Corrosion issues of ethylene glycol solutions used in refrigeration units
Thread Content
The existing refrigeration units operate at -25 degrees Celsius and use an ethylene glycol solution with a concentration of around 50%. According to available information, ethylene glycol solutions are somewhat corrosive; therefore, carbon steel is not suitable for use in the delivery pipes, nor even 304 material. My question is whether the corrosivity of the ethylene glycol solution stems from the oxidation of ethylene glycol. If the storage tank for the ethylene glycol solution is protected with nitrogen to keep it isolated from air, can this prevent or at least significantly reduce the corrosivity of the solution? Also, is it necessary to choose stainless steel for the pipeline material? If 304 isn’t suitable, should we choose 316?
Refer to the corrosivity of ethylene glycol solutions and countermeasures: https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=2861849&shareuid=301199
That post provides a very detailed description; it’s worth noting that you can preview it without having to download it:lol:lol:lol
I’ll use an example from our system to illustrate: we use a combination of 25% ethylene glycol solution and a corrosion inhibitor, with the pH controlled between 8 and 10, and the temperature kept at
The corrosion caused by ethylene glycol solutions is primarily electrochemical corrosion. Our company has conducted experiments in the past: when a fresh ethylene glycol solution was applied to a polished carbon steel piece and the container was sealed, severe rusting occurred after 24 hours. Therefore, ordinary ethylene glycol solutions are highly corrosive. The reason for this corrosion is the presence of water in the solution, which increases its electrical conductivity. There is plenty of information on electrochemical corrosion available on Baidu. Currently, there are manufacturers in China that specialize in dealing with the corrosion caused by ethylene glycol solutions, such as Chaoyang Guangda Chemical Industry. You can look it up on Baidu
In a previous project, a 20% solution was used for the chilled water, and the pipes were made of stainless steel
Could it be that the corrosion inhibitors added to the ethylene glycol solution are not very effective?
I wasn’t at the factory at that time, so I don’t know the specific details, but our nitrogen seal was always on, so the chances of oxidation by oxygen should be very low.