PSI - Issue 19

J. Rudolph et al. / Procedia Structural Integrity 19 (2019) 575–584 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

9

583

Fig. 9. Determination of stress range

10. Implementation of post weld improvement techniques

Post weld improvement techniques on the toe affects the fatigue strength of a welded joint as regards failure from the weld toe. The possibility of fatigue crack initiation from other features of the weld (e.g. weld root in fillet welds) should not be overlooked. Post weld improvement techniques improve the fatigue behavior of the weld detail. Important, the area dressed improved weld toe should be inspected before machining acc. to EN 13445-5 and after using improvement techniques by dye penetrant or magnetic particle. Post weld improvement techniques, Dressing or flush grinding of the seam welds justifies an upgrade from Class 80 to Class 90. Post This paper has presented the recent amendments of Clause 18 of EN 13445-3 addressing the main issues of this major and comprehensive revision developed within the framework of the European working group CEN/TC 54/WG 53 – Design methods. The structure of the new Clause 18 and related annexes NA, NB, NC and ND are discussed. The following six items are of particular relevance: • Detailed guidelines for the fatigue assessment of welded pressure vessel components based on the structural hot spot stress approach; • Detailed guidelines for the determination of the relevant stresses and stress ranges based on shell type and brick type finite element models; 11. Summary and conclusions

• Detailed guidelines for the cycle counting issue;

• Implementation of a critical plane approach;

• Weld improvement techniques;

• Criteria for In-service monitoring.

In addition special attention has been put on the step-by-step guidance of the User of the Code, in particular in the determination of the hot-spot structural stress by finite element methods. It expected that the new Clause 18 will lead Users of the standard EN 13445-3 to prefer detailed fatigue assessment to simplified assessment and to obtain more realistic evaluations of the fatigue life.