The April 29 explosion of a natural gas pipeline in Westmoreland County was caused by corrosion so aggressive that it is challenging industry models for how quickly a small anomaly can grow into a fireball, Spectra Energy officials said Tuesday.
The Texas-based company — whose Texas Eastern pipeline ruptured five months ago, destroying James Baker’s house in Salem and badly burning him — said it had never seen corrosion eat at the walls of a pipeline with such speed.
A 2012 test of the interior of the pipeline revealed that, at that point, the spot that failed had already lost a third of its metal due to corrosion.
But Spectra officials said that did not trigger them to act or move up their next inspection date, scheduled for 2019, because they were assuming, based on industry experience, that at worst it would lose another 2 percent or 3 percent a year.
“What we saw was about 10 to 15 percent a year, or about five times what conservative assessments would be based on,” said Andy Drake, vice president of operations and environmental health and safety for Spectra.
“We’ve never seen anything like this before,” Mr. Drake said Tuesday evening at a public meeting with the Salem Township board of supervisors, federal and state officials, Westmoreland County residents and Helen Baker, Mr. Baker’s mother.
“Here we stand before you apologizing that we were not far enough ahead of this,” he said. “This is the challenges we’ve put to ourselves: Imagine a person standing next to this pipe — your son, your mother — are we comfortable that this pipe is absolutely safe everywhere?”
Ms. Baker came to the event clutching a piece of paper but she never got the nerve to speak. Instead, she sat quietly, sobbing and texting with her son, who had been released from the hospital earlier this month.
Her sister, Carol Webb, spoke for the family. She said Mr. Baker, who cannot walk, is “doing well,” and comes to family functions, but he’s not the same.
“I thank God he’s alive, and only God knows the tears that this family has shed,” she said. “This storm, this horrific thing that happened, we live with it daily.”
Ms. Webb said she was shocked to learn the company’s test had detected the corrosion at the explosion site four years ago and wondered why the company didn’t do anything about it then.
“If there’s something wrong — the slightest thing that’s wrong — get people out there,” she implored. “Make sure it never happens again. That’s all I want. I don’t ever want a family to go through what we’re going through.”
“We share that with you,” Mr. Drake replied.
In its preliminary investigation of the accident, the Pipeline and Hazardous Materials Safety Administration, which regulates interstate transmission pipelines, found corrosion on two welds at the site of the explosion. The welds were coated with tape, an outdated method of protection, and the coating above the corroded welds showed defects, the agency said.
After its investigation, Spectra confirmed that the tape coating was a major contributor to the corrosion, in part because it has a tendency to come apart from the pipe and to shield the metal from the cathodic protection system that’s supposed to act as a second line of corrosion defense.
Since July, Spectra has gone over its previous assessments and pinpointed 625 anomalies along a 263-mile stretch of the Texas Eastern system that starts at the Delmont Compressor station and stretches into New Jersey.
It has already excavated and examined 400 of the anomalies, repaired a third, and found that none match distinct signature of the site of the explosion, where a confluence of factors such as the tape coating, loss of wall thickness, higher temperatures from the nearby compressor station and environmental conditions contributed to the blast.
The explosion has caused the company to reevaluate how it looks for anomalies — setting the thresholds lower than before — and to shorten the time between inspections to three years.
Spectra has estimated it will cost between $75 million and $100 million to carry out all the excavations and repairs.
Its findings in this case are likely to echo through the industry, Mr. Drake said, because many pipelines laid in the 1970s, 1980s, and 1990s have similar coatings.
Anya Litvak: email@example.com or 412-263-1455.
First Published September 13, 2016 4:45 PM