Hydrofluoric acid can be seen starting to leak out of a failed pipeline and turn into a flammable vapor.
Within a few minutes, a fireball erupts.
Five people were hurt in the June 21 explosion. The plant was eventually shut down.
Officials say the piping had not been inspected in the last 45 years.
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Earlier this week, the U.S. Chemical Safety and Hazard Investigation Board released a preliminary factual findings report that included a timeline and likely initial cause of the fire.
Investigators found the remnants of the failed elbow pipe, which they said had worn to .012 inches - about half the thickness of a credit card - likely contributing to the release of the flammable vapor.
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The board is continuing its investigation and plans to release a final report with an official cause and recommendations, agency investigators said.
The report is expected in 2020.