Design Fatigue Life Comparison of ASME Section VIII and EN 13445 Vessels With Welded Joints

In a recent study conducted by the European Commission, design fatigue life of welded vessels allowed by the ASME Boiler and Pressure Vessel Code was compared with that of the European Standard EN 13445. The allowable number cycles of the ASME Code was reported to be much larger than that of EN 13445, and, therefore, the ASME Code was regarded as unconservative for welded regions. This paper investigates the reason for the reported discrepancy between the two design codes. It is found that, when calculating the allowable cycles reported in the study using the ASME Code as a basis, no fatigue strength reduction factor on stress was used, which is contrary to the ASME Code design rules for welded joints. This paper recalculates the allowable cycles according to ASME Code rules and concludes that they are comparable with those of EN 13445.