Natural-gas trunk line through state at risk of cracking

By Craig Welch
Seattle Times staff reporter

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After the 46-year-old line ruptured twice in six months, the federal Office of Pipeline Safety yesterday told Williams Northwest Pipeline it must replace every section of line it hopes to use, or prove it's resistant to cracking.

"We felt this particular pipeline needed immediate attention and needed to be replaced in various sections," said Damon Hill, Pipeline Safety spokesman.

Since the company has a second, newer line 20 feet away running parallel between Sumas, Whatcom County, and Washougal, on the Columbia River in Clark County, the order is not expected to affect the flow of natural gas to homes or businesses. But company officials expect the costs of the replacement work to run into the millions of dollars.

"In order to put the line back into service, we have to demonstrate the integrity of the pipeline," said Bev Chipman, a spokeswoman for Williams. "We are already cutting out segments of the line and replacing it."

Four years after the Olympic Pipe Line explosion killed three people in Bellingham, action on the Williams line raises new questions — even among some state inspectors — about how equipped regulators are to prevent pipeline ruptures.

Williams Northwest Pipeline supplies 80 percent of Washington's gas, primarily from Canada and the Rocky Mountains, and is a subsidiary of the Tulsa, Okla.-based Williams Cos., which moves gas through 14,000 miles of interstate pipelines.

The company's natural-gas artery burst with a roar on May 1 near Lake Tapps, sparking evacuations at a school, a supermarket and about 40 homes. While such eruptions are typically caused by land movement or other outside forces, inspectors later identified the cause as "stress corrosion cracking" — a type of wear and tear influenced by weather, soil acidity and other environmental factors. The line had passed inspection within the previous year.

The same type of cracking caused another section of the Williams line to leak in 1999 and fail during tests in 1992. In 1994, a lateral line on the same system near Oregon City, Ore., failed 22 times during tests.

After repairs were made to the line near Lake Tapps in May, inspectors ordered the company to reduce the line's gas pressure 20 percent to 632 pounds per square inch.

Following a similar break on an oil pipeline in Arizona that sprayed 16,000 gallons of petroleum onto homes, federal inspectors issued a formal alert to pipeline operators about stress corrosion cracking.

Inspectors typically examine lines by running water through them at high pressure. But such hydrostatic testing "doesn't guarantee there's no problem there" and can't reveal stress corrosion cracks, said Alan Rathbun, pipeline safety director for the Washington Utilities and Transportation Commission. Until recently, companies weren't required to do the complex in-line inspections that might catch the problem.

"We have no actual regulation saying that you need to address (stress corrosion cracking) in your pipelines," said Hill, with the federal safety office. "Basically, it's a new phenomenon, and we're studying it."

But last week, in tiny Toledo, Lewis County, the Williams line ruptured again — 250 yards from a home, causing the additional evacuations of four other houses.

"Conventional wisdom says reducing pressure by 20 percent is how you keep a line safe," Rathbun said. "When the Toledo rupture hit, suddenly conventional wisdom went out the window.

"(Stress corrosion cracking) is at a higher profile now, and I think there are lessons that have to be learned by other operators," Rathbun said. "Just reducing pressure may not be sufficient."

Even today, state and federal regulators acknowledge stress corrosion cracking must be considered when evaluating a line's integrity, but in-line testing is required only where pipelines run through populated areas. Companies can get around even those tests, some said.

"The problem, particularly in the gas industry, is they aren't built for this kind of testing, so the law gives them an out," said Kim West, senior pipeline-safety engineer for the state.

For now, Williams is ramping down the gas in its pipeline to 100 pounds per square inch — roughly 12 percent of its capacity — which essentially takes the line out of service. The company must improve all lines in populated areas within three years and improve the entire system within a decade.

All told, Williams expects to have to replace about 100 miles of pipe, Chipman said.

Craig Welch: 206-464-2093 or cwelch@seattletimes.com

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