There are two types of heat exchanger welding: strength welding and sealing welding.

The welding process is simple, the joint strength is good, the tightness and the pull-off resistance of the joint can be ensured at high temperature and high pressure, and the welding method should be adopted for the fixing of the pipe and the thin tube sheet. When the joint is welded, the residual thermal stress and stress existing in the tube sheet and the tube concentrate, which may cause stress corrosion and fatigue damage during operation. In addition, there is a difference in concentration between the non-flowing liquid existing in the gap between the tube and the tube plate hole and the liquid outside the gap, and crevice corrosion is also likely to occur. At present, the inner hole welding is recommended in the case where the working condition is high.

Strength welding refers to the welding performance that guarantees the sealing performance and the tensile strength of the connection between the heat exchange tube and the tube sheet.

When the heat exchange tube is welded to the tube sheet, the residual thermal stress and stress existing in the tube sheet and the tube concentrate, which may cause stress corrosion and fatigue during operation. In addition, the non-flowing liquid present in the gap between the tube and the tube plate hole has a large difference in concentration from the liquid outside the gap, and crevice corrosion is also likely to occur. In addition to large vibration and crevice corrosion, as long as the material is weldable, strength welding can be used in any other occasion. The connection between the pipe and the thin tube sheet shall be by welding.

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