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Quebec Utility Disputes TransCanada Pressure Cut
As red maple leaves and frosty mornings herald the onset of heating season in Quebec, distributor Gaz Metro Inc. (GMI) is asking for cancellation of a pipeline safety directive that could make fall extra chilly for French Canadian natural gas consumers.
GMI has stepped forward to support a request by TransCanada Corp. for the National Energy Board (NEB) to lift a Sept. 8 order for a pressure cut on the Trans Quebec & Maritimes (TQM) leg in its international pipeline network.
“With the start of the heating season upon us, Gaz Metro is greatly concerned over the pressure restriction currently imposed on the TQM system,” GMI told the NEB in a filing made Thursday. “Pressure restriction may prevent TQM and TransCanada from delivering the volumes required to supply our customers.”
GMI’s distribution territory makes it responsible for delivering 97% of natural gas consumed in Quebec. The Montreal-based network serves about 180,000 customers of all sizes and classes: residential, commercial, institutional and industrial.
“Significant portions of Gaz Metro’s distribution network are solely supplied by and are totally dependent on the TQM system,” the appeal to the NEB said. “If the pressure restrictions are not lifted in a timely manner, Gaz Metro could be forced to curtail firm customers or face the failure of some sections of its distribution network. Neither of these scenarios is acceptable for Gaz Metro or for its customers that rely on natural gas for heating through the winter or for industries forced to cease their activities and incur significant economic loss in the event of a failure of their natural gas supply.”
GMI pointed out that the safety directive was a precautionary measure rather than an emergency response to an imminent threat.
The NEB ordered TransCanada to cut TQM’s operating pressure down to 90% of the average level over the preceding two months after nine potential sites for fresh outbreaks of pipe metal fatigue known as stress-corrosion cracking (SCC) were discovered.
The possible trouble spots were detected by roving robot inspection devices known in the pipeline industry as pigs. The equipment uses ultrasound probes to sniff out hairline cracks on the outside of pipe from inside by making subtle measurements of steel wall thickness.
Questionable pipe sections have to be dug up and inspected directly to determine whether the anomalies are characteristic of SCC’s spider web-like weak spots that interior pressure causes to spread and eventually burst.
The NEB directive anticipated that TransCanada would be able to do investigative digs prior to heating season. But the order set a tight deadline of Oct. 7 for completing the earth-moving, visual inspections and a report to the board. No such report has turned up yet in the public record that the board this fall began making available on safety issues and orders.
TransCanada discovered the potential sore spots in 2010 (see NGI, Sept. 19) but postponed making a start on the investigative digs and any repairs because the SCC hunt coincided with a parallel NEB pipeline engineering review.
The board has been reviewing hazard classifications — and construction standards — for locations along TQM to make its safety precautions catch up to real estate development since the line was built three decades ago.
Safety reclassifications can require increased precautions, such as concrete reinforcement of pipe sections that run near homes, schools and hospitals. TransCanada suspended the SCC prevention program on TQM until the parallel engineering review could establish any construction changes needed at the suspect locations.
“We understand that the results of the investigative digs conducted by TransCanada do not give any cause for concern,” GMI told the board. “While the security of the public is paramount, and great care must be given in order to ensure a safe operation of the pipeline, we believe that a safe and reliable supply to customers who rely on natural gas for basic necessities should not be overlooked either.”
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