Abstract: A pipe string component that connects an offshore platform with a sea bed is provided. The pipe string component includes a threaded tubular connection. The threaded tubular connection includes a male tubular element including a tapered male threading, and a female tubular element including a tapered female threading that cooperates with the male threading by makeup to produce a rigid mutual connection of the tubular elements with radial interference between radial load transfer zones of the threadings. The male and female threadings each have a load flank extending substantially perpendicularly to an axis of the male and female threadings. The radial load transfer zones are at a radial distance from envelopes of thread roots of the male and female threadings. The radial load transfer zones of the threadings comprise at least one surface substantially parallel to an axis of the connection.

Abstract: A tubular configured to mate with a second tubular so that sealing integrity is maintained between the tubulars before, during, and after expansion of the tubulars is disclosed. In one embodiment, a connector for connecting tubulars is provided. The connector includes a pin portion; a box portion, wherein the pin and the box portions are configured to mate; a sealing surface formed in an inner surface of the box portion; a seal disposed in a groove formed in an outer surface of the pin portion, wherein the seal is configured to engage with a sealing surface of the box portion upon mating of the pin and the box portions; and a bump formed on an inner surface of the pin portion, wherein the bump is substantially radially aligned with the groove and the bump is configured so that the seal remains engaged with the box portion during and after expansion of the pin and the box portions.

Abstract: A percussion adapter that is driven to generate a percussive axial motion on a wellbore structure. One percussion adapter includes a drive connection to mechanically convert rotational drive to axially directed percussive motion. Another percussion adapter employs a valve that creates back pressure causing axially directed percussive motion. A wellbore tubular connection is also disclosed that transitions torque to resist back off when left hand or right hand torque is applied.

Abstract: A male element for a sealed threaded tubular connection. Before tapered reduction swaging of an end region of a tube and machining in the region of a tapered male threading and a male lip to obtain a male tubular element for makeup into a female tubular element to form a sealed threaded tubular connection after diametrical expansion, the tube is shaped over a portion of its length to produce a cylindrical internal surface that connects via a chamfer to the cylindrical internal surface of the lip obtained subsequently by machining, the radius of the first surface being greater than the radius of the second surface.

Abstract: A threaded joint for steel pipes for use in an oil well which has enhanced galling resistance and which is protected from rusting comprises a pin and a box each having a contact surface including a threaded portion and an unthreaded metal contact portion. The contact surface of at least one of the pin and the box has a lower layer of a viscous liquid or semisolid lubricating coating comprising at least wax and a fatty acid alkaline earth metal salt and not containing a harmful heavy metal such as lead and an upper layer of a dry solid coating formed from an aqueous resin coating composition, an organic solvent type coating composition, or an ultraviolet curing coating composition.

Abstract: The invention relates to a connection system for double-walled pipes (1, 2) comprising an inner pipe (12, 22) made of a stainless steel and an outer pipe (11, 21) which surrounds the inner pipe (12, 22) and has a greater tensile strength than the inner pipe (12, 22), wherein threads (13, 23) are formed at the ends of the outer pipe (11, 21), and also comprising a screw-type sleeve (3) with internal threads (31, 32) which correspond in terms of design to the external threads (13, 23), and comprising a sealing ring (4) which is arranged in the sleeve (3), is formed from a stainless material and, in the screwed-on state, seals the sleeve (3) with respect to the medium transported through the inner pipe (12, 22).

Abstract: A threaded joint for steel pipes for use in an oil well which has improved galling resistance and which is protected from rusting comprises a pin and a box each having a contact surface including a threaded portion and an unthreaded metal contact portion. The contact surface of at least one of the pin and the box has a lower layer of a viscous liquid or semisolid lubricating coating comprising at least wax and a fatty acid alkaline earth metal salt and not containing a harmful heavy metal such as lead and an upper layer of a dry solid coating formed from an aqueous resin coating composition, an organic solvent type coating composition, or an ultraviolet curing coating composition.

Abstract: A threaded joint for steel pipes comprising a pin (1) and a box (2). The pin has a male thread (11) and a lip (12) which comprises (i) a sealing surface (13) and (ii) a nose portion (16) provided with a shoulder surface. The box has a female thread (21), a sealing surface (23) and a shoulder surface. The shoulder surface of the pin comprises two distinct adjacent surfaces, main shoulder (14) in the inner side and sub shoulder (15) in the outer side. Correspondingly, the shoulder surface of the box comprises two distinct adjacent surfaces, main shoulder (24) in the inner side and sub shoulder (25) in the outer side. The main shoulder surfaces of the pin and box are disposed such as to prevent a radially inward deformation of the lip end, and the sub shoulder surfaces of pin and box are disposed such as to limit a radially outward deformation of the lip end.

Abstract: A method of coupling segments of a borehole conduit is disclosed. The method includes: positioning a first conduit segment at a location selected from a surface location and a downhole location, the first conduit segment having a first end and a second end, the first conduit segment including a pin connector at the first end; orienting the first conduit segment so that the first end is located uphole relative to the second end; and coupling a second conduit segment in operable communication with the first conduit segment, the second conduit segment having a box connector at an end of the second conduit segment that is configured to engage the pin connector of the first segment.

Abstract: A double shoulder threaded tool joint connection has: a pin with external threads formed between a pin external shoulder and a pin internal shoulder, the pin having a nose section between the internal shoulder and the external threads; and a box with internal threads formed between a box external shoulder and a box internal shoulder. Both the external threads and the internal threads have a thread taper between 0.666 inch per foot and 1.0 inch per foot, and have a stab flank angle and a load flank angle that are equal to about thirty-three degrees. In another feature of the invention, both the external threads and the internal threads have roots formed in a shape of a portion of a circle.

Abstract: The invention relates to building oil and gas wells and can be used in casing strings and tubings. The inventive highly-tight screw joint comprises internal and external mating elements with conical surfaces. The internal and external elements are provided with a thread. Said thread has supporting and embedded faces. A sealing unit is made in the form of a wedge on the side of a small diameter. The sealing unit is provided on the internal and external elements. The sealing unit consists of the parts of the internal and external elements. The internal and external elements of the sealing unit are formed by conical radial and conical stop faces. The conical radial face is made at an angle of 25°-35° to the normal to the thread axis. The conical supporting surface is made at the angle of 10°-25° to the normal to thread axis.

Abstract: A threaded joint for a steel pipe comprises a pin and a box with a contact surface having a threaded part and a unthreaded metal contact part, wherein a solid lubricating film containing one or more kinds of lubricating powders selected from graphite, mica, calcium carbonate and kaolin, a copper powder, and a binder is formed on at least one contact surface of the pin and the box. An object of the present invention is to provide a threaded joint for a steel pipe which allows for repeated fastening and loosening of a threaded joint without adversely influencing on a human body and environment, and is excellent in galling resistance, rust preventing property and gas tightness.

Abstract: An expandable threaded connection between segments of expandable tubulars that provides a high bearing pressure seal at a specific area along the pin and box members is disclosed. The invention utilizes a “groove” in a surface of the box member and a corresponding “rib” on the pin nose. The radial expansion of the tubulars causes the pin to become shorter in length, thereby causing the pin nose to retract from the back of the box member. As the pin nose retracts, the rib on the pin nose moves backward until a portion of the rib contacts a portion of the groove in the box member. The point of contact between the rib and the groove creates a metal-to-metal seal between the pin and box members. Because the point of contact between the rib and the groove is a relatively small area, the force acting on the point of contact generates a high bearing pressure that is equal to or greater than the internal pressure within the expandable tubulars and, thus, generates a high pressure seal.

Abstract: A cycleable downhole tool such as a Jar, a hydraulic hammer, and a shock absorber adapted for telemetry. This invention applies to other tools where the active components of the tool are displaced when the tool is rotationally or translationally cycled. The invention consists of inductive or contact transmission rings that are connected by an extensible conductor. The extensible conductor permits the transmission of the signal before, after, and during the cycling of the tool. The signal may be continuous or intermittent during cycling. The invention also applies to downhole tools that do not cycle, but in operation are under such stress that an extensible conductor is beneficial. The extensible conductor may also consist of an extensible portion and a fixed portion. The extensible conductor also features clamps that maintain the conductor under stresses greater than that seen by the tool, and seals that are capable of protecting against downhole pressure and contamination.

Abstract: A tubular threaded connection for coupling drill pipe segments to form a drill string is provided. Each of the segments has a tubular pipe body having a wall thickness of >0.5 inches (1.27 cm). The threaded connection comprises a pin end with an external thread, and a box end with an internal thread for threadable engagement with the external thread of the pin end. The pin shoulder extends between a pin base diameter and an outer pin bevel diameter; the box shoulder extends between a box base diameter and an outer box bevel diameter. The outer pin and box bevel diameters are between 7.75-8.688 inches (19.05-21.59 cm). The pin and box shoulders define a contact area such that, when the pin and box ends are threaded together with a make-up torque of >75,000 ft-lbs (1,079.36 kg-m), a load capacity of >2.0 million lbs (908,000 kg) is provided.

Abstract: A method to improve fatigue resistance of a threaded tubular connection. Radial interference between a male and female threading operates between stabbing flanks inclined at about 27° with respect to an axis of the threadings, wherein mutual contacting surfaces are radially spaced from a root of the male threading, which is defined by a concave rounded portion.

Abstract: In a threaded joint for pipes constituted by a pin and a box, each having a contact surface comprising a threaded portion and an unthreaded metal contact portion, the contact surface of the pin has a solid corrosion protective, preferably transparent coating based on a UV-curable resin and the contact surface of the box has a solid lubricating coating having plastic or viscoplastic rheological behavior which is preferably formed by the hot melt technique from a composition comprising a thermoplastic polymer, a wax, a metal soap, a corrosion inhibitor, a water-insoluble liquid resin, and a solid lubricant.

Abstract: An improved seal and method for providing a watertight compression joint connection between a valve or fitting and a flare end of a copper tubing in a water service. The improvement includes an O-ring seal on a bull nose end of a valve and a frictional material inserted into straight AWWA threads on a male inlet or outlet of the valve to sealingly engage a flared end of the copper tubing to the bull nose end and to frictionally engage a flare nut with the tubing back onto the matching bull nose end of the valve when screwing the flare nut onto the male threads of the valve, respectively.

Abstract: A threaded connection includes a pin member having a pin thread having a pin load flank and a pin stab flank. The threaded connection includes a box member having a box thread having a box load flank and a box stab flank. The pin thread includes a first wedge segment on the pin stab flank and the box thread includes a second wedge segment on the box stab flank. Upon make-up of the pin member with the box member, a contact stress results from engagement of the first wedge segment with the second wedge segment.

Abstract: A connector part (3) for connecting a material supply device (10) to a spray gun (20) that includes a hollow cylindrical connection piece (5); a threaded wedge element (8) with a lower starting point (8a) and an upper end (8b) running around the outer circumference of connection piece (5) and serving to produce a threaded wedge connection to a counter-element (15) arranged on gun base (19) of spray gun (20); and a stop element (14) that forms a limit stop during the production of the threaded wedge connection. In order to prevent the counter-element on the spray gun from digging into the soft connection pipe made of plastic and removing plastic chips there, it is provided in the connector part according to the invention that stop element (14) is arranged at a distance in the circumferential direction from upper end (8b) of threaded wedge element (8), whereby a gap (11) is formed between stop element (14) and upper end (8b) of the threaded wedge element.

Abstract: A threaded joint for steel pipes comprising a pin 1 having a tapered male thread 11, a tapered sealing surface 13, and an end shoulder surface 14 and a box 2 having correspondingly a tapered female thread 21, a tapered sealing surface 23, and a shoulder surface 24 which is capable of easy tightening and has improved air tightness by the sealing surfaces is arranged such that the pin and the box each have a noncontacting region B where the peripheral surfaces of the pin and the box do not contact each other between the sealing surfaces 13, 23 and the shoulder surfaces 14 and 24. At least a portion of the noncontacting region of the pin adjoining the to end of the pin is a tapered surface portion 18 having substantially the same angle of slope as the tapered sealing surface 13, and the noncontacting region of the box is a substantially cylindrical surface.

Abstract: A bore seal for connecting and sealing oil and gas tubular members is disclosed which has a metal core manufactured from a high yield strength ferrous material and a protective overlay of corrosion and abrasion resistant stainless steel and/or nickel based alloy. The protective overlay is applied to the entire outer surface of the bore seal by a metal thermal spray process, such as plasma thermal spraying. In a preferred embodiment of the invention, the bore seal has a fishtail profile which facilitates the use of resilient seals to provide resistance to external pressures in addition to the traditional metal-to-metal seal between the bore seal and the tubular members. In an alternative embodiment, a pressure relief valve is disposed within the bore seal to verify the integrity of the metal-to-metal seal with respect to internal bore pressure.

Abstract: A lubricating coating which is free from harmful heavy metals is formed on a premium threaded joint for pipes constituted by a pin and a box each having a contact surface comprising a threaded portion and an unthreaded metal contact portion (a sealing surface and shoulder) in order to provide the joint with galling resistance, gas-tightness, and anticorrosive properties such that the unthreaded metal contact portion is prevented from yielding even when the joint is made up with a high torque. The lubricating coating comprises one or both of a rosin and calcium fluoride; metal soap; wax; and a basic metal salt of an aromatic organic acid, and preferably it further includes a lubricating powder, magnesium carbonate, and/or a carbohydrate, particularly a cyclodextrin.

Abstract: A drill pipe includes a pin end connector, a box end connector, a first communication connector and a second communication connector. The pin end connector includes a first region to form a threaded connection to join sections of the drill pipe together, and the first region includes at least one thread that begins at one end of the first region and ends at the other end of the first region. The box end connector receives the pin end connector, and the box end connector includes a second region to mate with the first region to form the threaded connection. The first communication connector is attached to the pin end connector and is located in the first region; and the second communication connector is attached to the box end connector and located in the second region to form a communication connection with the first communication connector.

Abstract: A threaded connection includes a pin member having a pin thread having a pin thread crest, a pin thread root, a pin load flank, and a pin stab flank, a box member having a box thread having a box thread crest, a box thread root, a box load flank, and a box stab flank, wherein at least one of the pin thread crest, the pin thread root, the box thread crest, and the box thread root has at least one perturbation formed thereon, and wherein upon a selected make-up of the pin member with the box member, at least one of a localized clearance or a localized interference exists between the pin thread and the box thread at the at least one perturbation.

Abstract: A marine riser assembly having a first tubular member having an external surface with a plurality of first axially spaced formations, a second tubular member having an external surface with a plurality of second axially spaced formations thereon, a segmented ring in surrounding relationship to the first and second tubular members, the segmented ring having an inner surface with a plurality of formations engageable with the formations on the first and second tubular members, the engageable formations serving to urge the first and second tubular members toward each other when the segmented ring is subjected to radially inwardly directed compressive forces, a sleeve in surrounding relationship to force the engageable formations together and a seal assembly for sealing against external and internal pressure.

Abstract: A floating shoulder ring is arranged to occupy the J.-space between pin ends of coupled pipe sections. The length of the ring is arranged to allow the pipe connection to approach the specified torque for shoulderless connections before the ring begins to function as an abutment between the approaching pipe ends: The torque accepted by the ring limits the radial force imposed by tapered threads on both pipe and coupling. The ring is provided with modified threads on the outer surface to engage the inner threads of the coupling, in the J-space, to retain the ring in the coupling during handling in preparation for assembly into a pipe string. The modified threads yield axially when substantially forced. Threads that slip axially, non-destructively, and threads that deform under sufficient axial force are provided.

Abstract: An expandable threaded connection between segments of expandable tubulars that provides a high bearing pressure seal at a specific area along the pin and box members is disclosed. The invention utilizes a “groove” in a surface of the box member and a corresponding “rib” on the pin nose. The radial expansion of the tubulars causes the pin to become shorter in length, thereby causing the pin nose to retract from the back of the box member. As the pin nose retracts, the rib on the pin nose moves backward until a portion of the rib contacts a portion of the groove in the box member. The point of contact between the rib and the groove creates a metal-to-metal seal between the pin and box members. Because the point of contact between the rib and the groove is a relatively small area, the force acting on the point of contact generates a high bearing pressure that is equal to or greater than the internal pressure within the expandable tubulars and, thus, generates a high pressure seal.

Abstract: An electrical conduit piece of the invention has two external threaded regions, one threaded region having a left hand threaded region and one having a right hand threaded region. This conduit piece is particularly well adapted to be used in conventional conduit systems by coupling two conventional conduit pieces through a coupling of the invention having two internal threaded regions, one threaded region having left hand threads and the other threaded region having right hand threads. A groove may be formed in the internal wall of the coupling, e.g., at or near its longitudinal center to provide an open region in which ends of conduit pieces inserted into the coupling can abut. Residing in the grooved region of the coupling is a locking ring which scores the threads of the conduit pieces at 90° preventing any tangential force from outside of the system from unscrewing one of the conduit pieces from the coupling. In a preferred embodiment, the conduit piece is embodied as a curved or elbow conduit.

Abstract: A method and apparatus for coupling expandable tubular members.

Abstract: A low cost threaded pipe connection for virtually any service is provided, that has selectively, unique sealing threads for general use that can be supplemented with a pin nose seal when specified by the user.

Abstract: A tubular connection including a first joint having outer threads and an inner bore, and a second joint having outer threads and an inner bore. The tubular connection further includes an outer nut having inner threads that cooperate with the outer threads of the first joint and the second joint. The tubular connection further includes an inner sleeve positioned within the first inner bore and the second inner bore. In one embodiment, the first inner bore contains a first groove having a first seal disposed therein and the second inner bore contains a second groove having a second seal disposed therein, wherein the first and second seals prevents a pressure from exiting the first and second inner bore.

Abstract: A clamp for clamping to two threadedly-connected items, and, in one aspect, two threadedly-connected components of a top drive system.

Abstract: A threaded oilfield tubular connection 10 includes a pin member 12 having a first external tapered thread 24 and a second external tapered thread 26. A box member includes a first internal tapered thread 14 and a second internal tapered thread 16. Helical torque shoulders 40, 42 are provided on the pin member and the box member, and an axially spaced between the respective first and second threads. The helix of each torque shoulder includes a plurality of revolutions with compression flanks on both the pin member and the box member.

Abstract: A threaded joint for steel pipes comprises a pin (1) and a box (2) each having a threaded portion (3a or 3b) and an unthreaded metal-to-metal contact portion (4a or 4b) as contact surfaces which contact each other when the joint is fastened. The contact surfaces (3a and 4a and/or 3b and 4b) of at least one of the pin (1) and the box (2) are coated with a lower layer of a solid lubricating coating containing a solid lubricating powder (e.g., molybdenum disulfide, tungsten disulfide, or graphite) and a binder (e.g., an epoxy or other organic resin) and an upper layer of a solid corrosion protective coating formed by an organic resin which does not contain solid particles.

Abstract: A threaded tubular joint comprising male and female members is provided. The ends of the male members comprise an upper portion and a lower portion located between an upper threaded portion and an inner surface of each of the male ends. The upper portion is formed by a thread bevel which transitions into a first rounded area and the lower portion is formed by a second rounded area. A reversibly deformable ring may be housed within a central section of the joint. When the male members are substantially engaged within the joint, the ring is compressed by the ends of the male members.

Abstract: A threaded tubular connection is provided. The connection includes a male tubular element provided with a male threaded portion and a female tubular element provided with a female threaded portion. The male threaded portion and the female threaded portion each include self-locking threads having a crest, a load flank, a stabbing flank and a root, a load flank lead of the self-locking threads being larger than a stabbing flank lead of the self-locking threads such that in a tightened position of the threaded tubular connection, the load flanks and the stabbing flanks of the male self-locking threads are engaged in tight contact with the load flanks and the stabbing flanks of the female self-locking threads. A transfer zone is axially disposed between the threaded portions and a free end of at least one of the tubular elements, while being axially spaced from the threaded portions.

Abstract: A threaded joint for steel pipes comprised of a pin (1) and a box (2) each having a threaded portion (1a, 2b) and an unthreaded contact portion (1b, 2a) exhibits adequate leakage resistance and galling resistance when used for makeup of oil country tubular goods with application of a green dope or even without any dope. The threaded joint has a first plating layer of Sn—Bi—Cu alloy plating formed on the contact surface of at least one of the pin (1) or the box (2). The first plating layer may have a second plating layer selected from Sn plating, Cu plating, and Ni plating on its lower side and at least one layer of a lubricating coating, and particularly a solid lubricating coating on its upper side.

Abstract: A sucker rod connection is disclosed. The sucker rod connection comprises a tapered male member including a plurality of trapezoidal threads, and, a tapered female member also including a plurality of trapezoidal threads, in which the male member is capable of being received in threaded engagement with the female member, wherein the threads of the male member are in flank-to-flank contact, both flanks on each thread, with the threads of the female member, thereby creating diametrical interference between the male and female members preventing disengagement and substantially reducing axial interference between the male and female members.

Abstract: The invention relates to a threaded joint for rock-drilling equipment of the type that includes female and male parts that are interconnected via threaded joints. The invention is particularly advantageous in connection with female parts (1) of the type that includes an internal trapezoidal thread in the form of a helix thread ridge, which is delimited by a top and two flanks (12a, 12b), a groove (13), having a bottom (14), running between two tops, and which thread ridge extends a plurality of turns between a front end and a rear end, the thread top touching an imaginary cylinder or cone that is concentric with a centre axis of the female part.

Abstract: A tubular coupling system and method; the system and method in at least certain aspects, using a coupling member with an interior protective ring that has at least one inner energizing member which, upon compression, forces the body of the coupling member against an interior wall of the coupling thereby inhibiting corrosive material from contacting the coupling's interior wall or, in the event some corrosive material does enter this area, holding the interior protective ring against the coupling's interior wall so that the corrosive material remains in and does not exit this area, thus inhibiting or preventing a continuous flow of corrosive material.

Abstract: A threaded connection between adjacent tubular members includes a pin member providing an external wedge thread and a box member providing an internal wedge thread, wherein the internal wedge thread corresponds with the external wedge thread. Further, the threaded connection includes at least one interruption along a helical thread length of one of the external wedge thread and the internal wedge thread and at least two regions along an axial length of the threaded connection where the external wedge thread and the internal wedge thread form a thread seal.

Abstract: A method for protecting a threaded metal joint from galling and corrosion includes providing a nanocrystalline coating on the metal surface. The nanocrystalline coating can include a solid or liquid lubricant to protect against wear. Threaded metal joint surfaces coated with the nanocrystalline coating can resist galling under high pressure and high torque, even after several fastening and unfastening operations and also over a long period of time. Protection from corrosion is also provided by the nanocrystalline coating. The method and nanocrystalline coating provide metal surfaces with both lubrication and protection against corrosion. Problems such as removal or leakage, which are associated with protective compounds that use oils, are avoided. The nanocrystalline coatings may be layers of the same material, or layers of differing materials, such as layers with lubricating particles dispersed throughout, and layers without lubricating particles.

Abstract: A tubular joint in which radial expansion caused by the passage of an expander, inclined shoulder fittings formed respectively on a peripheral surface of the female element facing radially inwards and on a peripheral surface of the male element facing radially outwards, are subjected to a relative axial displacement towards each other to be urged into sealed mutual contact with radial interference. The tubular joint is, for example, useful in hydrocarbon wells.

Abstract: A thread form is shown which is used to make a threaded pipe connection capable of being screwed together and subsequently unscrewed. A pin member is provided having external threads with stab flanks and load flanks and flat crests and roots for mating with the mating internal threads of a box member to make up a pipe connection. One of the stab or load flanks is made up of two facets and three radii. The other selected flank is made up of three facets and four radii, giving it irregular features forming a complex geometric profiles. The thread form can be used to form a premium threaded connection which is used with such tubulars as casing and tubing for oil, gas, water and waste disposal wells.

Abstract: Burrs which develop on the incomplete thread at the start of cutting of male threads (1) of a threaded joint and which are a cause of galling when connecting oil country tubular goods are eliminated. In the incomplete thread, the upper portion (11a) of a thread (11) having a pointed crest with a generally triangular cross-section (typically a beveled portion) is cut off to form a thread having a trapezoidal cross section and a crest face (11c). Cutting off of the upper portion (11) is carried out such that the angle ? formed between the crest face (11c) and the flank on the side opposing a thread (12) of a complete thread is an obtuse angle, and the thread height h from the root of the flank is at least 0.2 mm. Cutting is preferably carried out under the same feed conditions as in machining of the male threads.

Abstract: The engineering problem of the claimed invention is to enhance wear-resistance of drill pipe tool joints. The proposed drill pipe consists of a body with upset ends and tool joints connected by means of friction welding, having tapered thread and a double coating, the first layer being applied by means of thermo-diffusion zincing and the second one, by means phosphate treatment. Enhancement of tool joint life, as compared to the tool joints with phosphate coating only, allows no overdimension to be stipulated for future repair purposes, which saves up to several kilos of metal per tool joint, decreasing the drill string weight by several tons. With a view to increasing the joints' durability and reliability of welding seams the thickness ? of the first coating layer as function of thread conicity K is adjusted according to the following formula: ?=0.09 . . . 0.13 K. The segment at 15 to 25 mm from the welding spot on joints is coated with phosphate only.

Abstract: A long felt need for more reliable and safer pipe threads is provided which teaches (1) how to offset the mismatch of pipe threads that occurs due to elongation of the pin and contraction of the box during assembly; (2) how to prevent separation of mating pipe threads independent of radial thread interference; (3) a swaged box connection that is as strong as the pipe; (4) a thread that stabs easily without damage.

Abstract: A threaded tubular connection includes a male tubular element including a male threaded portion and a female tubular element including a female threaded portion that cooperates by screwing with the male threaded portion. The threaded connection includes at least one transfer zone that can transfer bending loads between the elements and that is axially spaced from the threaded portions, in which the male and female elements have an undulating surface and a smooth surface facing each other, the undulating surface defining a series of rounded annular ribs that come into contact with the smooth surface with a radial interference fit. The connection may find application to production strings for hydrocarbon wells.

Abstract: A threaded connection includes at least one contact zone axially separated from threadings in which male and female elements are in sealed contact via bearing surfaces respectively constituted by a cambered surface and by a tapered surface.