PSI - Issue 17

V. Chmelko et al. / Procedia Structural Integrity 17 (2019) 520–525 Chmelko, V., Bíro, D./ Structural Integrity Procedia 00 (2019) 000 – 000

525

6

It means, that real burst pressure is 1.51 times more than the calculated pressure. Let ’s con sider a calculated burst pressure 12 MPa. There is still a 1.51-multiple reserve (unaware or unwanted safety s unv ) and the true burst pressure is up to 18 MPa. Using numerical analysis, this unwanted safety is reduced to 1.11 (or less), i.e. the numerical model determines the burst pressure of 16.2 MPa corresponds to the true burst pressure of 18 MPa. From obtained results and comparisons can be seen the rate of conservativeness of used criteria as well as the potential of the destructive pressure determination process using the numerical models by FEM. Cause of this conservativeness of burst pressure calculated by standards can be caused by factors mentioned above (approximation of corrosion defects). These factors can be considered in numerical analysis which can lead to determination of burst pressures which are closer to real one. Therefore, numerical analysis can be suitable instrument, which may lead to prolongation of serviceability of damaged pipe sections and may specify the more real safety factor. Tab.3 The comparison of the burst pressures as a multiple of the value determined experimentally and the coefficient of "unwanted" safety of the used standards Specimen 1 s unv Specimen 2 s unv Specimen 3 s unv Experiment p=32.1 MPa 1 p=30 MPa 1 p=18.5MPa 1

Numerical simulation

0.93p

1.07

0.9p

1.11

0.89p

1.12

DNV-RP-F101

0.75p

1.34

0.73p

1.37

0.74p

1.35

ASME B31G

0.67p

1.49

0.66p

1.51

0.66p

1.51

Acknowledgements

This work was supported by the Slovak Research and Development Agency under the contract No. APVV-17 0666 and by the Research & Development Operational Programme funded by the ERDF ITMS: 26240220084 Science city Bratislava.

References

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