Chemical incidents have the potential for high risks with even higher consequences.
Health concerns, evacuations, and loss of life are some of the risks these incidents pose. Wayne Garland, technical associate in global process safety for Eastman Chemical Company, described an incident where a chemical truck driver in Atchison, Kansas inadvertently made a wrong connection.
"A truck driver connected the discharge valve of a sulfuric acid tanker truck to a fill line valve for sodium hydrochloride storage tank," Garland said. "Within an hour, 4,000 gallons of sulfuric acid mixed with 5,850 gallons of sodium hydrochloride to create a cloud of toxic chlorine gas over the facility and the town. The accident caused more than 140 people to seek medical attention and six were hospitalized. Approximately 11,000 people were forced to evacuate the area or shelter in place."
Two incompatible materials being inadvertently mixed is less common, according to Garland, but has the potential for extreme consequences. Still, an incident like the one that took place in Atchison can be avoided by implementing and improving safeguards.
"Facilities that evaluate chemical-unloading equipment and processes and implement safeguards, can reduce the likelihood of an incident," Garland said. "This can be done while taking into account human factors, issues that can impact how facility operators and drivers interact with the equipment."
At the recent 2022 EHS Seminar & Tradeshow held in Galveston, Texas, Garland described some of the protocols and preventative steps that Eastman Chemical Company has taken after reviewing incident investigation data.
"Although we experienced only minor incidents, we were concerned that the potential might exist for a larger incident like the one in Atchison," Garland said. "The data on the incidents showed that the largest number of incidents were overfills, pipe leakage, and pressure release valve leakage. We made sure we addressed all the major causal factors of previous incidents we've had, such as consistent asset integrity requirements based on chemical service, and controls for preventing overfill."
One of these controls that can prevent overfill incidents are bubbler level devices, which are installed at active loading spots, Garland said. The devices are not perfect as they can be inserted incorrectly, but using a manual encoder can help.
"A manual encoder designed for this purpose helps reduce insertion errors," Garland explained. "If the bottom of the inserted pipe is covered with liquid, the pressure switch activates to close the loading valve which is located at the loading station. This had proved itself useful when someone miscalculated or incorrectly entered the maximum fill quantity."
Risk management is key for a safe workplace with potential hazards, and taking precautions to protect employees and facilities from any possible chemical incident is vital. Garland explained what facilities could do to prevent accidents before they happen.
"The facilities that work with chemical distributors can conduct a risk assessment, and then develop and agree upon procedures for chemical unloading to ensure that the responsibilities are clearly defined," Garland said. "The facility management could evaluate the chemical transfer equipment and processes, and, when feasible, install alarms and interlocks in process control systems that can shut down the transfer of chemicals in an emergency."
Garland said establishing safeguards and applying them consistently greatly minimizes the risk of accidents and exposure.
"When large amounts of chemicals are involved, no operation, even a simple delivery, should be conducted without strict adherence to standard operating procedures for safety," Garland said.
