ASME Section VIII, Division 2 (ASME VIII-2) has long been valued for its advanced analytical approach to pressure vessel design, providing engineers with rigorous tools for balancing safety, efficiency, and cost. In 2017, ASME introduced Class 1 and Class 2 vessel designations within Division 2. Class 1 targeted simpler, general-service vessels, allowing designers to use Part 4 (Design by Rule) to optimize wall thicknesses and reduce material costs without compromising safety. Class 2 was intended for more complex vessels, requiring Part 5 (Design by Analysis) to address unusual geometries or more demanding service conditions, along with more comprehensive documentation and certification.
This dual-class approach appeared to offer an elegant solution. Class 1 provided a cost-effective path for routine applications, while Class 2 ensured rigorous analysis for critical or unconventional vessels. Engineers could choose the level of design sophistication based on the vessel’s purpose, complexity, and operating conditions, which seemed a sensible balance between safety, efficiency, and practical application.
However, in the 2025 edition of ASME VIII-2, these distinctions were removed, consolidating all static equipment under a single class. This change, part of the ASME Reshape Project Phase 2, reflects a broader goal of streamlining the code, harmonizing Division 2 with Division 1, and simplifying the design and certification process. While the simplification has clear advantages, it also highlights a challenge: the dual-class system was introduced and then reconsidered within less than a decade. For engineers and organizations that had adapted their procedures, documentation, and training to the Class 1/Class 2 framework, this represents yet another transition.
This evolution is understandable; standards must respond to industry feedback, emerging best practices, and a desire for clarity. Yet, the relatively short lifespan of the Class 1/Class 2 distinction underscores the tension between innovation and consistency in engineering codes. Frequent, significant changes – even with good intentions – require careful management to maintain confidence, reduce confusion, and ensure smooth adoption across the industry.
Today, Division 2 provides a unified framework for vessel design that remains rigorous and safe, with streamlined documentation requirements. Engineers can apply consistent principles without navigating multiple classifications, making the code more accessible and user-friendly.
Takeaway for Engineers and Organizations
The decade-long evolution of vessel classes offers an important lesson: adaptability is crucial, but stability is equally valuable. Organizations should remain agile, ready to adjust to code changes, while also designing internal processes that can accommodate updates efficiently. By maintaining clear documentation practices, training programs, and flexible design standards, engineers can minimize disruption from future revisions while ensuring safety and compliance remain uncompromised. ASME VIII-2’s journey illustrates that even well-intentioned changes in engineering codes require careful consideration of both immediate benefits and long-term impacts.
