by David A. Osage, P.E., ASME Fellow / Jul 18, 2010

The development of new toughness requirements was a major part of the effort to re-write the ASME B&PV Code, Section VIII, Division 2. The new toughness rules in this code were established using the fracture mechanics assessment procedures in API 579-1/ASME FFS-1 Fitness-For-Service, Part 9. The major changes in the toughness rules when compared to older editions of Section VIII, Division 2 and the current edition of Section VIII, Division 1 are for carbon and low alloy steel materials excluding bolting. The new toughness rules in Section VIII, Division 2 are based on a Charpy V-Notch impact requirement of 20 ft-lbs (27 Joules) consistent with European practice and the beneficial effects of post weld heat treatment are included consistent with the procedures in API 579-1/ASME FFS-1. This paper provides a technical background to the new toughness rules including the development of material toughness requirements and the development of impact test exemption rules.

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