Image: Natural gas pipeline network in 2009
Department of Energy /
This map shows the U.S. natural gas pipeline network in 2009.
By M. Alex Johnson Reporter
updated 9/14/2010 5:36:11 PM ET 2010-09-14T21:36:11

Almost two-thirds of America’s natural gas pipelines — including the 30-inch main that exploded last week in San Bruno, Calif. — are susceptible to potentially deadly faults because they can’t use the industry’s best technology for testing and cleaning them, federal records show.

The 2½-foot-wide gas main exploded Thursday night, killing at least four people, injuring dozens more and destroying scores of homes. The California Public Utilities Commission has ordered an inquiry and told Pacific Gas and Electric Co., the utility that owned and operated the pipe, to inspect all of the state’s gas pipelines for potential problems.

PG&E says it’s still too early to know why the pipe blew up. But disclosures since the blast make it clear that a trifecta of vulnerabilities meant the San Bruno main was prone to fail sooner rather than later:

  • It was 54 years old, at the outer limit of its expected 50-year lifetime.
  • It was made of steel. As reported last week regulators have long regarded steel — which is used in about half of all gas pipelines and nearly two-thirds of the nation’s larger gas mains — as a safety hazard because it’s too rigid and easily corrodible.
  • Because of the gas main’s age and the twists and turns of the pipeline, PG&E couldn’t use robots that would have been the best way to maintain and inspect it.
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Those robots are known as “smart pigs,” so-called either because of the squealing noise they make as they root through pipes or as an acronym for "pipeline intervention gadget," according to the Pigging Products & Services Association. The sensor-laden pigs are smart little critters that ride along on the flow of gas, cleaning interior surfaces, removing corrosive water, sending back data on possible structural flaws and even plugging some leaks themselves.

But records filed with the Office of Pipeline Safety, a division of the U.S. Pipeline and Hazardous Safety Administration, show that about 63 percent of the nation’s natural gas pipelines still aren’t inspected by the pigs because they’re too old or too twisty to be retrofitted to use them.

“These gas lines are definitely a ticking time bomb, and that is why people are concerned, and that’s why federal and state regulators need to intervene,” said Mark Toney, executive director of the Utility Reform Network, a nonprofit California watchdog group.

‘This is a national safety issue’
Pigs are the most effective way to inspect and maintain pipelines, with the most advanced of them approaching 95 percent reliability in detecting problems, the Gas Research Institute said. But PG&E President Chris Johns said at a news conference that the entire 51-mile segment of pipeline that included the faulty main in San Bruno couldn’t be inspected with pigs because of its twisty configuration.

Federal law — specifically, the Pipeline Integrity Management Program — requires all newly constructed lines to be inspected by pigs. But much of the nation’s natural gas infrastructure was installed in the 1950s and 1960s, and the law doesn’t require retrofitting of those older lines.

Three factors are primarily responsible for the slowness to adopt pigging and other state-of-the-art technology, said the Southwest Research Institute, a nonprofit applied engineering foundation that studies pipeline safety for the National Energy Technology Laboratory:

  • The “considerable cost” of installing and running pigs. There’s no rule of thumb because each installation is unique, dependent on expenses for excavation and replacement of buildings and other infrastructure that must be demolished or moved. But after the Pipeline Safely Improvement Act went into effect in December 2002, the American Gas Association, the industry’s trade group, projected that compliance would average out to about $10,000 per mile of pipeline per year.
  • Service disruptions that occur when infrastructure has to be torn up to do the work.
  • Unsuitability. While federal law calls for pigging whenever possible, “various geometrical and geographical constraints” — like the terrain through which the San Bruno pipe ran — can make pigs unusable.

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As the years have gone by without needed upgrades, “neighborhoods have grown and sprawled over these gas pipes,” said Jim Hall, former chairman of the National Transportation Safety Board, which is in charge of the San Bruno investigation because the federal pipeline bureaucracy is part of the Transportation Department.

“This a national safety issue in many local communities because of a lack of local rules and regulation” to beef up standards where federal rules don’t apply, he said.

Sen. Barbara Boxer, D-Calif., said utilities’ foot-dragging on maintenance and emergency planning had opened her eyes, adding, “I think many questions must be answered by all of us whose job it is to protect our people.”

Until those questions are answered, said Rep. Jackie Speier, a Democrat who represents part of San Francisco and San Mateo County in Congress, “the question that everyone’s asking is:  ‘Is this going to happen in my community?’”

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© 2013 Reprints

Video: 911 calls reveal chaos of California gas explosion

  1. Transcript of: 911 calls reveal chaos of California gas explosion

    BRIAN WILLIAMS, anchor: Now we turn to California , where, for the first time , we're hearing what it sounded like when that gas explosion leveled part of a neighborhood in San Bruno , south of San Francisco , and we're hearing it from the perspective of the first responders who were trying to make sense of what they were seeing and hearing, what was going on there. Again tonight, our own Miguel Almaguer is in San Bruno for us. Miguel , good evening.

    MIGUEL ALMAGUER reporting: Brian , good evening. That dinnertime blast claimed lives, and it destroyed the community behind me. We're only about three miles away from San Francisco International Airport , and after the explosion, just about everyone here feared the worst.

    Offscreen Voice #1: It appears that we have a plane down in the neighborhood, multiple structures on fire, and we have a fireball still coming out.

    ALMAGUER: As firefighters raced toward the flames, the blast sent neighbors running for their lives.

    Mr. KEN CHETCUTI (South San Francisco Police Department): It was a pretty chaotic scene going down the hill, people running up the hill just trying to get out.

    ALMAGUER: The heat was so intense, the inferno so massive, it took nearly a half hour to determine this was no plane crash.

    Offscreen Voice #2: This does not appear that this is an aircraft down. It appears that this is some sort of natural gas explosion .

    ALMAGUER: The cause of Thursday's gas line rupture that killed at least four people is still under investigation.

    Mr. JOHN PRIOLO: I grew up here, I work here, and it's my family.

    ALMAGUER: Firefighter John Priolo:

    Mr. PRIOLO: You're seeing people run up to you, they're burnt. They're looking at us for help, and right then and there we didn't have the resources.

    ALMAGUER: Chaos and confusion, and then no way to fight the fire.

    Offscreen Voice #3: We think we got a broken water main down here, so they need to lay in from the corner of San Bruno Avenue .

    Mr. BILL FORESTER (San Bruno Fire Department): It's a sinking feeling, to say the least , because you count on that water being there; and if there was ever a time where you needed it, it was there.

    ALMAGUER: This neighborhood burned for a day and a half. By the time crews beat back the flames, nearly 40 homes were destroyed, hundreds more damaged. Federal investigators have wrapped up their probe in the blast zone behind me. We're told their preliminary report could take about 30 days. And while at least four people are dead tonight, Brian , another three are still missing.

    WILLIAMS: Miguel Almaguer on the job in San Bruno , California , again tonight. Miguel , thanks for that.

Photos: Massive fire in San Bruno

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  1. Emergency workers sift through rubble of a burned down home on Sunday, three days after the natural gas pipeline explosion. (Tony Avelar / AP) Back to slideshow navigation
  2. Search and rescue teams escort a cadaver dog through a destroyed San Bruno neighborhood on Sunday. (Josh Edelson / EPA) Back to slideshow navigation
  3. An unidentified man inspects the roof of a house labeled with a 'green card,' indicating that it is undamaged. (Josh Edelson / EPA) Back to slideshow navigation
  4. Julie Frechette, left, comforts neighbor Janel Costanzo shortly after the two returned to their fire-ravaged neighborhood on Sunday. Police allowed some residents home for the first time since Thursday night's gas line rupture. Frechette and Costanzo, who live on Glenview Drive, suffered minor damage to their houses. (Noah Berger / AP) Back to slideshow navigation
  5. Hundreds of displaced San Bruno residents jammed a town hall meeting at St. Robert's Catholic Church in San Bruno on Saturday. (Tony Avelar / AP) Back to slideshow navigation
  6. The remains of burned vehicles and homes are seen Saturday near the site of a natural gas explosion. (Noah Berger / Pool via Reuters) Back to slideshow navigation
  7. A wrecked gas pipe lies on the street as investigators gather at the scene on Saturday. (Stephen Lam / Reuters) Back to slideshow navigation
  8. The sun rises on Friday to reveal rows of chimneys where homes once stood. (Peter Dasilva / EPA) Back to slideshow navigation
  9. The explosion left this crater, which by Friday morning had filled with water. (Jeff Chiu / AP) Back to slideshow navigation
  10. Homes sit destroyed or damaged by the fire, which spread from the explosion that produced the crater near top left. (Justin Sullivan / Getty Images) Back to slideshow navigation
  11. A for sale sign is shown in front of three San Bruno homes that were destroyed in the explosion. (Paul Sakuma / AP) Back to slideshow navigation
  12. A massive fire roars through the mostly residential neighborhood of San Bruno on Thursday. (Jeff Chiu / AP) Back to slideshow navigation
  13. Cars were among the possessions destroyed by the fire that followed the explosion. (Paul Sakuma / AP) Back to slideshow navigation
  14. A helicopter drops water on the huge blaze. (Paul Sakuma / AP) Back to slideshow navigation
  15. Firefighters battle house fires Thursday night. In all, 38 homes were destroyed. (Peter Dasilva / EPA) Back to slideshow navigation
  16. A woman is treated after the explosion. (Mike Adaskaveg / AP) Back to slideshow navigation
  17. Evacuees check in with officials in San Bruno. (Jeff Chiu / AP) Back to slideshow navigation
  18. Judy and Frank Serresseque move their cats and a few belongings after they were evacuated following the explosion. (Mike Adaskaveg / AP) Back to slideshow navigation
  19. A video frame grab from KNTV shows part of the fire. (NBC News) Back to slideshow navigation
  20. San Francisco firefighters monitor the flames. (Justin Sullivan / Getty Images) Back to slideshow navigation
  21. A law enforcement official runs toward the massive San Bruno fire. (Justin Sullivan / Getty Images) Back to slideshow navigation
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