1. Chris Wowk MANE 6970 Master’s Project

2.  The objective of this project was to evaluate the behavior of flat faced cover plate/flange joints using: ◦ Radial Beam Theory (Analytic Solution) ◦ Solid Element Finite Element Models ◦ Shell/Beam Element Finite Element Models  The effect of the following design variables on joint behavior were also investigated: ◦ Bolt pre-stress ◦ Cover plate thickness ◦ Nominal pipe size

3.  ASME B16.5 standard flange/cover plate sizes were used  Typical flange (steel) and bolting (CRES) materials were used

4.  Analytical solution developed by considering the annular portion of the flange and cover plate as a collection of radial beams  Moment diagram allowed for expressions for flange rotations and deflections be determined through integration  Separation of the joint was then calculated

5. Solid Element Model Shell/Beam Element Model

7.  Differences exist in the joint behaviors predicted by the different analysis types ◦ Shell/beam FEA predicted joint separations typically smaller than other methods  Bolt modeling method is the expected causes ◦ RBT not able to predict complete separation between cover plate and flange at zero pre-stress  General conclusions that the different analysis types were in agreement on: ◦ Joint separation decreases as bolt pre-stress and/or cover plate thickness increase ◦ Radial location of contact moves closer to the bolt circle as bolt pre- stress increases  Results from smaller pipe size could not be scaled for larger pipe size (non-linear)

8.  Radial and tangential stresses in the center of the cover plate generally decreased as bolt pre-stress and/or thickness increases  Values differed between the analysis types  FEA results showed increases in stress at 80% yield pre-stress ◦ Cause is unknown – potential element distortion issue

9.  Analysis type matters in evaluating flat faced bolted flange joints  High bolt pre-stress is required to limit separation of flange components and reduce leak potential  Separation can also be reduced by increasing cover plate thickness  Be wary of how you model bolts in FEA

10.  ASME Boiler and Pressure Vessel Code, Section VIII – Rules for Construction of Pressure Vessels, 2013 Edition, Appendix Y.  Galai, H and Bouzid, A.H, “Analytical Modeling of Flat Face Flanges with Metal-to-Metal Contact Beyond the Bolt Circle,” Journal of Pressure Vessel Technology, Vol 132, 2010.  Schneider, R.W, “Flat Face Flanges with Metal-to-Metal Contact Beyond the Bolt Circle,” Transactions of the ASME, Vol 90, 1968, pgs 82-88.  Waters, E.O and Schneider, R.W, “Axisymmetric, Nonidentical, Flat Face Flanges with Metal-to-Metal Contact Beyond the Bolt Circle,” Journal of Engineering for Industry, Vol 91, 1969, pgs 615-622.