Abstract: The cap is an ethylene-propylene elastomer cup which is forced over the ends of a pipe section to protect the pipe end from damage and to protect the inside of the pipe from contamination by foreign material. A retaining bead on the outside of the cap lip prevents tearing and holds the cap firmly on the pipe end. The cap wall is about twice as thick as the floor. The outer perimeter portion of the floor is of increased thickness. One or two ring-shaped depressions centered in the floor permit the floor to be expanded radially when the cap is installed, so that a single cap size can be used for various pipe diameters. A ventilating port is provided in the floor.