PSI - Issue 60

Sreerag M N et al. / Procedia Structural Integrity 60 (2024) 20–35 Sreerag M N/ Structural Integrity Procedia 00 (2023) 000 – 000

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5.2. Effect of repair length in cirseam weld In case of cirseam weld, the resisting circumferential area with reduced weld properties does not change as the weld bead width does not change and only the axial area resisting the meridional load changes with repair length in circumferential direction and the effect of same is studied in this section. Figure 5 shows a typical 3D FE model simulating the cirseam weld is shown.

Fig 5: Typical FE model simulating the virgin cirseam weld with weld repair and parent metal

Unlike in section 4.2, here a 3D model is required to simulate the repair length in cirseam weld. In the model, the region away from the weld, the parent metal property is used. In the entire long seam weld region for an axial weld bead length of 30mm, the virgin weld properties(R0) are used. The repair properties are simulated in the virgin weld region by specifying the circumferential length. As described above, as length of cirseam seam repair is increased in axial direction, the resisting circumferential area having lower weld property does not change and the failure pressure is not expected to decrease. To study this effect, a parametric study is done for estimating the failure pressure by varying the repair length i.e. 20 mm, 40mm, 60 mm, 80mm,100mm, 200mm and 500mm with R1 weld properties in entire R0 weld. Results are summarized in the table 8. As expected, it is found that for all cases the failure pressure matches with the failure pressure of model having seamless shell and no reduction is observed. Reduction in failure pressure will be observed only when the width of cirseam weld bead is increased from 30mm. When the entire cirseam weld is virgin weld, the failure pressure is 97.37 ksc which is the realistic failure pressure. This failure pressure is same as that for a shell with seamless weld. This shows that the increase in axial area with reduced properties resisting the meridional load is insignificant and does not affect the failure pressure

Table 8: Parametric study to estimate the failure pressure for R1 cirseam seam weld repairs in Virgin weld Axial length of R0 weld & repair in the virgin cirseam weld BP (ksc) % decrease in the failure pressure wrt R0 failure pressure Full R0 97 0.0 20mm R1 97 0.0 50 mm R1 97 0.0 100mm R1 97 0.0 200mm R1 97 0.0 500mm R1 97 0.0