The evaluation of flange designs has evolved with the incorporation of Code Case 2901 (CC 2901) into ASME Section VIII, Division 1 (UG-44(b)) and Division 2 (4.16.12). While external loads have always been a consideration under UG-22, the introduction of CC 2901 provided an explicit method for assessing weld neck flanges under these conditions.
This change also marked one of the first instances where Division 1 and Division 2 included a leakage-based methodology, diverging from the traditionally stress-based evaluations used in Division 2. However, despite being introduced as an optional method, CC 2901 is often treated as a mandatory requirement, leading to design challenges, particularly in flange classes that previously met compliance standards but now fail under the new criteria. Additionally, recent updates to ASME B31.3 piping code reference CC 2901, expanding its application beyond pressure vessels.
Given these industry shifts, engineers require advanced tools to evaluate flanged connections effectively while balancing stress-based and leakage-based assessments. Design By Analysis (DBA) offers a more precise, physics-based approach to evaluating flange performance, allowing engineers to move beyond simplified code formulas and apply finite element methods for a deeper understanding of stresses and potential failure points.
External nozzle loads—forces applied to the nozzle of a piping system—can induce bending moments and axial forces, altering the way the flange behaves under load. So, evaluating the effects of these external loads as part of a comprehensive stress-based analysis is vital to understanding the system's response. Design by Analysis (DBA) is the preferred method for evaluating how these external loads affect the flange assembly. By employing Finite Element Analysis (FEA), DBA models the stress and deformation induced by external loads, providing a more accurate and detailed analysis than traditional Design by Rule (DBR) methods.
You can read more about Rule-Based methods in comparison with Analysis-Based here.
DBA allows engineers to evaluate the complex interactions between external nozzle loads and the flange assembly, including bolts, gaskets, and nozzles. By considering axial forces, thermal expansion, and external moments, DBA provides an accurate assessment of how these loads influence stress distribution and potential failure points in the system. DBA also evaluates the entire flange system to ensure all factors influencing performance under external loads are considered.
Key advantages of DBA in external nozzle load evaluation include:
While Design by Rule (DBR) methods often oversimplify external nozzle load analysis, potentially overlooking critical stress points, Design by Analysis (DBA) provides a more comprehensive approach, capturing the full range of stress interactions, including internal pressure, external loads, and thermal stresses. This helps engineers predict the behavior of the system and ensures the long-term integrity of flange connections, particularly preventing leakage from external nozzle loads.
By adopting DBA, engineers ensure that flange designs can withstand complex operational environments and meet safety and reliability standards.
FlangePRO, developed by Paulin Research Group (PRG), is an advanced tool for performing Design by Analysis on flanged connections. Using Finite Element Analysis (FEA), FlangePRO helps engineers analyze stresses and rotations in flanged joints, predicting the impact of external forces and moments while ensuring compliance with global codes.
Key capabilities of FlangePRO include:
Modeling the effects of external forces and moments on the flange system.
Visualizing stress distribution across the flanged joint and identifying potential issues like leakage risks.
Predicting leakage to help ensure the integrity of the joint under different loading conditions.
When evaluating external nozzle loads in flange design, a stress-based analysis is critical for ensuring the system operates safely. Design by Analysis (DBA) is a highly effective method for accurately assessing how these external loads interact with the entire flange assembly, from the nozzle to the bolts and gasket. FlangePRO, developed by Paulin Research Group (PRG), provides engineers with the tools to simulate and evaluate these complex load interactions, ensuring that flanged connections remain robust under operational conditions.
By incorporating Design by Analysis into the design process, engineers can accurately model the impact of external nozzle loads, reduce risk, and optimize the performance of flange assemblies in demanding environments.