Explosion of acid tank during welding repair

Repair welding is a critical and delicate operation, especially when dealing with high-risk materials and environments, such as acid tanks. One paramount protocol before initiating any welding operation is thoroughly checking the welding object material. Failure to adhere to this precaution can lead to catastrophic results, as illustrated by the example of an explosion of an acid tank during repair welding. The incident involved a tank designed for transporting sulfuric acid in a certain unit, where a leak was detected at the bottom. The repair procedure mandated placing the tank on the ground with its bottom facing upward and the manhole downward. Despite the seemingly routine setup, when the welder commenced the arc, the tank exploded. The devastating explosion resulted in the welder sustaining severe burns and tragically, another worker lost their life instantly. Subsequent investigations and material analysis unveiled the primary cause of the accident to be the non-compliance with appropriate material selection for the tank. The material of the tank was found to be ordinary steel rather than acid-resistant steel which would have been suitable for containing sulfuric acid. The presence of the dilute sulfuric acid initiated a chemical reaction as per the equation Fe+H2SO4=FeSO4+H2. The outcome of this reaction led to the accumulation of hydrogen gas within the tank. Hydrogen, being a highly flammable gas, mixed with the air inside the tank, thereby creating an explosive atmosphere once the concentration of hydrogen exceeded its explosive limit. When the electric arc was struck by the welder, it ignited this hydrogen-air mixture, causing the explosion.

This tragic incident underscores two critical aspects of repair welding: the vital importance of material compatibility and the inherent dangers of welding in potentially explosive environments. Ensuring that the material of the object being welded is compatible with the substances it has contained or will contain is crucial. In the case of the acid tank, the use of acid-resistant steel could have significantly mitigated the risk, preventing the reaction that released hydrogen gas. Moreover, understanding and mitigating the hazards associated with the welding operation environment are equally important.

Implementing safety measures such as adequate ventilation, using explosion-proof equipment, and ensuring that the tank is free of flammable gases before beginning repair work are essential steps in preventing such accidents. Furthermore, workers must be trained in the correct handling and procedural protocols for repair welding operations, especially when dealing with volatile substances. The incident also highlights the necessity for regular maintenance and inspection regimes that include checking for material degradation and ensuring the ongoing suitability of materials exposed to harsh chemical environments. In summary, the lethality of repair welding operations exemplified by the explosion of the sulfuric acid tank stresses the compelling need for a comprehensive assessment of materials and meticulous adherence to safety procedures to prevent avoidable tragedies and preserve life.