Corrosion issues in carbon steel baffle and stainless steel tube heat exchangers

I have the same question, but that’s just how the equipment and materials are now. Do you think anything is wrong?

Carbon steel will definitely corrode over time during use. There is a risk of galvanic corrosion when carbon steel baffles come into contact with stainless steel pipes.

If galvanic corrosion occurs, the pipe holes may enlarge, causing the tube bundle to vibrate and the baffle plates to cut the pipes. I wonder if the inference is reasonable?

I find the material choice for this heat exchanger a bit strange; the heat exchange tubes are made of 316L, and since soft water may contain chloride ions, the shell side should also be made of stainless steel. If the lifespan of the heat exchange tubes under high-temperature steam is a concern, S30408 heat exchange tubes can be used. If it is confirmed that the shell-side fluid is non-corrosive, using carbon steel baffles is no problem. For many heat exchangers we design, where the tube side is made of stainless steel and the shell side of carbon steel, carbon steel baffle plates are used, and that’s no problem.

I agree quite a bit with the view from the 6th floor; we have also manufactured equipment featuring carbon steel baffle plates and stainless steel heat exchange tubes

A device like the one mentioned by the poster is also a common design. If handled properly, there’s no problem. The manufacturing process is complex, but the material costs are significantly reduced. For equipment manufacturers that are able to weld in this way, they have ways to handle it. I have seen many devices designed in this way, some made in China, some from Germany, and some from Italy.

I still think it’s better to choose carbon steel for the cooling water side of the tube bank. The stress corrosion caused by chloride ions occurs more suddenly than uniform corrosion.

This heat exchanger uses a condenser for steam and condensate. It is acceptable to use carbon steel for the shell side and baffle plates, but stainless steel should be used for the tube side. This design is adopted to mitigate risks; in other words, there is a risk of material leakage from the cooling water used. For example, the same cooling water may also be used in other heat exchangers, where it is used for heat exchange with certain materials (the leakage of such materials causes severe corrosion to carbon steel, but they do not contain halogens). In such cases, it would be counterproductive to prevent leaks in other heat exchangers from worsening the quality of the water overall, as this could affect those heat exchangers and even the entire plant. Then, to go back to the topic: if carbon steel is used throughout, it is not possible to avoid the aforementioned risks ； If 316 stainless steel is used for everything, the total investment cost for the equipment in the factory facility will at least triple. Now you think there shouldn’t be many problems with designing the heat exchanger this way, right? Is there any truth to my explanation? If it makes sense, please like it :)

This is the only piece of equipment in the entire plant that uses cooling water and austenitic stainless steel pipes.