Reasons for seal failure in plate heat exchangers

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Plate heat exchangers often experience problems such as seal failure, blockage, and corrosion during use. This article mainly explains the causes of seal failure in plate heat exchangers and the methods to avoid such failures. The reasons for seal failure are mainly related to pressure, temperature, and duration of use: 1. Pressure. If a plate heat exchanger leaks while operating within its rated working pressure, apart from factors related to assembly and manufacturing, it is primarily due to abnormal shock loads within the entire heat exchange system, such as water hammer and air hammer effects. Under normal circumstances, this phenomenon is not easy to detect and is often overlooked in practical operations. The peak pressure resulting from abnormal shocks can be 1-3 times higher than the normal operating pressure, which causes the gaskets to shift and leads to seal failure. In addition, the heat transfer elements of plate heat exchangers are made by pressing stainless steel sheets, with a thickness generally ranging from 0.5 to 0.8 mm. Their sealing rigidity is relatively poor, and the sealing perimeter is long, resulting in a low capacity to withstand impact pressures. 　　2. Temperature Sudden changes in temperature can also lead to seal failure. When the temperature changes too rapidly, the linear expansion coefficient of the gasket does not match the amount of elastic deformation and the sealing preload, resulting in a decrease in the sealing preload. This in turn reduces the pressure-bearing capacity of the plate heat exchanger below its rated design pressure, leading to seal failure. 　　3. Time 　　In heat exchangers that have been in use or unused for several years, the aging of the sealing materials themselves may affect the reliability of the seals, necessitating the replacement with new gaskets. Measures to avoid seal failure: 1. Increase the design pressure by 1.5–2 times, depending on the structural characteristics and operating conditions of the plate heat exchanger. 2. Try to avoid shock phenomena such as water hammer in the heat exchange system. 3. Depending on the actual application conditions, if phenomena similar to those mentioned above occur, the thickness of the plate can be increased appropriately, which will significantly improve the sealing effect. 4. Keep temperature changes as slow as possible during use. 5. Regularly maintain and service the plate heat exchanger to extend its service life and improve equipment utilization.