In order to accomplish this balancing, a constant volume device is used by the addition of a balancing bellows with a cross-sectional area equal to twice the cross-sectional area of the line or pipe size bellows.

Through proper cross-linking, the change in volume of the line bellows, due to an axial change in length, i.e. expansion or contraction, can be made to cause an equal but opposite change in volume of the balancing bellows.

Therefore, if a contraction of the pipe occurs, an equal expansion can be made to occur in the balancing bellows.

Using the principles of mechanics and hydraulics, if no volume change occurs, then all pressure forces remain constant and there are no forces out of balance. Thus the pressure thrust that would normally be present in a piping system containing an expansion joint is eliminated.

This unique design incorporates integral guide rings, a full thickness cover, self-draining convolutions and insensitivity to flow. It is easy to insulate and easy to handle during installation and can be supplied with a support foot which would act as an intermediate anchor. If high pressure thrust loads are causing the design of main anchors to be prohibitively costly and/or difficult, eliminate them by using Thorburn IPBE expansion joints.

• Absorbs large axial movement - up to 400mm

• Available from 50mm up to 4m

• Eliminates pressure thrust forces on the piping system

• Eliminates main anchors

• High pressure up to 50 BAR (750 psi)

• Leak proof, pack-less self-draining convolutions

• Self-guiding

• Maintenance free