The double tie rod type expansion joint is composed of two bellows connected by the middle pipe and the tie rod and end plate, etc. The flexible device compensates for the thermal displacement of the plane or three-dimensional bending pipe section by means of transverse displacement. The tie rod device should be able to withstand the pressure thrust and the action of additional external force. Compound rod type expansion joint is especially suitable for absorption of lateral displacement, in addition, this kind of design can also be used to absorb the axial displacement, angular displacement and arbitrary synthesized from these three forms of displacement, general usage is to this kind of expansion joint with connecting rod set in a 90 ° "Z" shaped pipe in the middle of the tube in the arm, adjust the connecting rod to prevent the axial displacement of the external, figure 2 and 3 are two examples of application.

 

 

Figure 2 shows that the compound connecting rod expansion joint absorbs the lateral displacement of the single-plane "Z" shaped curved pipe, the thermal displacement within the middle pipe arm and connecting rod is absorbed by the axial displacement of the expansion joint, and the horizontal pipe thermal displacement is absorbed by the lateral displacement of the expansion joint. Since the pressure thrust is borne by the connecting rod, the middle fixed support is used at both ends. As the axial force acting on the pipeline is the deformation reaction force generated by the expansion joint, the guiding support is needed only. The thermal expansion of the middle pipe arm beyond the connecting rod, such as the elbows at both ends, must be absorbed by the bending of the horizontal pipe

 

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Figure 3 is a typical example of a universal expansion joint with a connecting rod in a space "Z" bend. by

 

The universal expansion joint can absorb lateral displacement in any direction, so the two horizontal arms can be in any direction on the horizontal plane