William J. Koves

Flange Joint Bolt Spacing Requirements

The bolted flange joint assembly is a complex system. System stresses are dependent on elastic and nonlinear interaction between the bolting, flange and gasket. The ASME Code design rules provides a method for sizing the flange and bolts to be structurally adequate for the specified pressure design conditions and are based on an axi-symmetric analysis of a flange. The ASME rules do not address the circumferential variation in gasket and flange stress due to the discrete bolt loads. Proper bolt spacing is important to maintain leak tightness between bolts and to avoid distorting the flange. This paper provides an analytical solution for the gasket and flange stress variation between bolts. The analytical solution is validated with 3-D Finite Element solutions of standard flange designs.Copyright

A Simplified Approach to Finite Element Modeling of Anisotropic Screens

Structural pressure vessel internals such as flow inlet/outlet baskets, bed supports etc. often use anisotropic screens with wires (or beams) oriented in mutually orthogonal directions. Discrete modeling of the screen details result in excessive model size and prohibitive computing costs. It is preferable to model the structural response of these screens using an anisotropic plate. Commercial FEA codes offer linear elastic models with anisotropic inputs. Elastic coefficients for use in the commercial code ABAQUS™ were developed using anisotropic plate theory and were validated by comparing results from rigorous, discrete beam FEA models with isotropic material properties to anisotropic shell element models for static load, vibration and buckling analyses with various edge boundary conditions. Some of the limitations of the application of this particular method are discussed. Further, a procedure is outlined to extract discrete elastic screen stresses from the anisotropic results.Copyright

Design for Leakage in Flange Joints Under External Loads

This paper uses an analytical model based on the Pressure Vessel Research Council (PVRC) ROTT test gasket constants to compute leakage in gasketed flange joints subjected to internal pressure and external bending moments. The model results are compared with test data and design recommendations are made, consistent with the ASME/PVRC tightness based methodology.Copyright

PVRC Activities Supporting the Development of ASME Codes and Standards

This panel session provides a forum to discuss the future directions of the ASME Boiler and Pressure Vessel Codes. Historically the Pressure Vessel Research Council (PVRC) has played a strong role in providing the technology base for changes and advancements in the ASME Codes, and any discussion of the future direction of the ASME Codes would be incomplete without mention of PVRC activities. The topic of this discussion is the current structure of PVRC, and its relationship with ASME, and a brief overview of some of the Past, Current and Future projects that have or will impact the ASME Codes.Copyright