PSI - Issue 41

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

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

representation for the IHSI process is identical to that for conventional welding, except that the temperature history is extended to include the temperature history of the IHSI process. Figures 8 and 9 shows the estimated distributions of the stresses on the prolongation of the crack in the direction perpendicular to the cracked plane after the IHSI treatment, as well as the application of the operating condition.

Fig. 8. Axial residual stress distribution vs. the wall thickness after IHSI for complete circumferential cracked pipe with depth of 3 mm.

Fig. 9. Effect of applied stress on the axial residual stress distribution vs. the wall thickness.

In Figure 10 the calculation of K factors for various crack sizes was performed making use of the influence function implemented in PRAISE code for complete circumferential interior surface cracks. The stress intensity factors are calculated as a function of crack depth for sections with known residual stress distributions and the effectiveness of IHSI as a permanent countermeasure for IGSCC depends upon the level of service stress in the operating condition as well as on the crack depth. A long circumferential crack will be prevented from further extension by IHSI if the depth is under 30% of the thickness and the service stress is under 75% of membrane stress, which seems to be likely in normal circumstances. For the nominal membrane stress, IHSI cannot keep the crack tip stress in compression. But the level of the stress is well below the other case in which no IHSI was applied.