Cracking of stainless steel heat exchanger tubes
Thread Content
A stainless steel shell-and-tube heat exchanger, with toluene at 75°C on the tube side and circulating water at room temperature of 30°C on the shell side; after operating for about 10 months, it was found upon disassembly that the tubes had cracks of varying degrees. The heat exchange tubes are made of S30408 material, while the shell tube is made of Q235B material. Personal analysis: The material of the heat exchange tubes is incorrect, and there are quality issues. I would also appreciate it if fellow sailors could analyze this, thank you~
What is the chloride ion concentration in the circulating water?
This is likely a problem with the manufacturing of the heat exchange tubes; insufficient material was removed from both ends after tube fabrication, resulting in small imperfections that did not run through the entire tube. These imperfections expanded over time due to welding, expansion joining, and use, leading to leaks
Why do it seem that some of the heat exchanger tubes are made of welded steel pipes?!
This seems to be a welded pipe; if the welding quality of such a pipe is poor, there will definitely be many leakage points
In Figure 1, the tube in the middle; and in the upper left corner of Figure 3, there are traces that appear to be welds on those tubes – take a closer look
Isn’t it the weld inside the pipe that’s clearly visible?
Are you saying this is a welded pipe rather than a seamless pipe?
Welded pipes undoubtedly have poor material quality, thin walls, and incorrect weld joint designs.
What material is the tube sheet made of? Carbon steel? There’s no excess height at the pipe end!