Abstract: A screw joint in which an efficient screw length of a joint portion is achieved. This screw joint is for an oil well pipe of an integral type and includes: (i) a pin that is provided with a male screw portion which is a male taper screw, at one end of a steel pipe; and (ii) a box that is provided with a female screw portion which is a female taper screw fitted to the male screw portion, at one end of the steel pipe, in which a structure, in which the pin and the box are in metal contact with each other to seal a fluid, is provided at least at one place of a seal portion on an outer peripheral surface side of a pipe end side of the pin and a seal portion on an inner peripheral surface side of a pipe end side of the box.

Abstract: A threaded tubular connection comprises a first tubular component and a second tubular component. The first tubular component includes a female portion defined on an interior surface of the first tubular component. The female portion includes an inner threaded portion and an outer threaded portion which are offset radially with respect to a longitudinal axis of the first tubular component by a first shoulder. The second tubular component includes a male portion defined on an exterior surface of the second tubular component. The male portion is to be inserted into the female portion, and includes an inner threaded portion and an outer threaded portion which are offset radially with respect to a longitudinal axis of the second tubular component by a second shoulder. The second shoulder is to abut the first shoulder once the male portion is connected to the female portion.

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

Abstract: A punch pin assembly includes a punch rod, a punch pin and a punch pin connection rod connected therebetween. A heat-conducting medium conveying loop is arranged in the punch rod and the punch pin connection rod. The heat-conducting medium conveying loop communicates with the outside of the punch rod separately through a first medium port and a second medium port which are formed in the punch rod.

Abstract: The disclosed threaded connection for steel pipes includes a pin including a tapered male thread part and a shoulder part, and a box including a tapered female thread part and a shoulder part. In a made up state in which the shoulder parts are in contact with each other, clearances are provided between crests of the male thread part and roots of the female thread part. At a longitudinal section that includes a pipe axis of the threaded connection, the crests of the male thread part are formed in a convex curve that is tangent to both first corner portions which are formed in an arc that connect the crests and load flanks, and second corner portions which are formed in an arc that connect the crests and stabbing flanks. A solid lubricant coating is provided on the surface of the male thread part.

Abstract: A connection includes a first tubular member having a first screw threadform defined by a first plurality of crests, roots, and flanks, where each flank separates each crest from each root. The connection also includes a second tubular member having a second screw threadform defined by a second plurality of crests, roots, and flanks, where each flank separates each crest from each root. The crests and roots are substantially axial to the tubular members and the flanks are substantially radial to the tubular members. The first tubular member and the second tubular member are configured to connect when the first threadform engages with the second threadform. Thread compound relief spaces are formed between the first plurality of crests and the second plurality of roots when the first and second tubular members connect.

Abstract: A connection includes a first tubular member having a first screw threadform defined by a first plurality of crests, roots, and flanks, where each flank separates each crest from each root. The connection also includes a second tubular member having a second screw threadform defined by a second plurality of crests, roots, and flanks, where each flank separates each crest from each root. The crests and roots are substantially axial to the tubular members and the flanks are substantially radial to the tubular members. The first tubular member and the second tubular member are configured to connect when the first threadform engages with the second threadform. Thread compound relief spaces are formed between the first plurality of crests and the second plurality of roots and between the second plurality of crests and the first plurality of roots when the first and second tubular members connect.

Abstract: A double shoulder threaded tool joint connection includes a pin with external threads formed between a pin external shoulder and a pin internal shoulder, the pin including a nose section between the pin internal shoulder and the pin external thread and a box with internal threads formed between a box external shoulder and a box internal shoulder. The internal threads and the external threads are arranged and designed for connection with each other so that the box and the pin are connected with a common center-line and with a primary seal formed by the pin external shoulder forced against the box external shoulder and a secondary seal formed between the pin internal shoulder forced again the box internal shoulder. The invention may be applied to any threaded joint.

Abstract: The disclosure provides a bolt including a main body, a head portion and a thread portion. The main body has a central axis. The head portion connects the main body. The thread portion is connected to the main body and runs around the central axis. The thread portion has a bearing surface facing toward the head portion. The bearing surface is a continuous curved surface or has an inflection point. The bearing surface includes a concave curved surface, a convex curved surface and a flank surface. The concave curved surface connects the main body. The convex curved surface is located further away from the main body than the concave curved surface. One side of the convex curved surface connects the concave curved surface, and another side of the convex curved surface connects the flank surface.

Abstract: A threaded connection for steel pipes is provided that exhibits improved sealability against the external pressure while maintaining the sealability against the internal pressure. A threaded connection for steel pipes includes a pin and a box. The pin includes a nose, a tapered inner male thread, a tapered outer male thread, a pin inner sealing surface, a pin intermediate shoulder surface, a pin intermediate sealing surface, and a pin annular portion. The box includes a recess corresponding to the nose, a tapered inner female thread, a tapered outer female thread, a box inner sealing surface, a box intermediate shoulder surface, a box intermediate sealing surface, and a box annular portion. The threaded connection satisfies expressions (1) and (2), provided below. ?1 is a taper slope of the inner male thread, and ?2 is a taper slope of the outer male thread. ? ? 1 > ?2 , and ( 1 ) 0.5 ? L ? ? 1 ? ?1 L ? ? 2 ? ?2 ? 1.

Abstract: A threaded connection connecting a pair of pipes includes a pin and a box. The pin has a male thread on its outer diameter. The box has a female thread on its inner diameter, the female thread corresponding to the male thread. The male thread includes constant-thread-width and varying-thread-width portions. The constant-thread-width portion has a constant thread-groove width. The varying-thread-width portion has a thread-groove width equal to or larger than the groove width of the constant-thread-width portion and gradually increasing, from the constant-thread-width portion toward the tip of the pin. The female thread includes constant-thread-width and varying-thread-width portions. The constant-thread-width portion has a constant thread-ridge width. The varying-thread-width portion has a thread-ridge width equal to or larger than the thread-ridge width of the constant-thread-width portion and gradually increasing from the constant-thread-width portion toward the center of the box.

Abstract: A tubular member for threadably engaging another tubular member to form a tubular string includes a first end including a helical female thread formed in an outer surface of the tubular member, wherein the female thread includes a slot extending radially inwards from the outer surface, and a root extending radially inwards from the slot, wherein the root has a maximum width that is greater than a maximum width of the slot, a second end opposite the first end and including a helical male thread formed on an inner surface of the tubular member, wherein the male thread includes a shank extending radially outwards from the inner surface, and a notch extending radially outwards from the shank, wherein the notch has a maximum width that is greater than a maximum width of the shank.

Abstract: An internally threaded bit for percussion drilling is provided, which has thread roots wider than the thread crests. A single drill bit, configured according to the present invention, can be connected to a variety of rods, having differing crest widths in their male threads. The invention enables the service life of the rods to be optimized to suit the drilling conditions at hand, without the need to manufacture and keep in inventory a correspondingly large variety of drill bits. The bit of the invention exhibits a reduced rate of ringing off, and can accept drill rods having a range of crest widths.

Abstract: A cutting tool may include a flow path and a sealing part. The flow path may include an inflow port and an outflow port. The sealing part may be located continuously with the flow path and may include a male screw and a female screw. Screw threads in the male screw may include a first screw thread. Screw grooves in the female screw may include a first screw groove. A top portion of the first screw thread may be in contact with a bottom portion of the first screw groove.

Abstract: A mechanical connector, including a telescopically assembled mechanical connector, is provided with one or more sets of threads on substantially matching frustoconical surfaces of a pin and a box of the connector. Thread generatrix angles on the loaded and unloaded sides of the threads are measured to normals to the shared axes of the box and of the pin. This invention introduces mismatching of the generatrix angles along the interacting surfaces on the loaded and/or unloaded sides of the threads, which result in slight interference fit(s) along the thread surfaces. The effect is more even distribution of the bearing loads on the threads, reductions in the maximum shear loading and more uniform bending of the threads. Already good leak resistance of the connector can be additionally improved. The above modifications can be introduced to traditional connectors and to connectors designed to transfer high torsional loads.

Abstract: A threaded connection includes a pin including a wedge male thread having a varying-thread-width portion and a box including a wedge female thread having a varying-thread-width portion. The threaded connection is constructed such that, when both stab flanks and load flanks of the male thread of the pin contact the box, the shoulder on the pin is not in contact with the shoulder on the pin, and, with a further rotation in the make-up direction, the shoulder on the pin is capable of contacting the shoulder on the pin before the threads (i.e. male and female threads) yield.

Abstract: A threaded connection for steel pipe with improved sealability against the internal and external pressures is provided. A threaded connection 1 includes a pin 10 and a box 20. The pin 10 includes a male thread 11, a nose 12, a pin shoulder surface 13, and a pin sealing surface 14. The box 20 includes a female thread 21, a box shoulder surface 23, and a box sealing surface 24. The box sealing surface 24 has a seal point SP on the taper surface 242 located at the midpoint thereof as determined along the direction of the pipe axis CL. The distance LSP between the tip of the nose 12 and the seal point SP as measured in the direction of pipe axis CL is 13 mm or larger. The shoulder angle ? between the pin or box shoulder surface 13 or 23 and a plane VP perpendicular to the pipe axis CL is 2 to 13 degrees. The ratio TB/TP of the wall thickness TB of the box to the wall thickness TP of the pin 10 as measured at the seal point SP is 1.7 or higher.

Abstract: High sealing performance is provided in a threaded connection used for pipes for oil wells with large wall thickness and with a connection efficiency smaller than 1. A threaded connection (10) connects pipes for oil wells (1). The threaded connection (10) includes two pins (11) and a tubular coupling. Each of the pins (11) is provided on an end of the pipe for oil wells (1) and is in continuity with the pipe body (12), which has a wall thickness not smaller than 12 mm. The coupling (2) includes two boxes (21) and a recess portion (22). The box (21) is provided on both ends of the coupling (2). The recess portion (22) has a length not smaller than 10 mm. The threaded connection (10) has a connection efficiency smaller than 1.

Abstract: A threaded connection for steel pipe is provided that prevents cross-threading and provides good compression load resistance. A threaded connection (10) includes a pin (30) and a box (40). The male thread stabbing flank (34) of the pin (30) includes two male thread stabbing flank portions (341) and (342). The male thread stabbing flank portion (341) is located farther from the pipe axis (X) of the steel pipe (20) and has a stabbing flank angle (?1) of ?10 to 15 degrees. The male thread stabbing flank portion (342) is located closer to the pipe axis (X) and has a stabbing flank angle (?2) of 20 to 60 degrees. The female thread stabbing flank (44) of the box (40) includes two female thread stabbing flank portions (441) and (442). The female thread stabbing flank portion (441) is located farther from the pipe axis (X) and has a stabbing flank angle (?1) equal to the stabbing flank angle (?1) of the male thread stabbing flank portion (341).

Abstract: In a connection structure for fire extinguishing system piping in which a male piping member is connected to a connection opening portion of a joint by screwing a male thread and a female thread together, the male piping member includes a joint cylinder having a protruding portion that is inserted deeper into the connection opening portion than the female thread. Each male piping member and the connection opening portion includes a step portion. The connection structure further includes an indicator that engages the step portions and in a state in which the male piping member and the connection opening portion are connected together. At least one of the male piping member and the connection opening portion includes an unmountable portion that has an outside diameter different from an inside diameter of the indicator and cannot be engaged by the indicator.

Abstract: A threaded connection having a straight central axis, where the pin threads and the box threads are arranged such that when the connection is fully made up, the pin roots and box crests come into at least partial interference substantially in line with a pin root taper plane and a box crest taper plane, and wherein the angles of the pin root taper plane and box crest taper plane allow for reduction of axial compressive forces on the plurality of pin threads and plurality of box threads along the central axis.

Abstract: A threaded connection that provides high sealing performance is provided. A threaded connection (10) includes a pin (1) and a box (2). An inner male thread (13) of the pin (1) includes a parallel portion (131). The parallel portion (131) is located at an end portion of the inner male thread (13) adjacent to the pin inner sealing surface (11), and has thread roots parallel to the pipe axis. An inner female thread (23) of the box (2) includes a tapered portion (231). The thread height in the tapered portion (231) is larger than that in the parallel portion (131). Da<Db is satisfied, where Da is the difference in diameter between adjacent thread crests (231a) in the tapered portion (231) in a longitudinal cross section of the pin (1) and box (2) as found when the connection is not made up, and Db is the difference between the diameter of the thread root (131a) in the parallel portion (13) and the maximum diameter of the pin inner sealing surface (11).

Abstract: A wellhead includes a wellhead body and a locking end coupled to the wellhead body. The locking end includes an exterior surface with an exterior locking profile. The exterior locking profile includes an exterior groove formed between exterior stab and load flanks on the exterior surface. The locking end also includes an interior surface having an interior locking profile. The interior locking profile includes an interior groove formed between interior stab and load flanks on the interior surface. At least one of the exterior groove or the interior groove is a relief groove that undercuts at least one of the respective stab or load flank. The relief groove corresponds to a portion of the contour of an ellipse intersecting at least a portion of the respective stab or load flank, and an axis of the ellipse is at a tilted angle with respect to an axis of the wellhead.

Abstract: A pitch tube includes a first tube part and a second tube part. The first tube part and the second tube part are detachably connected to each other.

Abstract: A gas turbine includes a shaft, a turbine coupled with the shaft for rotation with the shaft, and a bearing coupled with the shaft to facilitate rotation of the shaft. A bearing nut is adjacent the bearing on the shaft. The turbine has a first load path and the bearing has a second load path. The bearing nut exerts a force on the bearing such that the first load path is not aligned with the second load path relative to a central axis of the gas turbine engine. A method of assembling a gas turbine engine is also disclosed.

Abstract: A method of converting a tubular having NC46 connections to CET®43 connections. A method of applying a CET®43 thread to a pin connection or a box connection or both. A box connection and a pin connection of the tubular are machined and a CET®43 thread applied to the box connection and the pin connection.

Abstract: A threaded joint for joining tubes used especially in the field of OCTG (Oil Country Tubular Goods), such as pipes in gas or oil production and/or casings when drilling wells can include a pin and a coupling, or box, having an end surface not facing against any surface of the pin when the joint is made-up. Following make-up of the joint, first sealing surfaces of the pin and box mate to form an internal metal-to-metal seal, and second sealing surfaces of the pin and box mate to form an external metal-to-metal seal, where the internal and external seals are defined by contact between one toroidal surface and one frusto-conical surface.

Abstract: A set for producing a threaded connection, includes first, second, third, and fourth tubular component with axis of revolution, the first tubular component including at each of its ends a first and a second threaded zone provided on the inner peripheral surface of the component, the second tubular component including at each of its ends a third and a fourth threaded zone provided on the outer peripheral surface of the component, the third tubular component including at one of its ends a fifth and a sixth threaded zone respectively provided on the inner and outer peripheral surface of the component, the fourth tubular component including at one of its ends a seventh and an eighth threaded zone respectively provided on the inner and outer peripheral surface of the component. The first and sixth, third and fifth, second and eighth, fourth and seventh threaded zones cooperate with one another on makeup.

Abstract: Thread profiles providing multi-point contact improving the vibration resistance of the threaded fastener, and thereby greatly reducing the need for fastener coatings, such as nylon patches. In various embodiments, the threaded faster may have a threaded portion configured to engage two or three points of a mating thread, and the threaded portion has a thread defined by a crest portion, a leading flank, at least one root portion, and a trailing flank, all of which may be oriented at angle relative to the normal axis.

Abstract: A threaded pipe joint, when acted upon by a tensile load, does not break on the female thread-side of a first thread section of a second thread series that extends from an intermediate shoulder. The threaded pipe joint reliably undergoes tensile rupture on the female thread-side of a first thread section of a first thread series, which is the original critical cross-section site. The threaded pipe joint is configured so that when the male and female threads of the intermediate shoulder are screwed together, the load flank-side thread gaps L1G and L2G of a first thread series, which is the radially inward thread series, and a second thread series, which is the radially outward thread series, on the two sides of the intermediate shoulder always satisfy the relationship L1G<L2G.

Abstract: A screwing tool includes a tool head and a tool shaft having an external thread. A first support section is disposed between the tool head and the external thread, and a second support section is disposed between the external thread and a free end of the tool shaft. The second support section has radially outwardly projecting supporting elements that are disposed at a distance from each other in the circumferential direction.

Abstract: A threaded tubular connection is provided. The threaded tubular connection includes a pin having external threads, a pin seal surface, and a pin torque shoulder at a free end and a box for receiving the pin, the box having internal threads for interacting with the pin threads, a box seal surface for contacting the pin seal surface and a box torque shoulder for contacting the pin torque shoulder. The pin and box define a longitudinal axis. The pin torque shoulder has a first pin shoulder surface and a second pin shoulder surface, the first pin shoulder surface intersects an axis perpendicular to the longitudinal axis at a first angle and the second pin shoulder surface intersects the perpendicular axis at a second angle. The box torque shoulder has a first box shoulder surface and a second box shoulder surface. The first box shoulder surface intersects an axis perpendicular to the longitudinal axis at a third angle and the second box shoulder surface intersects the perpendicular axis at a fourth angle.

Abstract: Devices, systems and methods for capturing CO2 in a form that can be stored, processed, and/or converted to usable products is desirable. Systems capture CO2 using small scale, individual devices at a vast number of locations which, in the aggregate, are capable of significantly decreasing CO2 concentrations in the atmosphere on a global scale. When such small devices are placed in areas already occupied with a structure, i.e., office buildings, apartments, homes, automobiles and the like, though the amount of CO2 removal by each individual device may be relatively small, in the aggregate, significant amounts of CO2 may be removed at a more macro or even global scale.

Abstract: A threaded connection including first and second tubular components configured for exploration or operating a hydrocarbon well; the first tubular component including an external abutment, a male threaded connection portion extended by a non-threaded terminal portion defining an internal abutment at its axial end; the second tubular component including a female end defining at a free end a bearing surface forced against the external abutment, a female threaded connection portion made up with the male threaded connection portion and terminating in an internal shoulder forced against the internal abutment, an initial non-threaded portion connecting the female threaded connection portion to the internal shoulder, which includes a maximum radial interference locally forming a sealing surface located between the male threaded connection portion and the internal abutment, and located at a non-zero distance from the internal abutment, the distance being more than half of an axial distance of the terminal portion.

Abstract: The dual-threaded screw structure 1 has a first thread (S1) and a second thread (S2) with various leads formed on the dual-thread portion and has a function of preventing loosening without insufficiency in strength of the dual-thread portion. This dual-thread portion is composed of a first thread (S1) consisting of a coarse thread with a standard pitch P and a specific second thread (S2). The second thread (S2) is formed continuously on the thread ridge of the first thread (S1). The second thread (S2) has a sectional shape of this thread groove same as or substantially same as the first thread (S1), has a same twisting direction as the first thread (S1) and is a multi-threaded thread having threads with a triangular sectional shape and having a lead (L=n*P) a determined number (n)-times of a standard pitch P.

Abstract: A casing collar locator including a housing having a first end, a second end, and a passage extending between the first end and the second end, a first cylindrical member having a passage extending therethrough and coupled to the first end of the housing, and a second cylindrical member having a passage extending therethrough and coupled to the second end of the housing, and a coil assembly disposed in the passage of the housing and configured to produce an electrical signal in response to a change in a magnetic field, wherein the coil assembly comprises an annular magnet having a diameter greater than an axial width of the annular magnet.

Abstract: A threaded joint for steel pipe is provided that ensures good sealing performance and reduces crevice corrosion. A threaded joint includes a pin (10) and a box (20). The pin (10) includes a first shoulder surface (11), a first male thread (14), a second shoulder surface (18), and a second male thread (17). The box (20) includes a first shoulder surface (21), a first female thread (24), a second shoulder surface (28), and a second female thread (27). Supposing that the distance between the shoulder surfaces of the pin (10) is represented as Lpin and the distance between the shoulder surfaces of the box (20) is represented as Lbox, and the interference ?shld is defined by Equation (1) given below, then, the threaded joint is constructed such that Equations (2) and (3) given below are satisfied.

Abstract: A threaded joint is constructed of a pin and a box. The pin includes, in order from a tubular body having the pin toward the free end thereof: a male threaded portion and a lip portion including a sealing surface. The box includes: a female threaded portion corresponding to the male threaded portion of the pin; and a recessed portion corresponding to the lip portion, the recessed portion including a sealing surface. The lip portion includes, in order from a male threaded portion toward the free end of the pin: a neck portion; and a sealing head portion including the sealing surface. The maximum outside diameter of the region of the sealing surface in the sealing head portion is larger than an outside diameter of the neck portion at a boundary between the neck portion and the male threaded portion.

Abstract: An example threaded connection includes first component and a second component. The first component may have a first outer diameter, a first threaded portion at or near the first outer diameter, and an end portion. The second component have may a second outer diameter a second outer diameter greater than the first outer diameter; a second threaded portion, at least one of the first or second sets of threads having at least one of a variable pitch and a variable taper; and an internal shoulder positioned to contact the end portion of the first component when the first threaded portion are engaged with the second threaded portion. A connection ring may be coupled to the second component and positioned to engage with a portion of the first component when the first component is positioned within the second component.

Abstract: A connection is established between a pin connector and a box connector defined on a pair of tubular members such as casing segments in the field of oil and gas recovery. The pin connector and box connector include features for the protection of metallic-sealing surfaces during assembly, disassembly, transport and handling of the tubular members. The pin connector includes a stabbing flank with an inwardly tapered annular flank surface thereon, and an alignment protrusion extending outward with respect to the pin-side metallic sealing surface in a direction normal to a cone angle defined by the inwardly tapered annular flank surface. The alignment protrusion engages internal surfaces of the box connector to concentrically align the pin connector with the box connector, and thereby protects the metallic sealing surfaces from damage that might otherwise result from collisions between the pin connector and the box connector.

Abstract: A threaded joint is constructed of a pin and a box, the box having an outside diameter less than 104% of an outside diameter of a tubular body having the pin. The box includes, in order from an end of the box toward the tubular body: a lip portion and a female threaded portion, the lip portion including a shoulder surface and a sealing surface. The pin includes a shoulder surface, a sealing surface, and a male threaded portion. The lip portion of the box has a nose portion disposed between the shoulder surface and the sealing surface and an annular portion disposed between the sealing surface and the female threaded portion. The nose portion and the annular portion are not in contact with the pin, and a length of the annular portion is longer than a thread pitch of the female threaded portion.

Abstract: Stand-alone interbody fusion devices and corpectomy devices suitable for use with an oblique implantation. The stand-alone interbody fusion devices may include a spacer having a substantially U-shaped body and a plate coupled to the spacer. The overall shape of the implant is asymmetrical such that a median plane, an oblique plane, or both planes divide the spacer and the plate into two asymmetrical halves. The implants are shaped and configured to allow for an oblique or anterolateral approach to the spine or an oblique corpectomy.

Abstract: Open implant closure structures include a helically wound guide and advancement flange form having splay control surfaces. Multi-start closures and closures with inner set screws have splay control contours for interlocking with cooperating flange forms of bone anchor receivers. Flange form heights, thicknesses and other geometry, such as splay control ramp angle may be varied.

Abstract: A threaded joint is adapted for tubes where the stress or the strain concentration hardly occur at a threaded corner portion of box side even when the threaded joint receives repeated tensile-compressive forces or repeated bending forces. In a radial seal type threaded joint, tensile efficiency TE (%) defined by a ratio Sc/Sp between a cross-sectional area Sc, an area of Critical Cross Section (CCS) including a portion where a tensile stress and a strain become the highest in a tube circumferential cross section of a box and a cross-sectional area Sp of a tube body satisfies formula TE (%)?2.25×t/?+99.9 having a ratio t/? between an internal thread height t of the box and a radius of curvature ? of a corner portion of internally-threaded bottom load surface side.

Abstract: A threaded joint is constructed of a pin and a box. The pin includes a shoulder surface, a seal surface, and a male threaded portion. The box includes a shoulder surface, a seal surface, and a female threaded portion. The male threaded portion and the female threaded portion are each a tapered threaded portion including threads having a trapezoidal profile. The male threaded portion has a width of the threads that gradually decreases along the thread helix and a width of grooves that gradually increases along the thread helix. The female threaded portion has a width of grooves that gradually decreases along the thread helix and a width of the threads that gradually increases along the thread helix.

Abstract: A threaded tubular connection including a first tube and a second tube is provided. The first tube includes a pin member which extends from an end of a main body of the first tube to a terminal end of the first tube. The second tube includes a box member which extends from an end of a main body of the second tube to a terminal end of the second tube. A cross-sectional area of a pin critical cross-section is within approximately ±5% of cross-sectional area of a box critical cross-section of the box member. The cross-sectional areas of each of the pin and box critical cross-sections are within approximately ±5% of the sum of the cross-sectional areas of a box intermediate critical cross-section of the box member and a pin intermediate critical cross-section of the pin member.

Abstract: A threaded joint in which the outer peripheral face of the pin nose has a single tapered shape, the seal face of the box has an outwardly convex curved shape, and a seal point xp defined by equation (1) is greater than or equal to 0.2 inches, x p = ? x 1 x 2 ? p ? ? x ? ? d ? ? x F ? ? F = ? x 1 x 2 ? p ? ? d ? ? x ( 1 ) where p is a contact face pressure, x is a distance from an end of the pin in a pipe axis direction, and x1 and x2 are respectively a lower limit and an upper limit of a domain of x corresponding to the seal portion.

Abstract: A thread structure in accordance to one or more embodiments includes a thread extending helically along the cylindrical member in spaced thread turns, the thread having a crest extending between a first flank and a second flank and a root extending between the thread turns, the root having a curvature defined by a portion of an ellipse tangentially adjoining the first and second flank at respective flank transition points, the ellipse having a major axis extending parallel to the axis and a minor axis extending perpendicular to the major axis and through a root bottom.

Abstract: A threaded tubular connection including a first tube and a second tube is provided. The first tube includes a pin member which extends from an end of a main body of the first tube to a terminal end of the first tube. The second tube includes a box member which extends from an end of a main body of the second tube to a terminal end of the second tube. A cross-sectional area of a pin critical cross-section is within approximately ±5% of cross-sectional area of a box critical cross-section of the box member. The cross-sectional areas of each of the pin and box critical cross-sections are within approximately ±5% of the sum of the cross-sectional areas of a box intermediate critical cross-section of the box member and a pin intermediate critical cross-section of the pin member.

Abstract: In a joint for oil country tubular goods, a pitch change is made such that an internally-thread pitch has the same value as an externally-thread pitch from a thread end portion on a box end side to a pitch change position taken on a box center side with respect to a position away from the thread end portion by ½ of an entire length of the threaded portion, and the internally-thread pitch is changed to a value less than the externally-thread pitch at the pitch change position so that a thread gap is gradually decreased from the pitch change position to a position of the thread end portion on the box center side, and the thread gap is eventually set to a value which is 0.2 to 0.8 times as large as the thread gap before the pitch change is made.