Sunil,
If your piping is in X direction, in plane lateral movement is DY and out of plane lateral movement is DZ.
Typically for expansion joints, the bending ( in plane and out of plane) as well as the lateral displacements( in plane and out of plane) along with the displacement are coverted into a 'TOTAL AXIAL DISPLACEMENT" and checked against the allowables for specified no. of cycles.
Hope this helps.
Regards
_________________________
anindya