Abstract: A closing system for pressurized pipes, includes an annular supporting structure, designed to be secured to one end of the pipe, a closing hatch mounted on the annular support, and elements for locking the hatch including a locking ring inserted into an annular cavity in the support to lock the hatch, wherein the inside edge of the hatch is tapered to form an inclined wall for coupling to a corresponding inclined wall in the annular support. The collapsible ring includes a number of sectors, one of which is fixed and integral with the hatch, while the others are hinged to the adjacent sectors, so that they can rotate on a plane parallel with the hatch until they exit from the annular seating and allow the hatch to open. The hatch is opened and closed simply by rotating it around a hinge.