Patent ID: 7694730

Claim:
A casing gripping clamp for gripping a joint of casing of a casing string, comprising: a spear having an axis and an axial passage for delivering drilling fluid into a casing string, the spear adapted to extend into the bore of a casing joint to be gripped; grippers that are radially movable to engage and grip the casing joint to be gripped; a primary seal element about the spear to create a seal between the spear and the inner wall of the casing joint, the primary seal element being urged radially outward relative to the axis of the spear into sealing engagement with the inner wall of the casing joint in response to drilling fluid pressure differential in the casing string; and a secondary seal element about the spear above and axially spaced out of contact with the primary seal element, the secondary seal element being selectively operable to create a seal between the spear and the inner wall of the easing joint in the event the primary seal element fails.