Poorly maintained gas pipelines put increasing numbers at risk
That means corrosion can eat through the three-eighths of an inch without compromising safety. But once that corrosion eats into the required inch-thick wall, the response is not to replace the corroded segment, but to just lower the pressure by calculating how much pressure the remaining wall can safely withstand. He said a 30-inch pipeline built for 1,500 pounds per square inch might be reduced in stages to 1,200 pounds and then 900 pounds until, ultimately, it is replaced or simply abandoned. The safety of the protocol relies on the assumption that engineers have accurately estimated erosion rates.
“Allowing producers to de-rate the pipeline does not give them any incentive to maintain the pipeline,” Aaker said.
Why would companies shut down pipelines, and the flow of revenue, “ when they can just de-rate it?” asked Aaker, who sees government rules as the underlying problem by creating the wrong incentives for pipeline owners.
Preventive action not taken
Professor Theofanous served on a 2004 National Academy of Engineering committee that issued a 144-page report on how to improve pipeline safety. It focused on the added risks of urban development into what had been rural areas when high-pressure pipelines were laid.
The professor believes the report was heavily influenced by industry concerns, muddling some issues and avoiding the exploration of others, including improving technology to detect corrosion and other damage.
The principal means of detecting leaks in a pipeline now is to fly overhead and look for desiccated grass and trees because leaking natural gas kills plant life at the roots.
Inline inspection tools, or pigs, are sent down some pipelines to test for corrosion, weak welds and other signs of wear and damage. The San Bruno pipeline had never been inspected internally after more than half a century in the ground because its size varies in places, Pacific Gas & Electric said.
Mayor Ruane of San Bruno said that the company’s rationale troubles him. “We put a man on the moon decades ago and we can’t build a pipeline pig that can measure pipelines of varying size?”
Professor Theofanous said the problem could have been solved long ago. “Yes there are engineering problems, but the reason they have not been solved is a failure of will, not skill,” he said, noting that a prototype pig capable of moving through a pipeline of changing size is being tested, but is not yet in field use.
Even when pigs are used to check inside a pipeline, government rules allow inspections to be conducted as infrequently as once every seven years. When natural gas is contaminated with water and other liquids, that leaves a long time for corrosion to eat into pipeline walls, too long in the view of Theofanous and some other experts, though PHMSA and the industry say in areas of high concern about internal corrosion inspections can be required every four years.
A proposal for change
California Senators Diane Feinstein and Barbara Boxer introduced a bill offered by Secretary LaHood six days after the San Bruno blast. It would provide for 40 pipeline inspectors in addition to the 88 now on the payroll and would increase the maximum fine per incident from $1 million to $2.5 million. It would also provide for more data collection and a review of whether all pipelines, not just the sections designated as “high consequence areas” should be subject to inspection and safety planning. The Strengthening Pipeline Safety and Enforcement Act of 2010, S.3824, has since languished in committee and will die this month.
Both senators and Rep. Jackie Speier, who represents San Bruno, say they will push for enhanced pipeline safety legislation in the new Congress.
How long will luck hold up?
In 1999, some 277,000 gallons of gasoline gushed from a burst pipeline into Whatcom Creek upstream from Bellingham, Washington. A high-rise apartment building for low-income seniors and the disabled was just 75 feet from the water’s edge, while the county jail with about 300 inmates was 120 feet from the water. If the gasoline had reached the heart of the city, its downtown could have been effectively blown up.
Instead, two boys had the bad luck and poor judgment to be playing with matches along the water’s edge near the leak. The explosion they accidentally set off killed them, another youth and every other living thing for two miles upstream, but the early explosion meant that the city itself was spared. Because of the lives that likely would have been lost had the gasoline reached downtown, Bellingham’s mayor called the boys “unwitting heroes.”
When a 30-inch El Paso Corporation natural gas pipeline exploded in the New Mexico desert near Carlsbad in June 2000, the blast burned an extended family of 12, some of whom lingered in agony for days before the last of them died. They had camped out 675 feet from the blast site.
The El Paso pipeline, buried at a low spot in the desert that exerts extra pressure on the steel, simply corroded through after more than 50 years, the National Transportation Safety Board ruled.
The Carlsbad pipeline and the San Bruno pipeline that exploded this past September were laid decades before and never inspected, much less maintained.
Photo credit: Wikimedia user: Mbz1; under a CC-SA-3.0 license.