A mechanical problem in the pump circulation system of an 80,000-barrel naphtha storage tank is suspected as the cause of the massive Intercontinental Terminals Company fire on the Houston Ship Channel in March, an update issued by the U.S. Chemical Safety Board states.

“The CSB is continuing to conduct its investigation of this incident,” the update states. “Components from the Tank 80-8 piping manifold were taken to a secure storage facility, where CSB completed an initial visual inspection of the piping and pump.”

Further testing is planned, the CSB update states.

A presentation on the ongoing investigation was made to the agency board today (Oct. 30) in a meeting held at the CSB offices in Washington, D.C.

The ITC Deer Park, TX, terminal fire took 77 hours to extinguish and burned its way through 10 storage tanks, the report states.

At the time of the fire the ITC Deer Park, TX, terminal contained 242 storage tanks with an overall capacity of 13.1 million barrels. At about 10 a.m. on March 17, 2019, a large fire erupted in the vicinity of Tank 80-8, an aboveground atmospheric storage tank surrounded by similar 80,000-barrel tanks in a tank farm known as the “First & Second 80’s.”

Tank 80-8 was leased to another company for naphtha storage and for naphtha-butane blending operations. The report outlines how ITC injected butane into the naphtha product using external piping and equipment to increase the octane level of the fuel product.

“ITC did not equip the Tank 80-8 piping manifold with emergency or remotely operated isolation valves,” CSB states. “Such isolation valves could stop an uncontrolled release if, for example, the pump or piping manifold were damaged.”

In the event of a major fire resulting from a leak near this equipment, neither ITC operators nor emergency responders could access the area to close these manually operated valves, the report states.

On the morning of March 17, the ITC distributed control system data indicates a series of unanticipated changes to the monitored pump operating pressures and tank volume. Pump discharge pressure fluctuated from 80 to 84 pounds per square inch. Consistent with these fluctuations, the recorded tank volume began to decrease steadily.

“The reduction in tank level and volume that occurred as naphtha product released from Tank 80-8 did not trigger any alarms in the ITC control room,” the update states. “As a result, ITC personnel were unaware of the naphtha product release before the fire erupted.”

ITC was unable to stop or isolate the naphtha being released, so the fire continued to “rage and intensify,” CSB states. That evening an adjacent tank west of Tank 80-8 became fully involved in the fire with firefighting efforts by ITC Emergency Response Team and the Channel Industries Mutual Aid hindered by shifting winds.

By the morning of March 18, four more storage tanks were on fire, all located west of Tank 80-8, the report states. Two more storage tanks caught fire later that evening.

ITC reached out to a third-party emergency response services provider, US Fire Pump, for assistance in extinguishing the fire. Meanwhile, on the morning of March 19, responders on hand struggled with a temporary reduction in water pressure that allowed flame to spread to two more storage tanks.

“At approximately 6:48 a.m., US Fire Pump arrived on-scene,” the update states. “After completing an initial scene assessment, US Fire Pump developed a response plan, and commenced firefighting activities by around 1 p.m.”

By approximately 3:03 a.m. on March 20, ITC, with assistance from CIMA and US Fire Pump, successfully extinguished the tank farm fire. The fire never spread beyond the perimeter of the First & Second 80’s tank farm.

Firefighters continued to monitor the site closely. On March 22, a section of the tank farm dike wall failed, releasing a mixture of chemicals from the tanks, water and firefighting foam to the surrounding waterways. A small secondary fire erupted in the tank farm that afternoon but was extinguished within several hours.

The CSB update identified several other areas of interest to investigators. The CSB plans to identify potential naphtha product release points and ignition sources, determine why the naphtha product release was not detected prior to ignition and why the release was not isolated post-fire.

“The CSB will also look into the emergency response to determine why prolonged emergency response efforts were necessary to control and ultimately extinguish the fire,” the update states. “To accomplish this, the CSB still needs to collect additional emergency response evidence including various incident command records, photos, videos and drone footage.”

A detailed final report will be published at the conclusion of the investigation, which will include additional information, analysis, findings and safety recommendations.