The present invention relates to a control valve (1) for controlling a gas flow in a gas line (3) of an internal combustion engine, in particular in a motor vehicle, comprising a rotationally adjustable flap (4) for controlling a flow cross section (13), a throttling sealing gap (14) which, in a closed position of the flap (4), is formed radially between a sealing contour (15) of the flap (4) and a sealing face (16) which faces the flap (4), and a drive shaft (5), on which the flap (4) is arranged fixedly in terms of rotation. In order to simplify the adjustment of the throttling sealing gap (14), a line piece (2) is provided for installation in the gas line (3) axially between line ends (9), wherein the flap (4) controls the flow cross section (13) of the line piece (2), wherein the sealing face (16) is formed on the line piece (2), wherein the drive shaft (5) penetrates the line piece (2) and is mounted in two bearings (18), wherein two bearing shells (19) are provided which are arranged on the outside of the line piece (2) and in each case have one of the bearings (18).