How to deal with corrosion in heat exchanger tube bundles?
Thread Content
Due to the properties of the medium, in fixed-tube-sheet heat exchangers where the circulating water flows through the shell side, the slow flow rate of this water (0.25 Mpa at the inlet and 0.15 Mpa at the outlet) suggests that underflow corrosion may have occurred, leading to leaks in the tube bundle. During maintenance pressure testing, it was found that some tubes in the bundle were leaking severely, while on many other tubes there were droplet-like substances at the tube ends (these tubes were not blocked). The pressure could be maintained during testing; it is possible that severe underflow corrosion at the welds between the tubes and the tube sheet caused slight leaks. After the leak in the heat exchanger was fixed and it was in operation for several months, leakage occurred again. Apart from carrying out repairs and replacing the heat exchanger, are there any other effective ways to completely stop the leaks?
What material are the tubes made of? Is it 304 stainless steel? What is the temperature at the outlet of the circulating water – is it above 50°C? Also, what is the chloride content in the circulating water? If it’s 304 stainless steel, the outlet temperature is above 50°C, and the chloride content exceeds 500 ppm, then it’s a matter of choosing the appropriate material for the heat exchanger as well as determining the appropriate heat exchange area; re-design and calculation are necessary
For a small leak, use a plug; if the leak is severe, replace the core.
What are pipe process materials? What are the values for concentration, temperature, pressure, etc.?
That’s right; we choose the water cooler design based on the heat exchange medium required. For cold exchange equipment with a fixed tube sheet design, a shell side that is free from corrosion or shows minimal corrosion is generally selected; in cases where corrosion is a concern, a tube side is used (to facilitate corrosion prevention or maintenance). There is a risk of corrosion on both sides of the heat exchange medium, so other structural designs must be chosen. Floating-head water coolers are convenient for maintenance or corrosion prevention. Corrosion exists on the circulating water side of the carbon steel tube bundle of the heat exchanger mentioned here. Check what the medium on the inner wall of the tube is; if its corrosion effect on carbon steel is within acceptable limits, perform some calculations and it may be possible to switch to another medium. In this way, anti-corrosion coating measures can be applied to the inner wall of the tube bundle for circulating water.
The material flowing inside the tube walls, due to the properties of that material, results in too many dead zones in the shell side; as a result, only circulating water flows through the shell side. Although the shell side is coated with anti-corrosion paint, this still leads to leaks in the tubes. Leaks start to occur after about 2 years of operation.
Applying anti-corrosion coatings to tube bundles of the fixed tube sheet type presents many difficulties, makes construction challenging, and leads to quality issues during installation. Materials are not allowed to pass through the shell layers; therefore, considering changing the design of the equipment, such as to a floating-head type, might be an option.
Can a corrosion prevention discussion question, without even knowing conditions such as materials, temperature, and pressure, yield any results? Having a result doesn’t necessarily mean it’s correct.
Please provide information on the heat exchange media on both sides of the heat exchanger, as well as relevant parameters such as the inlet and outlet temperatures, pressures, and flow rates of these media. Otherwise, it’s impossible to analyze the issues
You can try our heat-conducting anti-corrosion coating