A coupling for connecting downhole tubulars includes a tubular body, and at least one thread of a male screw thread formed on an outer surface of the body, and a female screw thread formed in an inner surface of the body. The at least one thread has a thread-form including a crest, a root, and a pair of flanks. The crest and the root are each cambered about a respective first and second camber radius. Each camber radius is greater than an outer diameter of the coupling.

A threaded tubular connection includes a box member having a female external thread, a female internal thread, and a female intermediate sealing surface between the female external thread and the female internal thread, and a pin member having a corresponding male external thread, a male internal thread, and a male intermediate sealing surface, such that male threads interlock by thread engagement with female threads, and intermediate sealing surfaces form an intermediate metal-to-metal seal when the threaded tubular connection is made up. The box member includes a minimal outer diameter at the intermediate metal-to-metal seal location, the minimal outer diameter being smaller than respectively an external and an internal outer diameter respectively being located above the female external thread and the female internal thread.

A coupling for joining a downhole pump to a sucker rod string is disclosed. The coupling includes a core having a first end, a central portion, and a second end. The first end and the second end each have an end surface. The first end tapers linearly inwards from the central portion to the first end surface. The second end has a rounded edge along the second end surface. The coupling is made from a spinodally-hardened copper-nickel-tin alloy and has a sliding coefficient of friction of less than 0.4 when measured against carbon steel.

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.

A connection for use in percussion drilling includes a male coupling and a female coupling. Each coupling includes a body and a respective screw thread formed on a respective inner or outer surface of the respective body. Each thread has a thread-form including a crest, a root, a contact flank and a non-contact flank. Each thread-form has a contact flank angle and a non-contact flank angle inclined relative to a respective baseline located at a respective minor or major diameter thereof. Each non-contact flank angle is greater than the respective contact flank angle. The crest of each thread-form is inclined from the respective contact flank to the respective non-contact flank such that an apex of the respective thread-form defining a respective minor or major diameter thereof is located adjacent to the respective non-contact flank.

A telescopic drill rod (2) has at least two rod members (20, 30} disposed coaxially to one another, with the inner rod member (30) being axially slidable relative to the cater rod member (20) in a telescoping mariner between an extended position and a retracted position. Both the inner rod member (30) and outer rod member (20) are equipped with joints at each end for connection, to a drill head and/or another section of drill pipe. The joints also lock the inner and outer rod members in either the extended of retracted positions, and this is accomplished with a unique frusto-conical threaded engagement that is well-suited for transmitting pressure forces.

A coupling for joining a downhole pump to a sucker rod string is disclosed. The coupling includes a core having a first end, a central portion, and a second end. The first end and the second end each have an end surface. The first end tapers linearly inwards from the central portion to the first end surface. The second end has a rounded edge along the second end surface. The coupling is made from a spinodally-hardened copper-nickel-tin alloy and has a sliding coefficient of friction of less than 0.4 when measured against carbon steel.

The present invention relates to a drill rod (2) for a fluid-operated apparatus, particularly a percussion drill tool (1). The drill rod (2) comprises a first connection interface (100) at a first end (101) and a second connection interface (102) at a second end (103). The first connection interface (100) is for connection of the drill rod (2) to a second connection interface (102) of a like drill rod (3) or to the apparatus (1). The second connection interface (102) is for connection of the drill rod (2) to a first connection interface of a like drill rod (3) or to a fluid transfer device. The drill rod also comprises a plurality of discrete fluid flow channels (4, 6, 8) through the drill rod, a first member (23) moveably mounted in the first connection interface (100) and a second member (22) moveably mounted in the second connection interface. The first moveable member is the innermost component in the first connection interface and the second moveable member is the innermost component in the second connection interface. When the drill rod (2) is connected to a like drill rod (3) or to the apparatus (1) or to the fluid transfer device, at least two of the fluid flow channels (4, 6) are placed in fluid communication with corresponding channels (4, 6) of the like drill rod or the apparatus or the fluid transfer device by movement of the first (23) and second (22) moveable members only.

Disclosed is a tool joint connection comprising a pin having a body and a helically extending external pin thread and box having a body and a helically extending internal box thread. The external pin thread and internal box thread are configured for connection with each other such that when connected the pin body and the box body are aligned longitudinally. The box thread has a box base in contact with the box body and the pin thread having a pin base in contact with the pin body and the pin base is wider than said box base. In a preferred embodiment, the area wherein the box base is in contact with the box body defines the box contact area and the area wherein the pin base is in contact with the pin body defines the pin contact area and the pin contact area and said box contact area are generally the same.

A side entry sub has an elongated main body with a longitudinal bore and a side passage intersecting the longitudinal bore. A removable hub has a nose portion which threadably engages mating threads in the side passage, with a resilient seal on the nose portion providing a fluid seal with the main body. The threads are formed such that a flange on the hub advances into contact with the main body with a desired contact force as holes in the flange come into alignment with threaded holes in the main body. Threaded flange bolts through the flange holes engage the threaded holes in the main body. Locking washers, preferably NORD-LOCK brand locking washers, are used on the flange bolts. The removable hub is structurally connected to the main body by the threaded connection and contact of the flange with the main body, and pressure- and fluid-sealed by the resilient seal.