Designing flanges for demanding environments often requires more than meeting standard specifications. Engineers are expected to manage stress concentrations, prevent leakage, and account for long-term deformation, often under complex load combinations and operating conditions that are difficult to simplify.
Bolt loads, internal pressure, piping reactions, and thermal effects interact in ways that influence flange behavior across the entire joint, from the gasket interface to the attached pipe. Understanding how these forces combine is important not only for safe operation, but for avoiding costly field problems and unplanned maintenance.
With simulation tools like FlangePRO by Paulin Research Group, engineers can model these conditions directly, evaluate detailed behavior, and refine their designs based on real-world performance indicators--not just assumptions.
The workarounds that follow highlight where this level of analysis is most effective--specifically in stress evaluation, gasket interaction, and flange deformation under load.
Traditional flange calculations provide a reliable basis for design under pressure and bolt preload, but real-world load conditions often involve additional forces. Axial loading, torsion, shear, and bending can combine in ways that create localized stress concentrations--particularly around the hub, flange ring, and attached pipe.
FlangePRO enables stress analysis under these combined loads using axisymmetric or 3D brick elements, with direct application of bolt preload, internal pressure, and external forces. Built-in support for ASME B16.5 and B16.47 Series A/B flange geometries simplifies model setup while preserving accuracy.
Simulation results include automatic stress linearization through critical sections and can be reviewed alongside code-based limits from ASME Section VIII-1 Appendix 2, VIII-2, EN 13445-3, and PD 5500. This helps engineers verify compliance while gaining more detailed insight into how each load contributes to overall stress distribution.
In bolted flange joints, gasket compression and sealing effectiveness depend on how loads are distributed across the flange face. While standard methods assume uniform seating pressure, real assemblies often experience uneven gasket loading due to flange rotation, preload variation, or applied moments.
With FlangePRO’s automatically generated contact elements, engineers can simulate the interaction between gasket, bolt, nut, and flange surfaces. Gasket stiffness is modeled directly, making it possible to observe how contact pressure changes during bolt-up and under operating conditions.
This supports leakage evaluation using methods such as the Kellogg Equivalent Pressure, UG-44 / Code Case 2901-1, and PRG’s own test-based leakage models. Engineers gain visibility into seating pressure gradients and can identify areas where sealing performance may require adjustment, especially in large-diameter or high-pressure connections.
Plastic deformation can develop in flange assemblies during bolt tightening or when exposed to elevated internal pressure. While often not visible during installation, these deformations can affect flange rotation, gasket compression, and long-term joint integrity.
FlangePRO includes nonlinear analysis capabilities using 3D brick elements. Engineers can simulate bolt-up loading that may cause material yielding, apply the operating pressure loads to see if any residual stress develops, and unloading behavior when all loads are removed, providing a detailed view of how the flange assembly behaves over time.
This analysis is particularly useful in:
High-temperature systems with differential expansion
Repeated thermal or mechanical cycling
Thin-walled or large-diameter flanges with limited stiffness
High bolt-up loads
Elevated operating pressure
With FlangePRO, engineers can perform both code-based stress calculations and finite element analysis within a single tool. Stress results from methods such as ASME Section VIII-1 Appendix 2, VIII-2, EN 13445-3, and PD 5500 are presented alongside FEA-derived stresses, allowing for direct comparison.
This side-by-side visibility helps engineers understand how traditional formulas relate to the more detailed stress distributions revealed through simulation. For designs involving unusual loading, geometry outside standard flange tables, or assemblies operating near code limits, this comparison provides a clearer basis for engineering judgment.
By integrating both approaches, FlangePRO enables more informed decision-making—helping engineers identify when additional conservatism is needed, or when FEA results confirm that a design meets code intent under realistic conditions.
FlangePRO brings together finite element modeling, code compliance tools, and gasket behavior simulation in a single platform designed for modern flange engineering. Whether you're designing to ASME or EN standards, analyzing bolt-up deformation, or assessing sealing performance under combined loads, FlangePRO supports reliable analysis of flanges across a range of loading scenarios.