The lockdown mechanism (10) and running tool (50) are provided for securing the casing hanger (12, 13) within the wellhead (14) and sealing the annulus between the casing and the wellhead. The lockdown ring (20) fixes the lockdown sleeve (40) to a wellhead in response to a lockdown piston (22). A first seal (24) energized by the running tool seals between the lockdown sleeve and the wellhead. Ball seat (30) is axially movable within the running tool, and a second seal also energized by the running tool (32) seals between the lockdown sleeve and the casing hanger.
