A report released by the Harris County Fire Marshal's office isolates the cause of the March 2019 terminal fire in Deer Park, Texas, as a mechanical failure at a key control point for an 80,000-gallon storage tank containing butane enriched naphtha.
The manifold power frame is a motorized assembly that regulates the delivery and withdrawal of product from the tank through the piping system that ties the terminal together.
"Investigators explored the hypothesis that the fire was the result of a mechanical failure near the pump, seal pot and coolant assembly within the manifold of Tank 80-8, thus causing a leak and subsequent ignition of the fire," the report states.
The fire at the Intercontinental Terminals Company terminal burned nearly four days, spreading through eight tanks of the same capacity. No injuries involving workers or emergency responders were reported. However, several shelter-in-place notifications issued to the community prompted local schools and businesses to temporarily close.
Nearly 9,000 gallons of flammable naphtha leaked from the assembly before igniting. However, investigators were unable to specify how the equipment failed or what ignited the leaking product.
An earlier report by the U.S. Chemical Safety Board states that the terminal was not equipped with gas detection alarms or emergency shutoff valves that could have immediately isolated the fire.
A timeline of events established by the Fire Marshal's report notes that two cargo trucks unloaded butane into Tank 80-8 the day before the fire. The butane is used to increase the octane level of the fuel involved. A pump in the manifold power frame was activated to circulate the product.
Data collected after the fire suggests that the pump went through a series of unanticipated changes in tank operating pressures and volume fluctuations that indicate a mechanical problem developed in the butane circulating system.
At 9:34 a.m. on March 17, the pump discharge pressure and the tank volume steadily drop for nearly half an hour, indicating the leaking naphtha. Telemetry from the manifold power frame ended when the fire erupted.
Due to the fire, neither ITC operators nor emergency responders could access the manually operated valves necessary to isolate the tank.
Care was taken that all evidence was left in place and undisturbed until the investigators could access the scene on April 9. The equipment was photographed and then removed to a secure location.
The official ruling of the fire marshal's office is that the terminal fire was "accidental."