Connection elements for interconnecting two duct ends, the elements comprising a tubular connection member for uniting the duct ends, the tubular member comprising at least one pair of half-bodies which is arranged so as to be closed on at least one duct end and which is associated with elements for gripping the duct end when the pair of half-bodies is closed on the duct end, the gripping elements comprising at least one outwardly-directed projection formed by plastic deformation of the duct end in a position set back from an end face of the duct end, and two inner shoulders of at least one of the half-bodies, which shoulders are spaced apart axially so as to receive therebetween the outwardly-directed projection.