Is rust removal necessary inside the cold box?

Are there any photos? It is likely that the pipe supports and instrument pipeline supports are corroded. For safety reasons, rust removal can be carried out; since there is a slight positive pressure inside the cold box, with dry inert nitrogen or nitrogen being used to fill it, the possibility of further corrosion is low. Rust formation usually occurs during installation.

It occurred during installation; there are many cold box walls and channel steel supports. I’m not sure if rust removal is necessary

How can anti-corrosion treatment be omitted? If failing to carry out such treatment in our factory is identified as a safety hazard, it is recommended that you implement proper anti-corrosion measures in accordance with safety regulations

In terms of usage, if there is severe rust during the initial installation, it can be simply rust-removed and anti-corrosion treatment applied. It is unlikely that rust removal can be carried out inside the cold box after it is put into operation; there are many dust particles inside the cold box after sand removal, and inhaling these particles poses a significant risk, making it impossible to carry out rust removal on the inner walls of the cold box. If rust removal is indeed necessary and costly, it is better to replace the corroded pallets. Referencing GB8923 also does not impose any specific requirements to carry this out; if there is relevant information in that standard, please send it over! ~Learn* more

Personally, I think the likelihood of corrosion after the equipment is put into use is relatively low; generally, nitrogen is used for protection inside the cryogenic chamber in accordance with safety standards. However, other factors could still lead to moisture accumulation within the chamber, which would require anti-corrosion measures to be taken before the equipment is put into operation. In my opinion, failing to do so could result in serious consequences

I agree with Ge’s view – corrosion is a serious issue on cold boxes; as long as nothing happens, it’s fine, but once problems arise, it becomes a big problem indeed~! Given the current installation and maintenance conditions of air separation equipment, it is inevitable that the cold boxes will suffer from water leakage and corrosion in some areas, or even throughout most of them. Nitrogen flushing for cold box protection cannot solve all the problems regarding the protection of certain areas. But I would like to add my own perspective as well. Looking at the actual situation: there are virtually no manufacturers that carry out rust removal and anti-corrosion treatment inside the cold box during installation. I have basically seen the actual equipment from Hangyang, Shengli, and Kaifeng in person, and I have also taken a rough look at it. The box walls are painted before being lifted into the cold box, while the outer walls undergo anti-corrosion treatment after installation is complete. And no anti-corrosion treatment was done inside the cold box. Can it be assumed that, fundamentally, there are no national or industry standards that require anti-corrosion treatment inside cold boxes (as Eirukge also said, this is your personal opinion rather than a mandatory requirement)? Is there no regulation regarding anti-corrosion treatment inside the cold box, or is it just a matter of limited knowledge? ~! ~! ~! ~! Looking forward to the tech expert~! ~! ~! ~! ~! ~! ~! ~! ~! ~! ~! ~! ~!

There is no need to rust-proof the interior of the cold box; painting is generally used for rust prevention and anti-corrosion. How can such materials be used inside a cold box! Another issue is rust, which occurs when moisture gets in during installation or when the sealing gas is turned off; as long as care is taken to maintain a slight positive pressure of nitrogen gas inside the cryogenic tank, there should be no major problems!

It’s fine to install it even if it’s rusty; there’s no need to remove the rust after installation

My suggestion is to call your engineering supervisor right now, have them take photos and prepare a written report. If the supervisor issues a certificate stating that the rusting of the internal structure does not affect the cold box’s ability to resist vibration, pressure, and wind, then that’s sufficient. If the work keeps getting delayed, then rust removal will definitely be necessary. You should know that fresh materials remain in better condition; rusty materials are no longer fresh, and as a result they tend to rust even more. It’s like keeping something out of the sun – the worse it stays in that condition, the more unpleasant its smell becomes. After rust removal, you can apply some lead paint or something similar. Will it rust when in normal use, or will rusting occur very slowly?

In the cold box of our 33,000 cubic meter air separation project, all materials have been coated with a layer of primer. The manufacturer’s specifications require that welds be polished and then primed again, but in practice this requirement isn’t followed as strictly; the primer is applied again, but the polishing isn’t thorough enough. This is the case for Linde Engineering’s projects