Abstract: A threaded joint for steel pipes comprising a pin 1 and a box 2 each having a contact surface comprising a threaded portion 3 or 4 and an unthreaded metal contact portion 8 is provided with improved anti-galling propertied by forming a lubricating coating on the contact surface of at least one of the pin and the box, the lubricating coating exhibiting a self-repairing function by liquid lubrication and having a decreased greasiness. The lubricating coating is (1) a coating which comprises a lower lubricant layer which is in liquid form in the temperature range of above 0° C. and below 40° C. and an upper lubricant layer which is in solid form at 40° C., or (2) a coating which is semi-solid or solid at 40° C. and is formed of a mixture comprising a lubricating oil which is in liquid form in the temperature range of above 0° C. and below 40° C. and a wax which is in solid form at 40° C., the mixture preferably having been heated so as to liquefy the wax and dissolve in each other the wax and lubricant oil.

Abstract: In a threaded joint for steel pipes which are connected by threaded engagement of a pin member having a tapered male thread, a metal seal-forming portion, and a torque shoulder-forming portion on the end of a pipe, and a box member having a tapered female thread, a metal seal-forming portion, and a torque shoulder forming-portion corresponding to these on the end of a pipe, a buttress thread having contact at the load flanks and the thread root surface and gaps at the thread crest surface and the stabbing flanks is mixed in a single joint with a rugged thread having contact at the load flanks and stabbing flanks and having gaps at the thread root surface and thread crest surface.

Abstract: A threaded pipe joint has a reduced overall diameter at the joint by controlling the thickness of both the box end and pin end. Each of the box and pin ends have defined cross sectional wall thicknesses Sc and Sp1, respectively. Each of Sc and Sp1 are sized as a fraction of the overall pipe cross sectional thickness Sp, the fraction ranging between (0.55-0.79). The box and pin ends can vary in taper from 1/12 to 1/20.

Abstract: A threaded joint for steel pipes comprises a pin (1) and a box (2). The pin has male thread (11), a sealing surface (13), and a shoulder surface (14) located on the end face of the pin. Correspondingly, the box has female thread (21), a sealing surface (23), and a shoulder surface (24) which can mate or contact with the corresponding portions of the pin. The shoulder surface (14) of the pin (1) is provided at an end face of the pin. The sealing surface (13) of the pin (1) is located on a pipe end side near the male thread (11). A a nose portion (15) is provided on the pin (1) between the sealing surface (13) and the shoulder surface (14), the nose portion (15) being not in contact with a corresponding portion of the box (2).

Abstract: A lubricating coating composition in which at least one basic lubricant selected from a basic sulfonate, a basic salicylate, and a basic phenate is dissolved in a volatile solvent is applied to the frictional surface of a box and a pin constituting a threaded joint for oil well pipes. The composition may further contain one or more of a thermoplastic resin powder, another lubricant, and an extreme pressure agent. The surface roughness of the frictional surfaces preferably has an Rmax in the range of 5-40 micrometers.

Abstract: A threaded joint for steel pipes comprising a pin 1 and a box 2 each having a contact surface comprising a threaded portion 3 or 4 and an unthreaded metal contact portion 8 is provided with improved anti-galling propertied by forming a lubricating coating on the contact surface of at least one of the pin and the box, the lubricating coating exhibiting a self-repairing function by liquid lubrication and having a decreased greasiness. The lubricating coating is (1) a coating which comprises a lower lubricant layer which is in liquid form in the temperature range of above 0° C. and below 40° C. and an upper lubricant layer which is in solid form at 40° C., or (2) a coating which is semi-solid or solid at 40° C. and is formed of a mixture comprising a lubricating oil which is in liquid form in the temperature range of above 0° C. and below 40° C. and a wax which is in solid form at 40° C.

Abstract: A threaded joint for steel pipes which is capable of metal-to-metal sealing and which can be subjected to repeated fastening and unfastening without the application of a liquid lubricant containing a heavy metal powder 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 are coated with an undercoating layer and a lubricating coating layer atop it. The undercoating layer is a porous metal coating having a porosity of 5-80% and a thickness of 1-30 &mgr;m and preferably a hardness of 50-250 Hv. The lubricating coating is a solid lubricating coating or a liquid lubricating coating, the latter containing substantially no heavy metal powders. The total thickness of the undercoating layer and the lubricating coating layer is at most 100 &mgr;m.

Abstract: A threaded joint for oil well pipes is provided which can guarantee a joint efficiency sufficient for practical use in deep wells, which has a decreased joint outer diameter, and which has an improved bending resistance, compression resistance, and over-torque resistance which are sufficient for use by the side track technique. It is an integral threaded joint for oil well pipes in which it has a joint efficiency of at least 70%, the outer diameter of the joint is larger than and at most 1.08 times the outer diameter of the oil well pipe bodies, and the threaded portions have a cross section of a trapezoidal shape with a load flank angle (&agr;) of the threads in the range of 0 to −20 degrees and a stabbing flank angle (&thgr;) thereof in the range of 35 to 50 degrees.

Abstract: A threaded joint for oil well pipes is provided which can guarantee a joint efficiency sufficient for practical use in deep wells, which has a decreased joint outer diameter, and which has an improved bending resistance, compression resistance, and over-torque resistance which are sufficient for use by the side track technique.

Abstract: A pipe joint formed by screwing a pin portion having a tapered male thread formed on the outer peripheral surface of the end of a pipe into a box portion having a tapered female thread formed on the inner peripheral surface of the end of a pipe or a short pipe so as to threadingly engage with the tapered male thread, the pipe joint having the following shape: clearance C between thread stab flanks: 0.5-1.0 mm thread stab flank angle &thgr;:  15-60 degrees thread crest surfaces and parallel to the pipe axis thread root surfaces: radius R of stab flank corner  1.0-1.25 mm portions of male thread: In addition, the taper of the incomplete thread portion of the pin portion is preferably 0.96-0.90 times the nominal taper of the complete thread portion.

Abstract: This invention relates to a threaded joint for steel pipes which comprises a pin and a box each having a contact surface including a threaded portion and an unthreaded metal contact portion and which guarantees galling resistance and gas tightness in a stable manner without application of a compound grease. A solid lubricating coating comprising a lubricating powder (e.g., molybdenum disulfide) and an organic or inorganic binder is formed on the contact surface of at least one of the pin and the box. The proportion of area of a cross section along the thickness of the solid lubricating coating which is occupied by secondary particles of the lubricating powder having an equivalent circular diameter of 15-60 &mgr;m is from 5-90%. Alternatively, the solid lubricating coating comprises, in addition to the lubricating powder, a fibrous filler (e.g., inorganic whiskers) in such an amount that the mass ratio of the fibrous filler to the binder is 0.01-0.5.

Abstract: This invention relates to a threaded joint for steel pipes which comprises a pin and a box each having a contact surface including a threaded portion and an unthreaded metal contact portion and which guarantees galling resistance and gas tightness in a stable manner without application of a compound grease. A solid lubricating coating comprising a lubricating powder (e.g., molybdenum disulfide) and an organic or inorganic binder is formed on the contact surface of at least one of the pin and the box. The proportion of area of a cross section along the thickness of the solid lubricating coating which is occupied by secondary particles of the lubricating powder having an equivalent circular diameter of 15-60 &mgr;m is from 5-90%. Alternatively, the solid lubricating coating comprises, in addition to the lubricating powder, a fibrous filler (e.g., inorganic whiskers) in such an amount that the mass ratio of the fibrous filler to the binder is 0.01-0.5.

Abstract: The gap L (mm) which is the smaller of the gap L1 (mm) between the crest 1a of a tapered male thread 1 and the root 2b of a tapered female thread 2, and the gap L2 (mm) between the root 1c of the tapered male thread 1 and the crest 2c of the tapered female thread 2, the load flank angle &agr;(°) and the stab flank angle &bgr;(°), and the axial gap &dgr;(mm) which forms in the widthwise direction and is the difference between the thread ridge width of the tapered male thread 1 and the thread valley width of the tapered female thread 2 threadingly engaged therewith have the following relationship

Abstract: A pipe joint formed by screwing a pin portion having a tapered male thread formed on the outer peripheral surface of the end of a pipe into a box portion having a tapered female thread formed on the inner peripheral surface of the end of a pipe or a short pipe so as to threadingly engage with the tapered male thread, the pipe joint having the following shape: 1 clearance C between thread stab flanks: 0.5-1.0 mm thread stab flank angle &thgr;:  15-60 degrees thread crest surfaces and parallel to the pipe axis thread root surfaces: radius R of stab flank corner  1.0-1.

Abstract: A lubricating coating composition in which at least one basic lubricant selected from a basic sulfonate, a basic salicylate, and a basic phenate is dissolved in a volatile solvent is applied to the frictional surface of a box and a pin constituting a threaded joint for oil well pipes. The composition may further contain one or more of a thermoplastic resin powder, another lubricant, and an extreme pressure agent. The surface roughness of the frictional surfaces preferably has an Rmax in the range of 5-40 micrometers.

Abstract: During conditions of use of a threaded joint comprising a box portion and a pin portion used to threadingly join oil well pipes, the stress acting on the outer surface of the box portion is prevented from exceeding the yield strength of the base metal of the joint, and the occurrence of stress corrosion in the joint portion is prevented. Specifically, the amount of thread interference T is controlled to be at most a specified value calculated as a function of the inner diameter D1 of the pin portion, the thread effective diameter D2 at the basic diameter position, the outer diameter D3 of the box portion, the internal pressure Pi, and the yield strength &sgr;y and Young's modulus E of the base metal. As a result, a threaded joint which is suitable for joining of oil well pipes can be provided.

Abstract: A thread joint for a tube which suppresses galling without deteriorating its sealing performance since a sliding distance L.sub.S which expresses a quantity of spiral sliding of sealing portions relative to each other during a tightening period from the start of a contact between the sealing portions until shoulder portions abut each other satisfies the following relationship:Sliding Distance L.sub.S .ltoreq.-0.0093.times. (Tube Outer Diameter).sup.2 +4.73.times. (Tube Outer Diameter).To shorten the sliding distance L.sub.S, the sealing portion of a box portion is formed shorter than the sealing portion of a pin portion. In this case, a circumferential groove may be formed to discharge a dope. Conversely, the sealing portion of the pin portion is formed shorter than the sealing portion of the box portion. In this case, a precedent-stage unthread portion whose inclination is smaller than that of the sealing portion of the pin portion is formed between a male thread and the sealing portion of the pin portion.

Abstract: A threaded joint for oil well pipes has excellent leak-tightness and a high disconnect torque and can withstand repeated make-ups. At the time of make-up, the load flanks (1) of the male and female threads contact each other, either the crest surfaces (3) or the root surfaces (4) are contacting and the other of the two pairs of surfaces has a gap, and a gap of at most 0.03 mm exists between the stab flanks (2) of the male and female threads.

Abstract: The assembly arrangement according to the invention concerns the tubes which are used primarily in oil industry installations. It permits the sealing assembly of a male end to a female end, each provided with frustoconical screwthreads.The end region of the male component comprises a convex frustoconical sealing surface for providing a metal-metal sealing connection with a surface of the female component, the internal edge of which is connected to the concave frustoconical abutment region and the external edge of which is connected to the external surface of the end region, having a portion parallel to the generatrix which is tangential to the bottom of the threads of the male screwthread. The diameter of the external edge is such that the prolongation of the generatrix which is tangential to the thread bottoms of the male screwthread passes beyond said external edge.Use for the assembly of tubes with male ends by means of female sleeves.