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Hurricane Harvey and Arkema Peroxide Plant Explosions
Posted on September 5th, 2017 by Dr. Sina Ebnesajjad in Chemical Manufacturing Excellence
The flooded Arkema plant in Crosby, Texas, where explosions continued to take place on September 1, 2017 (Source: ABC News, http://abcnews.go.com, September 1, 2017)
I doubt hurricane Harvey needs any introductions. Dozens of people have been killed and thousands of houses destroyed and damaged. Crosby, Texas, is a small town of 2.3 square miles located about 2 hours drive northeast of Houston. It has a population density of 1000 per square mile versus 26 for the entire State of Texas. A lot of people live in the small area of Crosby. They have felt the devastating impact of Harvey beyond water damage. Water has overtaken an Arkema Corp chemical plant that manufactures a class of chemicals called peroxides. Flooding of chemical plants can do far more harm than just ruining buildings.
Peroxides (or peroxies) are chemicals containing two oxygen atoms bonded with a single bond (-O-O-). The simplest example of this class of chemicals is hydrogen peroxide H2O2 (H-O-O-H). There are organic and inorganic types of peroxide compounds. The general chemical structure of organic peroxides is presented as R1-O-O-R2 in which R1 and R2 are chemical groups. If either R1 or R2 is hydrogen, the compound is called hydroperoxide. Examples of organic peroxides include peracetic acid [CH3(C=O)-O-OH) and cumene hydroperoxide [C6H5C(CH3)2-O-OH].
A common property of peroxides is their instability because of the ease of the rupture of the bond between the two oxygen atoms (-O-O-). When this bond breaks two fragments are produced (R1-O. and R2-O.) called free radicals (Figure 1). The unpaired electron of the oxygen atom makes the free radicals very reactive. Peroxide decomposition is also an exothermic reaction – in other words it produces heat. The reactive free radicals are capable of initiating polymerization of monomers and crosslinking rubbers.
R1-O-O-R2 → R1-O. + R2-O.
Figure 1 Free radical formation from the decomposition of a peroxide
Peroxides are designed to be unstable to allow the formation of free radicals. A large number of peroxide compounds with different chemical structures have been developed for different applications and processes. Peroxide free radicals (Figure 1) are used in a wide range of reactions such as polymerization of monomers like methacrylate, styrene and vinyl monomers. In addition to polymerization, peroxides are formulated in bleaching and disinfecting agents and used for synthesizing chemical compounds and manufacturing explosives. Some of the important products that require peroxides to manufacture include countertops, acrylic-based paints, polystyrene cups and plates, PVC for pipes, packaging and siding.
Peroxides decompose even at room temperature. When cooled, the decomposition rate of peroxides decreases which allows their safe storage. Temperature increase expedites and intensifies decomposition of peroxides. Generation of heat during decomposition increases the peroxide temperature. Self-Accelerating Decomposition Temperature (SADT) is defined as the minimum temperature at which peroxide will undergo a self-accelerating decomposition. At or above SADT the reaction is usually violent, gas pressure ruptures the container and spreads peroxide liquid and gaseous decomposition products to considerable distances. The heat generated auto-ignites flammable vapors. To prevent massive decomposition, peroxides are always stored under refrigeration. In laboratories bottles of peroxides are stored in refrigerators. When needed, the required amount of peroxide is removed from the chilled bottle, usually diluted in water or another liquid. Afterwards the peroxide bottle is put back in the refrigerator.
Similarly, commercial quantities of peroxide are refrigerated continuously to prevent temperature increase and rapid decomposition. Loss of refrigeration systems for an “extended” period of time can result in massive decomposition and fire in peroxide storage tanks. This is where things went wrong at the Arkema Corporation Plant that manufactures a large number of liquid organic peroxides in Crosby, Texas. Hurricane Harvey flooded this Plant where over one half million pounds of peroxides were stored. Water destroyed the plant’s electrical systems and backups thus shutting down refrigeration.
“Fearing that the chemicals might explode the Arkema workers, as a last resort, transferred the peroxides to nine refrigerated trailers on the property. All but one of the refrigeration units on those trailers eventually failed, the company said.” (Source: September 1, 2017 issue of the New York Times). Out of fear of explosions the workers had to abandon the plant on August 29, resolved to allow explosions take place and peroxides burn. A perimeter of 1.5 miles around the plant was evacuated due to the various hazards. As time passed trailers warmed up and they exploded one by one and caught fire. Billowing thick black smoke and noxious gases were released every time a tanker exploded and burnt. Scores of police officers and others were sent to hospital. It is unclear when or whether the town residents in the plant surroundings can return to their homes.
Coincidentally, Arkema has been among numerous chemical companies that have opposed and battled regulations issued by the Obama administration to tighten safety standards at the US plants. These rules were developed in response to a series of deadly accidents, including explosions at a fertilizer plant in West, Texas, that led to the death of 15 people in 2013. In June 2017, the enforcement of the regulations was suspended until at least 2019. That followed lobbying against the rules by the chemicals industry, including Arkema, which argued that they were too costly and would jeopardize trade secrets.
Hurricane Harvey has unearthed the hazards of dangerous chemistry and lax safety rules. Perhaps the existence of more strict safety regulations would have prevented the destruction of Arkema Crosby Plant, to say nothing of the human, social and environmental harms inflicted.
All opinions shared in this post are the author’s own.
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Dr. Sina Ebnesajjad
President at FluoroConsultants Group, LLC
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