A typical accident case of a heat exchanger explosion – a lesson learned through blood and tears!

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This post was last edited by yinkuilin6868 on 2016-6-14 12:12: A typical accident case of a heat exchanger explosion – a lesson learned through pain! The 7·26 Qingyang Petrochemical Fire Incident: On July 26, 2015, a leak and fire broke out at the 3 million tons per year atmospheric distillation unit in the First Joint Operation Department of CNPC’s Qingyang Petrochemical Company, resulting in 3 deaths and 4 injuries. Facilities at the company involved in the accident: CNPC Qingyang Petrochemical Company is located in Qingyang City, Gansu Province. It is a refining and petrochemical enterprise directly under China National Petroleum Corporation, and it has 15 production units including those for atmospheric distillation and catalytic cracking. The 3 million tons per year atmospheric pressure plant involved in the accident began maintenance on June 27; it was put back into operation at 11 a.m. on July 23, and was operating normally by 8 a.m. on July 25. Before the accident, 8 people, including those from Xuzhou Anti-Corrosion Engineering Corporation, were carrying out construction work at the site. Brief account of the incident: At 6:38 on July 26, 2015, operators of the atmospheric pressure unit at Qingyang Petrochemical discovered that there was a leak in the floating head plug of the residue/oil crude oil heat exchanger E-117/D, accompanied by smoking. Upon learning of this, Qingyang Petrochemical’s maintenance company sent three staff members from Shaanxi Xinning Industrial Co., Ltd. who were on duty to the site to investigate the leak and address it. At 7:01, during the handling process, the plug suddenly came loose, hot oil sprayed out and caused a fire, resulting in the death of 3 contractors who were carrying out insulation work on the platform above the heat exchanger, and 2 others were injured; in addition, 2 maintenance workers from Qingyang Petrochemical were also injured. After the accident, the operators of the atmospheric-pressure unit immediately initiated an emergency shutdown, activated the alarm system and brought into effect the emergency response plan. The fire brigade of Qingyang Petrochemical and the Qingyang Fire Department rushed to the scene to extinguish the fire; by 8:50, the fire was under control ； At 11:55, the open flame was completely extinguished. At 19:35, the General Office of the Qingyang Municipal Party Committee issued an update on the accident. A total of 8 workers were at the accident site; 1 of them was unharmed, 3 died, and 4 were injured by burns (1 with severe injuries, 1 with moderate injuries, and 2 with minor injuries). They are currently being treated in hospitals, and their vital signs are normal. Analysis of the accident cause: Preliminary analysis indicates that the direct cause of the accident was a leak in the floating head plug of heat exchanger E-117/D, which led to the release of high-temperature residue oil (at around 340–360°C). This oil came into contact with air and caught fire spontaneously. Accident prevention measures: This accident is quite typical; many similar incidents have occurred in petrochemical enterprises across the country. All enterprises should earnestly learn from the lessons of these accidents, take necessary preventive measures, and thoroughly carry out self-inspections and self-corrections to address potential safety hazards, thereby preventing similar accidents from occurring again. 1. Strengthen the detection of chemical leaks: Conduct comprehensive inspections of equipment in enterprises that handle flammable, explosive, toxic, and harmful chemicals, focusing on areas prone to leakage such as valves, flanges, plug threads, and welds, in order to detect issues early and carry out repairs promptly. 2. Strengthen equipment integrity management: Conduct a thorough inspection of the gaskets used in high-temperature equipment within the enterprise, determine the operating temperature suitable for those gaskets, and replace those that are not resistant to high temperatures in a timely manner, thereby preventing leaks caused by deformation or oxidation of the gaskets due to heat. 3. Strengthen the safety management during plant start-up and shutdown. Strictly control the rate of temperature increase and decrease during these processes; sudden changes in temperature should be avoided to prevent seal failure at the bolt connections of valves due to excessive thermal stress.