Spheroid joint

A spheroid joint (ball and socket) has a round convex head that articulates with a concave sm-face. This articulation has the greatest amount of motion, with freedom of motion in all three planes. An example of this type is the hip joint. 

A condylar Joint is a modified ball and socket, with partial flattening of both articular surfaces. This flattening limits the motions available as compared to a spheroid joint. An example of this is the metacarpal-phalangeal articulation. 

The ellipsoid Joint modifies the spheroid joint by a head shaped as an ellipsoid (football-shaped). It has greater motion than the condylar joint but less than the spheroid joint. An example of that is the radiocarpal articrrlatioa... 

Pipes made of ductile cast iron i.e. cast iron with spheroidal graphite according to DIN EN 1593 [22] are used extensively in communal and industrial waste water disposal systems. The technical terms of delivery DIN EN 598 [16] contain information on the material parameters, on their joints, as well as on the testing and quality control of pipes. Some material parameters are given in Table 6. 

The structure of the articular sitrfaces further classify joints into plane, spheroid, concfylar, ellipsoid, trochoid, sellar, wAginglymusioiris. 

Where the materials of interconnecting seawater piping and the mating surfaces of the heat exchanger are dissimilar, rubber-fined couplings will be required if galvanic corrosion would otherwise occur. This is particularly important in the case of titanium and Cu/Ni dissimilar metal joints. An alternative solution that may be considered is the use of sacrificial spool pieces of austenitic spheroidal graphitic cast iron between the titanium and Cu/Ni components. 

---