The invention relates to a valve provided with a housing which is to be arranged in a pipe and which has arranged therein a channel and a valve body which is movable between a position opening and closing the channel. In the closing position the valve body co-acts with a seat arranged in the housing, which seat is arranged in the housing by means of a clamping connection and is thereby simple to release for maintenance purposes. The seat and the housing can herein be conical. For clamping of the seat in the housing or release thereof from the housing the valve is further provided with movable ejecting elements and clamping elements which can be formed in each case by a double-action jack.