Abstract: The threaded connection between the pin and the box ends of two pipes is sealed externally and internally to protect the threads in the connection from exposure to corrosive fluids. Seals are provided at each axial end of the threads. The external seals may be formed by metal-to-metal engagement between the pin and box or may be provided by an annular, elastomeric ring engaging the pin and box of the connection. A threaded compression ring may be used to compress the elastomeric seal between the pin and box. The seals protect dynamically loaded threaded connections from fatigue-induced failure in corrosive environments.

Abstract: An elongated drive string assembly includes a plurality of hollow sucker rods and connecting elements with an axis, connected together and between a drive head located at the surface of an oil well and a rotary pump located deep down in an oil well. Each hollow sucker rod has at least a first end including an internal female threaded surface engaging an external male threaded surface on a connecting element, such as a nipple. The first end also includes a torque shoulder, which engages a torque shoulder formed on the connecting element. The threads are frusto-conical, non-symmetrical threads with a differential diametral taper. The torque shoulders have a maximized mean diameter and cross-sectional area to resist storing reactive torque in the drive string. The nipple has a wall cross-section that increases towards the torque shoulders from each free end, to increase fatigue resistance.

Abstract: A pipe connector has a rigid seal/support ring mounted on its pin. The pin has a nose and external threads extending rearward from the nose. The rigid seal/support ring is fixedly mounted on an exterior portion of the pin farther from the pin nose than the pin threads. The rigid seal/support ring is installed by a shrink- or press-fit and has a tapered exterior seal surface. The box has a rim and internal threads that mate with the external pin threads. The box has a seal surface for engaging the seal surface of the rigid seal/support ring to form an external seal. The box also has a seal surface to form an internal seal with the nose of the pin.

Abstract: The threading of a threaded tubular element includes at least one tangential multiple radius junction zone at the thread root, in particular on the load flank side. This zone include a principal arc with a radius where the support circle cuts the flank at a point. The tangent to this circle makes a strictly positive angle with the flank. The secondary arcs have lower radii that effect the tangential junction of the principal arc on one side to the flank and on the other side to the thread root. The radius of the principal are larger than that of the standard circle which passes through and which would alone constitute a tangential junction zone. Such a threaded element provides a threaded tubular connection which incorporates good resistance to both static and cyclic stresses.

Abstract: A thread form for a tubular connection of the type having a pin member adapted to be made-up with a box member to form a pipe joint as shown. The pin member has pin threads with thread crests and thread roots which are adapted to be made-up with a mating box member having a complimentary thread structure. The pin thread crests are formed between a stab flank and a load flank of the pin thread. The pin thread has a multi-facited complex profile stab flank for engaging a mating stab flank on the complimentary box member to provide a wedging interfit between the surfaces of the pin and box threads. The pin and box threads are also helically structured as a wedge.

Abstract: A fluid tank valve assembly of the type employed for water tanks for toilets has a tank refill valve located atop a fluid inlet supply tube. The refill valve has a lever that is raised and lowered to open and close the valve. An inverted, cup-shaped hood is positioned atop the valve and a float is located about the skirt of the hood and secured thereto by the force of friction. The float can be moved longitudinally along the skirt of the hood in order to vary the water level at which the hood bears down upon the lever arm or is lifted from the lever arm, thereby varying the water level at which the valve is actuated. The valve itself is equipped with a metering pin that is configured to reduce the likelihood of clogging in the longitudinal passage of the core of the valve diaphragm.

Abstract: A pipe joint comprising: a pin having a tapered male screw section formed on an outer circumferential face of an end of a pipe; a box having a tapered female screw section, which can be screwed to the tapered male screw section, formed on an inner circumferential face of an end of a pipe, wherein the tapered male screw section is screwed into the tapered female screw section, a top face of a male thread ridge of the tapered male screw section and a top face of a female thread ridge of the tapered female screw section have a predetermined width like a square screw thread, trapezoidal screw thread and buttress screw thread, and top faces of both thread ridges are inclined in a direction opposite to a tapered face of screw threads with respect to a face parallel to the pipe axis.

Abstract: A connection for threaded pipes and other tubular sections including a gasket for interposition between a first and an opposing second interface surface of the connection. The gasket includes a retainer and a generally annular seal element received in a groove formed into at least one side of the retainer. Such retainer side further is formed as having one or more channels extending extend radially through the groove and the inner or outer perimeter of the retainer. Each such channel defines a vent for relieving hydrostatic fluid pressure as the gasket is compressed between the interface surfaces.

Abstract: A threaded joint for an oil well pipe is provided which prevents the occurrence of galling at the time of repeated tightening and loosening and which provides a high degree of air tightness and has excellent galling resistance and air tightness without using a liquid lubricant such as a compound grease. 1. A lubricating film of an inorganic polymeric compound which has an M (metal element)—O (oxygen) backbone and has a solid lubricant dispersed therein is formed on a threaded portion or an unthreaded metal contact portion. 2. A phosphate film and the lubricating film of the inorganic polymeric compound is formed on the threaded portion or the unthreaded metal contact portion. 3. A Cu plating layer and the lubricating film of the inorganic polymeric compound or a lubricating film of a resin in which a solid lubricant is dispersed is formed on the threaded portion or the unthreaded metal contact portion. 4.

Abstract: A pipe-coupling device comprises a joint body 2 having an opening 2h with external threads 2d to receive a pipe P, a locknut 5 having internal threads 5a engaged with the external threads 2d of the joint body 2, an annular core member 6 disposed within the locknut 6, and a plurality of locking members 7 retained in apertures 6d of the core member 6 to be spaced circumferentially apart from each other. Upon tightening rotation of the locknut 5 around the joint body 2, the internal conical surface 5c of the locknut 5 slidably contacts with the conical surfaces 7a of the locking members 7 so as to press the locking members 7 radially inwardly, to cause the gripping portions 7b of the locking members 7 come into gripping engagement with the outer periphery of the inserted pipe P, thereby strongly preventing withdrawal of the pipe P from the joint body 2 even when the pipe is made of hard material.

Abstract: To seal a pipe mortar, a sealing element (3, 6) is inserted between the pipe (1) and the base (2), with the element elastically balancing out the axial relative movements between the pipe (1) and the base (2). The sealing element (3) is preferably prestressed, with the gas pressure supporting the sealing effect. The sealing element (3, 6) can be a U-shaped or L-shaped steel ring. In the U-shaped sealing element (3), the legs (3.1) are axially prestressed to the extent that the sealing ring (3) and the pipe (1) or the base (2) are pressed together to produce an adequate seal. In the L-shaped sealing element (6), the inside leg (6.1) produces the gas-tight connection when the pipe (1) and the base (2) are screwed together. A sealing lips (6.2) of the sealing ring (6) elastically absorbs changes in length between the pipe and the base that occur during firing.

Abstract: A gasket for interposition between a first and an opposing second interface surface of a sealing assembly. The gasket includes a retainer and a generally annular seal element received in a groove formed into at least one side of the retainer. Such retainer side further is formed as having one or more channels extending extend radially through the groove and the inner or outer perimeter of the retainer. Each such channel defines a vent for relieving hydrostatic fluid pressure as the gasket is compressed between the interface surfaces.

Abstract: An expandable threaded connection includes a first tubular member, a second tubular member and a threaded connection for coupling the tubular members that includes one or more sealing members.

Abstract: A threaded tubular connection has a box member including an internal thread, a pin member including an external thread engageable with the internal thread of the box member, and a protruding sealing surface disposed in the box member such that the pin member flexes radially inward upon passing the protruding sealing surface during make-up. The threaded tubular connection also has a recessed seal cavity disposed in the box member and a reverse angle shoulder at the pin nose that forces the pin member to flex radially outward into the recessed seal cavity of the box member upon final make-up. A method of forming a double flex seal for a tubular connection includes engaging an internal thread of a pin member with an external thread of a box member and flexing a pin nose of the pin member radially inward by passing the pin nose over a protruding sealing surface of the box member during make-up.

Abstract: A thread for expandable downhole tubular connections is disclosed. It features a locking pattern on the pin and box, which engages upon expansion of the connection. The locking pattern compensates for longitudinal shrinkage away from a torque shoulder, as a result of expansion. A resilient seal can be incorporated into the design with pin to box clearance disappearing around the seal as a result of expansion. Resilient seals can be used in tandem to trap atmospheric pressure between them. The wellbore hydrostatic pressure helps engage the locking feature by pushing the box into the pin, helped by the trapped low pressure between the seals.

Abstract: Threaded and coupled pipe connections are provided with a number of design features that increase resistance of the connection to fatigue failure from cyclical side loading. The features acting alone or in combination include the provision of a pin thread that is formed along a single taper and that vanishes at the surface of the pipe. The coupling engages the pin such that the threaded area of the coupling engages all of the pin threads and extends beyond the vanish point of the pin threads at the optimum coupling makeup position. The threads of the coupling and pipe may engage along both the stab and load flanks to distribute the side loading. The external surface of the coupling may be tapered from the center toward each coupling end to reduce the stiffness ratio of the connection, and the ends or faces of the coupling may be reduced in radial thickness to prevent coupling splitting.

Abstract: A radially expandable tubular connection including a box member having an internal thread and a first seal surface and a pin member having an external thread and a second seal surface. The external thread threadedly engages the internal thread and the first and second seal surfaces form a metal-to-metal seal upon engagement of the seal surfaces. At least one groove is formed on an outer surface of the box member, and the at least one groove is shaped so that the box member radially deforms in a direction toward the pin member in a region near the metal-to-metal seal after radial plastic expansion of the pin and box members after engagement of the threads.

Abstract: A device for coupling two pipes made of composite material based on a reinforced thermoplastic, includes a sleeve (40) threaded on its internal wall and intended to be joined to an end (21) of the first pipe (20) and to an end (31) of the second pipe (30). A sealing element (44) creates a seal in the coupling zone. A first end-piece (11) is intended to be fastened to the end (21) of the first pipe and a second end-piece (12) is intended to be fastened to the end (31) of the second pipe. Each end-piece has over at least part of its external surface (13, 14) a screw thread (15, 16) intended to engage in a complementary manner with the screw thread (48) of the sleeve (40).

Abstract: An expandable threaded connection includes a first tubular member, a second tubular member and a threaded connection for coupling the tubular members that includes one or more sealing members.

Abstract: A screw-threaded joint for a pipe has a male portion (10) and a female portion (12), having complementary screw threads (11, 13). The male thread (11) extends to a position adjacent a complementary stop shoulder (18) on the female portion (12) having a recess of conical cross-section having a rounded apex. The recess is adapted to receive a head portion having a conical cross-section with a rounded apex, the radius of curvature of which is greater than that of the recess's apex providing a seal with improved stress dispersal properties upon application of torque. The wall (33) of the cone's in-use outwardly facing surface on the male portion (10) can subtend an angle of from 28-36° to the longitudinal axis of the pipe. The corresponding cone wall on the female portion can subtend an angle of from 28-38° with the same axis. The male portion (10) can comprise a second stress dispersing surface (41), concave in shape.

Abstract: Socket (7) to be fitted on a pipe (1) and, respectively, coupling piece for joining two pipes. The pipe is provided, close to the end thereof, with a stepped-down section (4) on which a screw thread (5) is made. The transition to the main diameter extends at somewhat of an angle. The socket is provided with a lead-in section (8) that is of at least the same length as the adjoining threaded section. The lead-in section is provided close to the free end with a conical section equipped to engage on the sloping transition section of the pipe.

Abstract: The surface areas available for absorbing compressive loading of a threaded connection are increased by increasing the engaged area of a torque shoulder in the connection and by reducing the spacing between the stab flanks of the threads. The areas are increased by increasing the dimensions of the components and by decreasing the machine tolerances permitted in manufacturing the components. The gap in the connection adjacent the torque shoulder is reduced so that the contact surface area of the torque shoulder is increased while the close proximity of the surrounding cylindrical walls of the connection reduces voids that can receive plastic deformation of the torque shoulder corners. The surfaces adjacent the torque shoulder are cylindrical in shape rather than being tapered to reduce machining costs and increase the speed of manufacture of the connection.

Abstract: A sealant for an expandable connection. The threaded portions of a pair of expandable tubulars are coated with a sealant. The threaded portions of the expandable tubulars are then coupled. The sealant is cured. The expandable tubulars are then placed within a preexisting structure. The expandable tubulars are then radially expanded into contact with the preexisting structure.

Abstract: A device for protecting the internally threaded end portion of a tubular member includes an externally threaded portion for engaging the internally threaded portion of the tubular member and a collar for engaging the exterior of the internally threaded end portion of the tubular member.

Abstract: A seal for a radially expansible conduit connection is disclosed. The seal includes a first sealing surface disposed proximal to an end of a male portion of the connection and a corresponding second sealing surface disposed proximal to an end of a female portion of the connection. The first and said second sealing surfaces are substantially opposite each other upon connection of the male and female portions. The seal includes a first clearance surface proximal to the first sealing surface and a second clearance surface proximal to the second sealing surface. The first and second clearance surfaces are substantially opposite each other upon connection of the male and female portions.

Abstract: An improved coupling for joining together tubular sections is disclosed. The coupling includes a water exclusion seal which is a pressure energized elastomeric seal positioned in a groove near each end of the coupling to form a radial seal between the unthreaded area at each end of the coupling and the unthreaded cylindrical area adjacent each end of the tubular section. A thread compound relief groove adjacent each seal groove has sufficient volume for thread compound that is squeezed from the threads during or after make-up.

Abstract: A threaded connection for tubular members comprising a box connector having axially spaced threaded sections and a thread-free section therebetween, the threaded sections of the box connector defining a two-step thread, a pin connector having axially spaced threaded sections and a thread-free section therebetween, the threads in the box connector mating with the threads on the pin connector, there being at least one annular relief in the thread-free portion of at least one of the pin connector and the box connector, an axially facing pin torque shoulder being formed on the pin connector and an axially facing box torque shoulder being formed on the box connector, a metal-to-metal seal being formed between the thread-free sections of the pin and box connectors when the pin torque shoulder and the box torque shoulder are engaged, the annular relief being adjacent the metal-to-metal seal.

Abstract: A radially expandable tubular connection including a box member having an internal thread and a first seal surface and a pin member having an external thread and a second seal surface. The external thread threadedly engages the internal thread and the first and second seal surfaces form a metal-to-metal seal upon engagement of the seal surfaces. At least one groove is formed on an outer surface of the box member, and the at least one groove is shaped so that the box member radially deforms in a direction toward the pin member in a region near the metal-to-metal seal after radial plastic expansion of the pin and box members after engagement of the threads.

Abstract: A connection for threaded pipes and other tubular sections including a gasket for interposition between a first and an opposing second interface surface of the connection. The gasket includes a retainer and a generally annular seal element received in a groove formed into at least one side of the retainer. Such retainer side further is formed as having one or more channels extending extend radially through the groove and the inner or outer perimeter of the retainer. Each such channel defines a vent for relieving hydrostatic fluid pressure as the gasket is compressed between the interface surfaces.

Abstract: A pipe connector having a pin element having a tapered outer threaded section between an external shoulder and a pin end face, a first threadless pin section between the external shoulder and the outer threaded section, and a second threadless pin section between the outer threaded section and the pin end face. Provided for threaded engagement with the pin element is a box element having a tapered inner threaded section between an internal shoulder and a box end face, a first threadless box section between the internal shoulder and the inner threaded section, and a second threadless box section between the inner threaded section and the box end face. Suitably, the second threadless pin section and the first threadless box section in the area of the internal joint is at least twice as long as the first threadless pin section and the second threadless box section in the area of the external joint.

Abstract: The portable tank defines a chamber within which is disposed a liner having a sealing interface with a tank discharge assembly. The features of the sealing interface of the liner with the discharge assembly and this discharge assembly itself virtually eliminate any risk that contents of the tank will seep or flow into the space outside of the liner and between the liner and the inner walls of the tank. The method of installing and using the liner system are also disclosed.

Abstract: A pipe connector for offshore risers has conical thread forms. The connector has a pin with a nose, an external shoulder, and conical first and second pin threaded sections. The first and second pin threaded sections are axially separated by a pin intermediate section that is free of threads. The first and second pin threaded sections are formed on a single continuous taper and on a continuous helix. The intermediate section is also conical and at the same taper as the pin first and second threaded sections. The connecter has a box with a rim, an internal base, and a conical receptacle between the rim and the base. The conical receptacle has first and second box threaded sections that make up with the pin threaded sections. The box also has an intermediate section between its first and second threaded connections that is free of threads. The intermediate sections make up with radial interference. Upper and lower metal-to-metal sealing surfaces are located at the nose and at the base of the pin.

Abstract: A drill string includes a plurality of tubular members each having a connection with a pin connector and a box connector on adjacent tubular members. The pin connector has an external thread with negative load flanks and positive stab flanks, adapted for threadingly engaging an internal thread second threads with negative load flanks and positive stab flanks on the box connector of the adjacent tubular member. The positive stab flanks have corner radiuses and the negative load flanks have radiuses forming a S-shape. The pin connector has an outer groove for receiving a protuberance on the terminal end of the box member forming locking shoulders. The protuberance and groove have contoured surfaces providing large metal-to-metal contact for preventing the contoured surfaces from sliding during over-torquing and cyclic bending of the drill string. The negative load flanks and locking shoulders lock the connection together.

Abstract: A threaded connection for two metal pipes including a male element at the end of a first pipe and a female element at the end of a second pipe, the male element including a male external thread, the female element including a female internal thread. The male and female threads are screwed one into the other. At least one of the male or female threads includes a groove formed in the thread and opening either into a stabbing flank or into a crest of the thread or straddling the stabbing flank and the thread crest. The groove is disposed in the thread so as to increase the flexibility of the portion of the thread which comes into pressure contact with the mating thread or to reduce the contact surfaces or to affect the two aspects at the same time.

Abstract: An offshore riser includes a plurality of tubular elements, each having a pin member on one end and a box member on the other end for connection with adjacent tubular elements. The pin member has an external thread which engages an internal thread on the box member of the adjacent tubular element. A dual angle torque shoulder locks the box end securely into place against the pin, preventing radial distention of the box end and maintaining bearing pressure between the external sealing surfaces. Also, stress relief grooves are located on the box member and on the pin member, to reduce the incidence of stress fractures, thereby improving the fatigue life of the connection.

Abstract: An improved coupling for joining together tubular sections is disclosed. The coupling includes a water exclusion seal which is a pressure energized elastomeric seal positioned in a groove near each end of the coupling to form a radial seal between the unthreaded area at each end of the coupling and the unthreaded cylindrical area adjacent each end of the tubular section. A thread compound relief groove adjacent each seal groove has sufficient volume for thread compound that is squeezed from the threads during or after make-up.

Abstract: A modular shower arm mounting system includes a water conduit and a replaceable shower arm assembly in sealing engagement therewith. The water conduit has a generally uniform inner wall and an outer diameter wall having a hexagonally or polygonally shaped drive force receiving area adjacent a threaded area. The conduit has one end attached to a manifold behind a shower wall surface and an outlet end projecting from the wall surface of sufficient length therefrom so that the drive force receiving area and threaded area are spaced from the wall surface. The replaceable shower arm assembly has an inner wall with a threaded portion for engagement with the conduit and a substantially smooth portion of gradually decreasing inner diameter downstream of said threaded portion approaching an outwardly projecting end thereof. The seal ring is adjacent the outlet end of the conduit to form a seal with the assembly.

Abstract: Several embodiments of a wedgethread pipe connection are disclosed that have improved makeup, sealing and non-loosening characteristics. In one embodiment, an open wedgethread is disclosed that has an included angle measured in the gap between the stab flank and the load flank to be not less than zero, so as to prevent premature wedging between mating flanks before the position of full makeup is reached, as does occur between trapped wedgethreads wherein the included angle is less than zero.

Abstract: A pipe connecting structure incorporated in the male and female ends of the pipes rigidly secures pipes in sealed end-to-end relation. Each end has axially spaced tapered cylindrical surfaces with a continuous thread extended between the surfaces. Each thread has an axially inward directed leading wall extended from an annular inner wall to an annular outer wall. A radial trailing wall at the rear of the outer wall extends inwardly to the inner wall. The grooves between the threads have the same profile as the threads.

Abstract: A threaded connection for two metal pipes which includes a tapered male thread with trapezoidal threads on a male element and a mating female thread on a female element. The thread width of the male and female threads, at the thread crest, is less than the thread width at the thread root. The width of the thread crests is larger than the width of a space between the roots of the mating threads. The male and female elements are screwed to a position located beyond that of the position where two flanks of the male threads come into contact with two flanks of the female threads. Such a connection permits makeup with a very high torque. The threads of one and/or the other of the threads can optionally include a groove opening into the thread crest.

Abstract: Method of fixedly connecting together externally and internally threaded tubes by tight engagement of externally and internally threaded portions of the tubes, wherein a wrenching operation is performed to rotate the externally and internally threaded tubes relative to each other with the externally and internally threaded portions engaging each other while an axial force is applied between the tubes. A physical quantity relating to a coefficient of friction between said tubes is obtained on the basis of a detected wrenching torque applied to rotate the tubes relative to each other and the axial force, and a terminating condition for terminating the wrenching operation is determined on the basis of the obtained physical quantity. The wrenching operation is terminated when the terminating condition has been satisfied. Apparatus for practicing the method and recording medium storing a control program for the method are also disclosed.

Abstract: This invention provides sealed access to the interior of a pressure vessel and consists of a tube, a collar, redundant seals, and a port. The port allows the seals to be pressurized and seated before the pressure vessel becomes pressurized.

Abstract: A screw joint for pipes, in particular sanitary and floor heating pipes of, for example, plastic material or a composite material of metal and plastics is provided with at least one screw joint member with a substantially cylindrical portion, in which a thread with at least one helical raised portion of, in particular, triangular cross section is formed. The at least one raised portion of the thread has a base section adjoining or located in the cylindrical portion and an end section radially adjoining the base section. Within at least a part of the course of the thread, at least the end section of the at least one raised portion is made of a material that is more elastic than the material of the cylindrical portion.

Abstract: Integral joint of two pipes which comprises a first box element, equipped with an internal two-step thread, situated on the end of a first pipe, a second pin element, equipped with an external two-step thread, situated on the end of a second pipe, two metal-to-metal seals located at both ends and with at least two shoulders arranged at one end and at the centre of the joint respectively.

Abstract: The tubular connection includes a pin member having external tapered threads extending from a pin nose to a pin base and a box member having internal tapered threads extending from a box base to a box nose. The tapered threads are square or near square threads having stab and load flanks with accommodating grooves. The stab flanks have corner chamfers which engage upon stabbing the pin member into the box member. The comer chamfers increase the clearances between the threads and grooves and guide the crests to the root openings upon relative rotation of the pin and box members. The stab flanks may have an increased thread width at the thread pitch line forming cam flanks which cam the threads into the grooves. The crests and roots of the threads interferingly engage. The pin nose and box base engage to form a metal-to-metal seal and a primary torque shoulder which during power tight make-up causes the load to shift from the stab flanks to the load flanks.

Abstract: A tubular body made of a first metal and having a box end and a connection end, the box end having an internally threaded portion and an internal cylindrical thread-free portion axially outward of the threaded portion, the tool joint further including an anti-fretting section, preferably in the form of a sleeve of a second metal that is snugly received in a counterbore formed in the box end, the sleeve having an internal cylindrical surface having a diameter substantially the same as the internal diameter of the cylindrical thread-free portion of the box end, the second metal having a modulus of elasticity less than the modulus of elasticity of the first metal, the invention further including a drill pipe made by affixing first and second tool joints as described above to first and second opposed ends, respectively, of an elongate pipe body, the pipe body being affixed to the tool joints by a threaded shrink-grip connection, the first tool joint forming a box connection, the second tool joint forming a pin co

Abstract: A thread form for a tubular connection of the type having a pin member adapted to be made-up with a box member to form a pipe joint as shown. The pin member has pin threads with thread crests and thread roots which are adapted to be made-up with a mating box member having a complimentary thread structure. The pin thread crests are formed between a stab flank and a load flank of the pin thread. The pin thread has a multi-facited complex profile stab flank for engaging a mating stab flank on the complimentary box member to provide a wedging interfit between the surfaces of the pin and box threads. The pin and box threads are also helically structured as a wedge.

Abstract: A drill pipe 10 comprises an elongate pipe section 12 having a substantially uniform pipe outer diameter 18 and a substantially uniform pipe inner diameter 20. A pin tool joint 14 is welded at one end to the pipe section, and a box tool joint 16 is welded to the other end of the pipe section. Each of the pin and box tool joints includes a thread for mating engagement and preferably first and second shoulders. The drill pipe has a ratio, R, which takes into consideration the pipe inner diameter, PID, the pipe outer diameter, POD, the tool joint inner diameter, TJID, and the tool joint outer diameter, TJOD. This ratio may be expressed as: R = ( P ID + TJ ID ) ( TJ OD - P OD ) .

Abstract: A pipe fitting in the form of a male coupler and a female coupler both of which have imbedded therein a threaded metallic insert. Both the male coupler and female coupler have a metallic insert that is constructed to define a treacherous path at the surface boundary of the metal insert so as to minimize the possibility of any leakage exteriorly of the coupler from a liquid conducting bore passing through each of the couplers.

Abstract: This invention provides an oil well pipe threaded joint capable of preventing looping and squeezing of a soft synthetic resin ring and consequently, preventing catching of a tool during a logging operation and damage such as corrosion by a corrosive fluid, the oil well pipe threaded joint employs the construction wherein a soft synthetic resin ring is interposed between distal end surfaces of pins, each step surface of a shoulder portion on an inner peripheral side of a coupling and a step surface of each pin are brought into abuttment, and each inside thread of the coupling of the coupling and each outside thread of each pin are engaged, wherein a compressive ratio of the soft synthetic resin ring in an axial direction falls within the range expressed by an inequality 18,000/E≦compressive ratio (%)<0.038−1×1n[1−{(d1−d2)+0.36}/0.