1988 repair work on San Bruno pipe revealed

Pacific Gas and Electric Co. has handed over several documents to federal investigators probing the San Bruno natural-gas pipeline explosion that detail 1988 repairs to a nearby section of the pipe for a flaw that, by law, should have mandated an inspection that could have prevented last year's disaster.
The 1988 repairs in San Mateo were performed to replace a section of pipeline where a weld in a longitudinal seam - a seam running down the length of the line - had developed a leak, the newly released records show.
Under a 2002 federal law, a prior defect that caused a leak on a longitudinal seam weld would have required PG&E to check the entire 51 miles of the Milpitas-to-San Francisco transmission pipeline for such problems. The company, however, publicly questioned the cause of the 1988 leak when the repair was discovered this year - saying it might not have been on a longitudinal seam weld.
PG&E never checked the line for potentially flawed welds, and learned only after last year's disaster that its records falsely described the San Bruno section as being seamless. Federal investigators discovered the blunder after the blast, which metallurgists believe occurred at a poorly constructed longitudinal seam weld.
Documents that the National Transportation Safety Board made public this month reveal that PG&E did, in fact, have several records showing that the line had a defective longitudinal seam weld in 1988. However, it appears the company was unaware before the San Bruno explosion that the documents existed.