Dual member pipe joint for a dual member drill string

A system of pipe joints comprising:

• a plurality of pipe joints, each pipe joint comprising:
• an elongate, hollow outer member having an inner surface and an outer surface and having a pin end and a box end, wherein the pin end and the box end are correspondingly threaded;
• and
• an elongate inner member having a geometrically-shaped pin end and a box end forming a geometrically-shaped recess corresponding to the shape of the pin end of the inner member, the pin end being slideably receivable in connector-free, torque-transmitting engagement with the box end of a similarly formed inner member;
• wherein the inner member is arranged generally coaxially within the outer member forming an annular space between the inner member and the inner surface of the outer member;
• wherein the pin end of the inner member of each pipe joint is connectable to the box end of the inner member of another one of the plurality of pipe joints;
• and
• wherein the pin end of the outer member of each pipe joint is connectable to the box end of the outer member of another one of the plurality of pipe joints so that the outer members of the plurality of pipe joints, when connected, form a passageway extending the length of the system of pipe joints.

A horizontal boring machine comprising:

• a frame;
• a rotary machine supported on the frame;
• a drill string having a first end and a second end, the first end being operatively connectable to the rotary machine to drive the rotation of the drill string, the drill string comprising:
• a plurality of pipe joints, each pipe joint comprising:
• an elongate, hollow outer member having an inner surface and an outer surface and having a pin end and a box end, wherein the pin end and the box end are correspondingly threaded;
• and
• an elongate inner member having a geometrically-shaped pin end and a box end forming a geometrically-shaped recess corresponding to the shape of the pin end of the inner member, the pin end being slideably receivable in connector-free, torque-transmitting engagement with the box end of a similarly formed inner member;
• wherein the inner member is arranged generally coaxially within the outer member forming an annular space between the inner member and the inner surface of the outer member;
• wherein the pin end of the inner member of each pipe joint is connectable to the box end of the inner member of another one of the plurality of pipe joints;
• and
• wherein the pin end of the outer member of each pipe joint is connectable to the box end of the outer member of another one of the plurality of pipe joints so that the outer members of the plurality of pipe joints, when connected, form a passageway extending the length of the system of pipe joints;
• and
• a directional boring head attached to the second end of the drill string.

A horizontal boring machine, comprising:

• a frame;
• a drill string having a first end and a second end, the drill string comprising
• a plurality of pipe joints, each pipe joint comprising:
• an elongate, hollow outer member having an inner surface and an outer surface and having a pin end and a box end, wherein the pin end and the box end are correspondingly threaded;
• and
• an elongate inner member having a geometrically-shaped pin end and a box end forming a geometrically-shaped recess corresponding to the shape of the pin end of the inner member, the pin end being slideably receivable in connector-free torque-transmitting engagement with the box end of a similarly formed inner member;
• wherein the inner member is arranged generally coaxially within the outer member forming an annular space between the inner member and the inner surface of the outer member;
• wherein the pin end of the inner member of each pipe joint is connectable to the box end of the inner member of another one of the plurality of pipe joints;
• and
• wherein the pin end of the outer member of each pipe joint is connectable to the box end of the outer member of another one of the plurality of pipe joints so that the outer members of the plurality of pipe joints, when connected, form a passageway extending the length of the system of pipe joints;
• a directional boring head attached to the second end of the drill string;
• and
• a rotary machine supported on the frame, the rotary machine being operatively connectable to the first end of the drill string for driving the rotation of the drill string, the rotary machine comprising:
• a carriage assembly supported on the frame;
• an inner member drive group for driving the plurality of inner members comprising the drill string, the inner member drive group being supported on the carriage assembly and comprising an inner member drive motor, an inner spindle and a torque-transmitting member for transmitting torque from the inner member drive motor to the inner spindle;
• wherein the inner spindle is connectable to the inner member at the first end of the drill string;
• an outer member drive group for driving the plurality of outer members comprising the drill string, the outer member drive group being supported on the carriage assembly and comprising an outer member drive motor, an outer spindle and a torque-transmitting member for transmitting torque from the outer member drive motor to the outer spindle, wherein the outer spindle is connectable to the outer member at the first end of the drill string;
• and
• a biasing assembly supported on the carriage and adapted to urge substantially simultaneous, slideable, connector-free, torque-transmitting engagement of the inner member of a pipe joint loaded on the boring machine with the rotary machine and the inner member at the first end of the drill string.

A method for making directional boreholes using a boring machine having a rotary machine capable of simultaneously rotating and axially advancing a directional boring head attached to a drill string comprising a plurality of connectable pipe joints, each pipe joint having an inner member disposed generally coaxially within an outer member, each outer member being connectable to another one of the outer members comprising the plurality of pipe joints and each inner member being slideably receivable in connector-free, torque-transmitting engagement with the rotary machine and with another one of the inner members comprising the plurality of pipe joints, the method comprising the steps of:

• making one connection per additional pipe joint loaded on the boring machine for connection with the drill string by simultaneously axially advancing the rotary machine and transmitting torque from the rotary machine to the additional pipe joint, whereby the outer member of the additional pipe joint substantially simultaneously connects with the rotary machine and with the outer member at the first end of the drill string while the inner member of the additional pipe joint substantially simultaneously, slideably, nonrotatably connects in connector-free torque-transmitting engagement with the rotary machine and with the inner member at the end of the drill string;
• and
• axially advancing and rotating the directional boring head to make a borehole.

A horizontal boring machine, comprising:

• a drill string having a first end and a second end, the drill string comprising a plurality of pipe joints, each pipe joint comprising:
• an elongate, hollow outer member having an inner surface and an outer surface and having a pin end and a box end, wherein the pin end and the box end are correspondingly threaded;
• and
• an elongate inner member having a geometrically-shaped pin end and a box end forming a geometrically-shaped recess corresponding to the shape of the pin end of the inner member, the pin end being slideably receivable in connector-free, torque-transmitting engagement with the box end of a similarly formed inner member;
• wherein the inner member is arranged generally coaxially within the outer member forming an annular space between the inner member and the inner surface of the outer member;
• wherein the pin end of the inner member of each pipe joint is connectable to the box end of the inner member of another one of the plurality of pipe joints;
• and
• wherein the pin end of the outer member of each pipe joint is connectable to the box end of the outer member of another one of the plurality of pipe joints so that the outer members of the plurality of pipe joints, when connected, form a passageway extending the length of the system of pipe joints.