Abstract: A linear turn down valve structure is disclosed, for gaseous fuels. The valve structure can advantageously be produced with aluminum alloys of die-casting grade, by means of a squeeze die-casting process. The valve structure comprises a valve body and a cap having register members to provide a self positioning and assembly of the main components of the valve. This eliminates the possibility of radial and axial misalignment thereof and secures a gas tight connection; a valve plug having passages in cooperation with a cap cam having three steps, to allow the safe switching of the continuous gas flow from maximum to minimum flow positions, as well as a safe turn-off position in a single operation; and a minimum flow control device to allow flow metering in order to permit the burners to operate with a wide variety of commercial gaseous fuels.