Abstract: Method for assembling a rack portion (1) of a self-raising oil rig, which rack portion (1) is constituted by at least one rectangular plate (3) which comprises teeth (51) at the longitudinal lateral faces (5) thereof, and at least one reinforcement (8) which is in the form of a half-shell and which is welded to a main face (6) of the at least one rectangular plate, along the longitudinal edges (11) of the at least one reinforcement, according to which an internal chamfer and an external chamfer which are separated by a projection of thickness T are produced at each of the longitudinal edges (11) of the at least one reinforcement (8), the at least one reinforcement (8) is provided at a main face (6) of the rectangular plate (3), at least one welding pass is carried out at the internal portion of each of the longitudinal edges (11) of the at least one reinforcement in order to produce an internal weld bead having a connection radius R greater than or equal to 4 mm, and the chamfers are filled at the external po