A cap for an anchorage of a post-tension anchor system has an outer tubular portion having an inner wall and an outer wall, an inner tubular portion having an inner wall and an outer wall, an end wall extending between the outer tubular portion and the inner tubular portion, and a sheathing lock affixed to the inner wall of the inner tubular portion. The inner wall of the outer tubular portion is in spaced relation to the outer wall of the inner tubular portion. The outer tubular portion and the inner tubular portion are concentric with each other. The sheathing lock has a body having locking ribs extending radially inwardly therefrom. The locking ribs extend in parallel relationship to each other. The outer tubular portion and the inner tubular portion and the end wall are integrally formed of a polymeric material.