The corrosion problem of chloride ions on tower equipment
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Carbon steel tower body, martensitic stainless steel packing, medium containing a high amount of chloride ions. In this case, which material is more severely corroded by chloride ions, and what is the corrosion mechanism? If the packing is corroded first, can it provide protection for the carbon steel material of the tower?
What does “a large amount” mean? Chloride ions cause more severe corrosion of stainless steel; it would be best to specify the operating conditions.
Approximately 500-1000mg/l
The temperature is around 200 degrees Celsius
Maximum concentration: 0.1%? It’s a very low concentration; is it necessary to study it in detail? ;P In my experience, both materials are acceptable (at room temperature). There is a corrosion manual available for download; it might help you.
There must have been some problems; the tower suffered from corrosion and leaks, and the packing also became corroded. It’s not clear whether the packing or the tower was corroded first. The patent holder once said that this type of internal component was chosen for the tower because it could be replaced once it became corroded, and it also helped to provide corrosion protection for the tower itself. But I still don’t understand the principle behind this I once thought it might be cathodic protection, but I’m not sure
The medium corrodes whatever it comes into contact with; then why is there the notion of sequence? Why rely on gaskets to protect the casing? For carbon steel casings, apart from anti-corrosion paint, what’s left is simply providing a margin against corrosion. As for gaskets, they should be replaced regularly.
Have you heard of cathodic protection (sacrificial anodes)? If the tower is corroded and needs to be replaced, if the packing is corroded first, the packing can be replaced regularly without the need to replace the entire tower. Which option is more cost-effective from an economic perspective? Additionally, corrosion mainly affects the inner wall of the tower
Here’s some practical experience: our previous rupture disc clamps were made of 304 stainless steel, but we later switched to martensitic stainless steel with a Teflon coating – and the results were excellent
In fact, this issue is too complex to study theoretically; for engineering purposes, it is sufficient to eliminate the areas where problems occur. The inner wall of the tower can be lined, and in cases where temperatures reach 200 degrees, only a steel lining can be used. Composite steel plates can be used as a reference for fabrication (titanium composite steel plates). I wonder what else is in the solution? If corrosion resistance to chlorine is required for the tower material, cast iron is a better choice than carbon steel.