A single Bellow Expansion with peculiar arrangement of pins and plates becomes Hinged Bellow Expansion. Such Bellows takes only angular movement in one direction with support of pins. Hinge plates and pins should be designed by manufacturer in the way that they should withstand thrust force of Bellow Expansion due to internal pressure and forces.
The angular compensation of thermal expansion requires at least two, and for full compensation even three, angular expansion joints. Angular expansion joints offer a wide variety of combination options in so-called two-hinge or three-hinge systems.
Single-plane three-hinged systems make do with one-sided angularly flexible expansion joints, while multi-plane three-hinged systems for absorbing thermal expansion in three axial directions require at least two gimbal expansion joints that are angularly flexible on all sides. The following basic rules apply to angular compensation: