Pipeline Damage at Gräveneck Assessment Report

10 September 2007

Pipeline Damage at Gräveneck Assessment Report

Seite 2 Leitungsschaden Gräv eneck - Sachstandsbericht September 2007 TU CMy /Leu

Contents

1. Key Figures of E.ON Ruhrgas AG

2. Information on the Course of the Damage

3. Status of Investigations

4. Likely Cause of Damage

5. Pipeline Safety Measures


Key Figures of E.ON Ruhrgas AG

existing pipeline

underground storage facility

compressor station

field station

gas import point

S 426c

Gräveneck

Pipeline system

owned / partly owned by E.ON Ruhrgas and project companies 11,273 km managed by E.ON Ruhrgas 12,690 km Compressor stations managed by E.ON Ruhrgas 28 stations 90 units 853 MW Underground storage facilities

used by E.ON Ruhrgas 11 storage facilities 5.1 bn m³ of working gas

Essen

Berlin

Cologne

Saarbrücken

Frankfurt/ Main

Zw ickau

Hanover

Emden

Hamburg

Flens- burg

Waidhaus

Nürnberg

Passau

Munich

Stuttgart

Freiburg

Leipzig

Dresden


Information on the Course of the Damage Location of Damage in the Field

Pipeline Scheidt-Wetzlar Pipeline No. 022/019/000

Nominal diameter DN 600 Nominal pressure PN 67,5

Year built 1977 Pressure at time of rupture appr. 51

bar Material STE 480.7 TM Coating PE


Course of Events on 28 August 2007

Natural gas escapes, ignites and bursts into flame with loud noise.

Alarm is raised at central control room in Essen; gas flow into pipeline at Scheidt is immediately stopped

Immediate isolation of the relevant pipeline section stops gas flame

Fire in surrounding area is extinguished by fire brigade

Damage to houses, forest, railway track

Some local residents undergo medical examinations as a precaution

Event causes considerable emotional strain on local residents


Impressions from Damage Site


Detailed Course of Events

10:05 a.m. Pressure loss on pipeline 22/19

10:07 a.m. Alarm raised in responsible Operations Areas

10:15 a.m. Police arrives at site, followed by arrival of fire brigade

10:23 a.m. Initial information given by responsible operations officer (Betriebsmeister) at site

10:36 a.m. Information about isolated pipeline section received at reporting centre (ZMS)

10:50 a.m. Gas flame stopped and fire in immediate vicinity extinguished


Status of Investigations

The pipeline was in a faultless condition; its integrity had been confirmed

There was no corrosion / reduction of the pipe wall thickness

The cathodic protection system was working properly

The joint welds were tested during construction and found to be faultless

A stress test was carried out

An intelligent pig run (internal inspection) showed nothing unusual in this area

The documentation is complete (material test certificates, pipe log, etc.)


Likely Cause of Damage

The likely cause of the damage is the soil pressure on the slope, at the bottom of which the pipeline is located.

As result of the heavy rains and the high ground water level, the soil at the bottom of the slope had softened.

The open pipe trench for the parallel Lauterbach-to-Scheidt pipeline, which is under construction, further reduced the stability of the slope.

Moreover, the excavated material (which had been stored above the pipeline in service) further reduced the stability of the slope.

These influences caused the pipeline to be displaced by some 2 m from its original position, leading to a failure of a girth weld between a bend and a straight pipe.

Detailed material tests by the Competence Centre and independent experts are currently under way.


Likely Damage Factors

solid rock

slope loam

high flood loam

Aushubmaterial

Lauterbach-to-Scheidt pipeline

Scheidt-to-Weidenhausen

pipeline

water /

inundation

pipe trench

load exerted by excavated

material


Pipe Displacement

2.07 m

point of damage

original position


Construction of Natural Gas Transmission Pipelines

Material tests, workshop tests, material certificates

Stress testing

Intensive measurements (close interval surveys)

Pigging

TÜV certificate


Operation & Monitoring of Natural Gas Transmission Pipelines Pipeline protection

(coating, protective current)

Mobile and aerial surveys

Specialists, technicians and engineers Germany-wide

Central pipeline monitoring and Reporting Centre

Approved for operation in accordance with Energy Industry Act and applicable technical rules


BACK UP


Impressions from Damage Site


Measures to Remedy Pipeline Damage and Secure Gas Supply in the Area

Clear up site and and take safety precautions on slope

Remove damaged pipe parts (under the supervision of the State Office of Criminal Investigation)

Various activities by independent experts (TÜV, DVGW, soil experts)

Quickly restore of gas supply

Continue with construction work to ensure supply during winter


Four Delivery Points of SüWag and E.ON Mitte Affected by Isolation of Pipeline Section

SüWag

Stadtwerke Weilburg

E.ON Mitte

- Weinbach

- Gräveneck


Pressure Curve over Time at Weidenhausen (red) and Volume Flows into the Pipeline at Scheidt (black).


E.ON Ruhrgas and E.ON Gastransport

TSO

Hügelheim

Bierwang

Passau

Bamberg

Marburg

Werne

Essen

Hamburg

Hannover- Vinnhorst

Nürnberg

Weiden

Waid- haus

Regensburg

Epe

Breitbrunn

Scheidt

Berlin

Ummeln

Saarbrücken Natural gas pipelines

existing under design underground storage facility compressor station field site gas import point

Network length: approx. 13,000 km

Pipeline Damage at Gräveneck Assessment Report

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