Webinar Recap: Flanges and Design By Analysis | The Latest from the 2025 ASME Code

 The “Flanges and Design‑by‑Analysis—The Latest from the 2025 ASME Code” webinar, presented by CEI, Finglow,  and Paulin Research Group, covered what’s new in the 2025 ASME landscape for flanges and for Section VIII, Division 2, Part 5 design-by-analysis methods. Below are the practical takeaways engineers can apply now without wading through clause-by-clause detail. 

Access the full webinar playback below.

Key Takeaways

• Flange portfolio simplified: several legacy face/type options were removed or renamed; a welded slip‑on type was added; associated factors and equations were updated.
• Integral flange treatment: methodology emphasizes neck/hub geometry; expect additional failure checks when treating as integral.
• External loads: Division 2 methods explicitly address external loads and overturning moments; seating vs operating concepts are clarified across pressure‑only and combined cases.
• Div 1 → Div 2 alignment: clearer bridges help Division 1 users follow Division 2‑style direct equations where applicable.
• Fatigue framework: screening reorganized (A/B/C) with a welded‑joint path and visual flow charts.
• Thermal stress range: option to separate local thermal ranges is now explicit—useful for gradient‑dominated designs.
• Ratcheting and creep: elastic‑plastic analysis is emphasized; updated screening diagrams and clarified allowable bases support practical checks.

Flanges

• Type options were simplified to reduce ambiguity; a welded slip‑on type was added and treated with factors and moments consistent with integral‑type behavior.
• Method alignment for Div 1 users: 2025 language provides a clearer bridge into Div 2‑style calculations when appropriate, narrowing the gap between older Appendix‑style workflows and Div 2 direct equations.
• Facing and seating cleanup: several facing types were retired/renamed; gasket seating terminology was consolidated so calculations follow a more consistent path.
• External loads are not an afterthought: Division 2 explicitly covers external loads and overturning moments, encouraging consistent evaluation beyond pressure‑only cases.

Fatigue and Cyclic Loading

• Screening methods are now A, B, and C, with a dedicated welded‑joint fatigue screening path for joints that haven’t been machined smooth.
• Method A (elastic stress analysis) clarifies how to treat total versus local thermal stress ranges; new flow charts make it easier to follow the correct path.
• Method B’s text was expanded for designs without full cycle‑by‑cycle nonlinear capability—use a stabilized hysteresis approach to approximate cyclic behavior across the loading history.
• Theme across methods: when thermal gradients dominate, treat local effects explicitly instead of assuming global ranges will bound behavior.

Ratcheting

• Elastic‑plastic analysis is the preferred way to evaluate ratcheting; simplified elastic checks remain available in defined cases.
• Updated screening diagrams normalize primary and secondary stresses and show regions where ratcheting is not expected, where shakedown occurs, and where ratcheting may occur.
• Practical note: staying below familiar screens is not a guarantee—use the diagrams and, when needed, nonlinear checks to confirm stability.

Creep

• Creep is treated as its own failure mode with specific protections (load‑control rupture, creep buckling, creep ratcheting, creep fatigue).
• Allowables tighten in the creep regime; use isochronous stress‑strain curves at relevant service times to capture time‑dependent behavior.
• For buckling and long‑term behavior, handle geometric imperfections and time‑dependent properties explicitly in analysis.

FEPipe directly supports the updated Div 2 methodologies highlighted in the webinar by combining elastic-plastic FEA, nonlinear collapse, and fatigue analysis into automated ASME-compliant workflows—so users can accurately evaluate ratcheting, creep, buckling, and thermal stress effects under real operating conditions. It goes beyond simplified screening by generating code-based results (not just stresses), including external loads, flange behavior, and cyclic loading, with built-in tools for fatigue, crack growth, and fitness-for-service assessments.

In short:  FEPipe lets you quickly move from simplified checks to validated nonlinear analysis—giving you confidence in complex failure modes and making it easy to prove compliance or identify risk before it becomes a problem.

Div 1 vs Div 2: Making the Call 

• If external loads or thermal gradients drive the design, prefer the Division 2 path for explicit coverage.
• For Div 1 work that historically used legacy figures/tables, check whether 2025 bridges and direct‑equation routes now provide a clearer Div 2‑style method with fewer ambiguities.
• Standardize an internal decision point: Pressure‑only and simple geometry, stay in Div 1. External loads/thermal gradients or welded‑joint fatigue concerns, escalate to Div 2 methods.
  
  

Q&A Highlights

• Legacy Kellogg vs newer methods: For rated weld‑neck flanges addressed by contemporary external‑load methods with FM terms, designers often see more favorable capacity than legacy approaches. For flange styles not covered, legacy paths may still be used case‑by‑case.
• Elastic vs elastic‑plastic for ratcheting: Rules are intentionally conservative; when screening suggests risk, nonlinear checks provide the most reliable assessment.
• Dominant creep mechanism: There’s no direct diagnostic from analysis outputs; mechanism depends on temperature, stress level, and materials—accurate isochronous curves are essential.
• Why many Div 1 edits: Largely harmonization and re‑organization of methods already aligned with Div 2; the emphasis is consistency rather than reaction to specific failures.
  
  

What This Means for PVP Engineers

• Define a clear Div 1 to Div 2 handoff: use Div 2 methods by default when external loads or through‑thickness thermal gradients drive the design.

• Refresh flange templates: remove retired facing/type options, add the welded slip‑on type with its specific factors, and align terminology for seating/operating checks.

• Update fatigue SOPs: adopt the A/B/C structure, include the welded‑joint screening path, and embed the new flow‑chart steps in review checklists.

• Strengthen ratcheting reviews: require normalized screening diagrams early and set explicit triggers for elastic‑plastic verification when screens indicate risk.

• Prepare for creep assessments: source/validate isochronous stress‑strain curves for common base and weld metals at service times, and apply the tighter in‑range allowables.

Next Steps

If you’d like guidance on how these changes affect your projects, we recommend scheduling a demo or consultation with our experts. Our team can walk you through how the updated codes are reflected in our software tools and how to adapt your workflows effectively.

Be sure to follow CEI and Paulin Research Group on LinkedIn, where we regularly share engineering insights, code interpretations, and announcements on all 2024 and 2025 software releases related to these changes.