PSI - Issue 37

Jan Kec et al. / Procedia Structural Integrity 37 (2022) 598–605 Jan Kec / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 8. Pressure response during burst test of pipe (a) DN500 with Cold Lock and (b) DN700 with Clock Spring

Fig. 9. Stress-strain curve of (a) Cold Lock sleeve and (b) Clock Spring sleeve

3. Conclusions Two segments of transition oil pipeline DN500 and DN700, operating since 1980, were subjected to full-scale pressure testing. Both pipes were sleeve reinforced to increase the safety and reliability of the lines. The DN500 pipeline used the CL sleeve - the steel sleeve with a composite filling. On the other hand, the DN700 pipeline used the CS composite sleeve. Both sleeved pipes were subjected to static and full-scale fatigue testing. A greater reinforcing effect was observed on the CL sleeve, where a stress reduction of 70% was observed compared to the bare pipe. Higher strains were observed on the CS sleeve than on the bare pipe, which was attributed to the bulging internal corrosion defect. For the CS sleeve, the reinforcing effect of the sleeve increased with increasing stress. Both sleeves complied with the fatigue test for 10 000 cycles without leakage. The residual pipe strength was high for both sleeves corresponding to 2,8x MAOP and 3x MAOP for DN700 with CS and DN500 with CL respectively. Acknowledgements The support of institutional financing, grant MSM2579700001 is gratefully acknowledged.