At the forge: choosing tools

Soundproof lining for a gas pipe, in particular for a turbojet fan jet, of the type including a multiplicity of thin, perforated panels juxtaposed by tiling, as well as an intermediate layer between the wall of the pipe and each of said panels to delimit with said perforated panel a multiplicity of resonant acoustical cavities in which the acoustical vents consist of the ports in the perforated panel. According to the invention, in order to make the tubular vents, each perforated panel has a short, tubular sleeve at right angles to each port and located on its face opposite the wall of the pipe.