Federal officials investigating the March 23rd blast at BP's Texas City refinery have outlined the scenario leading up to the explosion, but have not found the ignition source that triggered the blast and gave no indications of who might be responsible.

In a release issued Thursday, a representative of the US Chemical Safety and Hazard Investigation Board said the accident occurred when excess pressure developed in a raffinate splitter, producing a geyser of flammable liquids and vapors.

Witnesses saw the liquid and vapor falling to the ground, he said. The hydrocarbon ignited, and within seconds a powerful explosion occurred. The explosion resulted in 15 deaths and injured many others in nearby trailers and elsewhere, the representative of the US Chemical Safety and Hazard Investigation Board said.

"The exact ignition source for the hydrocarbon remains unknown, as does the cause of the excess pressure in the raffinate splitter," he said.

Previously, the board had been focusing on a pickup truck near the site of the explosion. The board's investigators found 30 vehicles near the vent stack, some within 25 yards, but further examination is needed to determine what the ignition source was, the representative of the US Chemical Safety and Hazard Investigation Board said.

The field investigation into the explosion will continue for several more weeks. So far, the board has interviewed 75 eyewitnesses and has developed a joint plan with the Occupational Safety and Health Administration and BP for making the blast site safer to enter. The board is charting the blast damage to trace the origin of the explosion. It is also trying to recover and decipher computer records.

Source: The Oil Daily, 8th April 2005.