The Bureau of Ocean Energy Management, Regulation and Enforcement and U.S. Coast Guard show off the BP blowout preventer, which is lashed to a barge docked at the NASA Michoud Assembly Facility in eastern New Orleans Monday, September 13, 2010. nola.com

By Tom Doggett and Ayesha Rascoe; additional reporting by Braden Reddall; editing by Sofina Mirza-Reid and Lisa Shumaker WASHINGTON (Reuters) – The failure of the underwater blowout preventer that led to the massive BP oil spill in the Gulf of Mexico was caused by the inability of attached cutting devices to shear and seal the pipe of the leaking well, the U.S. government said on Wednesday. The cutting devices, known as blind shear rams, could not sever the drilling pipe because it was off center, according to a report commissioned by the Interior Department and U.S. Coast Guard. As a result, oil from the BP’s Macondo well flowed freely into the Gulf. The report is the first forensic examination of the BP blowout preventer after it was brought up from the sea floor. It does not change the conclusions of the White House’s oil spill commission, which found that missteps by the oil industry and government regulators set in motion the events that ultimately led to the biggest offshore oil spill in U.S. history. “The primary cause of failure was identified as the (blind shear rams) failing to close completely and seal the well due to a portion of drill pipe becoming trapped between the ram blocks,” said the report, which was conducted by the Norwegian company Det Norske Veritas. …

U.S. examines blowout preventer in BP oil spill