COMPRESS ASME VIII-2 (Division 2) Option

About the ASME Section VIII, Division 2 Option

The ASME Section VIII, Division 2 (VIII-2) Code rules are available as a COMPRESS option. ASME Section VIII, Division 2 pressure vessel design is currently available. We are working to expand this option to include Division 2 heat exchanger design. When available, access to Division 2 heat exchanger design will also require the Heat Exchanger Option.

Many companies are reconsidering using the alternative rules of Division 2 because of the cost savings made possible by the completely revised 2007 Edition.

Benefits of Using the New Division 2 Rules (2007 Edition and Later)

A wider range of pressure vessels and heat exchangers can now benefit from the application of Division 2. Areas contributing to cost savings include:

1. A lower design margin on material ultimate tensile strength (UTS). Starting with the 2007 Edition the UTS was changed to 2.4 from 3.0. For comparison, the design margin in Division 1 is 3.5. However, not all designs can benefit from this change. For example, this UTS reduction is of no benefit when S_Y (yield strength at temperature), not UTS, governs the allowable stress. This may occur at elevated temperatures.
2. More economical allowable compressive stress rules (external pressure design rules).
3. Fewer reinforcing pads and thinner forgings made possible by more accurate nozzle rules.
4. An option to perform partial non-destructive examination (NDE).
5. Explicit rules for tubesheets (the ability to design Division 2 heat exchangers in COMPRESS is in its final testing phase and will soon be available to users with both the heat exchanger and Division 2 options).
6. Thinner formed heads.

As before, the application of Division 2 may involve additional overheads such as increased inspection and testing. In addition, under Division 1 you may specify partial penetration nozzle groove welds whereas Division 2 requires full penetration welds. The designer is also required to complete a user design specification sheet (UDS). However, in practice the above mentioned items are often included in the end-user's specification and may not involve additional expense.

The material and fabrication labor savings realized from points 1-6 above are now more likely to outweigh the additional overheads imposed by other paragraphs. Of course, your specific situation will dictate whether or not these benefits can be realized.

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