The tank containing concentrated sulfuric acid has a hole in it; how can the tank be drained so that it can be repaired?
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There is a hole in the tank containing concentrated sulfuric acid. I would like to ask the experts: for a medium like concentrated sulfuric acid, how should the tank be purged in order to create conditions that permit maintenance work?
Is it true that once it’s emptied, we can start using fire right away, since there’s nothing flammable around? That’s my opinion:$
If it is discharged directly, residues will remain. When the tank’s blind plates are removed, concentrated sulfuric acid will absorb moisture; could it turn into dilute sulfuric acid, which would then react with iron to produce hydrogen?
In my opinion, it’s necessary to wash it until it reaches a neutral pH, then blow it with air; only when the explosive detector shows that there are no flammable or toxic gases present and the oxygen level is within acceptable limits can work be carried out!
Theoretically, it’s correct, but it’s possible to carry out hot work without using water for cleaning. Or maybe I’m just too bold: lol
You’re analyzing it perfectly; I’ve experienced this situation before. When the maintenance workers were performing welding work on the sulfuric acid pipelines in our workshop, an explosion occurred, and the reason was exactly what you’re worried about.
Once it’s cleaned out, work can begin with welding right away
After draining completely, replace it with nitrogen before proceeding with welding.
Concentrated sulfuric acid is an inorganic substance that does not catch fire under normal conditions as long as it is not in contact with organic materials or water vapor. For safety reasons, it is best to empty the container and then purge it with nitrogen; do not use compressed air, as it contains moisture and can result in the production of a small amount of hydrogen. Then work can proceed with welding after passing the inspection.
Several members upstairs have already explained things very well. The process for obtaining a fire permit should be straightforward, and the safety measures specified in that permit must be strictly followed: isolation using blind flanges, thorough nitrogen purging, satisfactory analysis results, availability of fire extinguishing equipment, and the presence of a person responsible for monitoring the fire… It’s also necessary to take into account the specific conditions of the area where the storage tank is located. Many people might think this is excessive, but accident cases involving explosions caused by working on sulfuric acid tanks can illustrate the point. Please search online for: 1. The investigation report on the “3•1” sulfuric acid leakage accident at Jianping County Hongshen Trading Co., Ltd.: http://www.chinasafety.gov.cn/newpage/Contents/Channel_5498/2013/1105/238229/content_238229.htm 2. An explosion caused by working on an old sulfuric acid tank at a phenol factory in Shandong Province: http://www.doc88.com/p-0711910286483.html In these cases, work was carried out on the tanks without first draining the sulfuric acid from them, or explosions occurred even after the tanks had been unused for several years. I remember an incident like this happened in Jiaonan, Shandong, but it couldn’t be found online. Therefore, the original poster should definitely not follow the advice that it’s okay to proceed with work once the acid has been completely drained
I didn’t fully understand my brother’s permit for working with fire; when working on tanks, it’s necessary to carry out certain preparations first, and only after those preparations are completed can work be done.