A parametric study of metal-to-metal contact flanges with optimised geometry for safe stress and no-leak conditions

This paper presents the results of a parametric study of the behaviour of metal-to-metal contact flanges that have different surface profiles. Using a finite element analysis approach, the important stress values in the flange and bolts and flange rotation/displacement have been obtained for variations in flange thickness, bolt pre-stress and taper angle (different surface profiles) whilst maintaining other leading flange dimensions (hub length and hub thickness) constant, when the vessel/flange component is subjected to internal pressure. In addition, results are compared for the flange geometry with no taper angle on the flange surface with the predictions obtained from the appropriate sections of the ASME, PD5500 and new European unfired pressure vessel standard EN 13445 Part 3. Based on the results of this study, the best flange dimensions are recommended for 'no leak' conditions from the joint