NEW ORLEANS | The blowout preventer that should have stopped the BP oil spill failed largely because of a faulty design and a trapped piece of pipe, an official probe found Wednesday, appearing to shift some blame for the blowout from the oil giant and toward those who built and maintained the 300-ton safety device.
A 551-page investigative report said the piece of drill pipe prevented the blowout preventer's blind shear rams from sealing the well around the time of the April 20 oil rig explosion off the coast of Louisiana. The shear rams are components in a blowout preventer that cut, or shear, through drill pipe and form a seal against well pressure.
The drill pipe's position within the wellbore caused it to buckle and bow when the well lost control, impeding the rams, according to the report. The Norwegian firm hired by the government to test the blowout preventer also faulted the performance and design of the fail-safe device.
Det Norske Veritas' report doesn't single out any one party involved in the well, but discusses in great detail why the device didn't work. The device was made by Cameron and maintained by Transocean Ltd.
BP, Cameron and Transocean did not respond to requests for comment on the report.
Speculation on why the blowout preventer failed has persisted during the year since the disaster.
Documents emerged early in the probe showing that a part of the device had a hydraulic leak, which would have reduced its effectiveness, and that a passive "deadman" trigger had a low, perhaps even dead, battery.
DNV noted loss of fluid and weak battery issues in its report, but did not seem to cite them as significant causes of the blowout preventer's failure.
Philip Johnson, a University of Alabama civil engineering professor, said the report indicates that the blowout preventer had a design flaw in its blind shear rams that may have gone unnoticed by the entire industry, not just by Cameron.
"This is the first time in all of this that there has been a clear design flaw in the blowout preventer cited," he said. "My reaction is, 'Holy smokes, every set of blind shear rams out there may have this problem.' We need to take a look at every set of blind shear rams out there and make sure they all don't have this problem.
"There are plenty of lawyers out there that are going to try to make this Cameron's fault, but I couldn't help [the lawyers]," he added.
The firm made several recommendations for the industry in its report, including changing the design of blowout preventers.
The firm's tests also indicated that some backup control-system components did not perform as intended. It recommended the industry revise its procedures for periodic testing and verification of the backup control systems to assure they will function properly at all times.
Blowout preventers sit at the wellhead of exploratory wells and are supposed to lock in place to prevent a spill in case of an explosion.
The device that was used with BP's Macondo well was raised from the seafloor Sept 4. Testing began at a NASA facility in New Orleans in November.