Help analyze the causes of tube cracks
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Heat exchanger tubes: 304 material; steam on the shell side, fluid on the tube side. The temperature difference between the tube side and shell side is around 100 degrees. 10 days after operation, the pipe started leaking. Inspection revealed transverse through-cracks at the lower part of the upper tube sheet (0–20 mm from the lower surface of the tube sheet). What’s the reason? Help analyze it
The lower side of the pipe doesn’t look like stainless steel anymore; it looks like carbon steel. The upper part is made of stainless steel; the break in the heat exchanger tubes is at the junction between the two, so it’s probably a problem with the material
The material is fine. I checked. Below the crack, on the outside of the pipe hole, caused by steam
I’m following this. Is there anyone who can explain the relevant knowledge? Also, has any microscopic testing been done on the fracture surface?
There is an issue with the strength calculation of the heat exchanger; it seems that expansion joints need to be added. The stress on the heat exchange tubes is too high.