Corrosion issue of double flanges at the bottom of the tower
Thread Content
The bottom liquid level gauge in our company tends to corrode frequently, and in each case it is the upper flange that gets corroded while the lower flange shows little signs of corrosion. Why does the upper flange corrode more severely than the lower one?
This type of corrosion should be electrochemical corrosion; when the liquid level is high, the upper flange comes into contact with the liquid, while when the liquid level is low, the upper flange is separated from the liquid and comes into contact with the gas. Due to manufacturing reasons, the lower flange is mostly submerged in liquid, resulting in a relatively stable environment. The upper flange, being frequently exposed to such unstable media conditions, suffers from electrochemical corrosion over time. Therefore, the upper flange is severely corroded.
The environments in which the upper and lower flanges are located are different; the upper flange suffers severe corrosion due to its frequent exposure to both gas and liquid phases.
The upper flange is generally in the gas phase, while the lower flange is generally in the liquid phase – does this have any impact?
Gas-phase corrosion is generally mild; low-temperature corrosion requires liquid water. First, check for acidic substances present in the medium, and second, examine whether there is any scale buildup on the flanges.
What process, medium, temperature?
The environments in which the upper and lower flanges are located are different.
The lower flange is submerged in the medium, which isolates it from oxygen and prevents corrosion!