Fargo, ND – A leaky natural gas pipe blamed for a Sept. 2 house explosion here that injured 13 members of a family was of a type that was the subject of a warning bulletin nine years ago.

The federal government in 1999 issued a bulletin warning that pipe manufactured by Century Utility Products Inc. from 1970 to 1973 might fail “due to its poor resistance to brittle-like cracking.”

The underground pipe serving the Fargo duplex that exploded was manufactured by Century in 1972, according to Xcel Energy’s incident report to the U.S. Pipeline and Hazardous Materials Safety Administration.

It was the same type of pipe blamed for a blast three years ago in Cottage Grove, Minn. That blast prompted Minnesota to launch a program with Xcel Energy to replace the pipe throughout the state by 2010.

In Iowa, where the suspect pipe was blamed for a 1994 fatal explosion at a bar in Waterloo, the two regulated utility companies in the state voluntarily agreed to find and replace the faulty Century pipe in their systems, said Rob Hillesland, spokesman for the Iowa Utilities Board. The process was completed in 1999.

Xcel said only about 2 percent of its plastic distribution pipelines in North Dakota and less than 3 percent of its service lines to homes and businesses in the state contain Century pipe.

“Presently, Xcel Energy has not made a determination to replace Century pipe in North Dakota,” the utility said in a statement.

Xcel said it performs annual leak surveys on Century mains and inspections every three years on service lines to homes and businesses.

“We are confident that our natural gas system is operating safely,” Xcel said. “Our ongoing maintenance work includes numerous procedures to ensure this.”

Properly installed Century pipe that isn’t under a lot of stress might not be at risk, officials said.

“It appears there’s always something else that needs to be put into the equation for this pipe to fail,” said Patrick Fahn, utility analyst with the North Dakota Public Service Commission.

“I wouldn’t say that just having that pipe is a hazard,” said Elizabeth Skalnek, chief engineer for the Minnesota Office of Pipeline Safety.

Fahn said that if Xcel followed federal guidelines for pipeline safety, it will not face penalties for the Fargo explosion. However, the PSC could recommend changes to the utility’s operations, he said.

In a recent e-mail about the investigation, Kevin Hanson, assistant director of the commission’s testing and safety division, wrote that he spoke to a Minnesota official about that state’s Century pipe replacement program.

“I think we are going to recommendation (sic) some form of replacement program also as a remedial action,” Hanson wrote in the e-mail, sent to PSC officials Oct. 2 and later obtained by The Forum newspaper in Fargo.