1. When the amplitude of the tube is sufficiently large, the tubes will collide with each other, and the tube located at the periphery of the tube bundle may also collide with the inner wall of the heat exchanger housing. In the collision, the wall wear becomes thinner and eventually cracks.
2. The pipe at the baffle cuts between the baffle hole and the pipe. When the amplitude of the lateral vibration of the pipe is large, it will cause repeated between the pipe wall and the inner surface of the baffle hole. collision. Since the thickness of the baffle is not large, the pipe wall is frequently and frequently contacted with it, and will be subjected to a large impact load, so that local damage of the pipe being cut may occur in a short period of time.
3. The connection between the pipe and the tube sheet is broken. The joint structure can be regarded as a fixed end constraint. When the tube vibrates to produce lateral deflection, the stress at the joint is the largest. Therefore, it is one of the areas where the tube bundle failure is most likely to occur. In addition, the shell-side nozzle is also located at the tube sheet, and the high-speed flow of the medium in the vicinity of the tube is more likely to generate vibration in this area.
4. Expansion of material defects causes failure.Although the design is conservative, the vibration of the tube bundle is unavoidable during operation, but the amplitude is small. Therefore, if the tube material itself has defects (including defects caused by corrosion and abrasion), then under the alternating stress caused by vibration, the defect crack in the direction of the principal stress will rapidly expand, eventually leading to tube failure.