Can a 20% fuming sulfuric acid tank be made of 304L?
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Design temperature 200. The corrosion manual states very clearly that all chromium-nickel steels are not suitable for use with nicotinic acid – it’s a blanket prohibition, as shown in the screenshot below. But I found some information suggesting it works, as well as some practical examples of its use. I’m thinking that this corrosion manual is quite old; materials have improved since then, so is what’s written in it still accurate? Could some expert please share their insights?
Theoretically, 304L can be used for such high concentrations of acid, but it’s better not to use it at a design temperature of 200 degrees. Easily corroded
That’s the situation in China’s chemical industry these days: everything seems fine when nothing goes wrong, but as soon as a problem arises, accountability is demanded. Even if 316L material is suitable, we still refuse to use it. After all, it isn’t that it can’t corrode – it just corrodes more slowly. If there’s a leak after 20 years and you’re still working at that factory, congratulations, you’ll have to take responsibility. The safest option is to use what’s designed by engineering firms; even if they design something using carbon steel, as long as it bears their approval mark, any problems that arise can at most be attributed to inadequate management on your part
Is 20% sulfuric acid the same as fuming sulfuric acid? Over 98% is sulfuric acid with fumes, right?
It should be 120%, that is, 100% sulfuric acid and 20% sulfur trioxide
The temperature is 200 degrees; further consideration is needed
I haven’t heard of this type of sulfuric acid; I’ve heard of models 104 and 106, in which case carbon steel is sufficient, and 304 steel should not be used.
Iridium-plated 304 is the best choice, ensuring longevity for a lifetime. 304L has a high corrosion rate, so a greater wall thickness is required.
No sense of responsibility, replies that shift blame, but it’s the correct approach. Perhaps there is a better way.
It’s only after suffering many losses that one realizes this. In the petrochemical industry, any problem can lead to serious consequences. When something goes wrong, people tend to shift the blame onto others instead of taking it on themselves. Fortunately, there are now job responsibility systems in place, which help prevent others from shifting the fault onto you. I have personal experience with this: a maintenance plan was prepared, and this equipment was included in it. However, the head of the equipment department refused to sign off on it, saying that maintenance was unnecessary and a waste of money. We had no choice but to remove that item from the plan. Eventually, when work started, problems arose with that equipment and production couldn’t proceed. The production manager won’t come to ask you what happened; he’ll go straight to the equipment department leaders. Those leaders will say that the maintenance task wasn’t included in their schedule, claiming that it’s their responsibility to take care of the equipment. With so many pieces of equipment in the factory, it’s impossible for them to keep track of everything. So, you end up having to bear the blame. Of course, you won’t be happy about that, so you turn to your superiors, but what can you say? There’s no evidence – it was originally included in the plan, but the equipment department head refused to approve it, so you removed it. Otherwise, he wouldn’t have signed off on the maintenance plan. In such cases, it’s considered shirking responsibility, and it’s very unfair.