The type of plastic pipe that caused a natural gas explosion and fire in a Cupertino condominium last month has long been considered a potential threat to the public, but federal pipeline regulators have allowed companies to keep it in the ground and secretly gather limited information about its failings, a Chronicle investigation shows.

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.

Timothy Alan Simon, one of the five PUC members appointed by the governor, said that should change.

"These are gas lines coming to your home," Simon said. "Every resident should have a certain level of assurance that we are not hiding information that they need to know to determine safety."

Cupertino blast

The Cupertino condominium was gutted Aug. 31 after a plastic pipeline fitting cracked, filling the garage with gas that exploded just minutes after the owner left for lunch. PG&E later found six other plastic pipe failures near the blast site.

The line was an especially problematic type of pipe manufactured by DuPont called Aldyl-A. PG&E has 1,231 miles of the early-1970s-vintage pipe in its system.

Federal regulators singled out pre-1973 Aldyl-A starting in 2002 as being at risk of failing because of premature cracking. Explosions caused by failed Aldyl-A and other types of plastic pipe have killed more than 50 people in the United States since 1971, the federal government says.

Instead of requiring utilities to remove the problem plastic, however, U.S. pipeline safety officials have allowed the industry to compile limited data about failures in Aldyl-A and similar pipe and to keep the findings confidential.

Pipeline operators like PG&E are not required by law to report all plastic pipeline failures, and those in the voluntary program are allowed to file reports anonymously. The operators insisted on those conditions when the industry and government agreed to create a committee to track the dangers of plastic pipe in 1999, and have since resisted mandatory reporting and full disclosure.

The 16-member committee is divided between utility and industry officials and representatives of federal and state regulatory agencies, along with a lone official from the National Transportation Safety Board.

It meets in private twice a year and generates an annual summary of failures involving plastic parts, from pipe to valves to molded fittings.

Public release spotty

The publicly released information is limited. For example, the committee's summary for 2010 said Aldyl-A pipe was failing at roughly the same rate as in the past - without saying what that rate was.

For every pipeline failure, the panel - known as the Plastic Pipeline Database Committee - asks pipeline operators to list the maker and type of plastic part involved, the type of soil nearby and the presumed cause. That information is not included in the committee's publicly released summary, however. Nor are numbers of failures or the extent of damage from accidents.

The panel keeps much of its data even from state regulatory agencies, such as the California PUC.

The U.S. Pipeline and Hazardous Materials Safety Administration, which enforces federal pipe safety law, has two representatives on the committee. But even that agency is unable to see which companies are providing specific data about failures, because of the anonymous nature of the reporting.

"It's crazy," said Rick Kessler, a lobbyist with the nonprofit Pipeline Safety Trust advocacy group. "What is most troubling is that even after they compile this data, they don't do anything and the government doesn't do anything."

PUC Commissioner Simon wants to go beyond the current voluntary industry database to make sure state regulators know the critical details of the failures - including the brands of plastic pipe involved - and act on the knowledge.

The Cupertino explosion, along with the September 2010 disaster in San Bruno that killed eight people and a 2008 natural-gas blast in Rancho Cordova (Sacramento County) in which a homeowner died "have created a new day," Simon said. "I'm going to take a very close look at this."

Dangers long known

The pipeline industry was first told about the dangers of Aldyl-A in 1982, when manufacturer DuPont sent letters to PG&E and other customers warning about a weakness in pipes made before 1973, said Gene Palermo, a former chemist with the company who is now a private consultant.

He said pipes that are pressed by soil against hard surfaces, such as a rock, could fail in as little as five years. They are also vulnerable at any point where pressure is concentrated.

In 1998, the National Transportation Safety Board said cracked plastic pipes of all varieties had been responsible for a dozen major accidents and more than 50 deaths since 1971. Thirty-three of those victims died in a 1996 blast in San Juan, Puerto Rico, in which improperly installed Aldyl-A pipe failed.

Citing a "serious potential hazard to public safety," the board urged federal regulators to identify which types of plastic pipe posed the most risk and to "identify and replace, in a timely manner, any of the pipe that indicates poor performance."

Four years later, federal regulators finally sounded the alarm on pre-1973 Aldyl-A, saying it was one of three classes of plastic pipe that the industry should monitor. The agency did not order or even recommend that operators remove the pipe, however.

PG&E is only now assessing its system of Aldyl-A pipe, which it routinely installed in early 1970s developments in Northern and Central California.

Plans now mandated

A recent federal law requires PG&E, which has nearly 21,000 miles of plastic distribution main in its system, to develop integrity management plans to account for the risks of Aldyl-A or other known problematic varieties of plastic pipe.

"Our engineers are developing a comprehensive integrity-management plan to address these issues, and we are bringing in nationally recognized plastics and integrity-management experts to assist us," spokesman Brian Swanson said.

In Cupertino, the company plans to replace about 6,000 feet of the plastic line around the 400-unit condominium complex where the Aug. 31 blast occurred. It will check the system weekly for leaks in the meantime.

Asked specifically about the risks posed by Aldyl-A, how often it failed and for data it provided to the industry-government confidential database, PG&E's Swanson said only that the company learned of "issues regarding Aldyl-A" by working with industry trade groups, the plastic pipe-database panel as well as reviewing federal safety advisories, talking to DuPont, consulting industry experts and "through our own operating experience."

Limited data

PG&E is one of 188 utilities nationwide that confidentially report failures in plastic pipe to the industry-government committee. The information is not made available to utilities that don't submit data, let alone the public.

"The only way some gas companies would participate is if they were anonymous," said Palermo, an early member of the industry-government panel. "They did not want their own state regulators to know that they were reporting certain data, data that they were not giving to the state regulators."

The U.S. Pipeline and Hazardous Materials Safety Administration would not comment on the secret reporting system. It said only that the committee's efforts help the government "better understand and address the performance of plastic pipes."

In 2008, however, the agency proposed that pipeline operators be required to report all plastic-pipe failures within 90 days, and suggested that agency officials - not an industry organization - analyze and share the information.

It also raised questions about the objectivity of the plastic database panel and what it considered the limited availability of its results.

Kate Miller, an official with the American Gas Association trade group that oversees plastic-pipe panel meetings, said in a letter at the time that the industry-operated committee was sufficient to "identify national trends" and that mandatory reporting was "unnecessary and counterproductive." Eliminating it, she said, would leave the government regulators with "zero data" going forward.

In the end, the industry's resistance doomed the mandatory-reporting plan.

Some benefits

The National Transportation Safety Board, whose concerns in 1998 led to the committee's formation, said the current system has its merits.

"Troublesome materials are identified in an open forum and a report is released," said Kelly Nantel, a board spokeswoman. "From our perspective, this is a good thing. The report is valuable in terms of providing industry, PHMSA (the Pipeline and Hazardous Materials Safety Administration) and state regulators and us with information on emerging trends and developing issues."

More public data about the sheer number of failures, pipeline safety advocates suggest, would help persuade lawmakers to require valves in older pipe that would automatically cut the flow of gas if the line fails.

Such valves are required for new or replacement lines installed after 2006, but not for older lines such as the one in Cupertino, where it took PG&E more than 90 minutes to cut the flow of gas after the Aug. 31 explosion.

Royce Don Deaver, a pipeline safety consultant in Texas who formerly worked in the industry, said federal regulators don't have enough leak and failure data to back up such tougher rules, thanks to the industry's secrecy provisions.

"The industry is controlling this, holding the key to the safe of the Ten Commandments for pipeline safety," Deaver said. "That key is the database as to what is going on about plastic pipe and all the problems out there."

Richard Kuprewicz, a consultant from Redmond, Wash., who advises federal regulators on pipeline safety, said keeping data hidden blinds regulators.

The current system, he said, creates "the illusion of safety, in that it gives people the impression that someone is keeping real data that means something. It may or may not - most likely not."

Complete coverage: To read "Report to America on Pipeline Safety" or to see Chronicle coverage since the San Bruno pipeline blast, video of the disaster, and company and government documents about PG&E's actions, go to www.sfgate.com/san-bruno-fire.