PSI - Issue 41

Chouaib Zeghida et al. / Procedia Structural Integrity 41 (2022) 384–393 Zeghida Chouaib et al. / Structural Integrity Procedia 00 (2022) 000–000

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Figure 6 compares the field cumulative leak probability given by Khaleel et al., (2009). In this case, the adjusted residual stress level used to limit the disagreement between predicted and observed leak probabilities was set at 75 % of their original values. The resulting predictions had a much more rational basis and were in very good agreement with operational conditions.

Fig. 6. Field observations of leak probabilities compared with M-PRAISE results for various values of the residual stress adjustment factors and plant cycles. 5.2. Effect of Changing Residual Stresses after IHSI An analysis of IHSI treatment after welding was then performed. The IHSI coil was modeled as being 152 mm long. The maximum outer surface temperature was 550 °C and the inner surface temperature was 100 °C. A region of nearly constant heat generation density was modeled over the central 76 mm of the coil. The heating decayed parabolically to zero heat generation density at the edge of the coil. These conditions are consistent with the conditions being used and observed in the experimental studies of IHSI (Tanaka and Umemoto, 1980). To induce the IHSI treatment the Ansoft Maxwell program simulation tools are linked within the ANSYS Workbench interface by definition of the project schematic as shown in Figure 7.

Fig. 7. Coupling between Ansoft Maxwell 3D IH design, transient thermal and fluid flow using ANSYS Workbench interface.

The residual stress distributions used in this paper were obtained from a computational model for predicting welding-induced residual stresses. The model consists of a thermo-elastic-plastic finite element model. The temperature histories resulting from the thermal model serve as input to the finite element analysis. IHSI treatment after welding can convert the tensile weld residual stresses to compressive values (Figure 5). The computational