call the kiln. At the shop the sections have alignment tabs welded inside the shell. These alignement tabs help hold and align the shell pieces untill field welded. Once welded the alignment tabs are removed.
It is critical that the kiln shell be as straight as possible. All drive and carrying components must be matched with size and tolerances. If mismatch or misalignment occurs refractory lining life can be drastically reduced because of stress and deformity on the shell.
If refractory lining is to thin or missing excessive heat can be applied to the shell. This heat can cause damage depending on the amount and time of heat applied. In some cases shell can be warped or blistered. 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. We call this bananaing.
Kiln shell sectional can be replaced. This requires the existing shell to be supported while the section is replaced.
More information on Kiln seals
Kiln services to analyze kiln
For kiln parts