Importance

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Abstract

Apparatus for coupling multi-conduit drill pipes to maintain arcuate registry between connected pipes, and for transferring the drive torque of one drill pipe to the next drill pipe. One end of one drill pipe (50) includes drive lugs (100) matable with corresponding drive recesses (102) in the end of the next drill pipe (52). An index lug (104) in the drill pipe end, different that the drive lugs (100), is matable with a corresponding index recess (106) in another pipe end ot maintain arcuate registry of the coupled pipes and thus longitudinal alignment of the respective conduits (30) throughout the drill string. An internally threaded coupling collar (84) with different thread pitches at each end thereof is threadable onto the joined lug and recess mated drill pipe ends to hold the pipes mated. The joined pipe ends respectively include external threads (88, 90) of pitches corresponding to that of the coupling collar (84) so that a differential thread action draws the pipes together. A seal (86) is provided between the pipe ends so that when compressed by rotation of the coupling collar (84) each conduit (30, 62) is sealed from adjacent conduits.

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First Claim