6.6　Preassembly

6.6.1　It is recommended that each ring of absorber wall plates be preassembled after prefabrication，and bottom and roof plates be generally preassembled after prefabrication.The preassembly platform shall be clean and the flatness tolerance shall not be greater than 2mm.The preassembly shall be stable and reliable.

6.6.2　The permissible perimeter deviation of each ring wall plates shall be 0.3% of corresponding absorber's diameter，and the permissible maximum deviation shall not exceed 30mm.

6.6.3　The permissible perimeter deviation of base plates shall be 0.3% of bottom plates'diameter，and the permissible maximum deviation shall not exceed 30mm.

6.6.4　When the absorber roof is preassembled，the permissible perimeter deviation of bottom ring shall be 0.3% of absorber body's diameter，and the permissible maximum deviation shall not exceed 30mm.