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Crews boxed up three segments of the ruptured pipeline and sent them on their way to NTSB headquarters in Washington, D.C. early Monday morning.
The section of gas pipeline that ruptured in a fiery explosion Thursday in San Bruno is making a journey to the nation's capitol for detailed inspection at the headquarters of the National Transporation Safety Board.
The blast launched a 28-foot section of pipeline from underground. It was found about 100 feet from a crater left behind from the explosion. That segment, along with the the sections before and after ruptured area, were packaged in large wooden crates early Monday morning and left the scene on a flatbed truck at about 6 a.m.
NTSB Vice Chairman Christopher Hart said Monday morning that all three segments will undergo thorough inspection at the as part of the investigation into the fatal blast.
Hart said it will take NTSB investigators about a week to 10 days to comb through the evidence in the San Bruno neighborhood where the explosion happened.
The entire investigation into the explosion could take up to a year, Hart said. It could take that long because as part of the investigation, officials will be looking into the history of the pipeline, reports of any calls to PG&E about the safety of that section, emergency preparations and several other aspects, he said.
Investigators will also be looking into reports of calls to PG&E about a gas smell in the area in the days and weeks prior to the blast. So far, PG&E says they have not found any reports of such calls in their records from Sept. 1-9.
Hart announced over the weekend that the NTSB will be the sole source of information regarding the investigation.
Investigators found multiple seams on the section of pipe, Hart said. The NTSB initially reported that the section of pipe was seamless.
"Longitudinal seams" found on the pipe means it started as a flat piece of metal that was curved and welded. The pipe also has "circumferential welds," meaning that section was made of smaller segments of pipe.
Welding does not automatically mean that segment of pipe had undergone repairs, Hart said. Segmented pipe is more expensive than pipe not welded together from smaller pieces, he added.
It's too early to tell if the pipe was corroded, Hart said. It's also unknown how deep underground the pipe was at the time of the explosion, he added. There was no automatic shutoff valve on the pipe and the locations of two manual shutoff valves on either end of the pipe are unknown, he said.
PG&E has provided the NTSB with information on the locations of other pipelines in the area, Hart said. The date of the last PG&E inspection of the pipe is unknown.
Bay City News contributed to this report.