The present invention relates to a method of manufacturing a pipe thread fittings and pipe thread joint, more particularly to a method for producing a threaded joint and a threaded joint for oil well pipes for oil well pipes.
BACKGROUND
[0002]
　For mining oil and natural gas fields, oil well pipe is used. OCTG, depending on the depth of the well is formed by connecting a plurality of steel pipes. Coupling of the steel pipe is performed by screwing the formed pipe thread joint between the ends of the steel pipe. OCTG are lifted for inspection, are unscrewing, after being examined, is again screwing, is used again.
[0003]
　Pipe thread joint comprises a pin and box. Pin includes a male screw portion formed on the outer peripheral surface and an unthreaded metal contact portion of the distal end portion of the steel pipe. Box includes a female threaded portion and an unthreaded metal contact portion formed on the inner peripheral surface of the distal end portion of the steel pipe. Threaded portion and the unthreaded metal contact portions of the pin and box, repeatedly subjected to strong friction at the time of the return screw tightening and screw of the steel pipe. These sites, if there is sufficient resistance to friction, galling when repeated back screw tightening and screw (with irreparable shrink) occurs. Therefore, the Pipe threaded joint, sufficient durability against the friction, i.e., is required to have excellent seizure resistance.
[0004]
　Conventionally, in order to improve the seizure resistance, heavy metal containing the compound grease called dope have been used. By applying a compound grease on the surface of the pipe thread joint, it can improve the seizure resistance of pipe thread fittings. However, heavy metals Pb, Zn and Cu or the like contained in the compound grease is likely to affect the environment. Therefore, development of a pipe thread joint not using compound grease is desired.
[0005]
　WO 2014/042144 (Patent Document 1) proposes a pipe thread joint having excellent galling resistance without the compound grease.
[0006]
　Solid lubricating coating layer-forming composition described in Patent Document 1, in a mixed solvent containing water and a dipolar aprotic solvent, powdery with an at least partially soluble in dipolar aprotic solvents is a composition containing an organic resin. The solid lubricating coating-forming composition of Patent Document 1, the powdery organic resin is present in the dissolved state or dispersed state in a mixed solvent. Thus, without using a compound grease, suppressing the occurrence of rust, you can have excellent seizure resistance, and is described in Patent Document 1.
CITATION
Patent Document
[0007]
Patent Document 1: International Publication No. WO 2014/042144
Summary of the Invention
Problems that the Invention is to Solve
[0008]
　Incidentally, threaded portion and the unthreaded metal contact portions of the pin and box comprises a metal seal portion and the shoulder portion. When screwing the pipe thread joint, shoulder portions of the pin and box are in contact. The torque generated at this time that the shoulder ring torque. The pipe thread fitting when screwing, after reaching shouldering torque, for further screwing until the fastening is complete. Thus, increases airtightness of pipe thread fittings. Further performing screw tightening, the metal constituting at least one of the pin and box begin to undergo plastic deformation. The torque generated at this time that the yield torque.
[0009]
　Engagement completion time of the torque (hereinafter, referred to as the fastening torque) regardless of the magnitude of the thread interference is set such that a sufficient seal surface pressure can be obtained. The difference between the shouldering torque and yield torque (hereinafter, torque that on shoulder resistance [Delta] T ') if there is a sufficient range of the fastening torque becomes large. As a result, it becomes easy to adjust the fastening torque. Therefore, the Pipe threaded joint, in addition to the seizure of the above, high torque on shoulder resistance [Delta] T ', to have That overtorque performance is required.
[0010]
　Since the patent document 1, the torque on shoulder resistance [Delta] T 'is not considered, it may over-torque performance is low.
[0011]
　An object of the present invention is to provide a pipe thread joint and a manufacturing method thereof with high overtorque performance.
Means for Solving the Problems
[0012]
　Pipe thread joint according to the present embodiment is a tube for a threaded joint comprising a pin and box. Pin and box has a contact surface having a threaded portion and an unthreaded metal contact portion. Pipe threaded joint, on at least one of the contact surfaces of the pin and box comprising a solid lubricating coating layer. Solid lubricating coating layer described above, a resin, a solid lubricant powder, Cr 2 O 3 containing a.
[0013]
　Method for manufacturing a pipe thread joint according to the present embodiment, on at least one contact surface of the aforementioned pin and box, comprising forming a solid lubricating coating layer described above.
The invention's effect
[0014]
　Pipe thread joint according to the present embodiment includes a solid lubricant coating layer. Solid lubricating coating layer described above, Cr 2 O 3 containing. Therefore, pipe threaded joint according to the present embodiment has a high over-torque performance.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015]
[1] Figure 1 is a diagram showing the relationship between the rotational speed and torque of the pipe thread fittings.
FIG. 2 is, Cr solid lubricating coating layer 2 O 3 is a graph showing the relationship between the content and the over torque performance.
FIG. 3 is, Cr solid lubricating coating layer 2 O 3 is a graph showing the relationship between the content and the seizure resistance.
FIG. 4 is a diagram showing a configuration of a pipe thread joint of the present embodiment.
FIG. 5 is a cross-sectional view of a pipe thread fittings.
FIG. 6 is a cross-sectional view of the contact surface of the pipe thread joint according to the present embodiment.
FIG. 7 is in the embodiment, is a diagram for explaining a torque on shoulder resistance [Delta] T '.
DESCRIPTION OF THE INVENTION
[0016]
　Hereinafter, with reference to the accompanying drawings, the present embodiment will be described in detail. Its description will not be repeated the same reference numerals designate like or corresponding parts in FIG.
[0017]
　The present inventors have made various investigations on the relationship between the pipe thread joint, an over torque performance and seizure resistance. As a result, the following findings were obtained.
[0018]
　[Overtorque performance]
　when the steel pipes screwing, optimum torque to terminate the screwing is predetermined. Figure 1 is a diagram showing the time of the pipe thread coupling having a shoulder portion and screwing, the relationship between the rotational speed and the torque of the steel pipe. Referring to FIG. 1, when screwing the pipe thread joint, initially, the torque is increased in proportion to the rotational speed. The rate of increase in torque at this time is low. Further if the screw tightening, the shoulder portion come into contact with each other. The torque at this time, that the shoulder ring torque. After reaching shouldering torque, further if the screw tightening torque increases in proportion to the rotation speed again. The rate of increase in torque at this time is high. When the torque reaches a predetermined value (engaging torque), screwing is completed. Torque when the screw tightening, if reached fastening torque, the metal seal portions interfere with each other at the appropriate surface pressure. In this case, it increases the airtightness of the pipe thread fittings.
[0019]
　By carrying out further screwing after reaching the engaging torque, the torque is too high. If too high torque, a portion of the pin and box plastically deformed. The torque at this time that the yield torque. The greater the torque on shoulder resistance [Delta] T 'is the difference between the shouldering torque and yield torque, can afford the range of fastening torque. As a result, it becomes easy to adjust the fastening torque. Thus, the torque on shoulder resistance [Delta] T 'is preferably higher. As used herein, over-torque performance and high, means that the high torque on shoulder resistance [Delta] T '.
[0020]
　To increase the torque on shoulder resistance [Delta] T 'reduces the shouldering torque, or, it is effective to increase the yield torque. Be contained hard particles in a solid lubricant coating layer, yield torque is considered to increase to a high surface pressure time. If Takamare the yield torque, increase the torque on shoulder resistance ΔT '.
[0021]
　However, the present inventors have studied investigated, be simply be contained in the hard particles the solid lubricating coating layer, high torque on shoulder resistance [Delta] T 'is not obtained. For example CaF 2 but is hard particles, as shown in Examples below, CaF 2 in the high torque on shoulder resistance [Delta] T 'is not obtained.
[0022]
　Accordingly, the present inventors have further conducted various studies, Cr in the solid lubricating coating layer 2 O 3 was found that a high torque on shoulder resistance by containing [Delta] T 'is obtained.
[0023]
　2, Cr solid lubricating coating layer 2 O 3 is a graph showing the relationship between the content and the over torque performance. Figure 2 is obtained by the Examples below. The horizontal axis of FIG. 2, Cr solid lubricating coating layer 2 O 3 shows the content of. The vertical axis of FIG. 2 shows the over-torque performance. Incidentally, the over-torque performance, in Test No. 1 in the Examples below, as a relative value the value of the torque on when using the API standard dope shoulder resistance [Delta] T 'as a reference (100) in place of the solid lubricating coating layer I was determined. White circle in FIG. 2 (○) shows the over-torque performance of the embodiment to form a solid lubricating coating layer. Open triangle in FIG. 2 (△) shows the over-torque performance when using the API (American Petroleum Institute) standard doping instead of a solid lubricating coating layer.
[0024]
　From FIG. 2, the solid lubricating coating layer is Cr 2 O 3 when containing, overtorque performance exceeds 100. That, Cr 2 O 3 when containing high overtorque performance.
[0025]
　[Seizure resistance]
　it further, Cr solid lubricating coating layer 2 O 3 by adjusting the content of not only overtorque performance was found that also increased seizure resistance.
[0026]
　3, Cr solid lubricating coating layer 2 O 3 is a graph showing the relationship between the content and the seizure resistance. Figure 3 is obtained by the Examples below. The horizontal axis of FIG. 3, Cr solid lubricating coating layer 2 O 3 shows the content of. The vertical axis of FIG. 3 shows a number of possible fastening without adhere baked (times).
[0027]
　From FIG 3, Cr 2 O 3 as long as 1.0 to 20.0 mass% content, the number that could be concluded without adhere baked exceeds 10 times. That, Cr 2 O 3 When the content is 1.0-20.0 wt%, high seizure resistance can be obtained.
[0028]
　Pipe thread joint according to the present embodiment has been completed based on the above findings includes the following features. Pipe thread joint comprises a pin and box. Pin and box has a contact surface having a threaded portion and an unthreaded metal contact portion. Pipe threaded joint, on at least one of the contact surfaces of the pin and box comprising a solid lubricating coating layer. Solid lubricating coating layer described above, a resin, a solid lubricant powder, Cr 2 O 3 containing a.
[0029]
　Pipe thread joint of the present embodiment, Cr in the solid lubricating coating layer 2 O 3 containing. Therefore, having a high over-torque performance.
[0030]
　In the solid lubricating coating layer described above, Cr 2 O 3 content of is preferably 1.0 to 20.0 mass%.
[0031]
Cr 　solid lubricating coating layer 2 O 3 as long as 1.0 to 20.0 mass% content of, increases galling resistance of a solid lubricating coating layer.
[0032]
　Solid lubricating coating layer described above, 1.0-20.0 mass% of Cr 2 O 3 , 50.0 ~ 90.0% by weight of the resin, and, 5.0 to 30.0 wt% of solid lubricant powder it may contain.
[0033]
　Preferably, the resin described above, an epoxy resin, a phenol resin, furan resin, polyamide-imide resins, polyamide resins, polyimide resins, and is one or more selected from the group consisting of polyetheretherketone resin.
[0034]
　In this case, further increases the over-torque performance and seizing resistance of a solid lubricating coating layer.
[0035]
　Above resins, epoxy resins, phenol resins, polyamide-imide resins, and polyamide resins, may be one or more selected from the group consisting of.
[0036]
　Preferably, the solid lubricant powder described above, graphite, zinc oxide, boron nitride, talc, molybdenum disulfide, tungsten disulfide, graphite fluoride, tin sulfide, bismuth sulfide, organic molybdenum, thiosulfate compounds, polytetrafluoroethylene and, it is one or more selected from the group consisting of melamine cyanurate.
[0037]
　Preferably, the solid lubricant powder described above, at least one selected from the group consisting of graphite and polytetrafluoroethylene.
[0038]
　In this case, further increases the over-torque performance and seizing resistance of a solid lubricating coating layer.
[0039]
　Method for manufacturing a pipe thread joint according to the present embodiment includes a coating step, and a solidifying step. The coating step, on at least one contact surface of the aforementioned pin and box, a resin, a solid lubricant powder and Cr 2 O 3 coating a composition containing a. The solidification step, and solidifying the applied composition on the contact surface to form a solid lubricating coating layer.
[0040]
　Above manufacturing method further comprises, prior to the coating step may comprise Zn alloy plating layer forming step. The Zn alloy plating layer forming step, on at least one of the contact surfaces of the pin and box to form a Zn alloy plating layer by electroplating.
[0041]
　Above manufacturing method further comprises, prior to the Zn alloy plating layer forming step may comprise a surface roughness-forming step. The surface roughness-forming step, on at least one of the contact surfaces of the pin and box to form a surface roughness.
[0042]
　It will be described in detail a method for manufacturing a pipe thread fittings and pipe thread joint according to the present embodiment.
[0043]
　[Pipe thread fittings]
　pipe thread joint comprises a pin and box. Figure 4 is a diagram showing a configuration of a pipe thread joint of the present embodiment. Pipe threaded joint 1 is provided with a steel pipe 2, and a coupling 3. At both ends of the steel pipe 2 is pin 5 having a male screw portion 4 on the outer surface is formed. On both sides of the coupling 3, box 8 having an internally threaded portion 7 on the inner surface is formed. By screwing the pin 5 and the box 8, the end of the steel pipe 2, it is mounted coupling 3. Although not shown, the pin 5 and box 8 of the coupling 3 of the steel pipe 2 that mating member is not attached, to protect the respective threaded portion, in some cases protector (not shown) is attached .
[0044]
　Typical pipe thread joint 1, as shown in FIG. 4, and a steel pipe 2 and the coupling 3, a coupling scheme. On the other hand, without using a coupling 3, one end of the steel pipe 2 and pin 5, also pipe thread joint of integral scheme in which the other end with the box 8. Pipe thread joint 1 of the present embodiment is applicable to any of the coupling type and integral type.
[0045]
　Pin and box has a contact surface having a threaded portion and an unthreaded metal contact portion. Figure 5 is a cross-sectional view of the threaded joint 1 for tubes. Pin 5 is provided with a male screw portion 4 and an unthreaded metal contact portion. Unthreaded metal contact portions of the pin 5 is formed on the tip of the pin 5, and a metal seal part 10 and the shoulder portion 11. Box 8 is provided with a female screw portion 7 and the unthreaded metal contact portion. Unthreaded metal contact portion of the box 8, formed at the tip of the box 8, and a metal seal part 13 and the shoulder portion 12. A pin 5 and the box 8 the portion contacting when screwing, that the contact surfaces 6,9. Specifically, when the pin 5 and the box 8 screwing, shoulder portions (shoulder portions 11 and 12), the metal seal portions (metal seal part 10 and 13), and, threaded portions (male screw portion 4 and internal thread portion 7) are in contact with each other. That is, in FIG. 5, the pin 5 side contact surfaces 6, the shoulder portion 11, a metal seal part 10 and includes a threaded portion 4. Contact surface 9 of the box 8 side, the shoulder portion 12, the metal seal part 13, and includes a threaded portion 7. In Figure 5, the pin 5, the shoulder portion 11 from the distal end of the steel pipe 2, including each configuration in the order of the metal seal part 10 and the male screw portion 4. Further, the box 8 is, from the tip of the steel pipe 2 or the coupling 3 comprises the constituent in the order of the female screw portion 7, the metal seal part 13 and the shoulder portion 12. However, placement of the shoulder portions 11 and 12, a metal seal part 10, 13 and the threaded portion 4 and 7 is not limited to FIG. Assignment of each component is appropriately adjusted.
[0046]
　[Solid lubricating coating 21]
　Pipe threaded joint 1, on at least one contact surface 6,9 of the pin 5 and box 8 comprises a solid lubricating coating layer. Figure 6 is a cross-sectional view of the contact surfaces 6,9 of the pipe thread joint 1 according to the present embodiment. Solid lubricating coating layer 21, as the manufacturing method described later, to a composition for forming a solid lubricating coating layer 21, it is coated on at least one contact surface of the pin 5 and box 8 6,9, solidifies in is formed.
[0047]
　Solid lubricating coating layer 21 includes a resin, a solid lubricant powder, Cr 2 O 3 containing a. Thus, even a composition for forming a solid lubricating coating layer 21, a resin, a solid lubricant powder, Cr 2 O 3 containing a. Composition, solventless type composition (i.e., only contains the aforementioned components) even may be a composition of the solvent type dissolved in a solvent. For the solvent-type composition, the weight percent of each component refers to the weight% in the case where the mass of the total of all components other than the solvent contained in the composition is 100%. That is, the content of each component in the composition, the content of each component in the solid lubricating coating layer 21 is the same. Also, each component other than the solvent in the composition, the components of the solid lubricating coating layer 21 is the same. Hereinafter also referred to simply as "composition" a composition for forming a solid lubricating coating layer 21.
[0048]
　It described in detail below each component.
[0049]
　[Resin]
　Resin has a function as a binder. Resin may be selected known ones.
[0050]
　Resins, for example, a one or two kinds selected from the group consisting of thermosetting resins and thermoplastic resins. Thermosetting resin, for example, is one or more selected from the group consisting of epoxy resins, phenol resins, furan resins and polyimide resins. Thermoplastic resins, for example, is one or more selected from the group consisting of polyamide-imide resin, polyamide resin and polyether ether ketone resin.
[0051]
　Preferably, the resin is an epoxy resin, phenol resin, furan resin, polyamide-imide resins, polyamide resins, polyimide resins, and is one or more selected from the group consisting of polyetheretherketone resin. These resins have a suitable hardness. Therefore, wear of the solid lubricant coating layer 21, seizing resistance, and over torque performance further enhanced.
[0052]
　More preferably, the resin is an epoxy resin, phenol resin, furan resin, polyamide-imide resin, and is one or more members selected from the group consisting of polyamide resins.
[0053]
　Particularly preferably, the resin is an epoxy resin, a polyamide-imide resin, and is one or more members selected from the group consisting of polyamide resins.
[0054]
　Epoxy resins are thermosetting resins. Epoxy resins, when the thermosetting treatment, the epoxy groups remaining in the polymer, crosslinking networking. Accordingly, the epoxy resin is cured.
[0055]
　Polyamide-imide resin is a thermoplastic resin.
[0056]
　Polyamide resin is a thermoplastic resin. Polyamide resins are polymers that many monomers by an amide bond was Deki bound.
[0057]
　The content of the resin solid lubricating coating layer 21 is preferably 50.0 to 90.0 wt%. When the content of the binder is more than 60.0 mass%, further enhanced adhesion of the solid lubricating coating layer 21. Therefore, the lower limit of the content of the resin solid lubricating coating layer 21 is more preferably 60.0 wt%, more preferably 64.0 wt%, more preferably from 70.0% by weight. The upper limit of the content of the resin solid lubricating coating layer 21 is more preferably 85.0 wt%, more preferably 80.0 wt%, more preferably from 75.0% by weight.
[0058]
　[Solid lubricant powder]
　solid lubricating coating layer 21, to further enhance the lubricity of the solid lubricant coating layer 21, containing a solid lubricant powder. The solid lubricant powder is a solid powder with lubricity. Solid lubricant powder can be used known ones.
[0059]
　Lubricants, for example, is roughly classified into the following five types. Solid lubricant powder contains at least one selected from the group consisting of the following (1) to (4).
　(1) slippery specific crystal structure, for example, shows the lubricity by having a hexagonal layered crystal structure (e.g., graphite, zinc oxide, boron nitride and talc),
　reactive addition to
　(3)(2) shows the lubricity by a chemical reactivity (e.g., thiosulfate
　compounds), (4) shows the lubricity by plastic or viscoplastic behavior under frictional stresses (e.g., polytetrafluoroethylene (PTFE), and melamine cyanurate (MCA)),
　and, (5) a liquid or grease form, shows the lubricity by present in the boundary of the contact surface prevent direct contact between the surface and the surface (e.g., perfluoro et Ether (PFPE)).
[0060]
　Either solid lubricating powder of the above-described (1) to (4) can also be used. Solid lubricant powder, any of the above (1) to (4) may be used alone. For example, it may be used alone (1) a solid lubricant powder. Solid lubricant powder may be used in combination of a plurality of the above (1) to (4). For example, in addition to the above (1), may be used in combination (4). In other words, preferably, the solid lubricating powder is graphite, zinc oxide, boron nitride, talc, molybdenum disulfide, tungsten disulfide, graphite fluoride, tin sulfide, bismuth sulfide, organic molybdenum, thiosulfate compounds, polytetrafluoro ethylene (PTFE), and is one or more selected from the group consisting of melamine cyanurate (MCA).
[0061]
　Preferably, the solid lubricant powder contains one or more selected from the group consisting of the above (1) and (4). The solid lubricant powder (1), graphite is preferred from the viewpoint of adhesion and corrosion resistance of a solid lubricating coating layer 21, earthy graphite is preferred from the viewpoint of film formability. Polytetrafluoroethylene as a lubricant additive (4) (PTFE) is preferred.
[0062]
　More preferably, the solid lubricant powder is a polytetrafluoroethylene (PTFE).
[0063]
　The content of solid lubricant powder of the solid lubricant coating layer 21 is preferably 5.0 to 30.0 wt%. When the content of solid lubricant powder is 5.0 mass% or more, further enhanced seizure resistance. Therefore, the number of times that can return screw tightening and screw without causing seizure increases. The lower limit of the content of solid lubricant powder is more preferably 10.0 mass%, still more preferably 15.0 mass%. On the other hand, if is less than 30.0 mass% content of the solid lubricant powder, further increases the strength of the solid lubricating coating layer 21. Therefore, wear of the solid lubricant coating layer 21 is suppressed. The upper limit of the content of solid lubricant powder is more preferably 28.0 wt%, more preferably 25.0 wt%, more preferably from 20.0% by weight.
[0064]
[Cr 2 O 3
　] Cr 2 O 3 may also be referred to as chromium oxide (III). Cr 2 O 3 is an inorganic compound. Cr 2 O 3 wherein the amount of is 151.99. Cr 2 O 3 is obtained by thermal decomposition of ammonium dichromate (ammonium dichromate). Cr 2 O 3 is the sublimation purification, the dark green metallic luster crystals. Cr 2 O 3 is a very stable, harder than quartz. Cr 2 O 3 , the toxicity and is not a danger.
[0065]
　As described above, the solid lubricant coating layer 21 is Cr 2 O 3 when containing, increases over torque performance. Cr 2 O 3 content is more if 1.0 to 20.0 mass%, also increased seizure resistance.
[0066]
Cr 　solid lubricating coating layer 21 2 O 3 content is preferably 1.0 to 20.0 mass%. Cr 2 O 3 When the content is 1.0 mass% or more, sufficient overtorque performance can be obtained and, also increased seizure resistance. Cr 2 O 3 When the content is less than 20.0 mass%, an increase and a decrease in friction strength of the solid lubricant coating layer 21 is suppressed, increased seizure resistance is. Cr 2 O 3 lower limit of the content is preferably 1.0 mass%, more preferably from 5.0 mass%, more preferably from 7.0 mass%, more preferably 10.0 wt% it is. Cr 2 O 3 the upper limit of the content is preferably 20.0 mass%, more preferably from 18.0% by weight, more preferably from 16.0 wt%, more preferably 15.0 wt% it is.
[0067]
　Cr 2 O 3 , for example, a dark green particles. Cr 2 O 3 preferred particle size is 45μm or less. More preferably from the viewpoint of uniform dispersibility it is 10μm or less. Particle size is the arithmetic mean value of the effective size distribution obtained by particle size distribution measurement by laser diffraction scattering method (Shimadzu SALD series). Cr 2 O 3 A preferred lower limit of the particle diameter of, for example, a 1 [mu] m.
[0068]
　Cr 2 O 3 , for example, a chromium oxide Wako Pure Chemical Industries, Ltd. (III).
[0069]
　Other Components
　solid lubricating coating layer 21, other known anti-rust additives, may contain a preservative or the like.
[0070]
　[Rust Additives
　solid lubricating coating layer 21 is required to have a rust resistant over a long period until it is actually used. Therefore, the solid lubricating coating layer 21 may contain a rust-preventive additive. The rust-preventive agent, is a general term for additives having corrosion resistance. Antirust additives, for example, contains at least one selected from the group consisting of aluminum tripolyphosphate, phosphorous acid Aruminimu and calcium ion exchange silica. Preferably, rust-preventive agent contains at least one selected from the group consisting of calcium ion exchange silica and phosphorous acid aluminum. As rust-preventive agents, such as other commercially available reactive water repellent may also be used.
[0071]
　The content of the rust-preventive agent in the solid lubricating coating layer 21 is preferably 2 to 10 mass%. When the content of the rust-preventive additive is 2 mass% or more, rust of the solid lubricating coating layer 21 is further increased in a stable manner. On the other hand, if the 10% by weight or less content of rust-preventive agents, lubricity of the solid lubricant coating layer 21 is increased in a stable manner. The content of the rust-preventive additive, if it exceeds 10 wt%, antirust effect is saturated.
[0072]
　[Preservative]
　solid lubricating coating layer 21 may further contain a preservative. Preservatives also a generic term for additives having corrosion resistance.
[0073]
　[The thickness of the solid lubricating coating]
　The thickness of the solid lubricating coating layer 21 is preferably 10 ~ 40 [mu] m. When the thickness of the solid lubricating coating layer 21 is 10μm or more, it is possible to stably obtain a high lubricity. On the other hand, the thickness of the solid lubricating coating layer 21 is not more 40μm or less, adhesion of the solid lubricating coating layer 21 is stabilized. Further, the thickness of the solid lubricating coating layer 21 is not more 40μm or less, the thread tolerance of the sliding surface (clearance) widens, surface pressure during sliding is low. Therefore, it is possible to suppress the fastening torque becomes excessively high. Therefore, the thickness of the solid lubricating coating layer 21 is preferably 10 ~ 40 [mu] m.
[0074]
　The thickness of the solid lubricating coating layer 21 is measured by the following method. For four places of contact surfaces 6, 9 to form a solid lubricant coating layer 21, Helmut Fischer GmbH made, using the eddy current phase film thickness meter PHASCOPE PMP910, to measure the thickness of the solid lubricating coating layer 21. Measurement is carried out in a way that conforms to the ISO (International Organization for Standardization) 21968 (2005). Measurement points, 4 points in the circumferential direction of the pipe of the pipe thread joint 1 is (0 °, 90 °, 180 °, 4 positions of 270 °). The arithmetic mean of the measurement results, the thickness of the solid lubricating coating layer 21.
[0075]
　Solid lubricating coating layer 21 may be a single layer or a multilayer. The multilayer, refers to a state in which the solid lubricant coating layer 21 are stacked two or more layers from the contact surface side. By repeating the solidified coating composition, a solid lubricating coating layer 21 can be formed of two or more layers. Solid lubricating coating layer 21 may be formed directly on the contact surface may be formed after the surface treatment to be described later.
[0076]
　[Preform pipe thread fittings]
　composition of the base material of the pipe thread joint 1 is not particularly limited. Matrix, for example, a carbon steel, stainless steel and alloy steel. Among alloy steels, Cr, high-alloy steel such as duplex stainless steels and Ni alloy containing alloy elements such as Ni and Mo has a high corrosion resistance. Therefore, the use of these high alloy steel base material, in a corrosive environment containing hydrogen sulfide and carbon dioxide, resulting excellent corrosion resistance.
[0077]
　[Manufacturing Method]
　Hereinafter, a method for manufacturing a pipe thread joint 1 according to the present embodiment.
[0078]
　Method for manufacturing a pipe thread joint 1 according to the present embodiment includes a solid lubricant coating layer forming step. The solid lubricating coating layer forming step, on at least one contact surface of the pin 5 and box 8 to form a solid lubricant coating layer 21.
[0079]
　[Solid lubricating coating layer forming step]
　The solid lubricating coating step includes a coating step and curing step. The coating step, on at least one contact surface of the pin 5 and box 8, the solid lubricating coating-forming composition (also simply referred to as composition) is coated. The solidification step, and solidifying the applied composition on the contact surface to form a solid lubricant coating layer 21.
[0080]
　First, to produce a solid lubricating coating-forming composition. Solid lubricating coating composition for forming the resin, solid lubricant powder and Cr 2 O 3 containing. The composition of solventless type, for example, by heating the resin to a molten state, a solid lubricating powder and Cr 2 O 3 can be produced by kneading added. All components of the powder mixture obtained by mixing a powder or as a composition.
[0081]
　The solvent-type composition, for example, in a solvent, a resin, a solid lubricant powder and Cr 2 O 3 can be produced by mixing by dissolving or dispersing the. The solvent may, for example, water, various alcohols, and an organic solvent. The proportion of the solvent is not particularly limited. The proportion of the solvent may be adjusted to correct viscosity depending on the application method. The proportion of the solvent, for example, in the case where the sum of all components except solvent is 100 mass%, 30 to 50 mass%.
[0082]
　[Coating Step]
　In the coating step is applied on the contact surfaces 6,9 of the composition in a known manner.
[0083]
　For solventless type composition can be applied to the composition using a hot melt method. The hot melt method, by heating the composition of the resin is melted, and the flow state of low viscosity. The composition in a fluid state, is carried out by spraying from the spray gun having a temperature maintaining function. The composition is melted by heating in a tank equipped with a suitable stirring device, is supplied to the spray head of the spray gun via a metering pump (maintained at a predetermined temperature) by a compressor, it is sprayed. Holding temperature in the spray head tank is adjusted according to the melting point of the resin in the composition. Coating method, instead of the spray coating, or a brushing and dipping. The heating temperature of the composition is preferably in a 10 ~ 50 ° C. temperature higher than the melting point of the resin. When applying the composition, at least one contact surface 6,9 ​​of the pin 5 and box 8 which the composition is applied, it is preferable to heat higher than the melting point of the resin temperature. Thereby it is possible to obtain a good coverage.
[0084]
　For the solvent-type composition, the composition became a solution state is applied on the contact surface by spray coating. In this case, the composition, under normal temperature and normal pressure environments, to adjust the viscosity to allow spray application.
[0085]
　[Solidification step]
　In solidifying step, and solidifying the applied composition on the contact surface to form a solid lubricant coating layer 21.
[0086]
　For solventless type composition, by cooling the applied composition on the contact surfaces 6,9, the solid lubricating coating 21 is formed composition in a molten state is solidified. Cooling method can be carried out in known manner. Cooling method, for example, an air cooling and air cooling.
[0087]
　For the solvent-type composition, by drying the applied composition to contact surfaces 6 and 9, the solid lubricating coating 21 is formed composition solidifies. Drying method can be carried out in known manner. Drying method is, for example, natural drying, low-temperature air drying and vacuum drying.
[0088]
　Solidification step may be carried out by rapid cooling of the nitrogen gas and carbon dioxide gas cooling systems. When carrying out the rapid cooling, indirectly cooling from the opposite surface of the contact surface 6 and 9 (the outer surface of the steel pipe 2 or the coupling 3 when the box 8, the inner surface of the steel pipe 2 in the case of pin 5). This can suppress the deterioration due to rapid cooling of the solid lubricating coating layer 21.
[0089]
　Solid lubricating coating layer 21 to cover all of the at least one contact surface 6,9 ​​of the pin 5 and box 8 are preferred. Solid lubricating coating layer 21, part of the contact surface 6,9 ​​only (e.g., a metal seal part 10 and 13 only) may be coated.
[0090]
　Method for manufacturing a pipe thread joint 1 according to the present embodiment further before the solid lubricating coating layer formation step may include a Zn alloy plating layer forming step. Zn alloy plating layer forming step, prior to the solid lubricating coating layer forming step, that is, performed prior to said coating step. The Zn alloy plating layer forming step, on at least one contact surface of the pin 5 and box 8, to form a Zn alloy plating layer by electroplating.
[0091]
　[Zn alloy plating layer forming step]
　In the Zn alloy plating layer forming step, on at least one contact surface of the pin 5 and the box 8, to form a Zn alloy plating layer by electroplating.
[0092]
　Or, in the Zn alloy plating layer forming step, on at least one contact surface of the pin 5 and the box 8, or, on the formed surface roughness on the contact surface to form a Zn alloy plating layer by electroplating.
[0093]
　By carrying out Zn alloy plating layer forming step, it increases the seizure resistance and corrosion resistance of pipe thread joint 1. Zn alloy plating layer forming step, for example, a single-layer plating treatment with Zn metal, two-layer plating of Zn and Ni layers, and a three-layer plating treatment with Zn layer and the Cu layer and the Sn layer. For steel pipe 2 Cr content is 5% or more steel, Zn-Co alloy plating, Cu-Sn-Zn alloy plating, and, Zn-Ni alloy plating process is preferred.
[0094]
　Electroplating process can be carried out in a known manner. For example, to prepare a plating bath containing ions of the metal element contained in the Zn alloy plating layer. Next, immersed in the plating bath of at least one of the contact surfaces 6,9 of the pin 5 and box 8. By energizing the contact surfaces 6, 9, Zn alloy plating layer is formed on the contact surface. Conditions such as temperature and plating time of the plating bath can be appropriately set.
[0095]
　More specifically, for example, the case of forming a Cu-Sn-Zn alloy plating layer, a plating bath containing copper ions, tin ions and zinc ions. The composition of the plating bath is preferably, Cu: 1 ~ 50g / L , Sn: 1 ~ 50g / L and Zn: a 1 ~ 50g / L. Conditions of electroplating, for example, plating bath pH: 1 ~ 10, the plating bath temperature: 60 ° C., a current density: 1 ~ 100A / dm 2 and the treatment time: 0.1-30 minutes.
[0096]
　When forming a Zn-Ni alloy plating layer, a plating bath containing zinc ions and nickel ions. The composition of the plating bath is preferably, Zn: 1 ~ 100g / L and Ni: a 1 ~ 50g / L. Conditions of electroplating, for example, plating bath pH: 1 ~ 10, the plating bath temperature: 60 ° C., a current density: 1 ~ 100A / dm 2 and the treatment time: 0.1-30 minutes.
[0097]
　Hardness of Zn alloy plating layer is preferably 300 or more in Vickers. If the hardness of the Zn alloy plating layer is more than 300, more stable increase in the corrosion resistance of the pipe thread joint 1.
[0098]
　Hardness of Zn alloy plating layer can be measured as follows. In the obtained Zn alloy plating layer pipe thread fittings 1, selects an arbitrary area five locations. In each selected regions, to measure Vickers hardness (HV) in compliance with JIS Z2244 (2009). Test conditions, the test temperature was room temperature (25 ° C.), the test force and 2.94 N (300 gf). The average of the values ​​obtained (total of five), defined as the hardness of the Zn alloy plating layer.
[0099]
　For multilayer plating, the lowermost plated layer is preferably less than the thickness 1 [mu] m. The film thickness of the plating layer (in the case of multilayer plating total thickness) is preferably set to 5 ~ 15 [mu] m.
[0100]
　The thickness of the Zn alloy plating layer is measured as follows. On the contact surface to form a Zn alloy plating layer, ISO (International Organization for Standardization) 21968 contacting a probe of an eddy current phase type film thickness measuring device that conforms to the (2005). A high frequency magnetic field on the input side of the probe, thereby measuring the phase difference between the eddy currents on the Zn-Ni alloy plating layer is excited. Converting the phase difference in the thickness of the Zn alloy plating layer.
[0101]
　The manufacturing method of this embodiment pipe thread joint 1 by further comprising, prior to Zn alloy plating layer forming step, on at least one contact surface of the pin 5 and box 8 to form a surface roughness, the surface roughness formation step it may be provided.
[0102]
　[Surface Roughness forming step]
　The surface roughness-forming step, on at least one contact surface of the pin 5 and box 8 to form a surface roughness. Surface roughness, arithmetic average roughness Ra of 1 ~ 8 [mu] m, and a maximum height roughness Rz is preferably 10 ~ 40 [mu] m. If the arithmetic average roughness Ra is 1μm or more and a maximum height roughness Rz of 10μm or more, further enhanced adhesion of the solid lubricating coating layer 21. If the arithmetic average roughness Ra is less and the maximum height roughness Rz 8 [mu] m 40 [mu] m or less, the friction is suppressed, damage and peeling of the solid lubricating coating layer 21 is suppressed.
[0103]
　Maximum height roughness Rz and the arithmetic average roughness Ra as referred to herein, on the basis of JIS B0601 (2013), it is measured. Measured using the SII Nano Technology Inc. scanning probe microscope SPI3800N. Measurement conditions, in the region of 2 [mu] m × 2 [mu] m samples as a unit of the number of acquired data, which is acquired data number 1024 × 1024. Reference length is set to 2.5 mm. As the maximum height roughness Rz is large, it increases the contact area between the solid lubricating coating layer 21. Therefore, adhesion between the solid lubricating coating 21 is increased by an anchor effect. If adhesion of the solid lubricating coating layer 21 is Takamare, further enhanced seizure resistance pipe thread joint 1.
[0104]
　Surface roughness of the contact surfaces 6,9 of the pipe thread fittings 1 is typically the maximum height roughness Rz of about 3 ~ 5 [mu] m. If moderately large surface roughness of the contact surfaces 6,9, adhesion of the film to be formed thereon (solid lubricating coating layer 21 or Zn alloy plating layer) is increased. As a result, further enhanced seizure resistance and corrosion resistance of pipe thread joint 1. Accordingly, the contact surfaces 6,9 before the composition for forming a solid lubricating coating layer 21 described above is applied, it is preferable to carry out surface roughness-forming step. The surface roughness-forming step, for example, sandblasting, at least one member selected from the group consisting of pickling and chemical conversion treatment.
[0105]
　[Sandblasting]
　sandblasting process is a process of projecting the contact surfaces 6, 9 in a mixture of blasting material and (abrasive) and compressed air. Blasting material, for example, a spherical shots and angular grid material. The sandblasting can be increased the surface roughness of the contact surfaces 6,9. Sandblasting can be carried out by known methods. For example, compressing the air in the compressor is mixed with compressed air and blasting material. The material of the blasting material are, for example, stainless steel, aluminum, ceramic and alumina. Conditions of the projection speed of the sandblasting can be appropriately set.
[0106]
　[Pickling]
　pickling process is a process for roughening sulfuric, hydrochloric, strong acids solution such as nitric acid or hydrofluoric acid, the contact surface by immersing the contact surfaces 6,9. This allows increasing the surface roughness of the contact surfaces 6,9.
[0107]
　[Chemical conversion treatment]
　conversion process is a process for forming a conversion coating of a large porous surface roughness. Chemical conversion treatment, for example, phosphate chemical conversion treatment, a oxalate chemical conversion treatment, and borate chemical conversion treatment. From the viewpoint of the solid lubricating coating 21 adhesion, phosphate chemical conversion treatment. Phosphate chemical conversion treatment, for example, a phosphate chemical conversion treatment with manganese phosphate, zinc phosphate, iron phosphate, manganese or zinc phosphate calcium.
[0108]
　Phosphate chemical conversion treatment can be carried out in known manner. The treatment liquid, an acidic phosphate chemical conversion treatment solution for general galvanized material can be used. For example, mention may be made of phosphate ions 1 ~ 150 g / L, zinc ion 3 ~ 70 g / L, nitrate ions 1 ~ 100 g / L, the zinc phosphate-based chemical conversion treatment containing nickel ions 0 ~ 30g / L. Manganese phosphate-based chemical conversion treatment solution which is commonly used pipe thread joint 1 can also be used. Liquid temperature, for example, a 100 ° C. from room temperature. The treatment time can be appropriately set according to the desired film thickness, for example, 15 minutes. To cause formation of a conversion coating, before phosphate chemical conversion treatment, it may be subjected to surface adjustment. Surface conditioning is the process of immersion in an aqueous solution for surface conditioning comprising a colloidal titanium. After phosphate chemical conversion treatment, from the washing or hot water, it is preferably dried.
[0109]
　Conversion coating is porous. Therefore, by forming a solid lubricating coating layer 21 on the conversion coating, by a so-called "anchor effect", further enhanced adhesion of the solid lubricating coating layer 21. The preferred thickness of the phosphate coating is 5 ~ 40 [mu] m. When the thickness of the phosphate coating 5μm or more, sufficient corrosion resistance can be ensured. If the 40μm or less the thickness of the phosphate coating, adhesion of the solid lubricating coating 21 is increased in a stable manner.
[0110]
　The surface roughness-forming step may be carried out only one type of treatment, or may be a combination of a plurality of processes. When carrying out one type of treatment, it is preferable to perform sandblasting, a process selected from the group consisting of pickling and phosphate chemical conversion treatment. The surface roughness-forming step may be performed two or more kinds of processing. In that case, for example, a phosphate salt chemical conversion treatment may be performed after the sandblasting. After performing the surface roughness-forming step to form a solid lubricant coating layer 21. This can further enhance the adhesion of the solid lubricating coating layer 21.
[0111]
　[Trivalent chromate treatment]
　When carrying out the above-described Zn alloy plating, before the after the A in the solid lubricating coating layer forming step of Zn alloy plating layer forming step may be performed a trivalent chromate treatment. The trivalent chromate treatment, is a film of chromate trivalent chromium. Film formed by the trivalent chromate treatment suppresses white rust on the surface of the Zn alloy plating layer. Thus, product appearance is improved (white rust of Zn alloy plating layer is not a rust pipe thread joint 1 matrix. Therefore, not give influence on the seizure resistance and corrosion resistance of pipe thread fittings 1). By forming the solid lubricating coating layer 21 on the film by trivalent chromate, further enhanced adhesion of the solid lubricating coating layer 21.
[0112]
　Trivalent chromate treatment can be carried out in a known manner. For example, spray coating immersion or chromate treatment solution to chromate treatment solution at least one contact surface 6,9 ​​of the pin 5 and box 8 to the contact surface 6,9. Thereafter rinsing the contact surfaces 6,9. Alternatively, the contact surfaces 6 and 9 were immersed into the chromate treating solution, rinsed with water after the energization. Alternatively, a chromate treatment liquid is applied to the contact surfaces 6 and 9, heating and drying. Processing conditions trivalent chromate can be appropriately set.
[0113]
　The thickness of the trivalent chromate film can be measured by the same method as the solid lubricant coating layer 21.
[0114]
　The pipe thread fitting 1 of the manufacturing method of this embodiment, the solid lubricating coating layer forming step at least one contact surface 6,9 ​​of the pin 5 and box 8 may be performed. That, Zn alloy plating layer forming step, a surface roughness-forming step and trivalent chromate treatment may be as the same process with the pin 5 and the box 8, the different processing between the pin 5 and the box 8 may be carried out .
Example
[0115]
　Hereinafter, an embodiment of the present invention. However, the invention is not intended to be limited by the examples. In embodiments, the contact surface of the pin the pin surface, the contact surface of the box as the box surface. The% in the examples, unless otherwise specified, refers to mass%.
[0116]
　In this embodiment, a VAM21 (registered trademark) manufactured by Nippon Steel Sumitomo Metals Corporation. VAM21 (R) outer diameter: 177.80mm (7 inches), a pipe thread joint thick 11.506mm (0.453 inches). Steel species, was 13Cr steel. The composition of 13Cr steel, C: 0.19%, Si: 0.25%, Mn: 0.8%, P: 0.02%, S: 0.01%, Cu: 0.04%, Ni: 0.10%, Cr: 13.0%, Mo: 0.04%, balanced by Fe and impurities.

WE claims

[Requested item 1]
　A pipe thread joint comprising a pin and box,
　the pin and the box has a contact surface having a threaded portion and the unthreaded metal contact portions,
　a threaded joint for the tube, at least one of the said pin and said box comprising a solid lubricating coating on the contact surface,
　the solid lubricant coating layer,
　the resin and,
　a solid lubricant powder,
　Cr 2 O 3 containing a tube screw joint.
[Requested item 2]
　A pipe thread joint according to claim 1,
　wherein the solid lubricant coating
　layer, the Cr 1.0 to 20.0 mass% 2 O 3 containing, Pipe threaded joint.
[Requested item 3]
　A pipe thread joint according to claim 2,
　wherein the solid lubricant coating layer
　is 1.0 to the Cr of 20.0 wt% 2 O 3 and,
　50.0 ~ 90.0% of the resin ,
　containing said solid lubricant powder of 5.0 to 30.0 wt%, pipe threaded joint.
[Requested item 4]
　A pipe thread joint according to any one of claims 1 to 3,
　wherein the resin is an epoxy resin, phenol resin, furan resin, polyamide-imide resins, polyamide resins, polyimide resins, and polyether ether one or two or more kinds, pipe threaded joint selected from the group consisting of ketone resin.
[Requested item 5]
　A pipe thread joint according to claim 4,
　wherein the resin is an epoxy resin, phenol resin, polyamide imide resin, and is one or more selected from polyamide resins, consisting of the group, the pipe threaded joint .
[Requested item 6]
　A pipe thread joint according to any one of claims 1 to 5,
　wherein the solid lubricant powder, graphite, zinc oxide, boron nitride, talc, molybdenum disulfide, tungsten disulfide, fluorinated graphite, tin sulfide, bismuth sulfide, organic molybdenum, thiosulfate compounds, polytetrafluoroethylene, and is one or more members selected from the group consisting of melamine cyanurate, pipe threaded joint.
[Requested item 7]
　A pipe thread joint according to claim 6,
　wherein the solid lubricant powder, graphite and at least one selected from the group consisting of polytetrafluoroethylene, Pipe threaded joint.
[Requested item 8]
　A method of manufacturing a pipe thread joint according to any one of claims 1 to 7,
　wherein on the pin and at least one of the contact surfaces of the box, the resin, the solid lubricant powder and the Cr 2 O 3 process and, applying a composition containing
　and forming the solid lubricating coating layer by solidifying the composition applied onto the contact surface, the manufacturing method of the pipe thread fittings.
[Requested item 9]
　Furthermore a method of manufacturing a pipe thread joint according to claim 8,
　said composition prior to said step of applying,
　to said pin and at least one of the contact surface of the box,
　Zn alloy plating by electroplating comprising the step of forming the layer, the manufacturing method of the pipe thread fittings.
[Requested item 10]
　Furthermore a method of manufacturing a pipe thread joint according to claim 9,
　before the step of forming the Zn alloy plating layer,
　the pin and at least one of the contact surface of the box,
　forming a surface roughness comprising the step of manufacturing method of the pipe screw joint.