1. Excessive thermal stress

In the operation of tubular heat exchanger, the temperature of shell and pipe wall are different due to the different temperature of cold and hot fluid. This difference makes the thermal expansion of the shell and the pipe different. When the temperature difference between the two is large, the pipe may be twisted, or make the pipe loose from the flower plate, or even destroy the whole heat exchanger. Therefore, the influence of thermal expansion must be considered structurally and various compensation methods should be adopted.

In the process of starting and stopping of the heat exchanger, the temperature rise rate and temperature drop rate exceed the provisions, so that the pipe and tube plate with high heat stress, the weld or expansion joint of the pipe and tube plate connection damage, resulting in port leakage.

2. Tube plate deformation

It is mainly caused by the machining deformation of the tube plate and the deformation during the machining. The tube is connected to the tube plate, and the deformation of the tube plate will cause the leakage of the pipe port.

3. Improper pipe plugging process

Tapered plugs are commonly used to weld plug pipes. The force should be moderate when driving the cone plug. If the hammer force is too large, the pipe hole will be deformed and the adjacent pipe and pipe plate will be affected, which will cause damage and cause new leakage.

In the process of welding, such as preheating, improper weld position and size, will cause damage to the adjacent pipe and pipe plate joint.

Other pipe plugging methods, such as expansion pipe plugging, explosion pipe plugging, etc., such as improper process, will also cause the leakage of the adjacent pipe mouth. Therefore, strict tube plugging process should be followed.

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