The invention relates to a sealing device (30) intended to be fixed against an edge of a tube and against a column. According to the invention, the body (3060) thereof comprises guides (3030), distributed around its cavity (316) between an inner side (3064) that opens into the cavity (316) and an outer side (3062) that opens out against a concentric clamping ring (305), mounted so as to rotate about the axis (A), fingers (303) integral with outer actuating members (3031) being guided in the guides (3030), the ring (305) having actuating zones (3051) that are able to be positioned against the members (3031) so as make the fingers (303) protrude into the cavity (316) by sliding in order to clamp the fingers (303) against the edge of the tube when the ring (305) and the base (306) are in a first position of relative rotation, the ring (305) and the base (306) being able to pass, by rotation about the axis (A), between the first position and a second position in which the zones (3051) are spaced apart from the members (3031) so as to allow the fingers (303) to be returned into the body (3060).