Leaking repair for shell and tube heat exchangers
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I’m seeking help from experts: As the title suggests, my factory uses shell and tube heat exchangers that are assembled through expansion jointing and welding. Leaks were detected during operation; after welding to repair those leaks, more leaks were found in other areas, so welding was done again. After the leak test is successful, leaks reappear after using it for some time. Does anyone have any good solutions for this? Additionally: When performing leak testing, we apply pressure of 13 kilograms directly in the tube side, with the shell side at atmospheric pressure. Is this method okay for leak detection? Shell-and-tube heat exchanger: 13 kg of material in the tube side, 4 kg of circulating water on the shell side; the temperature of the material is around 85 degrees Celsius. Additionally: there are also double-shell plate heat exchangers; under similar operating conditions, any leaks are repaired by welding, but this only results in more leaks over time. Is there any way to solve this?
Direct patch welding won’t work; contact the manufacturer, as they have the necessary tools to carry out further welding to ensure a strong bond. In fact, once there’s a leak, it’s unlikely that the problem can be completely resolved
Actually, once it’s missed, the chances of causing a full-blown problem are low
If there is a small amount of leakage, the best solution is to seal both ends of the tube sheet at the location of the leakage.
1. Check the drawings; pressurization should be applied to the shell side, and the tube bank needs to be removed for inspection.
It was meant to be done by blocking it off. But you know, after plugging two, I found that seven more were leaking; after plugging seven, eight more started leaking. I don’t dare to block it; otherwise, the heat exchange area of the heat exchanger, as well as the thermal stresses, won’t be able to handle it.
Firstly, it is not allowed to block both ends of the heat exchange tube, as this affects the heat exchange area and has implications for the chemical processing process. Second, on-site patch welding only covers the surface of the leak; affected by the welding conditions, the internal leaking pipes remain unresolved, posing a potential hazard. Therefore, to completely resolve the problem, it is necessary to identify all leakage points, remove contaminants such as water and oil, ensure a proper welding environment, appropriately grind the leaking welds to determine the cause of the leakage, and then carry out repair welding. The simple surface coating used by the original poster is useless.
It’s quite strange that the material flows through the tube side while water flows through the shell side; I’m not sure what kind of material it is Is the leakage point at the tubes, or at the tube sheet and tubes? With welding, high temperatures lead to inevitable welding stresses; stress relief makes it easier to address defects. In other areas affected by hand temperature, defects can occur, and leakage is likely to happen. One can try using imported polymer repair materials, which allow for repair and curing at room temperature without the formation of stress defects. Also, regarding the heat exchanger itself, is the expansion tube up to standard?
May I ask if the leak is inside the tube or at the end of the heat exchange tube? If it’s inside, then it’s possible that the heat exchange tubes have leaked; you should describe it in more detail
Does the term \"augmented joining + welding\" mentioned by the poster refer to strength enhancement + sealing welding, or strength welding + surface bonding?
It is recommended to contact the manufacturer for assistance in identifying the cause, whether it is an incorrect welding process or some other quality issue