ASME Section VIII Division 1: 2025 Edition - What You Need to Know

The 2025 Edition of ASME Section VIII, Division 1 brings the biggest changes to pressure vessel standards in decades. Here's what matters for your work.

1. New Structure: Subsection D

What Changed: All specialized equipment rules are now in one place—the new Subsection D.

What Moved:

➡️ Heat Exchangers (was Part UHX in Subsection C).

➡️ Jacketed Vessels (was Appendix 9, now Part UJV).

➡️ Expansion Joints (was Appendices 5 & 26, now Parts UEJ & UEB).

➡️ Non-Circular Vessels (was Appendix 13, now Part UNC).

➡️ Plate Heat Exchangers, Bellows, Clamp Connections, and more.

2. Division 1 Now Uses Division 2 Math

What Changed: Many Division 1 calculations now reference Division 2 rules instead of having their own formulas.

Key Example - Flanges:

Old: Appendix 2 had its own calculation formulas

New: Appendix 2 points you to Division 2, Part 4.16

Important: Division 2 checks flange stiffness (rigidity), not just stress. Flanges must now be stiff enough to prevent leakage, which often means thicker flanges.

Other Changes:

➡️ Jacketed vessels → Division 2, Part 4.11

➡️ Non-circular vessels → Division 2, Part 4.12

➡️ Expansion joints → Division 2, Parts 4.19 & 4.20

3. Designer Qualifications: New Rules

What Changed: No more "Certifying Engineer" or "Responsible Charge" requirements. Now it's about proving competence, not having specific licenses.

New Requirements:

➡️ Manufacturers must define minimum qualifications for designers.

➡️ Document that designers understand the code, the software they use, and the equipment they design.

➡️ Show training records proving competence.

What Inspectors Will Check:

➡️ "Show me your designer training procedures"

➡️ "Prove this designer is qualified for heat exchanger design"

➡️ "How do you keep designers updated on code changes?"

4. New Materials Available

17-4PH Stainless Steel (SA-693):

➡️ Much stronger than regular stainless (100+ ksi yield vs. 30 ksi).

➡️ Good for high-pressure applications.

➡️ Now allowed without special approval.

Rod and Bar Stock (UG-14):

➡️ Easier rules for machining vessels from solid bar.

➡️ Saves money for small vessels and complex nozzles.

➡️ Requires ultrasonic testing to verify quality.

Diffusion Welding (UHA-51):

➡️ New joining method for printed circuit heat exchangers.

➡️ Important for hydrogen and advanced energy systems.

5. Better Welding and Testing Rules

Welding Control (UW-26):

➡️ Manufacturers must directly supervise ALL welding

➡️ Can't just hire contractors and walk away

➡️ You control the filler metal, procedures, and quality checks

Impact Testing (UG-84):

➡️ Clearer instructions on where to cut test samples

➡️ Better rules for when retesting is needed

➡️ Less confusion about pass/fail decisions

Vacuum Vessel Testing (UG-99):

➡️ If designed for vacuum only, test at 1.3 times the external pressure

➡️ Or use vacuum test plus leak detection

➡️ Prevents collapse when testing thin shells

Radiographic Records (Appendix 10):

➡️ Digital images only need to be kept until inspector approves

➡️ Keep the approval form permanently, not all the image files

➡️ Saves massive data storage costs

The 2025 Edition represents the biggest modernization of pressure vessel standards in generations. Organizations that adapt quickly will be ahead of the curve.

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The updates summarized above reflect only the changes publicly highlighted across technical forums and ASME newsletters. However, the 2025 Edition of ASME Section VIII, Division 1 contains many more subtle revisions that become evident only through a detailed study of the full code.

In an industry where regulatory evolution directly impacts design integrity, safety, and compliance, staying aligned with the latest standards is no longer optional—it is essential.

To help engineers remain competitive and future-ready, Texvyn has fully updated all Static Equipment Design training programs to incorporate the 2025 revisions of ASME Section VIII, Division 1.

Our curriculum is designed and delivered by industry experts who combine deep practical experience with thorough code interpretation, ensuring you gain both conceptual clarity and application-level proficiency. Stay compliant, stay confident, and stay ahead.

To learn more about our Static Equipment Design Course, visit the link below.

Static Equipment Design & Detailed Engineering

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