A cap assembly for enclosing an end portion of a bolt fastener includes a first cap member which includes a bore and a surface positioned within the bore which defines first threads and the first cap member also includes an external surface which defines second threads. A second cap member includes a sidewall which defines a receptacle with an opening which provides access to an interior of the receptacle and the sidewall includes an interior surface which defines third threads compatibly configured to engage the second threads. The third threads are positioned along the interior surface of the receptacle extending along a length of the receptacle a first distance and the second threads are positioned along the external surface of the first cap member extending along a length of the external surface a second distance wherein the first distance is greater than the second distance.