Sheets, and more in general, the stratifications provided by Jordan classes in a Lie algebra or in an algebraic group have been proven to be related to various problems in representation theory, e.g. representation theory of finite groups of Lie type through character sheaves, the orbit method. In a semisimple Lie algebra, a complete list of semisimple Jordan classes such that the closure of their image through the Steinberg map is normal, is to be found in the works of Richardson, Broer, Douglass-Rohrle. In an ongoing joint work with Giovanna Carnovale, we solve the analogous problem in the case of a semi simple simply connected group.