One of the biggest natural-gas safety issues threatening Californians is a notoriously brittle brand of plastic pie, made in the 1970’s, that failed and caused two recent explosions, both within the past year.
Ruptures on the DuPont pipe, made out of a plastic called Aldyl-A, were responsible for explosions in Cupertino and the Sacramento suburb of Roseville (Placer County) within a month’s time in 2011. Pacific Gas and Electric Co., whose lines were involved in both blasts, said late last year that it would remove more than 1,200 miles of the pipe from its system.
Companies such as Pacific Gas and Electric Co., which owns the line that caused the Cupertino blast, don’t have to routinely report what they know about failure rates of particular brands of plastic pipes, even to the federal and state agencies that regulate pipeline operators. The federal government, bowing to industry resistance, has never required it.
Officials with the California Public Utilities Commission, which oversees PG&E, say the utility does account for plastic pipe leaks in quarterly reports, but does not indicate the maker of the pipes involved. PG&E provides that and other key information about plastic pipe failures on a voluntary, anonymous basis to an industry-maintained confidential database.
The pipes are found in distribution networks that deliver natural gas directly into people’s homes and businesses. They are smaller than transmission lines such as the PG&E pipe that exploded in San Bruno in 2010, killing eight people, but they are capable of causing major damage – as evidenced by December 2008 blast in Rancho Cordova (Sacramento County) that killed a homeowner.
The Aug. 31 blast in Cupertino destroyed a condominium, and the Roseville explosion less than a month later resulted in the shutdown of a major intersection for more than 12 hours. No one was hurt in either incident.
A task force that the Public Utilities Commission formed after the San Bruno disaster said Wednesday that Aldyl-A pipe was among 17 major hazards connected with the state’s natural-gas delivery system that require immediate action.
It said in a statement that it would investigate whether other utilities in California besides PG&E were taking steps to identify and deal with the risk from the plastic pipe, which federal officials first recommended be removed in 2002.
Aldyl-A pipe is especially failure prone when it is pressed against rocks or has been pinched off. DuPont issued warnings to utilities about the failure risk from its pre-1973 Aldyl-A starting in 1982.
A month after the Cupertino explosion, however, state regulators downplayed the risk from the pipe.
At a gas-safety workshop held last September, Sunil Shori, a gas engineer with the commission, said Aldyl-A leakage rates were “not drastically different” from other types of plastic lines, although he acknowledged that the material was “not as tough” as later plastics and was prone to sudden rips from cracking.
The next day, Sept. 27, the Roseville pipeline exploded. The utilities commission is investigating both failures.
The commission’s task force said it would seek details about how widely Aldyl-A is used throughout the state. PG&E and other utilities nationwide have been reporting Aldyl-A failure rates to an industry-run data-tracking system, which is not required to share its findings with state regulators.
Assemblyman Jerry Hill, D-San Mateo, who has been critical of the commission since the San Bruno blast, called its recognition of risks from Aldyl-A “a day late and a dollar short.”
Hill is sponsoring legislation that would require state regulators to act on gas-safety recommendations by the National Transportation Safety Board, which issued a 1998 warning about plastic pipe similar to Aldyl-A.
“It’s about time they recognize something that was known about 14 years ago and was first identified in 1982 when DuPont said it was a problem,” Hill said. “For all this time, they didn’t do anything about it.”
Other risks identified by the commission’s task force include gas-transmission lines that were exempted from strength testing in 1970, accidental pipeline puncturing by third parties, utilities’ ignorance of the quality of their pipes, inadequate pipeline leak surveys, lax regulation and utility mismanagement.
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