Abstract: A flange closure formed of a flange body having a cylindrical opening therethrough and having in the opening a concentric internal groove, a cylindrical closure plate for removably closing the opening in the flange body, the closure plate being removable and sealably positionable in the flange opening, a pair of cam plates each hingedly affixed to the closure plate, each of the cam plates having a peripheral edge portion configured as a segment of a circle substantially equal to the diameter of the flange internal groove, and a cam plate actuator removably attachable to said closure plate, the cam plate actuator engaging said cam plates, the actuator is rotated in one direction to forceably retract the cam plates so that the segmented circular edges are within the diameter of the closure plate and when the actuator is rotated in the other direction to extend the cam plates so that the semi-circular edges extend within the flange groove to retain the closure plate in position within the flange opening.