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

33

Outer surface Inner surface (Gauges 45-L to50-H will have correspondence to radial locations of gauges 39-L to 44-H) Fig 8: Strain gauge pattern followed at RT 17+242

Outer surface Inner surface (Gauges 57-L to 62-H will have correspondence to radial locations of gauges 51-L to 56-H) Fig 9: Strain gauge pattern followed at RT 17+74

Table 11 shows the comparison of PPT measured strain and simulated FE model hoop strain. A close match is observed between the predicted and simulated values. This indicates that geometry is accurately captured in FE model and no flaw burst pressure estimated from FE is realistic. When conservative FE model is used with full R2 weld properties, the minimum unflawed burst pressure of 82.1 ksc and flawed burst pressure of 75.7 ksc is found at RT 17+74mm. There is negative margin of safety of 0.03 over design ultimate burst pressure of 78.4 ksc. When new FE model (considering the R2 properties near weld region and parent metal properties near away weld region) the unflawed burst pressure and flawed burst pressure is found to increase to 93.7 ksc and 84.4 ksc respectively. Unflawed burst pressure is found to increase by 14%. Margin of safety of 0.08 over design ultimate burst pressure of 78.4ksc. The details were presented in design review forums and hardware was cleared for further processing.

Table 11: Summary of failure pressure and MS available for Cirseam weld of SC 596 to SC 594 RT spot (Location) Conservative model with full R2 weld properties

Realistic model with Parent metal & R2 properties

P b (ksc)

*MS

P b (ksc)

*MS

No flaw

5x2 defect

No flaw 0.055 0.054 0.054 0.056 0.057 0.047 0.054 0.047 0.051 0.054

5x2 defect

No flaw

5x2 defect

No flaw 0.205 0.203 0.203 0.207 0.210 0.195 0.203 0.198 0.200 0.203

5x2 defect

17+227 17+242 17+252 17+263 17+278 17+74 17+89 17+97 17+105 17+120

82.7 82.6 82.6 82.8 82.9 82.1 82.6 82.1 82.4 82.6

76.1 75.9 76.0 76.3 76.4 75.7 76.1 75.8 75.9 76.1

-0.029 -0.032 -0.031 -0.027 -0.026 -0.034 -0.029 -0.033 -0.032 -0.029

94.5 94.3 94.3 94.6 94.9 93.7 94.3 93.9 94.1 94.3

84.9 84.5 84.8 85.1 85.4 84.4 85.0 84.6 84.5 84.8

0.083 0.078 0.082 0.085 0.089 0.077 0.084 0.079 0.078 0.082

* MS over design ultimate failure pressure of 78.4 ksc