Pantograph linkages

Pantograph linkages are scissors-like mechanical devices integrated into Universal Expansion Joints, specifically engineered for demanding applications such as FCCU (Fluid Catalytic Cracking Unit) systems.

Their primary function is to positively and uniformly distribute axial movement between the two bellows of a Universal Expansion Joint throughout its full range of motion. This ensures synchronized movement, prevents over-extension, and enhances the reliability and service life of the joint under high-temperature and high-pressure FCCU conditions.

Note: Pantograph linkages are not designed to absorb or restrain pressure thrust. Suitable external anchors and guides must be used to control pressure-induced forces within the piping system.

In universal expansion joints, slotted hinges ensure equal axial movement absorption by both bellows. When installed horizontally, they also support the weight of the connecting pipe including refractory and medium load.

A pantograph central bar, always used in combination with a pantograph linkage, performs the same function as slotted hinges. In vertical or inclined installations, it additionally supports a component of the pipe’s weight between the bellows.

Central Gimbal

When a pantograph linkage is used and out-of-plane lateral movement exceeds 10 mm, a central gimbal system must be included.

The gimbal allows for controlled large lateral movements out of plane, while also supporting the weight of the connecting pipe, including refractory and medium load.