The influence of geometric mismatch on steam generator U-bend stresses

The realities of material properties, manufacturing processes and design practices cause geometric mismatches to occur between the steam generator U-tube legs and their holes in the support plates. These offsets of centerlines give rise to additional stresses in the U-tube due to the pinching or spreading of its legs. This paper presents the computational effort using a finite element program done to characterize the stress changes attributable to the net geometric mismatch in a full length row 1 U-tube 22.22 mm [0.875 in] O.D. and 1.27 mm [0.050 in] uniform wall thickness under full operating temperature and pressure. A previous paper by the author [ 1 ] covered the classical approach to the U-bend analys is.