Apparatus for gripping oilfield tubulars without causing damage to such tubulars

Abstract

An apparatus for gripping tubular members in a single or multi-string arrangement about their outer diameter without causing surface damage or structural deformation to the tubular members, so that they may be axially rotated or secured against axial rotation. A generally cylindrical internal sleeve is contained within a molded flexible liner. One side of the internal sleeve is releasably attached to the flexible liner, forming an annular bladder-like structure within the flexible liner. Introduction of pressure into the bladder-like structure causes the flexible liner to inflate radially inward causing the flexible liner and torque transmitting bushing to thereby grip the tubular work piece within the new improved friction grip. Movable anti-extrusion rings at the axial edges of the flexible liner prevent deformation of the liner into the annular space between the outer sleeve of the new improved friction grip and the tubular, and also prevent wear between the axial edges of the liner and the edges of the outer sleeve. An additional, non-rigid sleeve, or coating, of friction enhancing material may be placed on the inner face of the torque transmitting bushing to increase the frictional characteristics of the new improved friction grip and/or increase service life of the surface of the torque transmitting bushing. The new improved friction grip may be made of two, or more, hingedly connected sections, and has a small enough outside diameter to be mounted side-by-side with an identical second grip in a multi-pipe string arrangement without deflecting the pipe.

Dependencies are inferred from the claim text.