Tuesday, March 14, 2006

BP Houston Refinery Disaster: One Year Later

On March 23, 2005, some temporary workers in a Texas City, Texas oil refinery owned by BP (formerly British Petroleum) were just finishing lunch near the trailers that housed their offices, when they saw a geyser of clear liquid spurting out the top of a steel tower only a few yards away from them. According to the Houston Chronicle, one of them cried into a radio, "God, I hope that's water." A few seconds later, a highly flammable pool of an intermediate product called raffinate spread throughout the area. Although the exact cause of ignition was never officially determined, some witnesses recalled that an idling diesel pickup truck suddenly sped up as if somebody stepped on the gas. Then came the explosion.

It killed fifteen workers, injured 170, and wrecked acres of refinery equipment. In the year following, both the U. S. Chemical Safety and Hazard Investigation Board and BP carried out independent investigations, which reached similar conclusions. While the investigators found that outmoded and nonfunctional hardware contributed to the accident, the single most important cause was a culture of carelessness and bad management.

In a highly automated business such as oil refining, it is easy to look at the vast expanse of fractionating towers, pipes, flares, and tanks, and get the impression that such a system basically runs itself. But when you realize how many dangerous chemicals—corrosive, flammable, volatile—go through intense heat and pressure inside thousands of pipes and vessels, the amazing thing is that there are not major refinery accidents every day. More important than the visible structure of hardware, controls, and even the computer software that helps operators run the plant is the human structure of management, authority, will, energy, memory, obedience, and trust. As many industries mature, more and more is known about the physical and chemical processes involved. Computer models can predict even unexpected and dangerous behavior before two pipes are ever welded together to build an actual refining unit. This improved physical understanding can lull managers and operators into thinking that no thinking is required, or at least very little.

As with many accidents, a combination of relatively unlikely events and decisions conspired to bring about the tragedy of a year ago. First, a number of temporary trailers were brought into the borders of the active plant within a few yards of equipment that processed hazardous materials. If the plant had been treated like what it is—potentially, a bomb about to go off—these trailers would have been blocks away. Inconvenient, perhaps, for the workers who would have had to travel farther and get less done each day, but better than dying. Next, operators tried to restart a unit that had been down for maintenance without clearing the area. Starting and stopping chemical-plant processes are much more dangerous than periods of smooth operation, and more things are likely to go wrong. A fractionating tower that should have been filled to a depth of only about six feet instead filled up to a height of over a hundred feet with flammable raffinate. The operators were misled into thinking the levels were normal by malfunctioning and nonfunctioning instruments. When they realized there was too much hot raffinate in the tower and attempted to drain it away, the action one worker took to improve things actually made them worse, because the heat from the hot material drained away at the bottom was exchanged back into the tower, causing both it and an auxiliary "blowdown" stack to overflow. This was what caused the geyser that a worker prayed was water.

BP has paid for this accident in several ways. The entire plant was shut down for months, the U. S. Occupational Safety and Health Administration levied a $21 million fine against the company (which it paid without admitting the correctness of the charges), and numerous lawsuits arising from the accident continue. But wouldn't it be better if before a tragedy like this happens, enough pressure could be brought to bear on an organization to make it mend its ways?

The Internet may be one way this can happen. I would be very interested to hear from anyone who has had experience with the BP accident (directly or indirectly), or who can share factual insights about it and suggest ways to keep the next major refinery accident from happening. You can respond to this posting by clicking on the comments link below. I hope to hear from you!

Sources: A more detailed summary of the incidents leading up to this disaster is available at the
U. S. Chemical Safety and Hazard Investigation Board website, complete with a narrated video simulation of the incidents and the vapor and pressure waves resulting from the explosion. BP has also posted its completed investigation report at www.bpresponse.org.

1 comment:

  1. Here in Europe we have both compulsory standards for engines and trucks that work in hazardous areas, plus voluntary self-assessment codes of practice within the refinery industry.

    All the oil companies require a 'Chalwyn' automatic overspeed safety valve device, plus an exhaust spark arrestor on all diesel equipment and vehicles that enter the refinery gates.

    This followed some accidents in the 1960's at Esso (Exxon) Fawley plant in the UK.

    Engine runaway protection has been an essential part of basic safety in Canada (a legal requirement) and offshore under Federal MMS regulations, but onshore operations like at Texas City are not currently required by US law to follow this example, and hence the truck that was reported to ignite the gas cloud in 2005 was not equipped to shutdown when it ranaway and sparked the explosion.