Safety | A Typical Incident of Heat Exchanger Explosion: A Lesson Learned from Painful Experience!

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Preface: In the first half of 2016, **minor safety incidents kept occurring, and safety undoubtedly became a sword of Damocles hanging over everyone’s head. As holidays approach, special attention must be paid to safety issues! Safety means responsibility; one’s safety is not only a matter of being responsible for oneself, but more so a responsibility to the family who care about you ； Safety is equivalent to efficiency; we can better appreciate the vitality that safe production brings to chemical enterprises. For more details, visit the PIDCAD official website at pidcad.com; numerous additional resources are available on the site. http://www.pidcad.com/uploads/allimg/160615/1-160615093011T3.jpg The Qingyang Petrochemical fire accident: On July 26, 2015, a leakage 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; this incident resulted in 3 deaths and 4 injuries. Facilities at the company involved in the accident: China Petroleum 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. http://www.pidcad.com/uploads/allimg/160615/1-160615093212F4.jpg Photos of the accident scene; brief account of what happened. At 6:38 on July 26, 2015, operators at Qingyang Petrochemical’s atmospheric pressure unit discovered that there was a leak in the gasket of the residue/oil crude oil heat exchanger E-117/D, along with smoke emission. Upon learning of this, Qingyang Petrochemical’s maintenance company sent three staff members from Shaanxi Xinning Industrial Co., Ltd. to the site to investigate and fix the leak. At 7:01, during the handling process, the plug suddenly came loose, hot oil sprayed out and caught 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. http://www.pidcad.com/uploads/allimg/160615/1-16061509332K63.jpg After the accident, the operators of the atmospheric-pressure plant immediately initiated an emergency shutdown, activated the emergency response plan, and the fire department of Qingyang Petrochemicals as well as the Qingyang city fire brigade 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 stable. 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, in order to prevent similar accidents from occurring again. 1. Strengthen the detection of chemical leaks: Conduct comprehensive inspections of equipment in enterprises that handles flammable, explosive, toxic, and harmful chemicals, focusing on areas prone to leakage such as valves, flanges, plug fittings, and welds at elbows, 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 cannot withstand 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 startup and shutdown operations. 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.