(Bloomberg) -- The five-story blowout preventer that sat atop BP Plc’s Macondo well in the Gulf of Mexico was supposed to be a final check against uncontrolled surges of oil and explosive gas.

It wasn’t.

Now, nearly six years later, the Obama administration is forcing oil companies to make changes to those emergency devices in hopes of preventing a repeat of the Deepwater Horizon disaster that killed 11 workers and spewed millions of barrels of crude into the Gulf of Mexico — the largest oil spill in U.S. history.

The mandates, laid out in a final offshore well-control rule unveiled Thursday, would require more frequent testing of the devices, swift reporting when parts fail, and retrofitting the equipment with extra shearing rams meant to slash through drill pipe and help seal an open well hole.

“We intend to increase the performance and reliability of these complex systems,” said Brian Salerno, director of the Interior Department’s Bureau of Safety and Environmental Enforcement. “That critical system can be the last line of defense in preventing a human and environmental catastrophe.”

Sever Pipe

The Interior Department stopped short of requiring companies to deploy new, yet-to-be-developed shear rams capable of slicing through almost anything in their path, after receiving just a handful of comments on the possibility. Salerno said that remains an option in the future, but even without it, the new rule “certainly improves the level of performance expected from blowout preventers for the foreseeable future.”

Investigations into the 2010 disaster highlighted deficiencies in massive metal blowout preventers, which contain an array of shearing and sealing rams that can be activated to sever drill pipe in a well and close it off. Those blades can be stopped if they encounter too much debris or one of the thick joints connecting segments of pipe. They might not move with enough force if there isn’t sufficient hydraulic fluid available to drive them. And if the drill pipe is off center when the rams slam closed, they may not make it all the way through.

That’s part of what may have gone wrong at BP’s failed Macondo well in 2010. Engineers who took apart the blowout preventer used at the site concluded a powerful rush of oil and gas caused the drill pipe to buckle and shift off-center, ultimately preventing the device’s shearing rams from cutting the pipe and sealing the hole.

Device Manufacturers

The major blowout preventer manufacturers, including Cameron International Corp., General Electric Co. and National Oilwell Varco Inc., responded by developing new designs, including blades shaped to help ensure any drill pipe they encounter stays in the center, without shifting to the side. And some companies drilling in the Gulf of Mexico, including Royal Dutch Shell and BP, voluntarily began using a second shearing ram, hoping that the redundancy would boost the odds of containing oil and gas in an emergency.

A voluntary industry standard now compels the use of a second shear ram in many instances offshore. The new Interior Department rule would require them all the time at subsea blowout preventers and those used above the water at floating facilities.

Companies would have three years to comply with the requirement, and they’d have seven to start using blowout preventers with new pipe-centering technology. Oil industry leaders have questioned whether that’s enough time to test and manufacture the new equipment, much less deploy it to the drillships and rigs plumbing the Gulf today.

Implementation Timeline

But the timeline is too long for many environmentalists, who say blowout preventers need to be more reliable to protect workers and the water.

“It’s unfortunate that the rule took so long to issue and we are disappointed that there’s a long timeline for implementation given that BOP (blowout preventer) incidents are not declining,” said Lois Epstein, an engineer with the Wilderness Society. “Development of the rule has the support of expert committees formed after the BP tragedy and it has a stronger technical justification than any other I’ve seen in 20-plus years of work on federal rules.”

The new rules don’t make blowout preventers completely fail-safe, said Kristen Monsell, an attorney with the Center for Biological Diversity. The mandates “do little to prevent another Deepwater Horizon disaster or protect our climate,” she said.

Voluntary Standard

Oil and gas companies have already bolstered blowout preventers with extra rams and are conducting more tests, partly to fulfill a voluntary standard from the American Petroleum Institute. That puts them in good shape to comply with the blowout preventer requirements in the new rule, said Erik Milito, an API director.

“The industry is looking at the BOP provisions and to the extent they are consistent with standard 53, is going to be well prepared to handle that and incorporate that into Gulf of Mexico operations,” Milito said.

Although scrutiny has focused on the integrity of the blades and rams in blowout preventers, a series of failures in the bolts that affix them to wells has also sparked concern.

At least one of those incidents occurred as far back as 13 years ago, but it wasn’t until recently that federal regulators realized it was a more widespread problem. In February, Interior’s Bureau of Safety and Environmental Enforcement warned that the bolt problems weren’t limited to a single manufacturer and could be “a systemic problem that requires immediate attention.”

Bolt Issue

“The bolt situation looked like a minor issue until we started digging into it,” said Doug Morris, chief of offshore regulatory programs at the bureau. The failures show “there continues to be work that needs to be done,” Morris said. “It’s one of the least complex components of a BOP system and we’ve discovered in the last two years that we have some additional work to be done.”

Under the final rule, offshore operators will have to notify regulators and the original manufacturers of their blowout preventers within 30 days after a component fails.

Had those reporting requirements been in place already, the agency might have learned sooner about the bolt failures, said Allyson Anderson Book, associate director of the Bureau of Safety and Environmental Enforcement.

“These are the pieces that actually attach the blowout preventer to the well head,” Book said. “If those don’t work, you’ve got to question the overall reliability of the system. If you can’t attach it and keep it there, that’s your weakest link.”