The problem of 98 acid absorbing water
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Generally, carbon steel can be used for storage tanks containing 98% concentrated sulfuric acid, but this acid absorbs water easily; if its concentration is reduced, it may corrode the tank walls and even produce hydrogen gas. There are cases of such accidents. How is this situation generally considered?
Our unit’s storage tanks have breather valves; there is no other protection – let’s learn about this! In my personal opinion, concentrated sulfuric acid is corrosive only when its concentration is below 78%. As long as the container is not open, the likelihood of it absorbing moisture and dropping to 78% is low, so this can be ignored.
Some fittings that pass through air exposed to sulfuric acid may suffer from moisture-induced corrosion
There are dryers; you can take a look at the design of the sulfuric acid storage tanks
Add a nitrogen seal or a vent line with a dryer
Measure the wall thickness. One issue is its tendency to explode due to hydrogen; if corrosion is severe and there is a leak, the accident will be even more serious.
Installing a breathing valve will greatly improve the situation; it is also possible to apply a special coating to the inner wall of the storage tank to prevent corrosion
In such cases, design considerations generally do not take this into account: when hydrogen is produced, the sulfuric acid concentration must be at least below 70%, and the large amount of water that needs to be absorbed is not something that can occur under normal conditions, nor as a result of a normal fault condition. Sulfuric acid has a very low vapor pressure, and the amount of moisture absorbed through breathing is also quite small; therefore, unless the liquid surface remains unchanged for an extended period of time (several days or more), there is no need to worry about corrosion at the phase interface. However, situations of prolonged inactivity should be considered within the framework of production management, with appropriate measures taken to prevent such issues. But in the case of production management, this needs to be taken into consideration; at least before starting any work involving fire, it is necessary to determine whether that acid tank has not been in use for a long time Is it possible that water has gotten in? And so on; therefore, analysis and testing must be carried out before starting any firework-related activities to prevent explosions.