We investigate the QCD flux tubes linking static colour charges of different SU(3) representations, relevant to the understanding of confinement and of the Lund strings of Heavy Ion Collisions. The colour field densities, the Casimir scaling factors and the widths for the flux tubes of the first five different representations are computed in quenched SU(3) Lattice QCD. This study is relevant to understand the mechanisms of confinement and also the flux tubes utilized in the Lund Model and in other models of Heavy Ion Collisions.