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At around 13:25 on January 15, 2023, Panjin Haoye Chemical Co., Ltd. exploded and caught fire during the pressure sealing operation of the inlet pipe of the water washing tank of the alkylation unit, resulting in 13 deaths and 35 injuries, and direct economic losses of about 87.99 million yuan。Through on-site investigation, expert technical analysis and investigation by public security organs, the possibility of man-made damage, natural disaster and other factors causing the accident has been ruled out。The accident investigation team determined that the "1·15" explosion and fire accident of Panjin Haoye Chemical Co., Ltd. was a major production safety responsibility accident。

On January 11, 2023, Panjin Haoye Chemical Co., Ltd. found that the edge of the accident pipeline elbow fixture (leak position on April 19, 2022) was leaked, and the equipment department of Panjin Haoye Chemical Co., Ltd. organized maintenance, and organized three times on January 11, 12, 14 to stop the leak, all without success。

At around 13:00 on January 15, Panjin Haoye Chemical Co., Ltd. and maintenance units began to organize and implement pressure sealing operations again。Two cranes were used at the site to lift a hanging basket, and two leak-blocking operators were arranged in each hanging basket to be lifted by the crane to the leak point。Crane command by walkie-talkie (walkie-talkie is non-explosion-proof type)。

At 13:24 minutes and 10 seconds, when installing and fastening a set of bolts on each side of the new fixture, the pipeline weld at the horizontal end of the original fixture suddenly broke, and a large amount of media erupted from the fracture。On-site monitoring personnel immediately evacuated and arranged for emergency parking of personnel inside the alkylation device.

At 13:25, 53 seconds, the alkylation unit area exploded and caught fire。

Direct cause of accident

The accident pipeline leaked and broke during the pressure-sealed operation. The reaction effluent in the washing tank was sprayed out in large quantities and mixed with air to form an explosive vapor cloud, which exploded and caught fire when it met the ignition source (see Fig.3 for the explosion area), resulting in heavy casualties in the field operation, monitoring and explosion shock wave。

Due to technical reasons such as power failure of the on-site video surveillance device and the arrangement of the surveillance camera, the existing video data cannot be viewed to the location of the explosion point and the scene situation of the explosion moment。The investigation found that the four walkie-talkies used for operation command belong to non-explosion-proof walkie-talkies, and the minimum use voltage is 4.5V, the passing current is estimated at the lower value of 100mA, if the on-time continues 0.1s, then the spark energy is E=UIt=45mJ。

In addition, there are two cranes working on the site, and the high temperature hot surface temperature of the exhaust pipe can be as high as 800 ~ 900 ° C。In the leakage medium, the minimum ignition energy of n-butane is 0.25mJ, ignition temperature is 405℃;The minimum ignition energy of isobutane is 0.52mJ, ignition temperature 460℃。

According to the comprehensive analysis of the expert group, the ignition source caused by the explosion is: one is the interconnection energy during the intercom call, and the other is the high temperature hot surface of the exhaust pipe of the crane at the work site。

The accident was a huge loss and a painful lesson。

One of the ignition sources that caused the explosion was the connecting energy of the non-explosion-proof walkie-talkie used in the field operation command。