Abstract: The present invention concerns a lance composed of a top lance (1t) and of a sublance (2) coupled to the top lance (1t), which forms a shoulder (1s) between the top lance and the sublance. The sublance (2) of the present invention is provided with a protective device (3) comprising a coupling end (2c) opening to the cavity (2v), wherein, when at rest, the protective device (3) is in an initial configuration characterized by an outer maximum diameter (D3o) which is not more than 10% larger than the diameter (D2) of sublance (2) (D3o?1.1 D2), when the sublance (2) is coupled to the lance the protective device (3) contacts the shoulder (1s) and is deformed into a deformed configuration, forming a surface impervious to molten metal and slag, which spans over a whole area of the shoulder (1s).