O’Donnell Consulting performed FEA and ASME Code Section VIII Division 2 calculations on feedwater heaters. The Feedwater Heater and its components are comprised of carbon, stainless and Cr-Mo steels.
In modelling the heaters, the assumptions included:
• Linear elastic material behavior with small displacements
• The geometry, loading and boundary conditions consistently have one plane of symmetry down the axis of the vessel. Then analyses were completed on a half model of the heater with symmetry boundary conditions applied on the cut boundary. The nozzle was treated as having half symmetry.
• A reduced set of U-tubes was modelled. Properties of the modeled tubes were adjusted to account for the not-modeled tubes.
• The tubesheet was modeled as solid material, with appropriate adjustments in the values of Elastic Modulus and Poisson ratio to account for the effects of the holes.
• No credit was taken to increase the ligament efficiency for the effect of tubes being rolled into the tubesheet holes.
• The portion of the Feedwater Heater near the tubesheet was selected for analysis (rather than model the entire Feedwater Heater).
• No fatigue analysis was performed.
For over 30 years, our team of Engineers has been performing (Finite Element) design, analysis and troubleshooting services to ASME and Other Codes.