【Haichuan Chemical Accident Update】Valves failed due to a power outage at a chemical plant in Cangzhou, resulting in a leak of 48 kilograms of chlorine gas

According to a report issued on the 7th by the Haixing Economic Development Management Committee in Cangzhou City, Hebei Province, around 23:00 on September 6, the No. 2 storage tank’s low-pressure absorption valve at Haixing Yienuo Chemical Co., Ltd. stopped functioning due to a power outage. The company’s on-duty staff took immediate action to address the situation, and as a result, approximately 48 kilograms of chlorine gas were released. Currently, 17 people are under observation in the hospital due to discomfort, and the city’s medical expert team has determined that their lives are not in danger. Monitoring shows that the air quality is currently normal. The relevant departments at the city and county levels are carrying out follow-up actions. It is understood that the registered address of Haixing Yino Chemical Co., Ltd. is in the Qingxian Industrial Park of Haixing County. Its business scope includes the production and sale of calcium hypochlorite, sodium bicarbonate, sodium carbonate, calcium carbonate, calcium chloride, sodium chloride, bromochlorohydrin, chloroxides, calcium hydroxide, hydroxychlorides, sodium sulfate, aluminum sulfate, copper sulfate, sodium thiosulfate, polyaluminum chloride, benzalkonium chloride, as well as the manufacturing of plastic raw materials and plastic products, along with import and export activities.

At 3:30 a.m. on May 13, 2017, a chlorine leak occurred at Lixing Special Rubber Co., Ltd. in Cangzhou City, Hebei Province (hereinafter referred to as Lixing Company). This leak caused poisoning among the employees on site as well as people living in the vicinity; more than 1,000 residents were evacuated urgently. As a result of the incident, 2 people died and 25 others were taken to hospitals for treatment. The direct cause of the accident was that, in order to reduce the costs associated with the use of chlorine and avoid frequent switching between liquid chlorine cylinders, Lixing Company illegally constructed a storage tank with a capacity of 15 m3, thereby increasing the amount of liquid chlorine stored there without authorization ； In the early hours of May 13, during the unloading of liquid chlorine into the tank using a liquid chlorine tanker, the discharge pipe behind the bottom valve of the tank broke, resulting in a leak of liquid chlorine ； Lixing Company failed to respond promptly to the emergency, resulting in a prolonged and large-scale leakage of liquid chlorine, which caused poisoning among the employees on site and people in the vicinity. At that time, the State Council’s Safety Committee issued a statement on this incident: the nature of this accident was extremely serious, and its consequences were severe; had the weather conditions been unfavorable, it could have led to even more serious outcomes. At the same time, it also reveals prominent issues such as lax and careless administrative licensing by local safety regulatory authorities, and safety assessments conducted by evaluation agencies that ignore the facts.

It should be known that ① chlorine is a yellow-green, irritating, and toxic gas that can easily be liquefied to form liquid chlorine. ②Inhalation can cause damage to the respiratory system, and in severe cases, pulmonary edema may occur. Liquid chlorine and high-concentration chlorine gas can cause burns. ③The person who inhaled the substance should be immediately moved to a place with fresh air; oxygen therapy or nebulization with a 2%–4% sodium bicarbonate solution may be necessary, and those with burns should have their wounds rinsed thoroughly with plenty of water. ④Protection requires the use of a gas mask equipped with a yellow-colored filter canister, as well as appropriate protective clothing, shoes, and gloves. ⑤Store away from flammable materials and sources of fire. ⑥When there is a leak, non-rescue personnel should evacuate the area immediately.

I wonder why a power outage would cause the control valves to fail, and how such failures can lead to a massive leakage of highly toxic materials I hope those who are interested can help answer the questions!

The Iraqi Ministry of Health said on the 15th that a chlorine leak occurred in the eastern Iraqi city of Kut on the same day, causing around 90 people to be poisoned. Saif Badr, a spokesperson for Iraq’s Ministry of Health, said in a statement that night that a chlorine leak occurred at a drinking water treatment plant in Kut, the capital of Wasit province, resulting in the poisoning of around 90 people. The health authorities in Wasit province promptly dispatched ambulances and medical staff to provide assistance. The statement said that most patients suffered from mild to moderate poisoning and had left the hospital after receiving treatment. The statement did not explain the cause of the chlorine leak.

Does a power outage cause the automatic control valves to fail? Since this valve is so important, why not define the electrical load as a particularly critical load among the first-class loads and supply it with emergency power? Why wasn’t the consequence of valve failure due to power outages taken into account during the design phase? And why wasn’t this scenario simulated during the Hazop analysis? Why didn’t the process emergency plan account for such a situation? Don’t want to take the blame for a power outage.