First instance, it should be defined that a simple cardanic expansion joint has the capacity to absorb an angular movement in two planes as shown in the graphs. The structure of the joint limits the bellows to have any axial or lateral movement and contains the pressure reaction force, a force generated by the bellows when they are pressurized.
The cardan joints must work in pairs, in this way they can absorb thermal expansion movements in two planes, guaranteeing a low stress system and freeing sensitive rotating equipment nozzles, such as pumps, compressors, fans or turbines from excessive stresses. We are able to supply this type of seals for systems operating at pressures up to 450 PSI and maximum temperature of 400°C.
When two of these joints are joined by a structure, the assembly becomes a cardanic universal expansion joint; the principle and benefits are the same as working with two separate joints. Generally we speak of X,Y plane and Z,Y plane; the movement absorbed by the two joints together is a lateral movement. A typical case of this application is when a pipe line forms a zeta (Z) and the two end pipes are perpendicular to each other.