Abstract: A method for building a dual-member drill string comprising an inner drill string and an outer drill string. Inner pipe sections are connected using non-threaded connections, while outer pipe sections are connected using threaded connections. A new inner pipe section is rotated in a first direction until the inner pipe section applies torque to the existing inner pipe string. If the magnitude of the torque applied to the inner pipe string exceeds a pre-determined threshold value, the inner pipe section is automatically rotated in an opposite second direction. The inner pipe section rotates between opposite directions, once torque is sensed in each direction, until the inner pipe section is coupled to the inner pipe string.

Abstract: An insert for installation on an inner pipe member of a dual-pipe member assembly. The insert is interposed between an external shoulder formed on the inner pipe member and an internal shoulder formed in an outer pipe member. Shoulder-to-shoulder impacts between pipe members results in wear to the insert, rather than to either pipe member. The insert has the shape of an unclosed loop and is positioned within an endless external groove formed in the inner pipe member.

Abstract: A dual member drill string having a plurality of dual member drill string sections for use in horizontal directional drilling operations. Each drill string section having an outer member and an inner member that is rotatable independently of the outer member. The outer member has a pin end and a box end. The inner member has a pin end disposed within the pin end of the outer member and a box end disposed within the box end of the outer member.

Abstract: A retention system for attaching a collar to a pipe. The collar has an internally-disposed groove configured for placement of a ring. The ring is sized such that in one orientation, it can enter the collar between torque-transmitting features into the internally-disposed groove. Once in the groove, the ring may be adjusted such that its aperture is generally aligned with the axis of the collar. In this orientation, the features retain the ring within the groove. A bolt and a pipe may then be placed within the collar from opposite sides. The bolt is attached to the pipe through the ring. Once joined, the collar is joined to the pipe, forming its box end. Such a retention system may be used to join a series of inner pipe members of a dual-member pipe assembly, as in horizontal directional drilling.

Abstract: A pipe assembly used in horizontal directional drilling operations. The pipe assembly has an outer member, an inner member, and first removable collar. The inner member has a polygonal outer profile of uniform shape along its length and is partially contained within the outer member. The first removable collar is supported on the inner member within the outer member and limits relative axial movement of the inner member and the outer member.

Abstract: An apparatus and method for preventing drill string drag. Rotation encoders are provided for tracking the rotation of an inner and outer member of a dual-member drill string. Based upon the drilling conditions, the readings of the encoder can detect when the inner member is dragging on the outer member. When such a drag condition is detected, a processor can trigger remedial measures, which may include increasing a rotation rate of the inner member, sending a warning signal, stopping operation, or a combination of these.

Abstract: A spindle assembly for connecting a drill string to a rotational drive for use in a horizontal directional drilling operation. The assembly comprises a saver sub attached to the rotational drive, and a drive chuck for connection to the drill string. The drive chuck and saver sub form a torque-transmitting connection by engaging through a seat in the saver sub and an engagement point on the drive chuck. Dowel pins may be used to rotationally lock and provide the engagement between the saver sub and the drive chuck. A collar may thread to the saver sub and cause an interference fit by engaging the drive chuck at a shoulder.

Abstract: An angular offset tool for directionally drilling an underground borehole is formed from a collar, a housing, and a wedge. The collar and the housing are joined by a ball-and-socket connection. An internal wedge is situated between the collar and the housing within the ball-and-socket connection such that the collar and housing are joined at a non-straight angle. At least one of the collar and the housing has a recess formed in an element of the ball-and-socket connection. The wedge is situated in the recess in contacting relationship with the collar and the housing. The wedge and the housing have interlocking features that prevent rotation of the wedge within the recess.

Abstract: An assembly for a torque-transmitting connection in an inner pipe string of a dual-member drill string is formed from a collar, a retaining ring, and an inner pipe member. An endless internal groove having adjacent shallow and deep sections is formed in the collar. Formed in the inner pipe member, an external grooved region is situated in adjacent relationship with the internal groove. The retaining ring, situated within the grooves, resists disconnection of the collar from the inner pipe member. When the assembly is subjected to an axial force that might otherwise tend to pull it apart, the retaining ring resists the tendency by wedging between the bottom of the shallow section of the internal groove and the crest of the external groove.

Abstract: A system for connecting a drill bit and pipe puller to a drill string. The system includes a downhole tool having an internal cavity and a through-hole in its wall. A coupler may be slidingly received in the cavity and connected using one or more fasteners which interconnect a groove in the coupler to the wall of the downhole tool. Fasteners used may be screws or bolts interconnecting the wall of the tool with radial holes in the coupler. Alternatively, bolts may interconnect the wall with a circumferential groove on the coupler. A drill bit may be threaded into the coupler. The coupler allows drill bits and other tools to be connected and disconnected from a downhole tool without unthreading the drill bit.

Abstract: A stacked-plate system for a backreamer. The backreamer has a set of plates disposed about a central shaft for providing fluid for use in reaming operations. A distributor plate forms a cavity within a plate assembly for receiving fluid from the central shaft through radial fluid ports. Fluid from the cavity is then expelled through nozzles that overlay the cavity in a separate plate. The direction of fluid flow at the nozzles is axial, rather than toward the sidewall of the enlarged bore.

Abstract: An assembly for a torque-transmitting connection in an inner pipe string of a dual-member drill string is formed from a collar, a retaining ring, and an inner pipe member. An endless internal groove having adjacent shallow and deep sections is formed in the collar. Formed in the inner pipe member, an external grooved region is situated in adjacent relationship with the internal groove. The retaining ring, situated within the grooves, resists disconnection of the collar from the inner pipe member. When the assembly is subjected to an axial force that might otherwise tend to pull it apart, the retaining ring resists the tendency by wedging between the bottom of the shallow section of the internal groove and the crest of the external groove.

Abstract: An assembly for a torque-transmitting connection in an inner pipe string of a dual-member drill string is formed from a collar, a retaining ring, and an inner pipe member. An endless internal groove having adjacent shallow and deep sections is formed in the collar. Formed in the inner pipe member, an endless external groove is situated in concentric relationship with the internal groove. The retaining ring, situated within the grooves, resists disconnection of the collar from the inner pipe member. When the assembly is subjected to an axial force that might otherwise tend to pull it apart, the retaining ring resists the tendency by wedging between the bottom of the shallow section of the internal groove and the crest of the external groove.

Abstract: A bearing assembly having independently rotatable concentric inner and outer tubes. A bearing chamber containing multiple bearings is disposed between the tubes, allowing thrust but not rotation to be transferred between them. The bearing chamber is sealed from the inside of the inner tube. To prevent high pressure fluid from leaking from the inner tube to an exterior of the tool through the bearing chamber, damaging components, a flow path is formed. An annular piston responds to high pressure within the bearing chamber and the inner tube, opening a flow path from the inner tube to the environment.

Abstract: A method for building a dual-member drill string comprising an inner drill string and an outer drill string. Inner pipe sections are connected using non-threaded connections, while outer pipe sections are connected using threaded connections. A new inner pipe section is rotated in a first direction until the inner pipe section applies torque to the existing inner pipe string. If the magnitude of the torque applied to the inner pipe string exceeds a pre-determined threshold value, the inner pipe section is automatically rotated in an opposite second direction. The inner pipe section rotates between opposite directions, once torque is sensed in each direction, until the inner pipe section is coupled to the inner pipe string.

Abstract: A pipe assembly used in horizontal directional drilling operations. The pipe assembly has an outer member, an inner member, and first removable collar. The inner member has a polygonal outer profile of uniform shape along its length and is partially contained within the outer member. The first removable collar is supported on the inner member within the outer member and limits relative axial movement of the inner member and the outer member.

Abstract: A dual member drill string having a plurality of dual member drill string sections for use in horizontal directional drilling operations. Each drill string section having an outer member and an inner member that is rotatable independently of the outer member. The outer member has a pin end and a box end. The inner member has a pin end disposed within the pin end of the outer member and a box end disposed within the box end of the outer member.

Abstract: A pipe assembly used in horizontal directional drilling operations. The pipe assembly has an outer member, an inner member, and first removable collar. The inner member has a polygonal outer profile of uniform shape along its length and is partially contained within the outer member. The first removable collar is supported on the inner member within the outer member and limits relative axial movement of the inner member and the outer member.

Abstract: An insert for installation on an inner pipe member of a dual-pipe member assembly. The insert is interposed between an external shoulder formed on the inner pipe member and an internal shoulder formed in an outer pipe member. Shoulder-to-shoulder impacts between pipe members results in wear to the insert, rather than to either pipe member. The insert has the shape of an unclosed loop and is positioned within an endless external groove formed in the inner pipe member.

Abstract: A dual member drill string that has a plurality of dual member drill string sections, The drill string may be used in horizontal directional drilling operations. Each drill string section has an outer member and an inner member that may rotate independently of the outer member. The outer member has a pin end and a box end. The inner member has a pin end disposed within the pin end of the outer member and a box end disposed within the box end of the outer member.