It is a special design of expansion joint which restrains the pressure thrust and also balances it so that the thrust force on the main anchors or the adjacent load sensitive equipment can be reduced significantly or eliminated. This type of expansion joint consists of a balancing bellows and two/one line bellows.
The balancing bellows is subjected to axial deflection only, while the line bellows absorbs lateral and/or axial deflections. This type of expansion joint is also a constant volume system. The pressure thrust is absorbed by the tie rods, so the main anchors can be eliminated. Pipe guides and intermediate supports are only required to direct the movement of the piping systems.
This type of bellows should not be used where the connection between the line bellows and the balancing bellows can be clotted due to the properties of the fluid medium. These bellows can be also used at the bends of the piping or change in direction of piping, where adequate support or main anchors is not possible.