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The strength of the tubes of the heat exchanger tubesheet
Dec 26, 2016

1, strength expansion

Strength expansion is to ensure the tube and tube sheet pulling strength of the tightness of the connection and expansion. Use the Expander insert nozzle rotation, through the tube ends of pipe plate hole of swell, reach plastic deformation of the pipe and pipe plate hole was swollen, elastic deformation. Tube Expander quits after tube sheet elastic recovery, have a large contact surface of tube and tube plate extrusion, tube and tube plate firmly together, to both seal and tensile force for two purposes. Tube holes on the Board, Kong Bikai Groove and hole without slot 2, as shown in Figure 1.

Tube technology currently being used include rolling, hydraulic expansion, explosive expanding 3.

Expansion applies pressure ≤ 4 MPa, temperature ≤ 300 degrees centigrade, no violent vibration, no excessive variations in temperature, no obvious stress corrosion of occasions. Due to the tube and tube hole tightly, can reduce corrosion of the fitting, and able to withstand pulling forces.

2, the strength of welding

Between tube and tube sheet welding end of welding and holes welded structure type. End-welded structure as shown in Figure 2.

Application of tube and tube sheet weld connection are as follows:

(1) tube spacing is too small or thin tube plate cannot be used when the expansion;

(2) thermal cycling and violently when the temperature is high;

(3) when the pressure is high or Compact connection has strict requirements. It ensures that resist pulling out strength of welded joints;

(4) maintenance difficulties, like Atomic Energy and heat exchanger in certain chemical processes.

End welding belongs to the incomplete welding, according to different requirements, the weld depth can be divided into:

(1) the intensity of welding (guaranteed connections between tubes and tube-sheet strength);

(2) seal welding (only to play a role in sealing).