The in-place tensioning washer apparatus mounts about a stud to be tensioned. The apparatus has an upper portion, a lower portion, and an expanding torus positioned therebetween. With the stud threaded into the workpiece, the washer is slid onto the stud and a nut is threaded hand tight onto the stud. Pressurization of the torus then forces the upper portion of the apparatus away from the lower portion, putting the stud in tension. Shims are inserted into the gap between the upper and lower portions caused by pressurization of the torus. The torus is then depressurized and the shims maintain the gap between the upper and lower portions, thereby maintaining the stud in tension. To relax the stress in the stud, the torus is repressurized to force the upper and lower portions of the washer apart, freeing the shims for removal. Depressurization of the torus then relaxes the stress in the stud.