Reasons for cracks in heat exchangers
Thread Content
One of our company’s vertically installed U-tube methanol vaporization superheaters has the following specifications: Shell side: P=0.6 MPa, t=170 (inlet)/280 (exit), DN=400; Fluids: methanol and water; Shell material: 0Cr18Ni10Ti, 6 mm thick. Information on the tube side is not available. After 6 years of use, 8 cracks were found within a 1-meter range above the liquid level in the shell side. After replacing the shell, cracks reappeared in the same areas after 2 months. What could be the cause of this? This device is used for hydrogen production through methanol cracking; we have used many of them in the past and there have been no problems.
Is it a problem with the operation? The exit valve was not opened in time when starting up or shutting down the process, which caused the liquid substances inside to vaporize rapidly and led to excessive internal pressure. Thus, cracks occur at the stress concentration areas.
It took 6 years for the original device to develop this problem; after replacing it with another one, the same issue arose after 2 months. It’s probably not a problem with the operation; could there be an issue with the materials?
It must be a temperature issue! Is the pressure stable? There is a problem with the operating temperature difference
We once had deep grooves at the gas-liquid interface; by adjusting the height of the outlet baffle, it was used for a few more years.
Has there been a change in the set liquid level? The high inlet pressure creates vortices that exert force on the shell side, leading to stress concentration.
I think the same; there must be a problem with the materials.
It should be stress concentration or some other form of stress corrosion; it would be best to attach a photo
It’s probably stress corrosion or pitting caused by the material
It is indeed a bit hard to understand that cracks have appeared again in the same area; it is also believed that stress corrosion is the most likely cause.
In my opinion, the reason it appears in the same area is that there are suitable conditions there in terms of temperature, chemical composition, etc., which lead to some chemical reaction taking place. The device didn’t have any problems before, but it is having issues now; however, that doesn’t mean the problem lies in this device itself. I think it’s more likely that a device related to it is the cause of the problem. Also, what are the materials for the pipe train? Has a leak occurred? Will it cause cracking after leakage? It is recommended to check the composition of the materials in the shell side.
If cracks appear right after use, it won’t last 6 years, will it? Go and check on the status of your process adjustments