By DANIEL GILBERT, Wall Street Journal, December 30, 2011
Regulators, Preparing to Tighten Safety Rules, Focus on Combination of Causes
Safety regulators are increasingly focusing on how seemingly minor problems with a natural-gas pipeline can combine to magnify the risk of an explosion or serious leak, as some experts say was probably the case in a blast that shook a rural Ohio neighborhood last month.
The regulators, who are preparing to tighten pipeline-safety rules, are considering whether to require companies to change the way they assess risk.
Jeff Gilliam, director of engineering and research at the U.S. Pipeline and Hazardous Materials Safety Administration, told a meeting of regulators and industry officials in August that the current models companies use are "ineffective to analyze the risks" posed in a combination of threats.
Until last year, regulators collected data only on what was deemed to be the primary cause of a pipeline failure. But PHMSA, which other federal regulators have faulted for lax oversight, is stepping up pressure on companies in the wake of several serious explosions, including one near Glouster, Ohio, that destroyed two houses on Nov. 16 and a deadly 2010 explosion in a PG&E Corp. pipeline that leveled a neighborhood in San Bruno, Calif.
In investigating the Glouster explosion, regulators are trying to determine what caused sections of the Tennessee Gas Pipeline, owned by El Paso Corp., to fail after decades of safe operations and recent safety checks. The pipeline, which stretches from South Texas to the Canadian border, ruptured where two sections were welded together. The blast destroyed two houses more than 300 yards away and caused minor injuries.
Another explosion in Ohio on Nov. 16, on the same El Paso pipeline, destroyed two houses.
El Paso, which is being acquired by Kinder Morgan Inc., said in a report to federal regulators on Dec. 12 that it hadn't yet determined what caused the weld to fail. It said in a statement that it is "committed to determining and implementing appropriate mitigation measures to do its best to prevent similar incidents from occurring."
El Paso has been among the most aggressive of its peers in modifying its pipelines so that they can be inspected internally, with a device called a smart pig. The device travels the interior of the pipe and is widely regarded as one of the most effective ways of detecting weaknesses. So far, El Paso says, it has inspected 98% of its more than 12,000 miles of transmission pipeline on land at least once. But such inspections were performed on the sections of the Tennessee Gas Pipeline that failed in Ohio, and didn't raise any alarms, according to the company.
Nationally, the number of major failures on high-pressure natural-gas pipelines climbed 50% in the last decade, while the number of miles of such pipe increased less than 5%, according to federal data. Accidents caused by people inadvertently digging into pipelines have decreased 43% over that time; those caused by the failure of pipeline materials have nearly quadrupled.
While age may be a factor in some cases, experts say that forces acting in concert, such as the freezing and thawing of ground that adds stress on weakened pipe, can help explain the increase.
"When you start looking at combinations, the possible risk goes up exponentially," said Paul Oleksa, a pipeline-safety consultant in Ohio. Federal regulators, he said, "need to be paying more attention to this kind of thing."
In March—nearly five years after auditing El Paso's operations—pipeline regulators concluded that the company had violated a rule requiring it to evaluate all potential threats, and ordered it to revise its methods. El Paso, which in 2008 maintained that its methods to assess risk were sound, now says it has revised its models "to better evaluate the interaction of various threat conditions."
PHMSA said in a statement that it has "taken steps to address interactive threats to the safety of pipelines, including implementing rule-making actions, issuing safety advisories and holding industry workshops to raise awareness and share ideas."
Two failures along the Tennessee Gas Pipeline before November's—an explosion in February and a leak in March—occurred at welds known to have cracks but long considered stable, according to the company. In the March incident, El Paso found that shifting soil had added to stress on the pipeline, and now says there is evidence of ground movement where the pipe failed in November.
The Interstate Natural Gas Association of America, an industry group, says the threat to pipelines posed by interacting conditions has received relatively little attention because it isn't as serious as corrosion or damage by excavators.
"We've addressed some of the bigger threats," said Don Santa, the association's chief executive. Now, as the industry seeks to further reduce incidents, it is looking to "peel back the layers" to identify secondary causes, he said, adding that a task force formed by the association is studying the issue.
Some experts say gas-pipeline companies aren't doing enough.
"A lot of them are in denial," said Richard Kuprewicz, a pipeline-safety consultant based near Seattle who has been critical of the industry and believes the interaction of multiple problems caused the fatal explosion in San Bruno.
After the Tennessee Gas Pipeline welds gave way in February and March, federal officials ordered El Paso to re-evaluate the results of its smart-pig tests and to perform an additional inspection. A June inspection found one place in the pipe where metal had thinned that needed a repair, which El Paso made in September, but nothing amiss in the weld that ruptured two months later, El Paso says.
El Paso says it believes the smart pig was operating properly. "This suggests that any anomaly in the weld would have been of a size or type or in a location that was not detectable" with current technology, it said in a statement.
Write to Daniel Gilbert at daniel.gilbert@wsj.com
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