As a marathon hunt continues for cases of a Canadian pipeline plague, an additional effort aims to catch up with a U.S. method of easily and rapidly distributing hazard information.
Potential sites for fresh outbreaks of pipe metal fatigue known as stress-corrosion cracking (SCC) have been discovered in Quebec’s main natural gas line. At the same time, industry and the National Energy Board (NEB) have partnered to propose a Canadian counterpart to the uniform telephone number across the United States — 811 — for the safety service Call Before You Dig.
The 2010 round in an SCC hazard detection and repair program by TransCanada Corp., dating back to the mid-1990s, found nine possible trouble sites on its Trans Quebec and Maritimes Pipeline (TQM), the NEB has disclosed.
But the discoveries coincided with a board safety review expected to generate reclassifications of the potentially afflicted TQM segments. The review was launched to keep up with real estate development along the pipeline route across French Canada. TransCanada postponed digging up the flagged spots for further investigation and repair until the review is completed and new construction standards for the locations are determined.
Safety reclassifications require increased precautions such as installations of concrete slabs to reinforce the pipeline. The potential SCC sites are “anomalies” that may turn out to be the plague’s characteristic spider web-like networks of spreading cracks. Causes remain a mystery.
The irregularities are subtle hairlines detected by roving in-line inspection robots known as pigs that probe pipe walls from the inside with ultrasound. To confirm whether the odd spots are hazards, the pipe has to be unearthed for visual checkups.
In an order this month, the NEB directed TransCanada to do the investigative digs on TQM without waiting for completion of the safety standards reclassifications. A deadline of Oct. 7 was set for reporting the results.
While the work proceeds, TransCanada was also ordered to reduce operating pressure in the TQM segments under investigation to 90% of their levels over the previous 60 days. The October deadline ensures that the safety investigation work will be done before the onset of high heating-season demand for gas.
The SCC hunt has been a Canadian industry institution since the NEB handed down results of an inquiry into the pipe affliction in 1996. The probe was triggered by 22 pipeline accidents including a dozen outright ruptures and 10 leaks.
The inquiry uncovered SCC in all Canadian long-distance pipelines. TransCanada was the worst single victim, accounting for eight of the ruptures including an explosion and fire near homes in Rapid City, Manitoba. The only injury reported was singed fur on a house cat, but the mishap was regarded as a close call and warning to take national action.
A dozen years ago a line break on the NOVA Gas Transmission Ltd. system was believed to have been caused by SCC (see Daily GPI, Feb. 22, 1999).
Although SCC outbreaks are spectacular, they remain rare. The chief cause of pipeline accidents is excavations by construction or other digging activity.
Canada’s most dramatic recent spill — an oil leak that swamped a street and stained houses in Surrey, BC, a Vancouver suburb — resulted from an earth-moving machine banging into the Trans Mountain Pipe Line carrying oil from Alberta to the Pacific coast.
Trans Mountain’s owner, Kinder Morgan Canada, is among companies that have teamed up with the NEB to seek a Canadian version of the U.S. Call Before You Dig telephone line, 811. TransCanada is also supporting the move, along with all the nation’s principal oil and gas trade associations.
The industry is seeking authorization to use 811 as a pipeline information number from the Canadian Radio-Television and Telecommunications Commission (CRTC). The case is in a public comment stage, with no target date set yet for a decision and implementation of the call-center plan.
In Canada the 811 number is only used in four of the 10 provinces for buried communications systems. The new proposal calls for national use of 811 to dispense information on all buried infrastructure such as electricity, water and sanitation lines as well as oil and gas pipelines.
“The greatest threat to the continued, uninterrupted operation of these critical infrastructure networks is unintended damage during excavation of the soil. Easy public access via 811 to locate services prior to excavation is the best way to prevent disruption,” said the CRTC application. The package includes photos of the U.S. system, which uses an array of displays ranging from promotional hats to big billboards and narrow vertical signs on posts where buried services cross fences.
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