Fatigue Design for Non-Welded Regions According to New European and American Pressure Vessel Standards

EN 13445-3 [1], which was first published in the year 2002, includes separate fatigue design checks for unwelded and welded regions. Furthermore, the new 2007 ASME Boiler & Pressure Vessel Code Section VIII Division 2 [2] includes separated design checks for welded and unwelded regions. Because of differences in the procedures, the approaches of these standards are not directly comparable. Therefore, comparable design curves for special cases and/or for extreme values of parameters are evaluated. Differences in the procedures are discussed and examples are given for special cases. For the unwelded regions, which are covered by this paper, the following approach was chosen: Design curves from EN 13445-3 are corrected by the extreme values of the necessary correction factors. These corrected EN 13445-3 fatigue design curves are compared to the design curves given in ASME VIII-2. As examples of typical usage, some experimental results are compared to the specific design curves.