Pipeline Accident in North Rhine-Westphalia, Germany

1. Pipeline Accident in North Rhine-Westphalia, Germany

2. Contents • The pipeline • The accident and it´s consequences • Measures taken after the accident • Findings of investigations • Conclusions and initiated actions

3. Contents • The pipeline • The accident and it´s consequences • Measures taken after the accident • Findings of investigations • Conclusions and initiated actions

4. Pipeline Data • ethylene gas transmission • DN 300 (Da = 316 mm, s = 7 mm) • date of construction: 1939 • pN = 20 bar; pop = 17 bar • material: analogical St 35 • 1,5 m underground • Regulation: German Ordinance on High Gas Pressure Pipelines (Gashochdruckleitungsverordnung) German Ordinance on Long-Distance Pipelines (Rohrfernleitungsverordnung)

5. Pipeline Data • ethylene gas transmission • DN 300 (Da = 316 mm, s = 7 mm) • date of construction: 1939 • pN = 20 bar; pop = 17 bar • material: analogical St 35 • 1,5 m underground • Regulation: German Ordinance on High Gas Pressure Pipelines (Gashochdruckleitungsverordnung) German Ordinance on Long-Distance Pipelines (Rohrfernleitungsverordnung)

6. Pipeline Data Requirements: • impermeable and resistant to expected strain • resistant to damage caused by mining activities • protection against external influences and corrosion • safety devices for protection against inadmissible increase of pressure • monitoring and recording operating pressures • recording loss of gas • limiting release of gas

7. Contents • The pipeline • The accident and it´s consequences • Measures taken after the accident • Findings of investigations • Conclusions and initiated actions

10. The accident and it´s consequences 03.03.2006: • 14:00 h: leak and release of ethylene gas  cloud • residents  fire brigade • simultaneous: significant decrease of pressure  shut-down of sluice valves • no ignition • 15:30 h: release stopped • 50 persons in the neighbourhood affected • split, not cracked open completely

11. Contents • The pipeline • The accident and it´s consequences • Measures taken after the accident • Findings of investigations • Conclusions and initiated actions

12. Measures taken after the accident • 6 persons evacuated • roads within a radius of 500 m closed • purged with nitrogen  no ignition hazard • maximum strain estimated • stretching devices excavated • relief cuts set • sleeve sockets welded

13. Contents • The pipeline • The accident and it´s consequences • Measures taken after the accident • Findings of investigations • Conclusions and initiated actions

14. Findings of investigations • rupture without macroscopic deformation  brittle fracture • split of 11 mm • 50% of perimeter

15. Findings of investigations • hook connector enlarged • coarse-grain inside the welded seam • finest cuts on surface of welding deposit

16. Findings of investigations • rupture in coarse-grain zone near heat affected zone • coarse-grain development and local increase of hardness • no relevant corrosion • no indication to any enlarging due to inadmissible increase of pressure • inconspicuous measurement of wall thickness

17. Findings of investigations • regular plant management and maintenance • no necessity of mining safety measures due to previous informations • no specified mining region • less number of stretching devices • hook connector accordant state of the art (1939) But: distinctly measurable bending and axial tensions outside the region of damage

18. Contents • The pipeline • The accident and it´s consequences • Measures taken after the accident • Findings of investigagtions • Conclusions and initiated actions

19. Cause ? spontaneous failure due to forces from outside the pipeline • damage done by mining? • geotectonics? • . . . . . ? Conclusions • no inadmissible increase of pressure • material sufficient resistant without any indications to deterioration

20. Initiated actions • setting of further relief cuts • welding of sleeve sockets for relief • Pipeline without tension • setting of resistance strain gauges • Check-up of distances of stretching devices • geodetic measurements

21. Conclusions and initiated actions Question: If former mining activities cannot be excluded definitely: Is it necessary to take hazards from mining activities into account in any case irrespective of specified former mining region or not?

22. Thank you for your attention !