is interposed between metallic seal rings having lips the elastomeric ring is thicker than the metal rings the lips are of specific configuration and the seat is supported to permit downward movement of the upper seal ring after compression setting application_number US 41927082 A description inner casing hanger body 10 carrying a string of casing has been supported from intermediate casing hanger body 12 typical arrangements are shown in u s pat nos 3 492 026 and 3 797 864 it is desired to pack off the annular space 14 to prevent high pressure from the bore 16 reaching and pressurizing the annular space between the casing strings it is desired to place seal 18 in the annular space 14 the seal comprises an upper metallic ring 20 an intermediate elastomeric seal ring 22 and a lower metallic seal ring 24 to this end a seal packing nut 26 is threadedly engaged with the hanger body 10 and may be rotated by a running tool not shown a slot 28 exists in the upper seal ring and a slot 30 exists in the packing nut a snap ring 32 fits within both slots so that the seal may be carried on the packing nut and lifted thereby for removal of the seal it is illustrated in this position in fig1 when the packing nut is rotated the seal meets resistance as it enters space 14 and the space above the teflon bearing 34 closes with compression force being placed on the seal assembly by shoulder.