Abstract: A device for closing pipes, in particular conveyor pipelines for gas or fluid media, which device comprises an annular carrier extending transversely of the passage of the pipe for a number of plates supported pivotally relative to the side wall of the carrier, in addition to a control ring which is arranged coaxially of the annular carrier and which is in engagement with all plates, which control ring and carrier are rotatable relative to each other on the common central axis thereof such that the plates are movable from a first position, wherein the passage is left clear, to a second position wherein the passage is closed, and vice versa, wherein each plate takes a triangular form, wherein the pivot point with the carrier is arranged outside this triangle, which triangular plates together precisely close the passage.