Flawed safety procedures led to toxic chemical leak, 4 deaths at DuPont plant
A federal agency looking into the exact causes of a toxic chemical leak at a DuPont plant in Texas that killed four workers says its investigation uncovered flawed safety procedures, design problems and inadequate planning.
During delivery of a raw material by tank truck on Nov. 10, 2014, a water dilution system was inadvertently activated and the raw material’s storage tank overflowed, resulting in the shutdown of the insecticide unit.
When operators attempted a restart on Nov. 12, material blocked a reaction system.
While trying to clear the blockage, two thousand pounds of water were inadvertently sent to a storage tank containing methyl mercaptan, creating a solid, ice-like hydrate in piping.
A Nov. 14, a troubleshooter team of managers and engineers developed a plan to apply hot water under the pipes’ insulation to break up the hydrate. Two valves were opened to give the methyl mercaptan a place where it could expand. But the plan didn’t undergo a safety review, and there were no written procedures to guide the plan.
As methyl mercaptan began to flow in the piping, high pressure alarms for process equipment registered on computer consoles.
Two workers went to drain pipes, and liquid methyl mercaptan escaped into the building. It quickly began to vaporize, filling the room with a highly toxic gas.
The two workers who responded to the distress call and subsequently died were brothers.