How terrifying is sulfuric acid, really?

On July 17, 2001, workers at the Motiva Refinery in Delaware City, Delaware, USA, were performing maintenance welding work near the sulfuric acid storage area. The work site was adjacent to Sulfuric Acid Storage Tank No. 393. This tank—along with five others—stored 99% concentrated sulfuric acid feedstock and spent sulfuric acid (approximately 88–95% concentration) mixed with volatile hydrocarbons. Although all previously identified breaches in Tank No. 393 had been repaired between 1998 and May 2001, a breach located on the tank’s roof remained undetected. On the day of the incident, Motiva refinery personnel confirmed the absence of flammable gases in the work environment at 7:45 a.m. and commenced welding operations. Over the following hours, ambient temperature rose by 14°F, causing volatile hydrocarbons in the spent sulfuric acid inside Tank No. 393 to vaporize and escape into the work area through the undetected roof breach. At 1:30 p.m., sparks from the welding ignited the hydrocarbon vapors in the air; flame propagated back through the breach into the tank, triggering an explosion of the flammable hydrocarbon vapors inside. The violent explosion launched Tank No. 393—holding a capacity of 1,570,945.89 liters (415,000 gallons)—into the air. Instantly, 999,348.71 liters (264,000 gallons) of spent sulfuric acid surged out of the ruptured tank.

Case Study | Hazardous Chemical Accidents That Occurred in January Throughout History

On January 13, 2007, an explosion occurred in the nitration reactor of the nitroester workshop at Kunshan Kangda Pharmaceutical & Chemical Co., Ltd. in Jiangsu Province, resulting in seven fatalities. The direct cause was that operators, seeking to accelerate the melting process, excessively opened the steam supply valve, causing a rapid temperature rise that ultimately triggered the reactor explosion. 7. Pesticides 7.1 "January 9" Significant Poisoning Accident at Anhui Kanda Chemical Co., Ltd. On January 9, 2014, a poisoning accident occurred during pipeline maintenance at Anhui Kanda Chemical Co., Ltd., resulting in four deaths and two minor injuries. The direct cause was that workers violated safety procedures by entering the pump operation pit to perform maintenance on a sodium methanethiolate pipeline and subsequently inhaled toxic gases—including hydrogen sulfide and methanethiol—causing poisoning. Inadequate on-site emergency response further aggravated the incident. 7.2 "January 12" Significant Reactor Explosion Accident at Hubei Shalonda Co., Ltd. On January 12, 1995, an explosion occurred in the phosphorus trichloride reaction vessel at the Two-Phosphorus Workshop of Pesticide Plant I, Hubei Shalonda Co., Ltd., resulting in three deaths and one injury. The direct cause was overcharging of phosphorus trichloride into the reactor, leading to incomplete reaction with sulfur and accumulation of unreacted material. As the mixture boiled, the accumulated phosphorus trichloride reacted increasingly vigorously, rupturing the explosion-proof diaphragm. High internal pressure then fractured the flange bolts on the enamel-lined reactor lid, culminating in the explosion. 8. Coal Chemical Industry 8.1 "January 24" Significant Flash Explosion Accident at Xinjiang Turpan Hengze Coal Chemical Co., Ltd. On January 24, 2018, a flash explosion occurred during construction of the 180,000-ton-per-year tar processing environmental upgrade project at Xinjiang Turpan Hengze Coal Chemical Co., Ltd. in Turpan City, Xinjiang Uygur Autonomous Region, resulting in three deaths and one injury. The direct cause was serious violations by relevant workers: they used open flames to heat flange bolts without obtaining a hot-work permit, without implementing necessary safety measures, and without supervisors present onsite—triggering a flash explosion of volatile flammable gases inside the asphalt elevated tank. 8.2 "January 6" Significant Carbon Monoxide Poisoning Accident at Xinjiang Dahuangshan Hongji Coking Co., Ltd. On January 6, 2011, a carbon monoxide poisoning accident occurred in the decarbonization pump room of the synthesis workshop at Xinjiang Dahuangshan Hongji Coking Co., Ltd. in the Dahuangshan area of Xinjiang Uygur Autonomous Region, during trial production. The incident resulted in three deaths and one minor injury. The direct cause was a design flaw: a single gate valve was used to connect the condensate line to the saturated tower inlet; the pump room’s piping was interconnected with the coke oven gas system, yet no toxic/hazardous gas alarm system was installed indoors, and drain valves were not placed outdoors. Internal leakage of the condensate valve allowed coke oven gas from the saturated tower to backflow into the decarbonization pump room, causing poisoning. (II) Overseas Incidents 1. Fire Accident at Toho Oil Co., Ltd. (Japan) Refinery On January 18, 2017, a fire broke out during cleaning operations at an oil storage tank at Toho Oil Co., Ltd.’s refinery in Wakayama Prefecture, Japan. The fire reignited on January 22. It occurred near the No. 2 propane dewaxing unit and the No. 2 lubricating oil extraction/hydrodesulfurization refining unit within the lubricating oil production facility complex, prompting emergency evacuation of nearly 3,000 residents in surrounding areas. The direct cause was spontaneous ignition of iron sulfide deposits remaining in sludge inside the storage tank. Initial fire detection failed due to lack of on-site supervision, allowing the incident to escalate.

One Person Dies, One in Serious Condition After Greek Refinery Incident

15 hours ago

One person died and another remains critical following an incident at the Motor Oil refinery west of Athens during maintenance. The company stated the facility continues normal operations with no reported fire or damage while authorities investigate.

reuters

2026-10-09

One Person Dies, One in Serious Condition After Greek Refinery Incident

One Person Dies, One in Serious Condition After Greek Refinery Incident

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