The National Transportation Safety Board's interim report on the Sept. 9 natural-gas pipeline rupture and explosion that killed eight people in San Bruno, Calif., focuses on defective pipe welds as a cause of the blast. Photo: Courtesy NTSB A new report says a portion of the California pipeline that exploded on Sept. 9 was seam-welded. The study rules out external corrosion and damage caused by a third party as causes of the blast. Owner Pacific Gas & Electric’s records indicate the pipeline was seamless, but NTSB's report, released on Dec. 14, says a portion near the rupture was seam-welded. The
The market is generally healthy and steadily growing, and margins are up for large specialty contractors. Further, advances in design tools and owner demand for collaboration are giving subcontractors a seat at the table early on in projects.