A non-frustoconical coupling provides a mechanical connection used in fluid transport for hydrocarbon recovery operations.

Aspects of the disclosure describe a non-frustoconical coupling used in connections for tubulars in hydrocarbon recovery operations.

This invention builds up on technical features and on the industry experience with the use of Merlin™ family connectors. In addition to friction, structural means utilized to transfer high torsional loads include shear pins and may also include: interlocked thread systems, dog-clutch teeth, keys and splines, all used in isolation or in arbitrary combinations. Static and fatigue bending load capacities of the connectors remain high, while the axial load capacities may or may not be high, depending on the design requirements. Connectors according to this invention can be built as new, carefully optimized designs. In some cases upgrading existing Merlin™ family connector designs to increase they torque transfer capacities may be also feasible.

A threaded connection for steel pipe is provided in which galling does not easily occur on any of the inner and outer threads. A threaded connection for steel pipe 1 includes a pin 10 and a box 20. The pin 10 includes: a nose 12; a tapered inner male thread 14; a tapered outer male thread 17; a pin inner sealing surface 13; a pin intermediate shoulder surface 18; and a pin intermediate sealing surface 16. The box 20 includes: a tapered inner female thread 24; a tapered outer female thread 27; a box inner sealing surface 23; a box intermediate shoulder surface 28; and a box intermediate sealing surface 26. Each of the inner male thread 14, outer male thread 17, inner female thread 24 and outer female thread 27 includes a perfect thread portion 141, 171, 241, 271. Each perfect thread portion includes an inner end located relatively close to the tip of the pin 10 and an outer end located relatively close to the end of the pin 10 opposite to its tip. The threaded connection for steel pipe 1 satisfies the following Expressions (1) and (2):

x.sub.1+L.sub.1<X.sub.2  (1), and

u.sub.1+L.sub.2<U.sub.2  (2).

A threaded tubular connection for drilling or operating hydrocarbon wells comprising a longitudinal axis, a metal pin member having a tapered two-step wedge pin thread with dovetail wedge threads and a pin sealing surface located between the small and large diameter pin thread steps, and a metal box member having a tapered two-step wedge box thread with dovetail wedge threads and a box sealing surface located between the small and large diameter box thread steps, wherein the tubular connection is free from any final make-up stop shoulder defining a final make-up position for the pin member relative to the box member, the small diameter wedge thread set and the large diameter wedge thread set are dimensioned to have a first axial clearance and a second axial clearance.

A system for blocking rotation between a first tubular and a second tubular includes a key positioned within a recess formed in the first tubular. The system also includes a retention fastener securing the key to the first tubular, the retention fastener being arranged within an elongated aperture extending through the key. The system further includes an installation fastener moving the key from a storage configuration when in a first position to an engaged configuration when in a second position, the installation fastener having a tapered face that engages at least a portion of the key. The system also includes teeth arranged along a bottom portion of the key, proximate the second tubular, the teeth engaging the second tubular via rotation of the key about the retention fastener and blocking rotation of the first tubular relative to the second tubular in a first direction.

A mechanical connector, including a telescopically assembled, Merlin™ Family Connector is provided with one or more sets of threads on substantially matching frustoconical surfaces of a pin and a box of the connector. Strengthening means are introduced involving at least one of: a mechanical stiffening arrangement on an outside surface of the box or a mechanical stiffening arrangement on an inside surface of the pin. The strengthening means provided may involve systems of arbitrarily oriented ribs and/or fairing surfaces. The mechanical stiffening arrangements may be integral with the box or the pin, or they can be separate external/internal strengthening arrangements, as applicable. They can be also essentially annular clamps that would have relatively regular shapes essentially conforming to the external or internal surfaces of the box or the pin, respectively. The above modifications can be introduced to traditional connectors and to connectors designed to transfer high torsional loads.

A Merlin™ family mechanical connector provided with a thread on substantially matching frustoconical surfaces extending between two sets of nipple seals utilize assembly/disassembly fluids that solidify after the assembly and are brought to liquid state before the disassembly. They include resins or tar-like non-metals and liquid metals solidifying in single phases as well as in multiple phases like for example binary, ternary etc. eutectics. That improves already very good leak resistance of Merlin™ family connectors and benefits good heat transfer between pins and boxes. Thread angle mismatching between box and pin threads can be introduced in order to improve loading. The above modifications can be introduced to traditional connectors featuring torsional load capacities limited to frictional resistance and to connectors designed to transfer high torsional loads.

In a threaded connection for pipe having a two-step thread construction with intermediate shoulder surfaces, compression resistance is further improved. Upon completion of make-up of the pin 2 and box 3, the diameter of a stabbing clearance is 0.15 mm or smaller, where the stabbing clearance is defined between the stab flank of a male thread including an inner thread portion 27 and an outer thread portion 23 and the stab flank of a female thread including an inner thread portion 36 and an outer thread portion 32, thereby causing the stab flanks of the male and female threads to start to be in contact before the angle of rotation θ of the intermediate shoulder surfaces 25 and 34 as appearing in a longitudinal cross section starts to rapidly increase, thus preventing accumulation of damage in the intermediate shoulder surfaces 25 and 34.

There is provided a pipe thread protector having first and second ends, threading extending from the first end towards the second end thereof, and a bore extending from the first end to the second end thereof. A seal couples to the first end of the pipe thread protector and is tubular. The seal tapers in a direction extending from a proximal end thereof towards a distal end thereof, and tapers in a direction extending from an outer surface thereof to an inner surface thereof. There is additionally provided a pipe thread protector assembly including a pipe thread protector, a coupling via which the pipe thread protector and a male threaded end of a pipe threadably couple together, and a seal coupled to an inner end of the pipe thread protector. The seal is shaped to protect and extend along an outer end surface of the pipe.