Effect of Tubes on Stresses and Deflections in Steam Generator Tubesheets

“The Effect of the Tubes on Stresses and Deflections in U-Tube Steam Generator Tube Sheets”

W. J. O’Donnell, Bettis Technical Review, No. 21, p. 89, November 1960.

Keywords: steam generator; rolled-in tubes; tube sheet; ligament strains

The results of tests run on an actual steam generator tube sheets are used to evaluate the effect of rolled-in tubes on stresses and deflections in the perforated portion of the tube sheet. Measured ligament strains are compared with theoretical values calculated for two cases: (1) assuming that the rolled-in tubes contribute no support to the tube sheet, and (2) assuming that the entire thickness of the rolled-in tubes is effective in stiffening the tube sheet and reducing ligament strains. 

Strain values calculated for Case No. 1 are found to average more than 75% higher than measured strains, and strain values are calculated for Case No. 2 are found to agree with average measured values within about 5%. It is concluded that the tubes contribute substantial support to tube sheets, and this support should be included in design calculations by taking the ID of the as-rolled tubes as the diameter of the perforations.

Company President, Bill, Sr. began his career in the Naval Nuclear Program at Westinghouse/ Bettis. He is active on the ASME Subgroup on Elevated Temperature Design, and the Subcommittee on Design – as well as a Contributing Member of the ASME (BPV III) Working Group on Fatigue Strength. He has also co-authored numerous papers on topics including design, fatigue and fracture.

O’Donnell Consulting performs engineering design and analysis to ASME Code including B&PV Section VIII Division 1 and 2 – as well as the Power & Process Piping Codes. 

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