When workers used Tenna water (a flammable and explosive chemical hazard, second only in volatility to gasoline) to clean the machine, gas deflagration occurred.
Cause identified: Improper operation by workers
The Guangdong Provincial Government Investigation Team held a plenary meeting and initially determined that the explosion was a production safety accident.
After investigation, the accident occurred as follows: On December 31, 2014, the axle assembly workshop of Workshop 3 of Guangdong Fuhua Engineering Machinery Manufacturing Co., Ltd. stopped production during the trial production period. The person in charge of the workshop notified some departments Employees go to the workshop for inventory, cleaning, equipment maintenance and modification, etc. At 7:30, 87 employees went to work one after another. During this period, 24 people used flammable liquid thinner on both sides of the axle assembly line A and B to clean the paint on the surface of the assembly line; 5 people were preparing for electric welding operations near the axle assembly line B; 3 people were cutting near the axle assembly line A; and other personnel Inventorying, marking ground marking lines, maintenance, overhaul and modification of equipment, etc.; Line A uses about 165 kilograms of diluent, and Line B uses about 150 kilograms of diluent. During the cleaning process, the diluent flows into the trench of the axle assembly line. At about 9:28, Liang Moumou (who has not obtained a special operation certificate) and others used an electric welder on the I-beam about 5 meters above the ground directly above the B line of the axle assembly and opposite the No. 17 steel column in workshop three. An explosion occurred in the B-line area during welding and installation of the pipe reel, followed by an explosion in the A-line area of ??the axle assembly.
After investigation and inquiry, on-site investigation and physical evidence identification, it was initially determined that the direct cause of the accident was the volatilization of diluent that flowed into the trench of the axle assembly line when workers used a large amount of diluent to clean the axle assembly line equipment and the ground. The combustible gas mixes with air to form an explosive mixture, which may cause an explosion if sparks occur during illegal welding operations on site.