BP Texas City Refinery Explosion 2005 | Animation

Summary

On March 23, 2005, a catastrophic incident unfolded at an isomerization unit when operators unknowingly overfilled a tower with flammable hydrocarbons. Despite a high-level alarm, critical indicators failed, leading to an accumulation of liquid above safe levels. Operators continued to introduce more liquid, resulting in the tower being filled to 138 feet, far exceeding the normal limit. As pressure built, emergency relief valves opened, causing a geyser-like eruption and a massive vapor cloud. This cloud ignited, triggering a series of explosions that resulted in significant destruction, including the death of 15 contract workers and extensive damage to the facility.

Takeaways

• 🚨 At 2 A.M. on March 23, 2005, operators began introducing highly flammable hydrocarbons into the raffinate splitter tower.
• ⚠️ The tower's level indicator was only designed to measure liquid up to 10 feet, leaving operators unaware of dangerous liquid levels above that mark.
• ⏱️ By 3:30 A.M., the liquid level had exceeded the indicator's range, filling the tower to approximately 13 feet.
• 🛑 Operators mistakenly added more liquid to the already full tower, despite no outflow due to a closed valve.
• 🔥 By 10 A.M., the liquid level surged to over 20 times the normal level, reaching 138 feet while the indicator falsely reported a lower level.
• ⚠️ A high-pressure alarm was triggered around 12:40 P.M., but the pressure control valve failed, leading to manual venting of gases.
• 🚰 Operators attempted to relieve conditions by opening a valve to send liquid to storage tanks, but this heated the feed entering the tower.
• 💥 The tower began overflowing at 1:10 P.M., creating dangerous pressure in vertical piping and triggering emergency relief valves.
• 🌫️ At 1:20 P.M., a vapor cloud formed and ignited, likely caused by a nearby diesel truck, resulting in a series of explosions.
• 🔥 The explosion led to significant destruction, injuring 15 workers and damaging over 50 chemical storage tanks.

Q & A

What was the initial action taken by the isomerization unit operators at 2 A.M. on March 23, 2005?

The operators began introducing highly flammable hydrocarbons into the raffinate splitter tower.

What was the normal liquid level expected in the tower, and how did the actual level exceed this?

Normal operations dictated a maximum liquid level of 6.5 feet, but the actual level exceeded 13 feet due to a malfunctioning level indicator.

What was the primary failure of the level indicator used in the tower?

The level indicator was only designed to measure liquid up to 10 feet, leading operators to be unaware of the dangerously high liquid levels.

What actions did operators take after the high level alarm was activated?

Despite the high level alarm, operators continued to add liquid to the already full tower, which contributed to the overfilling situation.

How did the temperature of the liquid entering the tower change during the incident?

As hot liquid exited the tower and passed through a heat exchanger, it raised the temperature of the incoming feed by over 150 degrees.

What critical failure occurred regarding the emergency pressure management system?

The valve specified for controlling pressure did not work, forcing an operator to use a manual chain valve to vent gases instead.

What occurred at 1:10 P.M. that indicated a severe problem in the isomerization unit?

The tower began overflowing, leading to a significant liquid buildup in the vertical piping and causing pressure on emergency relief valves.

What was the result of the overflow from the blowdown drum?

The blowdown drum filled completely, leading to a geyser-like eruption that created a large flammable vapor cloud.

What triggered the ignition of the vapor cloud at 1:20 P.M.?

The vapor cloud ignited, likely due to a nearby diesel pickup truck parked about 25 feet from the blowdown drum.

What were the immediate consequences of the explosion that occurred after the vapor cloud ignited?

The explosion caused extensive destruction, fatally injuring 15 contract workers and damaging over 50 large chemical storage tanks.