Stress mitigation design of a tubesheet by considering the thermal stress inducement mechanism

Ando, Masanori ; Takasho, Hideki*; Kawasaki, Nobuchika ; Kasahara, Naoto*

The stress generation mechanism of a tubesheet was revealed through finite element analysis. Semi-spherical tubesheet models were investigated for the first survey of the thermal stress mechanism. The calculated results of the semi-spherical tubesheet model indicated an extensive peak stress around the outermost hole. The recognized thermal stress mechanism of a semi-spherical tubesheet is summarized, and on the basis of the stress generation mechanism, we proposed a stress-mitigated tubesheet, a center-flattened spherical tubesheet (CFST), as an improved configuration. The stress generation mechanism of the CFST was also desicibed.