What’s New in ASME Section VIII 2025: Updated Methods, Materials, and Organization Explained

The 2025 Edition of ASME Section VIII brings an extensive series of updates across Divisions 1 and 2.

These include expanded use of shared design rules, reorganized paragraph numbering, updated material data, and major revisions to flange design equations.

The result is more consistency between divisions and a clearer structure for engineers performing design and analysis work.

Division 1 and Division 2 Integration

Several Division 1 design rules now refer directly to Division 2 for calculation methods, part of ASME’s ongoing “common rules” effort.

Division 1 retains inspection, testing, and material provisions, but references Division 2 where the analytical methods are already equivalent.

Key changes include:

• Mandatory Appendix 2 (Flanges) → now directs to Division 2, Section 4.16.

• Appendices 5, 9, 13, and 14 → now refer to Division 2 calculation methods.

• Nonmandatory Appendix EE (Half-Pipe Jackets) → now references Division 2.

• UG-35 → now points to Division 2.

These updates unify the calculation approach across both divisions, minimizing differences in analytical results.

Renumbering and Improved Organization

Many paragraphs have been renumbered or relocated for clarity:

• UG-16(b) (Minimum Thickness) → now UG-16.2.

• UHA-51(d) (MDMT Exemptions) → now UHA-51(g)(3).

A new Subsection D consolidates rules for specific vessel types and components that were previously scattered throughout the Code:

• UHX appears in Subsection D with no content changes.

• Acrylic Cylindrical Shells → moved to Part UAS.

• Former Appendix 24 → now Part UCC.

• Many other paragraphs and appendices have been moved to this new Subsection and have been renamed.

This structure makes the Code easier to navigate and groups component-specific rules together for quicker reference.

Appendix 46: Design-by-Analysis Material Guidance

A new Paragraph 46-2 in Mandatory Appendix 46 provides clear guidance for using additional material properties required in design-by-analysis.

It outlines how engineers can obtain and apply properties beyond those listed in UG-23(a), ensuring consistent use of material data in Division 2–style analytical evaluations.

Material Updates in VIII and Section II, Part D

Several material tables and notes have been updated, including Tables 1A, 1B, U, and Y-1.
Specific changes include:

• Addition of 3.5 Ni – 1.5 Cr – 0.5 Mo – 0.5 Mn to TE-1 Group 1.

• Addition of N06617 to TE-4, with corresponding updates to the Elastic Modulus Group B tables.

• Addition of SA-372 classes N100/N120 and P100/P120.

• Addition of N08354 to SB-625, SB-649, and SB-677.

• Addition of N08367 to SA-182, SA-213, SA-240, SA-312, SA-403, SA-404, SA-479, SA-688, and SA-965.

• Addition of SA-693 (UNS S17400, Type 630) to UHA-23.

Several table notes were also added, revised, or deleted to improve clarity and accuracy.

Flange Design Revisions (Division 2, Section 4.16)

Flange design rules have been significantly updated, reflecting new calculations and expanded coverage:

• Added welded slip-on flange with hub, treated as an integral type, in Table 4.16.4.

• Introduced new flange stress-factor equations (FS and VS) in Table 4.16.5.

• Updated moment-arm definitions (HD, HT, HG) in Tables 4.16.6–4.16.10.

• Simplified flange facings in Table 4.16.3:

  • Removed facing types 2–5 (0.4 mm / 1⁄64-in raised nubbin).

  • Renamed the ring-type facing (previously Type 6) to Type 2.

  • Streamlined basic seating-width (b₀) columns.

These refinements align the design treatment of integral and slip-on flanges and make the section more concise. 

Additional Design Updates

• UW-20 (Tube-to-Tubesheet Joints): Interface-pressure equations now use yield strength at ambient temperature instead of design temperature; a new variable was added, and subscripts were corrected.

• Division 2, Section 4.18 (Heat Exchangers): Corrected equations in Sections 7.4, 8.4, and 9.4; updated nozzle-diameter terminology; revised concentric-conical-channel equations to prevent division-by-zero errors.

• Division 2, Sections 4.57 and 4.59 (Oblique Nozzles): Updated formulas for effective nozzle lengths (LH, LI) and effective wall length (LR) for more accurate reinforcement calculations.

To explore the full scope of 2024–2025 ASME code revisions—including detailed discussions on Section VIII, Section IX, and related updates—watch the complete Code Update Webinar hosted by CEI, Finglow, and Paulin Research Group.

Key Takeaways

The 2025 Edition introduces consistent, well-structured updates across both divisions:

• Expanded Division 1 → Division 2 calculation references.

• Clearer paragraph numbering and a new Subsection D.

• Updated guidance for design-by-analysis in Appendix 46.

• Multiple material property revisions in Section II, Part D.

• New and revised flange equations in Division 2, Section 4.16.

• Corrected heat exchanger, tubesheet, and nozzle formulas.

These revisions make Section VIII more coherent and precise, improving usability and accuracy for design professionals.