lower seal member 36 with respect to the energizing ring member 37 until a predetermined amount of force is applied between the lower seal member 36 and the energizing ring member 37 until a predetermined amount of force is applied between the lower seal member 36 and the energizing ring member 37 as will be hereinafter described in greater detail similarly as previously described at least one shear pin not shown may be utilized in lieu of second shear ring 111 to serve as the means for initially restraining movement 116 of the lower seal member 36 with respect to the energizing ring member 37 with reference to fig5 9 a method of the present invention for sealing an annulus 21 between a tubing hanger 29 and a wellhead housing 31 will be described after seal assembly 20 has been assembled as illustrated in fig2 and after the casing or tubing hanger 29 has been landed in wellhead housing 31 as illustrated in fig1 the seal assembly 20 is run through the blowout preventer stack while attached to a installation tool not shown the installation tool may be of conventional construction and have a plurality of projections not shown for engagement with a plurality of mating openings 120 disposed along the periphery of actuation sleeve member 39 so as to permit actuation sleeve member 39 to be rotated as will be hereinafter described seal assembly 20 may be preferably passed through the blowout preventer stack on one or more joints of drill pipe not shown as seal assembly 20 reaches tubing hanger 29 seal assembly 20 slides over the top of the tubing hanger 29 until threads 72 on actuation sleeve member 39.