A joint is disclosed having a structure, a fastener passing through the structure with an end of the fastener protruding from the structure, and a cap installed on the end of the fastener. The end of the fastener includes an axially extending shaft, a fastener head carried by the shaft, and one or more washers located between the fastener head and the structure, the one or more washers spacing the fastener head and the structure apart by a distance. The cap has a cap body with a cavity which encloses the end of the fastener, and the joint further comprises a cured sealing material which seals the cavity. One of the fastener head and the cap body is formed with two or more first locking features which are axially spaced apart by a pitch.