Fires caused by welding operations

1. Accident Process

At 8:05 on April 16, gas leaked from the upper thermocouple receiving flange of the No. 1 electrostatic precipitator in the recycling workshop of Anhui Huaibei Coking Plant, but no one noticed it. The coking and chemical production workshops were carrying out equipment maintenance at the same time. When the welder connected the grounding wire of the welding machine to the gas pipeline and ignited the welding, the current was transmitted through the gas pipeline to the upper thermocouple receiving part of the electrostatic precipitator, causing mechanical vibration, sparks, and igniting the leaked gas.

2. Accident Analysis

The direct cause of this accident was that the grounding wire was connected to the gas pipeline during the welding operation. The indirect cause of the accident was the leakage of the gas pipeline. Similar accidents have occurred in the plant due to welding with the grounding wire connected to the process pipeline, causing sudden pump stop and motor burnout.

3. Lessons from the accident and preventive measures

Chemical plants are mostly high-temperature and high-pressure operations, with many flammable and explosive substances, and a harsh operating environment. Process pipelines and containers can be seen everywhere. Electric welders, in order to save trouble, simply connect the ground wire of the welding machine to the process pipeline and container, which is very likely to cause a medium combustion accident. In severe cases, it can also cause an explosion, resulting in a vicious accident in which the machine is destroyed and people are killed. Therefore, some chemical production enterprises have clearly stipulated that during electric welding operations, the ground wire is not allowed to be connected to the pipeline at will, and the purpose is to prevent such accidents from happening.