Process Safety · Case study

T2 Laboratories, 2007: a runaway nobody expected

During a routine batch, the reactor cooling failed. The reaction ran away and the reactor exploded with enormous force.

Date19 Dec 2007

WhereJacksonville, Florida, USA

ProductMCMT, a gasoline additive

Deaths4 employees

Injuries32 (4 employees, 28 nearby)

Investigated byUS Chemical Safety Board

What happened

T2 made methylcyclopentadienyl manganese tricarbonyl (MCMT) in a 2,450-gallon batch reactor. The first step, metalation with sodium in diglyme, is exothermic, and above about 390 °F (199 °C) an undesired, much more energetic reaction starts. The company relied on cooling water in the jacket to control the temperature, with no backup.

On the 175th batch, the cooling failed, probably because of a blockage in the water supply or a valve failure. The temperature rose into the range of the side reaction. The 4-inch rupture disc opened but was far too small for a runaway. About ten minutes after the operator reported a cooling problem, the reactor burst. Debris was thrown up to a mile and buildings were damaged within a quarter mile.

Sequence of events

13:23Process operator reports a cooling problem; the owners are called.

~13:30Temperature and pressure rise rapidly; the rupture disc bursts but cannot vent the runaway.

13:33The reactor explodes. Four people die, including an owner and the operator.

Why it happened

Hazard not recognised: the owners were chemists and chemical engineers, but did not recognise the runaway potential of the side reaction, nor that scale-up removed the safety margin seen in small batches.
Single safeguard: the whole protection was the cooling water. No redundant cooling, no automatic shutdown, no quench.
Relief not sized for the runaway: the rupture disc was sized for normal operation, not two-phase runaway relief.
No reactive-hazard testing or formal hazard analysis of the process.

Lessons for your plant

Test the chemistry: DSC / ARC for undesired reactions, reaction calorimetry for the main reaction, then the cooling-failure scenario and Stoessel class.
Never rely on a single layer of protection for a high-class reaction: add redundant cooling, interlocks, and quench or dump options.
Size emergency relief for the runaway (two-phase, DIERS methods), not the normal case.
The CSB recommended that reactive-hazard awareness be added to chemical engineering education. That is the reason this section exists.

Learn more on PharmaChemE

Sources

Summary written for training. Figures are as published by the investigating bodies and widely cited sources; see the sources for full details.