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Pipeline Technology Journal 2-2015

Latest developments and news from the pipeline industry

RESEARCH / DEVELOPMENT / TECHNOLOGY The investigation revealed that the coating was a usually used bitumen insulating primer. The primer must had penetrated into the crack at a hot temperature during a coating process. It clearly showed that this longi- tudinal crack created already in the process of production and has ex- isted in the pipeline for more than 40 years. During the whole period it remained hidden to all available internal inspection methods used in the last 13 years. CEPS EXPERIENCE CEPS has performed integrity tests together with internal inspections using MFL and TFI tools on more than 250 km of high pressure pipe- lines in Europa during last 10 years. In these tests more than 20 pass- through defects already in the time of an internal inspection or defects that caused a pipeline destruction during hydraulic tests were detected. These critical defects were not only recommended for repair, but quite often they were not detected by the intelligent tool (For example see Figure 8). THE CONCLUSION Revalidation of the DN 700 oil pipeline section by the application of all currently commercially available methods determined and proved the actual level of the pipeline safety and reliability. At the same time it in- creased the current value of these parameters at least to a level that the pipeline had right after its construction. The safety of the pipeline was also demonstrated to the public and to authorities of state technical su- pervision during the revalidation process. This approach significantly reduces the required number of pipe repairs after internal inspection and provides significantly higher pipeline relia- bility because during the integrity test also other defects that were not within the inspection recommended for repair or were even not detected at all are stabilized The defects, that were recommended for repairs after the standard evaluation of the internal inspection but due to performed strength calculations were not repaired, withstood the twofold pressure than was calculated during TFI evaluation. Moreover, the pipeline destruction of the longitudinal weld occurred in a place where neither TFI nor Ultrasonic or MFL detected anything sig- nificant, although the weld crack of the given size existed during the inspections. Figure 9 Another undetected defect Authors Aleš Brynych CEPS a. s. General Director Jesenice, Czech Republic Alexandrs Jelinskis SIA “LatRosTrans” Director of Operations Riga, Latvia Figure 8: Undetected defect PIPELINE TECHNOLOGY JOURNAL 23

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