The pressure-balanced expansion joints have two working bellows at each end and one balancing bellows in the middle. They withstand internal pressure thrust through load-bearing components (large tension rods or bellmouths). Consequently, the pipeline only requires a central fixed support. This type of expansion joint can only absorb axial displacement.

Axial displacement of the straight pipe pressure-balanced type expansion compensation system is self-balanced by internal pressure thrust, making this structure suitable for high-level straight pipelines or large-diameter lines where fixed supports are not advisable. The straight pipe pressure-balanced expansion joint consists of a bellows and two end connections, along with other components. It absorbs pipeline axial displacement (with a small amount of lateral and angular displacement) through the flexible deformation of the bellows. The end connections are either directly welded to the pipeline fittings or法兰-mounted and then connected to the pipeline flanges. The small tie rods on the expansion joint primarily serve as rigid supports during transportation or for product pre-deformation adjustment; they are not load-bearing components.

Installation and usage precautions for straight pipe pressure balanced expansion joints:

1. The bellows expansion joint with straight pipe pressure balancing is generally used on suspended straight pipe lines, installed horizontally.

After the installation of the straight pipe pressure-balanced bellows expansion joint, all small bolts must be removed.

3. To reduce the elastic reactive force of the bellows expansion joint on the support, pre-tension or pre-compression can be applied to such bellows expansion joints before installation (this can be achieved by adjusting the small tension rod on it).