In 2000, Enbridge began the relocation of 11 control centres to an expanded Control Centre in Edmonton after it was determined that advances in pipeline control technology made it possible to safety operates numerous pipelines from a single location. Included in this move to Edmonton was the control console for the Enbridge Gas Distribution system, previously located in Toronto and the controls for the Vector natural gas pipeline. Consolidating the Control Centres into a single location has increased efficiency and ensures the continued safety and integrity of the pipeline and gas distribution systems.

Enbridge applies Supervisory Control and Data Acquisition (SCADA) computer systems for the safe, efficient operation of its numerous pipelines. Pipelines are electronically monitored from the Operations Control Centre in Edmonton using the PROCYST pipeline control pipeline control technology. Information is relayed back and forth between Edmonton and remote sites 24 hours a day, seven days a week using Wide Area Network system technology.

Widely recognized for the quality of its operator training programs, Enbridge exports its pipeline operations and training expertise to countries around the world.

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Corrosion Monitoring

Because of their location and the products they carry, pipelines are often in contact with water, bacteria, and various chemicals, all of which can corrode steel. Both the interior and exterior of the line are potentially subject to corrosion. Corrosion can occur, for example, if the pipeline's protective coating separates from the pipe, allowing water to come into contact with the steel.

For safety, constant monitoring and inspections alert Enbridge to locations to inspect for corrosion, cracks, faulty welds or other defects. With one of the lowest pipeline incident frequencies in the industry, Enbridge Pipelines has proof this vigilance pays off.

In order to determine the extent to which known internal corrosion is affecting the system, Enbridge employs high resolution In-Line Inspection equipment capable of detecting metal loss, and a relatively new technique which measures the movement of hydrogen ions generated in the corrosion process to detect the presence of active corrosion. This technology is known as "hydrogen or Beta foils". Representative locations are selected throughout the pipeline system, and the devices are installed directly on the exterior surface of the pipe. Inferred corrosion rates are transmitted to Enbridge via satellite and are accessed through the Internet. The corrosion rates can then be used in planning for pipeline integrity maintenance.

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Stress Corrosion Cracking

For more than a decade, the North American pipeline industry has been aware of problems associated with Stress Corrosion Cracking (SCC) - a crack initiation and growth process that can result in pipeline failure.

Research has shown that SCC is caused by a number of factors. Two main contributors are stress in the pipe steel and a particular type of corrosive environment around the pipe. Under certain conditions, what begins as a tiny hairline crack on the exterior of the pipe can become a 'colony' of cracks with the potential to penetrate the steel and cause a pipeline break.

Although SCC has had little impact in the fitness of Enbridge Pipelines' system, we remain committed to being at the forefront of technological developments and research related to the phenomenon and its diagnosis. These efforts have resulted in rigorous programs for monitoring and managing SCC.

For example, Enbridge contributes to the advancement of SCC research through participation in an industry consortium and participation in the Canadian Energy Pipeline Association's Pipeline Integrity Working Group. Enbridge Pipelines has devised and continues to refine SCC landscape models for the entire pipeline right-of-way, and whenever excavations are conducted for any reason, we routinely examine all exposed pipe for evidence of SCC.

Enbridge Pipelines has also been an industry leader in funding the development of ultrasonic technology to inspect for pipeline cracks.

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In-Line Inspection

Increasingly sophisticated In-Line Inspection (ILI) technology is a vital tool in Enbridge's Pipeline Integrity program. Enbridge specialists use sensitive ILI instruments to measure size, frequency, and location of even minute changes in the pipeline wall on every line in the system. For example, a geometry tool is dispatched down the line to detect the kind of abnormality that occurs when a pipe rests on a rock for long periods of time; and high resolution instruments use ultrasonic or magnetic flux technology to measure various forms of metal loss and/or cracks. These sophisticated tools allow Enbridge Pipelines to inspect the inside and outside of the pipe on a millimetre-by-millimetre basis.

Although most defects identified by the ILI tools are minor and don't threaten the integrity of the system, all are evaluated against specific engineering criteria to assess requirements for corrective action. Modeling and comparison of sequential ILI runs are also used to project corrosion growth rates and guide In-Line Inspection frequencies. All of the Enbridge pipelines are inspected at regular intervals, driven by a number of factors such as projected defect growth which define the requirements of a preventative maintenance program.

By using the best available technology, Enbridge Pipelines has become a recognized leader among transmission pipeline companies on the use of ILI.

Line Patrol

Pipeline safety begins with prevention. A key element of this is pipeline patrol. Using aircraft, land vehicles or foot patrol, Enbridge Pipelines regularly surveys the pipeline route on the lookout for potentially damaging activities such as unauthorized digging and construction.

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