The heat exchanger shall not be formed or assembled by force means such as hammering; the material marking, welder stamping shall not be scored or struck on the pressure component. Pressure components made of steel that has been normalized, normalized and tempered, quenched and tempered are easily formed by cold forming or tempering temperatures. When using warm forming, the heat exchanger must avoid the steel fire brittle zone. If it is thermoformed above the tempering temperature, the same or similar heat treatment as the base metal should be carried out as needed.
The U-shaped elbow adopts a cold pipe, and when the bending radius is less than 10 times the outer diameter of the heat exchange tube, the stress relief heat treatment is performed after the cold bending. For the heat-treated pipe, the same heat treatment as the original heat treatment process shall be repeated after the cold bending of the hot-bending or bending radius of less than 10 times the outer diameter of the heat-exchange tube.