Explosion of acid tank during welding repair

Welding to repair industrial equipment, such as acid transport tanks, is an essential yet inherently hazardous task, requiring stringent safety measures to prevent catastrophic accidents. A tragic incident underscored the critical nature of this work when a tank used for transporting sulfuric acid leaked acid at its bottom, leading to a fatal explosion during the repair attempt. The scenario unfolded as follows: the tank was positioned with its bottom facing upwards and the manhole downwards. When the welder ignited the arc, the tank exploded, instantly burning the welder and causing another worker's death on the spot. Investigations revealed that the primary cause of this devastating accident was the use of non-acid-resistant steel for the tank. In the presence of dilute sulfuric acid, the iron content in the tank’s material underwent a chemical reaction, generating a mixture of hydrogen and air within the tank. This mixture surpassed the hydrogen explosion limit, making the tank a ticking time bomb. When the welder struck the arc, the spark ignited the highly explosive hydrogen-air mix, triggering the blast.

This tragic event highlights the critical importance of specific precautions and standards to prevent similar incidents. Firstly, comprehensive knowledge of the internal environment of the tank is paramount. Before welding begins, the tank must be thoroughly cleaned with water, ensuring that all residual liquid or gas is eliminated. Furthermore, it is crucial that the weldment is not in a sealed state to allow any trapped gases to escape. Additionally, for tanks containing dilute sulfuric acid, it is imperative to use materials specifically resistant to acid corrosion, such as acid-resistant steel or lead-lined steel plates. Acid-resistant materials prevent the chemical reaction between the tank walls and the sulfuric acid, thus averting the production of hydrogen gas and reducing the risk of explosions.

These preventive measures underscore the importance of rigorous safety protocols in industrial welding operations, especially when hazardous materials are involved. The unfortunate incident serves as a grim reminder of the potential dangers when these precautions are neglected. Proper training, adherence to safety standards, and the use of suitable materials can significantly mitigate these risks. Industrial entities must implement comprehensive risk assessments and ensure ongoing education and vigilance to protect workers from the inherent dangers of welding on tanks storing corrosive substances. Moreover, continuous monitoring and adherence to industry best practices are essential to fostering a culture of safety and preventing such tragic accidents in the future.