PSI - Issue 72

Dražan Kozak et al. / Procedia Structural Integrity 72 (2025) 270 – 277

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4.2. SINTAP – FAD integrity assessment

SINTAP (Structural Integrity Assessment Procedure) is a standardized method used at the European level to evaluate the integrity of structures. This assessment is based on the understanding of how fractures form and propagate within these structures. The integrity of the stone diverter pipe was analyzed using the SINTAP procedure, employing the Failure Assessment Diagram (FAD) approach. Specifically, the 1b class of integrity analysis, as outlined in the SINTAP algorithm, was utilized. The fracture resistance of the material is specified as K IC =35.78 MPa √m . The FAD diagram for the material S355, depicting the initial state of the semi-elliptical crack in the stone diverter pipe, is presented in Figure 8.

Fig. 8. FAD diagram of material S355 showing the initial state of the semi-elliptical crack on the stone diverter pipe.

According to the SINTAP integrity assessment procedure, the initial state of the crack indicates that the structure is safe, as the point shown in Figure 8 is below the failure curve. 5. Conclusion A shock load occurs when a load suddenly acts on a structure, or when the existing load on the structure experiences a sudden change. Calculating the stresses resulting from impact loads is quite complex and cannot be done using traditional strength science methods. An analysis of the fatigue strength due to the impact of stones on the pipe indicates that the pipe is likely to fracture after 35090 cycles, which is equivalent to 7 hours and 46 minutes of operation. To reduce maintenance costs, it is recommended to consider installing pipes with a larger diameter or made from more resistant materials. The results suggest that the crack will propagate by 50.938 mm from its initial size during the crack propagation phase, after which unstable crack growth is expected. According to the SINTAP procedure and the FAD diagram, the structure is considered safe for the initial state of the semi-elliptical crack, as it is below the failure curve. Fatigue related failures are common based on empirical evidence. Conducting a thorough analysis is crucial because it facilitates preventive maintenance, which can lead to potential cost savings for the company and help prevent injuries to workers. This step is important, as repairing the structure may take longer than anticipated.