Accidental production of flammable gas in a chemical plant

A vessel exploded at a plant producing pharmaceutical products. At the time of the incident, the plant was producing a substance called Dekon 139. The Dekon had already been synthesised, and excess liquid from the production process had been removed from the solid product (“cake”) within the vessel under protective nitrogen atmosphere. The process used an agitator to smooth the cake and remove lumps that formed during drying to remove the liquid from the cake.
After the testing, the company discovered that Dekon can undergo exothermic, self-accelerating decomposition when heated to 280 degrees Fahrenheit (138 degrees Centigrade). The decomposition releases flammable gases, including hydrogen, methane, and carbon monoxide.
In the incident investigation, the company determined that the agitator had loosened and was rubbing a plate at the bottom of the filter dryer vessel, generating heat from friction. The friction likely caused an area of high temperature (a hot spot), which likely reached the temperature of decomposition of the Dekon. The decomposition reaction released energy, which increased the temperature of the material in the vessel and caused more Dekon to decompose.
The gases produced by the reaction rapidly increased the pressure within the vessel, causing the vessel’s discharge door to open. The released flammable materials (gas and Dekon dust) ignited, causing an initial weak explosion. Shortly after that, the vessel’s rupture disc opened and a second larger explosion occurred when the vessel failed.
The CSB estimated that approximately 600 pounds of Dekon decomposed into flammable gases that were consumed during the incident.
The explosion and fire fatally injured one operator unable to escape the area and caused approximately $48 million in loss from property damage, which led to the permanent closure of the facility.

The INTITATING CAUSE was a chemical reaction run-away which caused the production of a flammable gaseous mixture. The start of the run-away was triggered by the malfunctioning of a component (the agitator).
The ROOT CAUSE was the failure of the company to identify, document, assess and prevent risks related to the chemicals involved in the process.

reactor

DESCRIPTION of the EQUIPMENT
The vessel was a ‘Pressure Nutsche Filters’. This device has the task to separate the liquid from the solid part of a reaction product, and uses a single filter medium at the base of the vessel, through which the liquid is forced under pressure.

From the pictures I the news an exnsive damage to the building is visible, in particular to the roof. Part of the reactor is visible in the courtyard outside, probably propelled there by the force of the explosion. The explosion and fire fatally injured one operator unable to escape the area and caused approximately $48 million in loss from property damage, which led to the permanent closure of the facility.

A U.S. Department of Labor investigation found that “pharmaceutical company could have prevented an employee's fatal injuries from an explosion on May 4, 2023, but lacked the required safeguards in a chemical manufacturing process.
The OHSA identified numerous deficiencies in the facility's process safety management program for highly hazardous chemicals for the production and drying of Dekon 139 and for combustible dust hazards.
Therefore OSHA cited the company for 11 violations, including eight serious and two repeat and one other-than-serious. The agency assessed $298,254 in proposed penalties.

The OSHA found that the company failed to:
(1) Determine the combustibility hazards of materials used in the Dekon 139 production process, exposing employees to fire and explosion hazards from combustible dust.
(2) Include safe upper and lower temperature limits to prevent the decomposition of Dekon 139.
(3) Evaluate the consequences of deviation in the Dekon 139 production process.
(4) Establish written procedures to maintain the ongoing integrity of process equipment and provide clear instruction on consequences of deviation from steps in the operating procedures.
(5) Update the process safety information to include steps to avoid consequences of deviation in temperature, properties and hazards of the chemicals used in the process.
(6) Update standard operating procedures for producing Dekon 139 and its safety data sheet.