Abstract: This study investigated a typical benzene tank explosion incident in a benzene tank caused by stray welding currents. Through on-site inspection, video surveillance, interviews, potential ignition source exclusion, and simulated on-site tests, it was determined that the fire was caused by stray welding currents. The fire risk from stray welding currents is often overlooked due to its concealed pathways and the specialized knowledge required for its recognition. Analyzing the mechanism of stray current generation in welding shows that the existence of multiple current paths is a necessary condition for the generation of stray currents, and the fundamental reasons for the stray currents exceeding the safety values are the aging of welding machine components, poor contact of current paths, improper positioning of welding clamps, and welding cable specifications and parameters not meeting the requirements, resulting in excessive normal path resistance. A fault tree for the benzene tank explosion caused by stray welding currents was established, analyzing the influencing factors of the explosion from three aspects: reaching the explosive limit concentration of mixed gases, stray welding currents exceeding safety values, and electrode discharge or overheating of the medium. Specific measures to prevent similar fires are then proposed to provide references for the safety management of welding.

Key words: stray welding current, benzene tank explosion, fire investigation, fault tree