[Haichuan Safety Document Sharing] Investigation Report on the "8·31" Acetylene Gas Tank Flash Explosion Accident of Jinfeng Chemical Industry in Jianou, Fujian

1 Basic situation (1) Basic situation of the unit where the accident occurred Jianou Jinfeng Chemical Gas Co., Ltd. (hereinafter referred to as Jinfeng Chemical) is located in Taiping Village, Nanya Town, Jianou City, under the jurisdiction of Nanping City, Fujian Province. It was established on October 15, 2004； Industrial and commercial business license issued by the Jianou City Administration for Industry and Commerce of Fujian Province (registration number: 3507832002351), unified social credit code: 9135078376618937XC, business period: October 15, 2004 to October 14, 2034 ； The enterprise type is a joint-stock company and its legal representative is Ren Yuanfeng. ； It is mainly engaged in the production and operation of acetylene dissolved by calcium carbide method. It has built a set of acetylene production equipment by calcium carbide entering water method. The main equipment includes a 3m3 acetylene generator, a 20m3 wet gas tank, supporting 6 sets of 40-head charging rows and other auxiliary facilities, with a production capacity of 200km?/a ； The company obtained a safety production license, numbered: (Fujian) WH Anxu Certificate [2006] 000098 (change) number, license validity period: May 31, 2018 to May 30, 2021. On June 19, 2018, it obtained the Level 3 (Small and Micro) standard enterprise for safety production standardization. The company currently has 13 employees including legal representatives, managers, full-time safety officers, fillers, drivers, and escorts. It does not have a registered safety engineer.

(3) Contracted maintenance personnel With the consent of the legal representative of the company, Ren Yuanfeng, and the manager, Deng Xianglin, Jinfeng Chemical Production Safety Manager Cao Bifu hired unqualified personnel Lin Desheng (died in the accident) from the public as the contractor, and hired unqualified personnel Huang Shuguang (died in the accident) and Jiang Zhiqiang to perform maintenance operations. The contractor is mainly responsible for cutting and updating the corroded part at the bottom of the bell jar of the acetylene gas tank. ； Heighten the purification tower section of the purification system and replace the delivery pump ； Reinforce the acetylene generator platform, cover, etc.

(1) After the accident, the entire plant was shut down for maintenance on August 20, 2019. Main maintenance items: Lift out the bell jar of the acetylene gas tank, cut and update the corroded part at the bottom, and then lift it in ； Heighten the purification tower section of the purification system and replace the delivery pump ； Reinforce the acetylene generator platform, cover, etc. On the morning of August 29, the organization hoisted and installed the repaired bell jar back into the gas cabinet. On the morning of August 30, Ren Yuanfeng directed the charging of materials for production and inspected the maintenance of the bell jar. The generator was put into production for about 5 hours. During this period, it was found that the gas tank bell jar was not moving smoothly. Therefore, personnel were arranged to stop production again for maintenance. The main tasks were to repair the acetylene generator and adjust the gas tank bell guide wheel. At about 6:35 a.m. on August 31, Lin Desheng, Huang Shuguang, and Jiang Zhiqiang entered the site under the leadership of safety officer Cao Bifu and performed hot work on the acetylene generator. They left the site for dinner around 11:35.

At around 12:16 on August 31, four people, Cao Bifu, Lin Desheng, Huang Shuguang, and Jiang Zhiqiang, entered the factory through the gate, took scaffolding and other equipment, walked to the acetylene gas tank operation site behind the filling plant, and jointly built a maintenance operation platform at the gas tank. After the platform was built, Cao Bifu, Lin Desheng and Huang Shuguang climbed to the top of the gas tank to perform hot work on adjusting the bell guide wheel of the gas tank. Jiang Zhiqiang went alone to the acetylene generator about 6.1m away from the gas tank to perform cleaning operations. At 13:11 on August 31, the explosive mixture of acetylene and air remaining in the gas cabinet was ignited by the ignition source generated by the work on the top of the gas cabinet, causing a flash explosion. At the same time, the water column formed by the water seal in the gas cabinet rushed out, and the gas cabinet bell was jacked up. Cao Bifu, Lin Desheng, and Huang Shuguang, who were working on the top of the gas cabinet bell, were instantly thrown into the air and landed around the gas cabinet.

(3) On-site investigation after the accident. After the accident, the lower cylinder exposed by the bell jar of the gas tank collapsed inward. The top manhole cover was basically flat and shifted two-thirds to the west. There was only one bolt left in the manhole cover connected to the gas tank body. The east side of the manhole cover was leaning on a short steel sled bar for maintenance.； There is also a welding gun and a piece of wire with a plug hanging on the guide wheel bracket on the top of the gas tank. ； Among the four guide wheels, the south direction guide wheel is missing, the upper part of the west side guide rail is disconnected, the east side guide rail is completely disconnected, and the east side guide rail fixing frame is disconnected and deformed. ； On the southeast side are parts of a hand-held grinding (cutting off) machine, fragments of a non-explosion-proof socket, and a wrench tool.

Analysis of the cause of the accident and the nature of the accident (1) The direct cause of the accident was that Jinfeng Chemical hired unqualified personnel to perform hot work and did not conduct replacement exhaust and concentration testing of the acetylene gas in the gas cabinet before the work. It violated regulations and directed hot work, which caused the explosive mixture of residual acetylene and air in the gas tank to flash and explode, causing the accident.

Indirect causes of the accident 1. Jinfeng Chemical Company failed to implement the main responsibility for safety production and the company's safety management was chaotic. The enterprise illegally outsources maintenance work to unqualified individuals and fails to sign a special production safety management agreement. ； Failure to carry out safety training and education for maintenance personnel entering the factory ； The safety technical force is seriously insufficient, and the registered safety engineer certificate of others has been used for a long time without permission. ； Safety production rules and regulations are not implemented, safety risk management is lacking, and hidden danger investigation and management are just a formality. ； Safety operating procedures were not implemented, special operation management was a mere formality, hot operation approval procedures were not performed as required by specifications, and gas tank maintenance plans and on-site emergency response plans were not formulated. After the accident, he filled out the hot work permit privately, which was suspected of fraud.

2. Safety management at the work site was chaotic, and cigarette butts were found on site. Before the maintenance work, the on-site safety officer failed to perform his duties and conduct a safety risk assessment of the work site and the surrounding environment as required, and did not perform replacement exhaust before the fire started, and did not test the combustible gas concentration (acetylene) in the gas cabinet. ； Directing operators to conduct hot work in violation of regulations ； The "three violations" phenomena such as workers using non-explosion-proof electrical tools in the explosion-proof area on the top of the acetylene gas tank, failing to take any safety protection measures, and illegally bringing mobile phones and lighters into the work site were not stopped and corrected, and the "three violations" were prominent.

3. Workers have weak safety awareness and lack professional safety skills and knowledge. When performing gas cutting operations on the acetylene generator, laying down all oxygen cylinders and acetylene cylinders and placing them messily on the ground for use violates the provisions of the "Safety Code for Special Operations in Chemical Production Units" (GB30871-2014) ； The use of red gas tubes for oxygen cylinders and black for acetylene cylinders violates the regulations of "Rubber Hose for Welding, Cutting off and Similar Operations of Gas Welding Equipment" (GB/T2550-2016) ； Use non-explosion-proof electrical maintenance tools in the explosion-proof area of ​​acetylene gas cabinets, and illegally carry mobile phones and lighters into the work site.