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 of the pin and box and the unthreaded metal contact portion, repeatedly subjected to strong friction at the time of the return screw tightening and screw of the threaded joint. 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]
　JP 2002-221288 (Patent Document 1) and JP 2008-215473 (Patent Document 2) proposes a pipe thread joint having excellent galling resistance without the compound grease.
[0006]
　The contact surface of the pin or box of the pipe threaded joint described in Patent Document 1, at least one of the threaded portion and the unthreaded metal contact portions of the pipe thread fittings, Zn or Zn alloy layer porous by impact plating It is formed and thereon a solid lubricating coating or a heavy metal powder does not contain a liquid lubricating coating (eg, coatings and main agent highly basic organic metal salts such as highly basic sulfonates) are formed. Accordingly, without using a liquid lubricant containing heavy metal powder such compounds grease, it has high corrosion resistance, it is possible to suppress the seizure generation and airtightness deterioration due to rust generation at the time of repeated tightening and loosening , and it is described in Patent Document 1.
[0007]
　Pipe threaded joint described in Patent Document 2, at least one of the contact surfaces of the pin and box, and having a first plating layer made of Cu-Zn alloy. Thus, a threaded joint is excellent has leakage resistance and galling resistance was further crevice corrosion is improved in the case of forming a lubricating coating on the plating layer, and is described in Patent Document 2 there.
[0008]
　To suppress the seizure of the pipe thread joint, it is effective to form a plating layer hardness and melting point includes a higher metal. Therefore, conventionally, copper (Cu) plating or Cu alloy plating has been used. Hardness and the melting point of Cu is high. Therefore, Cu is by inclusion in the plating layer increases the hardness and the melting point of the entire plating layer. Thus, it increases seizure of pipe thread fittings.
CITATION
Patent Document
[0009]
Patent Document 1: JP 2002-221288 Patent Publication
Patent Document 2: JP 2008-215473 JP
Summary of the Invention
Problems that the Invention is to Solve
[0010]
　Incidentally, the evaluation of seizure resistance is usually performed in a state of being matched core steel pipes for screwing. However, if indeed the pipe thread joint for screwing, which may lead between steel pipe screwing (or steel pipe and coupling) is shifted. This is called misalignment. If misalignment occurs, threaded portion and unthreaded metal contact portions of the pin and box, in addition to the strong friction, subjected to strong shearing stress. This shear stress, as compared with the case of no misalignment, significantly large. Therefore, when misalignment occurs, the seizure is more likely to occur. Therefore, the Pipe threaded joint, suppressing performance seizure even if misalignment occurs, i.e., resistance to misalignment is required.
[0011]
　On the other hand, the unthreaded metal contact portions of the above, 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.
[0012]
　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 resistance to misalignment of the above is required to have a high torque on shoulder resistance [Delta] T '.
[0013]
　On the other hand, OCTG, after being manufactured, transported by ship or the like, is stored a certain period until used. Transport and storage of oil country tubular goods, there is a case in which over a long period of time. Furthermore, storage of oil well pipes might be carried out outdoors. If long term stored outdoors, rust is generated in the pipe thread fittings, airtight and seizure resistance of pipe thread joint may be lowered. Therefore, the Pipe threaded joint, in addition to the resistance to misalignment of the foregoing and high torque on shoulder resistance [Delta] T ', it is excellent corrosion resistance requirements.
[0014]
　Pipe threaded joint disclosed in Patent Document 1, Zn or Zn alloy layer is porous. Therefore, adhesion between the solid lubricating coating layer is good, with sufficient seizure resistance. However, since it is porous, the void between the Zn or Zn alloy layer and the base material occurs. Therefore, the base metal of the resulting void portion, which may corrode during long-term course.
[0015]
　Pipe threaded joint disclosed in Patent Document 2, although being considered for seizure resistance, has not been studied resistance misalignment resistance. Therefore, seizure resistance when misalignment is not generated be sufficient, in some cases a lower resistance to misalignment resistance. Furthermore, lowered torque on shoulder resistance [Delta] T ', it may be a low corrosion resistance low adhesion of the solid lubricating coating layer.
[0016]
　An object of the present invention is to provide a resistance to misalignment and high torque on shoulder resistance [Delta] T 'has, furthermore, to provide a pipe thread joint and a manufacturing method thereof has excellent corrosion resistance.
Means for Solving the Problems
[0017]
　Pipe thread joint of the present embodiment includes a pin and box. Pin and box has a contact surface having a threaded portion and an unthreaded metal contact portion. At least one of the contact surfaces of the pin and box has an arithmetic average roughness Ra of 1 ~ 8 [mu] m, and a maximum height roughness Rz has a surface roughness of 10 ~ 40 [mu] m. Pipe threaded joint, the contact surface having a surface roughness of the above, the Zn-Ni alloy plating layer consisting of Zn-Ni alloy, a Cu-Sn-Zn alloy plating layer consisting of Cu-Sn-Zn alloy, the solid lubricant and a coating layer. The layers from the contact surface side, Zn-Ni alloy plating layer are laminated in this order Cu-Sn-Zn alloy plating layer and the solid lubricant coating layer. Solid lubricating coating layer is at least one element selected from the group consisting of an epoxy resin and a polyamide-imide resin, and a fluorine-containing resin particles.
[0018]
　Here, arithmetic mean roughness Ra and the maximum height roughness Rz is determined based on JIS B0601 (2013).
[0019]
　Method for manufacturing a pipe thread joint of the present embodiment is a method for producing a pipe thread joint comprising a pin and box. Pin and box comprises a contact surface having a threaded portion and an unthreaded metal contact portion. The manufacturing method of this embodiment includes a surface roughness forming step, a Zn-Ni alloy plating layer forming step, a Cu-Sn-Zn alloy plating layer forming step, a solid lubricating coating layer forming step. The surface roughness-forming step, the at least one contact surface of the pin and box, the arithmetic average roughness Ra of 1 ~ 8 [mu] m by blasting, and the maximum height roughness Rz to form a surface roughness of 10 ~ 40 [mu] m. The Zn-Ni alloy plating layer forming step, the contact surface forming the surface roughness of the above, to form a Zn-Ni alloy plating layer consisting of Zn-Ni alloy by electroplating. The Cu-Sn-Zn alloy plating layer forming step, after forming the Zn-Ni alloy plating layer to form a Cu-Sn-Zn alloy plating layer consisting of Cu-Sn-Zn alloy by electroplating. The solid lubricating coating layer forming step, after forming the Cu-Sn-Zn alloy plating layer to form a solid lubricating coating layer.
The invention's effect
[0020]
　Pipe thread joint of the present embodiment is excellent in resistance to misalignment, have high torque on shoulder resistance [Delta] T ', further, it has excellent corrosion resistance.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021]
[1] Figure 1 is a case where misalignment has occurred, a schematic diagram of a screwing of pipe thread fittings.
FIG. 2 is a diagram showing the relationship between the rotational speed and torque of the pipe thread fittings.
FIG. 3 is a diagram showing a configuration of a pipe thread joint according to the present embodiment.
[4] FIG. 4 is a cross-sectional view of a pipe thread joint according to the present embodiment.
FIG. 5 is a cross-sectional view of the contact surface of the pipe thread joint according to the present embodiment.
FIG. 6 is in the embodiment, is a diagram for explaining a torque on shoulder resistance [Delta] T '.
DESCRIPTION OF THE INVENTION
[0022]
　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.
[0023]
　The present inventors have conducted a pipe thread joint, resistance to misalignment of the torque on shoulder resistance [Delta] T ', and various studies about the relationship between the corrosion resistance. As a result, the following findings were obtained.
[0024]
　[Resistant misalignment resistance]
　In the conventional pipe thread joint, galling resistance when misalignment is not generated be sufficient, in some cases anti-misalignment resistance is insufficient. The misalignment, refers to the situation shown in Figure 1. Referring to FIG. 1, the coupling 2 is mounted on the tip of the steel tube 1. The other tip of the steel tube 1, the pin 3 is formed. The distal end of another steel pipe 4, coupling 5 is attached. The inner peripheral surface of the coupling 5 box is formed. Pin 3 of the steel pipe 1 is inserted into the coupling 5, it is screwed. Thus, the steel pipe 1 is connected to the steel tube 4. During screwing, not aligned and the longitudinal center axis of the longitudinal central axis and the steel pipe 4 of the steel tube 1, which may be cross. This is called misalignment. Cross angle in FIG. 1 shows a misalignment of theta °. By carrying out screwing in a state in which misalignment has occurred, as compared with the case of no misalignment, more likely to occur seizure.
[0025]
　Zn-Ni alloy plating layer, are collectively Cu-Sn-Zn alloy plating layer and the solid lubricant coating layer, referred to simply as the coating. To increase the resistance to misalignment of the pipe thread joint, enhance the adhesion of the coating. At least one of the threaded portion and the unthreaded metal contact portions of the pin and the box (hereinafter, referred to as contact surfaces) on an arithmetic mean roughness Ra of 1 ~ 8 [mu] m and a maximum height roughness Rz of the surface roughness of 10 ~ 40 [mu] m, (hereinafter, also referred to as "specific surface roughness") is formed. If the film is formed contacting surface having a specific surface roughness, by a so-called anchor effect, the adhesion is improved. The higher the adhesion of the coating, even if it is repeatedly exposed to high temperature and low temperature, peeling of the coating can be suppressed. If the peeling of the coating is suppressed, lubricity is maintained high during the return screw tightening and screw. Therefore, it increases resistance to misalignment of the pipe thread fittings.
[0026]
　To increase the resistance to misalignment of the pipe thread joint, further formed on the contact surface of the plating layer having a high hardness and high melting point. The higher the hardness of the plating layer, the plating layer is not easily damaged during the return screw tightening and screw the pipe thread fittings. Furthermore, the higher the melting point of the plating layer, during the return screw tightening and screw the pipe thread joint, locally plated layer even when heated to a high temperature is hard to put to melt. Cu-Sn-Zn alloy has a high hardness and high melting point. Accordingly, in the present embodiment has a Cu-Sn-Zn alloy plating layer consisting of Cu-Sn-Zn alloy. Therefore, further increases the resistance to misalignment of the pipe thread fittings.
[0027]
　Torque on shoulder resistance [Delta] T ']
　when the steel pipes screwing, optimum torque to terminate the screwing is predetermined. Figure 2 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. 2, 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.
[0028]
　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.
[0029]
　To increase the torque on shoulder resistance [Delta] T 'reduces the shouldering torque, or, it is effective to increase the yield torque. In the present embodiment, in order to reduce the shouldering torque, reducing the frictional resistance.
[0030]
　In this embodiment, increase the lubricity of the solid lubricant coating layer to reduce the frictional resistance. Solid lubricating coating layer is a fluorine resin particles, and, if at least one selected from the group consisting of an epoxy resin and a polyamide-imide resin, lubricity is improved. In this case, it remains low the shouldering torque.
[0031]
　Corrosion Resistance
　The use of Zn-Ni alloy, it is possible to increase the corrosion resistance of pipe thread fittings. Zinc (Zn) is iron (Fe), a base metal as compared with nickel (Ni) and chromium (Cr). Therefore, by forming a plating layer containing zinc (Zn) on the contact surface, preferentially plating layer is corroded than steel (sacrificial protection). This increases the corrosion resistance of the pipe thread fittings.
[0032]
　[Each layer of the laminated Order
　In this embodiment, Zn-Ni alloy plating layer, the stacking order of the Cu-Sn-Zn alloy plating layer and the solid lubricant coating layer is important. In particular, stacking sequence of the Zn-Ni alloy plating layer and the Cu-Sn-Zn alloy plating layer is important. Table 1 shown below is an excerpt partially data described in Examples below.
[0033]
[Table 1]

[0034]
　Table 1, the structure of the coating of the pipe threaded joint for Test No. 1 and Test Number 8 embodiments described later, shows the evaluation results. In Table 1, it means the contact surface of the pin and the pin surface. It refers to the contact surface of the box and the box surface.
[0035]
　And Test No. 1 and Test No. 8, all conditions other than stacking order of the plating layer of the box surface had the same. In Test No. 1 and Test No. 8, the surface roughness of the pre-plating were the same. Specifically, the arithmetic average roughness Ra is 0.3 [mu] m, the maximum height roughness Rz of the pin surface was 5.8 [mu] m. Arithmetic average roughness Ra of the box surface 2.0 .mu.m, the maximum height roughness Rz was 24.0Myuemu. In both Test Number 1 and Test Number 8, on the Zn-Ni alloy plating layer on the pin surface a chromate film is formed. In both Test Number 1 and Test Number 8, the outermost layer of the box surface, the solid lubricant coating layer was formed containing 10% of polytetrafluoroethylene particles and an epoxy resin.
[0036]
　Referring to Table 1, the pipe threaded joint for Test No. 8, Zn-Ni alloy plating layer, comprising a Cu-Sn-Zn alloy plating layer and the solid lubricant coating layer. Pipe thread joint Test No. 8, with a Zn-Ni alloy plating layer on the Cu-Sn-Zn alloy plating layer. Seizure resistance of the pipe threaded joint for Test No. 8 is 5 times in the evaluation by the hand tight, the evaluation of resistance to misalignment resistance evaluation test was 5 times. Pipe thread joint boxes Test No. 8, rust occurs 750 hours after salt spray test. On the other hand, the seizure resistance of the Cu-Sn-Zn pipe thread joint of the alloy plating layer with a test number 1 on the Zn-Ni alloy plating layer, in the evaluation by the hand tight a greater 20 times, resistance to misalignment It was also 20 times greater than in the evaluation of in sexual evaluation test. Furthermore, Test No. 1 of the box, rust did not occur even if the salt spray 4000 hours.
[0037]
　Compares the test numbers 1 and Test No. 8, Cu-Sn-Zn be Zn-Ni alloy plating layer on the alloy plated layer is disposed, resistance to misalignment of the pipe thread joint, the torque on shoulder resistance ΔT 'and it can not be increased any corrosion. Only by Cu-Sn-Zn alloy plating layer on the Zn-Ni alloy plating layer is disposed, resistance to misalignment of the pipe thread joint, it is possible to improve all of the torque on shoulder resistance [Delta] T 'and corrosion resistance.
[0038]
　Cause stacking order of each alloy plating layer greatly affect the performance of the pipe thread joint is considered as follows. Zn-Ni alloy plating layer, the sacrificial protection, enhances the corrosion resistance of the pipe thread fittings. When Zn-Ni alloy plating layer is separated from the base material of the pipe threaded joint, the effect of sacrificial protection is reduced. Therefore, corrosion resistance of pipe thread joint is reduced. Cu-Sn-Zn alloy plating layer has high hardness and high melting point. Thus, even if there is a misalignment, to protect the Zn-Ni alloy plating layer under the Cu-Sn-Zn alloy plating layer from damage. Cu-Sn-Zn alloy plating layer is this effect can not be obtained if there below the Zn-Ni alloy plating layer. Therefore, on the contact surface, from the side of the contact surface, Zn-Ni alloy plating layer, it is important to be stacked in the order of Cu-Sn-Zn alloy plating layer.
[0039]
　Thus, it threaded joint for pipes, can be enhanced all the first time, resistance to misalignment of the torque on shoulder resistance [Delta] T 'and corrosion by laminating alloy plating layer having a specific composition in a specific order.
[0040]
　Been completed based on the above findings, pipe thread joint of the present embodiment includes a pin and box. Pin and box has a contact surface having a threaded portion and an unthreaded metal contact portion. At least one of the contact surfaces of the pin and box has an arithmetic average roughness Ra of 1 ~ 8 [mu] m, and a maximum height roughness Rz has a surface roughness of 10 ~ 40 [mu] m. Pipe threaded joint, the contact surface having a surface roughness of the above, the Zn-Ni alloy plating layer consisting of Zn-Ni alloy, a Cu-Sn-Zn alloy plating layer consisting of Cu-Sn-Zn alloy, the solid lubricant and a coating layer. The layers from the contact surface side, Zn-Ni alloy plating layer are laminated in this order Cu-Sn-Zn alloy plating layer and the solid lubricant coating layer. Solid lubricating coating layer is at least one element selected from the group consisting of an epoxy resin and a polyamide-imide resin, and a fluorine-containing resin particles.
[0041]
　Pipe thread joint of the present embodiment is excellent in resistance to misalignment, have high torque on shoulder resistance [Delta] T ', further, it has excellent corrosion resistance.
[0042]
　Hardness of Zn-Ni alloy plating layer is 300 or more in Vickers, the thickness of the Zn-Ni alloy plating layer is preferably 5 ~ 20 [mu] m.
[0043]
　In this case, the corrosion resistance is enhanced.
[0044]
　The hardness of Cu-Sn-Zn alloy plating layer is not more than 500 micro-Vickers, the thickness of the Cu-Sn-Zn alloy plating layer is preferably 5 ~ 20 [mu] m.
[0045]
　In this case, resistance to misalignment is enhanced more.
[0046]
　Hardness of the solid lubricant coating layer is 15 to 25 micro-Vickers, the thickness of the solid lubricating coating layer is preferably 10 ~ 40 [mu] m.
[0047]
　In this case, the torque on shoulder resistance [Delta] T 'increased to more stably.
[0048]
　Preferably, the fluorine resin particles, polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer (4.6 fluoride), tetrafluoroethylene-ethylene copolymerization coalescence, polyvinylidene fluoride (2 fluorinated), and is one or more selected from the group consisting of polychlorotrifluoroethylene (trifluoride).
[0049]
　Method for manufacturing a pipe thread joint of the present embodiment is a method for producing a pipe thread joint comprising a pin and box. Pin and box comprises a contact surface having a threaded portion and an unthreaded metal contact portion. The manufacturing method of this embodiment includes a surface roughness forming step, a Zn-Ni alloy plating layer forming step, a Cu-Sn-Zn alloy plating layer forming step, a solid lubricating coating layer forming step. The surface roughness-forming step, the at least one contact surface of the pin and box, the arithmetic average roughness Ra of 1 ~ 8 [mu] m by blasting, and the maximum height roughness Rz to form a surface roughness of 10 ~ 40 [mu] m. The Zn-Ni alloy plating layer forming step, the contact surface forming the surface roughness of the above, to form a Zn-Ni alloy plating layer consisting of Zn-Ni alloy by electroplating. The Cu-Sn-Zn alloy plating layer forming step, after forming the Zn-Ni alloy plating layer to form a Cu-Sn-Zn alloy plating layer consisting of Cu-Sn-Zn alloy by electroplating. The solid lubricating coating layer forming step, after forming the Cu-Sn-Zn alloy plating layer to form a solid lubricating coating layer.
[0050]
　The manufacturing method of this embodiment, the pin and box of at least one contact surface to a particular surface roughness, Zn-Ni alloy plating layer, the pipe threaded joint having a Cu-Sn-Zn alloy plating layer and the solid lubricant coating layer prepared it can. Pipe threaded joint, excellent in resistance to misalignment and corrosion resistance. Pipe thread joint further has a high torque on shoulder resistance [Delta] T ', it is easy to adjust the fastening torque.
[0051]
　It described in detail below pipe thread joint and a manufacturing method thereof according to the present embodiment.
[0052]
　[Pipe thread fittings]
　pipe thread joint comprises a pin and box. Figure 3 is a diagram showing a configuration of a pipe thread joint according to the present embodiment. Referring to FIG. 3, the pipe threaded joint is provided with a steel pipe 11 and the coupling 12. At both ends of the steel pipe 11, a pin 13 having a male threaded portion on an outer surface is formed. At both ends of the coupling 12, box 14 having a female screw portion on an inner surface is formed. By screwing the pin 13 and the box 14, the end of the steel pipe 11, the coupling 12 is attached. On the other hand, without using a coupling 12, and one of the end pin 13 of the steel pipe 11, and the other end with the box 14, there is also a pipe thread joint of integral form. Pipe thread joint of the present embodiment can be used in the coupling method and the integral form of both pipe thread fittings.
[0053]
　Pin 13 and box 14 has a contact surface having a threaded portion and an unthreaded metal contact portion. Figure 4 is a cross-sectional view of a pipe thread joint according to the present embodiment. Referring to FIG. 4, the pin 13, and a male screw portion 15 and the unthreaded metal contact portion. Box 14 is provided with a female thread portion 20 and the unthreaded metal contact portion. Unthreaded metal contact portion is formed at the tip of the pin 13 and box 14, and a metal seal part 16, 19 and the shoulder portion 17, 18. A pin 13 and box 14 the portion contacting when screwing, that the contact surfaces 130 and 140. Specifically, when the pin 13 and the box 14 screwing, shoulder portions (shoulder portions 17 and 18), the metal seal portions (metal seal part 16 and 19), and, threaded portions (male screw portion 15 and internal thread portion 20) are in contact with each other. In other words, the contact surface 130 of the pin side, a shoulder portion 17, a metal seal part 16, and includes a male threaded portion 15. Box side of the contact surface 140, the shoulder portion 18, a metal seal part 19 and, includes a female threaded portion 20.
[0054]
　Figure 5 is a cross-sectional view of the contact surfaces 130, 140 of the pipe thread joint according to the present embodiment. Referring to FIG. 5, the pipe threaded joint has a certain surface roughness (not shown) on at least one contact surface 130, 140 of the pin 13 and box 14. Pipe threaded joint, the contact surfaces 130 and 140 having a specific surface roughness, comprising a Zn-Ni alloy plating layer 21, Cu-Sn-Zn alloy plating layer 22 and the solid lubricant coating layer 23. These are the contact surfaces 130 and 140 side are laminated in the order of Zn-Ni alloy plating layer 21, Cu-Sn-Zn alloy plating layer 22 and the solid lubricant coating layer 23.
[0055]
　Specific surface roughness of the contact surfaces]
　arithmetic average roughness Ra of 1 ~ 8 [mu] m, and a maximum height roughness Rz of the surface roughness of 10 ~ 40 [mu] m (the specific surface roughness), at least one of the pin 13 and box 14 formed on the contact surfaces 130 and 140. Specific surface roughness is formed by blasting. In this case, the contact surfaces 130, 140 has an uneven. Therefore, adhesion of the Zn-Ni alloy plating layer 21 to be described later is improved by the anchor effect. If adhesion Zn-Ni alloy plating layer 21 is Takamare, increases resistance to misalignment of the pipe thread fittings.
[0056]
　If the arithmetic average roughness Ra is 1μm and less than the maximum height roughness Rz is less than 10 [mu] m, no sufficient anchor effect can be obtained. On the other hand, if the case the arithmetic mean roughness Ra exceeds 8μm and maximum height roughness Rz is more than 40 [mu] m, sometimes galling resistance and airtightness is deteriorated.
[0057]
　The lower limit of the arithmetic mean roughness Ra is preferably 1.5 [mu] m, more preferably 2 [mu] m. The upper limit of the arithmetic mean roughness Ra is preferably 7 [mu] m, more preferably 5 [mu] m. Maximum minimum height roughness Rz is preferably 12 [mu] m, more preferably 15 [mu] m. Maximum maximum height roughness Rz is preferably 35 [mu] m, more preferably 30 [mu] m.
[0058]
　Arithmetic mean roughness Ra and the maximum height roughness Rz in the present specification are measured in accordance with JIS B0601 (2013). 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 an arithmetic mean roughness Ra and the surface height roughness Rz is large, it increases the contact area between the Zn-Ni alloy plating layer 21. Therefore, adhesion between the Zn-Ni alloy plating layer 21 is increased by an anchor effect. If adhesion Zn-Ni alloy plating layer 21 is Takamare, increases resistance to misalignment of the pipe thread fittings.
[0059]
　Blasting, pursuant to JIS Z0310 (2016), may be a known method. For example, sand blasting, shot blasting, and the like grit blasting. Depending on the object, by adjusting the abrasive grain type and size, spraying pressure, the projection angle, the distance between the nozzle, and the time zone, it is possible to obtain a desired surface roughness. Be about the size of the abrasive grains 100 mesh, it is possible to obtain a specific surface roughness relatively easily present invention.
[0060]
　[Zn-Ni alloy plated layer 21 '
　on the contact surface 130, 140 having a specific surface roughness to form a Zn-Ni alloy plating layer 21 made of Zn-Ni alloy. Zn-Ni alloy plating layer 21, for example formed by electroplating.
[0061]
　Zn contained in the Zn-Ni alloy plating layer 21 is a base metal. Therefore, by forming a plating layer containing Zn in contact surfaces 130 and 140, preferentially plating layer is corroded than steel (sacrificial protection). This increases the corrosion resistance of the pipe thread fittings. And Zn-Ni alloy plating layer 21, if Irekaware the order of lamination of the Cu-Sn-Zn alloy plating layer 22 to be described later, can not be obtained the effect of sacrificial protection due to Zn. Thus, Zn-Ni alloy plating layer 21 is formed on the contact surface with a specific surface roughness.
[0062]
　Zn-Ni alloy contains Zn and Ni, the balance being impurities. Preferred Zn content of Zn-Ni alloy plating layer 21 is 85 to 90 wt%, preferably Ni content is 10 to 15 mass%. Zn-Ni alloy plating layer 21 has a large content of Zn. Therefore, a large effect of sacrificial protection.
[0063]
　The lower limit of the Ni content of Zn-Ni alloy, and more preferably 12% by mass. The upper limit of the Ni content of Zn-Ni alloy, and more preferably 14% by mass. The lower limit of the Zn content of Zn-Ni alloy, and more preferably 86% by mass. The upper limit of Zn content Zn-Ni alloy, and more preferably 88% by mass.
[0064]
　The chemical composition of the Zn-Ni alloy plating layer 21 is measured by the following method. Measured using a hand-held X-ray fluorescence analyzer (manufactured by Nippon Electronics Co., Ltd. DP2000 (trade name DELTA Premium)). Measurements, Zn-Ni 4 positions of the surface of the alloy plating layer 21 (the circumferential direction of the pipe 0 ° of pipe thread joint, 90 °, 180 °, 4 positions of 270 °) the to composition analysis. Obtaining measured content of Zn and Ni by Alloy Plus mode. Those obtained by dividing the measured content of Ni in a total amount of the measurement content obtained Zn and Ni and Ni content (wt%). Those obtained by dividing the measured content of Zn in a total amount of the measurement content obtained Zn and Ni and Zn content (wt%). Ni content (% by weight) and Zn content (wt%) is the arithmetic mean of the measurement results of four positions and composition analysis.
[0065]
　Hardness of Zn-Ni alloy plating layer 21 is preferably 300 or more in Vickers. If the hardness of the Zn-Ni alloy plating layer 21 is 300 or higher, more stable increase in the corrosion resistance of the pipe thread fittings.
[0066]
　The lower limit of the hardness of the Zn-Ni alloy plating layer 21 is more preferably 350 micro-Vickers, even more preferably 400 micro-Vickers. The upper limit of the hardness of the Zn-Ni alloy plating layer 21 is not particularly limited. However, the upper limit of the hardness of the Zn-Ni alloy plating layer 21 is, for example, 700 micro-Vickers.
[0067]
　Hardness of Zn-Ni alloy plating layer 21 is measured as follows. In Zn-Ni alloy plating layer 21 of the resultant pipe thread joints, to select any 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-Ni alloy plating layer 21.
[0068]
　The thickness of the Zn-Ni alloy plating layer 21 is preferably 5 ~ 20 [mu] m. When the thickness of the Zn-Ni alloy plating layer 21 is 5μm or more, it is possible to improve stably the corrosion resistance of pipe thread fittings. If the at 20μm or less the thickness of the Zn-Ni alloy plating layer 21, the adhesion of the plating becomes stable. Therefore, the thickness of the Zn-Ni alloy plating layer 21 is preferably 5 ~ 20 [mu] m.
[0069]
　The lower limit of the thickness of the Zn-Ni alloy plating layer 21 is more preferably 6 [mu] m, more preferably from 8 [mu] m. The upper limit of the thickness of the Zn-Ni alloy plating layer 21 is more preferably 18 [mu] m, more preferably from 15 [mu] m.
[0070]
　The thickness of the Zn-Ni alloy plating layer 21 is measured as follows. On Zn-Ni alloy plating layer 21, ISO (International Organization for Standardization) 21968 contacting a probe of an eddy current phase type film thickness measuring instrument conforming to (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 21 is excited. Converting the phase difference in the thickness of the Zn-Ni alloy plating layer 21.
[0071]
　[Cu-Sn-Zn alloy plating layer
　22 ' on the Zn-Ni alloy plating layer 21, to form a Cu-Sn-Zn alloy plating layer 22. Cu-Sn-Zn alloy plating layer 22, for example formed by electroplating.
[0072]
　Cu-Sn-Zn alloy plating layer 22 is made of a Cu-Sn-Zn alloy. Hardness and melting point of the Cu-Sn-Zn alloy plating layer 22 is high. Therefore, even after repeated back screw tightening and screw, having a high resistance to misalignment resistance.
[0073]
　Cu-Sn-Zn alloy contains a Cu, and Sn, and Zn, the balance being impurities. Preferred Cu content in the Cu-Sn-Zn alloy plating layer 22 is 40 to 70 mass%, preferably Sn content is 20 to 50 mass%, preferably Zn content is 2 to 20 mass%.
[0074]
　The lower limit of the Cu content of the Cu-Sn-Zn alloy is more preferably 45 wt%, more preferably 50% by mass. The upper limit of the Cu content of the Cu-Sn-Zn alloy is more preferably 65 wt%, more preferably from 60 mass%. The lower limit of the Sn content of the Cu-Sn-Zn alloy is more preferably 25 wt%, more preferably 30% by mass. The upper limit of the Sn content of the Cu-Sn-Zn alloy is more preferably 45 wt%, more preferably from 40 mass%. The lower limit of the Zn content of Cu-Sn-Zn alloy, and more preferably 5 wt%, more preferably 10% by mass. The upper limit of Zn content Cu-Sn-Zn alloy is more preferably 18 wt%, more preferably from 15% by mass. The chemical composition of the Cu-Sn-Zn alloy plating layer 22 is measured by the same method as the chemical composition of the Zn-Ni alloy plating layer 21 described above.
[0075]
　The hardness of Cu-Sn-Zn alloy plating layer 22 is preferably 500 or more in Vickers. If the hardness of the Cu-Sn-Zn alloy plating layer 22 is 500 or more, increases resistance to misalignment of the pipe thread joint further stably. The hardness of Cu-Sn-Zn alloy plating layer 22 is measured in the same manner as in Zn-Ni alloy plating layer 21 described above.
[0076]
　The lower limit of the hardness of the Cu-Sn-Zn alloy plating layer 22 is more preferably 550 micro-Vickers, even more preferably 600 micro-Vickers. The upper limit of the hardness of the Cu-Sn-Zn alloy plating layer 22 is not particularly limited. However, the upper limit of the hardness of the Cu-Sn-Zn alloy plating layer 22 is, for example, 800 micro-Vickers.
[0077]
　The thickness of the Cu-Sn-Zn alloy plating layer 22 is preferably 5 ~ 20 [mu] m. When the thickness of the Cu-Sn-Zn alloy plating layer 22 is 5μm or more, it is possible to improve the resistance to misalignment of the pipe thread joint stable. If the at 20μm or less the thickness of the Cu-Sn-Zn alloy plating layer 22, the adhesion of the plating becomes stable. Therefore, the thickness of the Cu-Sn-Zn alloy plating layer 22 is preferably 5 ~ 20 [mu] m. The thickness of the Cu-Sn-Zn alloy plating layer 22 is measured in the same manner as in Zn-Ni alloy plating layer 21 described above.
[0078]
　The lower limit of the thickness of the Cu-Sn-Zn alloy plating layer 22 is more preferably 6 [mu] m, more preferably from 8 [mu] m. The upper limit of the thickness of the Cu-Sn-Zn alloy plating layer 22 is more preferably 18 [mu] m, more preferably from 15 [mu] m.
[0079]
　[Solid lubricating coating
　23] on the Cu-Sn-Zn alloy plating layer 22 to form a solid lubricant coating layer 23. The solid lubricating coating layer 23, increases the lubricity of the pipe thread fittings. Solid lubricating coating layer 23 includes a binder and lubricant additives. In this embodiment, the binder solid lubricating coating layer 23 contains is at least one selected from the group consisting of an epoxy resin and a polyamide-imide resin. In the present embodiment, the solid lubricating coating layer 23 contains a fluororesin particle. Solid lubricating coating layer 23, if necessary, may contain a solvent and other ingredients.
[0080]
　For each component of the solid lubricant coating layer 23, described in detail below.
[0081]
　[Binding agent]
　binder, a lubricant additive is attached to the solid lubricating coating layer 23. In this embodiment, the binder is at least one selected from the group consisting of an epoxy resin and a polyamide-imide resin. In the present embodiment may further contain another binder.
[0082]
　Binding agents may be used alone or in combination of two or more selected from the group consisting of organic resins, inorganic resins and mixtures thereof. When using an organic resin, it is possible to use a thermosetting resin or a thermoplastic resin. Thermosetting resins such as epoxy resins, polyimide resins, polycarbodiimide resins, polyether sulfone resins, polyether ether ketone resins, phenolic resins, furan resins, one or selected from the group consisting of urea resin and acrylic resin it is 2 or more. Thermoplastic resins such as polyamide-imide resin is polyethylene resin, polypropylene resin, one or more members selected from the group consisting of polystyrene resins, and ethylene-vinyl acetate resin.
[0083]
　When using the inorganic resin can be used polymetalloxane. The polymetalloxane, metal - repetition of oxygen bond refers to a polymeric compound is a main chain skeleton. Preferably, the inorganic resin is polytitanoxane (Ti-O) and one or more members selected from the group consisting of a polysiloxane (Si-O). These inorganic resin is obtained by allowing a metal alkoxide hydrolysis and condensation. Alkoxy group of the metal alkoxide, for example, methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, an isobutoxy group, a lower alkoxy group such as butoxy and tert- butoxy.
[0084]
　When the melting temperature of the binder is too high, it is difficult to apply the composition in a hot melt process. On the other hand, when the melting temperature of the binder is too low, the solid lubricating coating layer 23 in a high temperature environment is softened, the adhesion may decrease. Therefore, the binder preferably contains at least one selected from the group consisting of melting temperature (or softening temperature) is 80 ~ 320 ° C. of ethylene vinyl acetate resin and polyolefin resin. More preferably, the binder preferably contains at least one selected from the group consisting of melting temperature (or softening temperature) is 90 ~ 200 ° C. of ethylene vinyl acetate resin and polyolefin resin.
[0085]
　Ethylene vinyl acetate resins, in order to suppress an abrupt softening due to a temperature rise, is preferably a mixture of two or more ethylene-vinyl acetate resins having different melting temperatures. Similarly, polyolefin resins, is preferably a mixture of two or more polyolefin resins having different melting temperatures.
[0086]
　The content of the binder in the solid lubricating coating layer 23 is preferably 60 to 80 mass%. When the content of the binder is 60 mass% or more, further enhance the adhesion of the solid lubricating coating layer 23. When the content of the binder is 80 mass% or less, lubricity of the solid lubricant coating layer 23 is better maintained.
[0087]
　The lower limit of the content of the binder in the solid lubricating coating layer 23 is more preferably 65 mass%, more preferably from 68 mass%. The upper limit of the content of the binder in the solid lubricating coating layer 23 is more preferably 78 wt%, more preferably from 75% by mass.
[0088]
　[Fluororesin particles]
　solid lubricating coating layer 23 contains a fluororesin particle.
[0089]
　Fluorine resin particles, PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), FEP (tetrafluoroethylene-hexafluoropropylene copolymer (4.6 fluoride)), ETFE (tetrafluoroethylene-ethylene copolymer), PVDF (polyvinylidene fluoride (2 fluorinated)), and PCTFE 1 kind or two kinds selected from the group consisting of (polychlorotrifluoroethylene (trifluoride)) or more. In this embodiment, PTFE is particularly preferred.
[0090]
　Fluororesin particles are particles of the polymer having a C-F bond in the molecular structure. C-F bond of the fluorine resin particles is strong. The molecular structure, the fluorine resin particles, chemical resistance, very excellent heat resistance and electrical properties. Fluororesin particles are in the following 100 ° C. at a low surface pressure indicates a very low coefficient of friction, when exceeded high surface pressure and 100 ° C., the friction coefficient is high. In this case, obtain a high torque on shoulder resistance [Delta] T '. Specifically, the fluorine resin particles, metal seal portions 16, 19 and the shoulder portion 17, 18 at the time of still smaller shouldering the frictional heating at a low surface pressure contributes to low friction, reducing the shouldering torque. On the other hand, if it exceeds 100 ° C. by and frictional heating a high surface pressure, suddenly becomes high friction. Fluororesin particles further metal seal portion 16, 19 and the shoulder portion 17, 18 is hardly plastically deformed even at a high torque. The preferred content of the fluorine resin particles is 2 mass% to 20 mass%. The lower limit is more preferably 5 mass% of the content of the fluorine resin particles, more preferably from 8% by mass. 15 wt% upper limit of the content is more preferably fluorine resin particles, more preferably from 12 mass%.
[0091]
　In the present embodiment, the solid lubricating coating layer 23 may further contain a lubricant additive.
[0092]
　The lubricating additive is a general term for additive having lubricating properties. Lubricant additive reduces the coefficient of friction of the surface of the solid lubricating coating layer 23. Lubricating additives, it is broadly classified into the following five types. Lubricant additive contains at least one selected from the group consisting of the following (1) to (5).
　(1) slippery specific crystal structure, for example, shows the lubricity by having a hexagonal layered crystal structure (e.g., graphite, zinc oxide, boron nitride),
　a reactive element in 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., polyamide), and
　(5) a liquid or grease-like, between the surface and the surface is present on the boundary of the contact surface shows the lubricity by preventing direct contact (e.g., perfluoropolyether (PFPE)).
[0093]
　Any lubricant additive of (1) to (5) may also be used. Lubricating additives, in addition to the fluororesin particles may be used in combination of a plurality of the above (1) to (5). That is, the solid lubricant coating layer 23, in addition to PTFE, further, for example, graphite, zinc oxide, boron nitride, molybdenum disulfide, tungsten disulfide, graphite fluoride, tin sulfide, bismuth sulfide, thiosulfate compounds, polyamides, and it may contain one or two or more selected from the group consisting of perfluoropolyether (PFPE).
[0094]
　The content of the lubricant additive in the solid lubricating coating layer 23 is preferably 10 to 25 mass%. When the content of the lubricity additive is 10 wt% or more, further increases the torque on shoulder resistance [Delta] T '. On the other hand, if the content of the lubricity additive is less than 25 mass%, further increases the strength of the solid lubricating coating layer 23. Therefore, it is possible to suppress the wear of the solid lubricant coating layer 23.
[0095]
　The lower limit of the content of the lubricant additive in the solid lubricating coating layer 23 is more preferably 12 wt%, more preferably from 15% by mass. The upper limit of the content of the lubricant additive in the solid lubricating coating layer 23 is more preferably 23 mass%, still more preferably 20% by mass.
[0096]
　If it is necessary to dissolve or disperse a lubricating additive and binder, a solvent. Solvent, as long as it can disperse or dissolve the components contained in the solid lubricating coating layer 23 is not particularly limited. The solvent may be an organic solvent or water. The organic solvent for example, toluene and isopropyl alcohol. The solvent is mostly volatilized during the formation of the solid lubricating coating layer 23, it may remain for example less than 1% by weight in the solid lubricating coating layer 23.
[0097]
　Other Components
　of this embodiment the solid lubricant coating layer 23, in addition to the above components, anti-rust additives, plasticizers, surfactants, coloring agents, inorganic powders for the adjustment of antioxidants and slidability it may contain a small amount additive component like. Inorganic powders are, for example, bismuth oxide and titanium dioxide. The content of the other components are, for example, 5 mass% or less in total. Composition further extreme pressure agent, if such be 2 wt% or less of a very small amount liquid oil may contain. The content of the other components in the solid lubricating coating layer 23, for example, 10 mass% or less in total.
[0098]
　Hardness of the solid lubricant coating layer 23 is preferably 15 to 25 micro-Vickers. If hardness of 15 to 25 of the solid lubricating coating layer 23, further increases the torque on shoulder resistance [Delta] T '. Hardness of the solid lubricant coating layer 23 is measured in the same manner as in Zn-Ni alloy plating layer 21 described above.
[0099]
　The lower limit of the hardness of the solid lubricant coating layer 23, more preferably from 16 micro-Vickers, even more preferably 18 micro Vickers. The upper limit of the hardness of the solid lubricant coating layer 23, more preferably 24 micro-Vickers, even more preferably 22 micro-Vickers.
[0100]
　The thickness of the solid lubricating coating layer 23 is preferably 10 ~ 40 [mu] m. When the thickness of the solid lubricating coating layer 23 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 23 is not more 40μm or less, adhesion of the solid lubricating coating layer 23 is stabilized. Further, the thickness of the solid lubricating coating layer 23 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 23 is preferably 10 ~ 40 [mu] m.
[0101]
　The lower limit of the thickness of the solid lubricating coating layer 23 is more preferably 15 [mu] m, more preferably from 20 [mu] m. The upper limit of the thickness of the solid lubricating coating layer 23 is more preferably 35 [mu] m, more preferably from 30 [mu] m.
[0102]
　The thickness of the solid lubricating coating layer 23 is measured by the following method. Preparing a pin 13 or box 14 with a solid lubricant coating layer 23. The pin 13 or box 14 to cut perpendicularly to the axial direction of the tube. Performing microscopic observation with respect to a cross section including a solid lubricant coating layer 23. Power microscope observation and 500 times. Thus, determining the thickness of the solid lubricating coating layer 23. The arithmetic mean of the measured values ​​of the arbitrary three points, the thickness of the solid lubricating coating layer 23.
[0103]
　[Solid corrosion protective coating]
　above pipe thread joint, at least one contact surface 130, 140 of the pin 13 and box 14 having a specific surface roughness. Pipe thread joint further contact surfaces 130 and 140 having a specific surface roughness, comprising a Zn-Ni alloy plating layer 21, Cu-Sn-Zn alloy plating layer 22 and the solid lubricant coating layer 23. Pipe thread joint further the other contact surface 130, 140 of the pin 13 and box 14 may comprise a solid corrosion protective coating. As described above, until the pipe thread joint is actually used, it may be stored for a long period of time. In this case, if the solid corrosion protective coating is formed, corrosion resistance of the pin 13 or box 14 is increased.
[0104]
　Solid corrosion protective coating, for example, a chromate coating of chromate. Chromate film is formed by a known trivalent chromate treatment.
[0105]
　Solid corrosion protective coating is not limited to the chromate film. Other solid corrosion protective coating, for example, containing an ultraviolet curable resin. In this case, having an intensity not destroyed by the force the solid corrosion protective coating is applied during protector mounting. Moreover, during transport or storage, the solid corrosion protective coating is not dissolved even when exposed to condensed water from the relationship between the dew point. Furthermore, the solid corrosion protective coating even at high temperatures exceeding 40 ° C. is not easy to softening. UV-curable resins are known resin compositions. UV-curable resin, a monomer, containing oligomer and a photopolymerization initiator, as long as it causes a photopolymerization reaction to form a cured coating film by being irradiated with ultraviolet rays is not particularly limited.
[0106]
　The other contact surface 130, 140 of the pipe thread joint, specific surface roughness, Zn-Ni alloy plating layer 21, Cu-Sn-Zn alloy plating layer 22 and the solid lubricant coating layer 23 is formed, the solid lubricating coating above solid corrosion protective coating may be formed over the layer 23 may be directly solid corrosion protective coating is formed on the other of the contact surfaces 130 and 140.
[0107]
　[Preform pipe thread fittings]
　composition of the base material of the pipe thread joint 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.
[0108]
　[Production Method]
　method of manufacturing a pipe thread joint according to the present embodiment, the surface roughness forming step, a Zn-Ni alloy plating layer forming step, a Cu-Sn-Zn alloy plating layer forming step, the solid lubricating coating formed and a step. Each step has a surface roughness forming step, Zn-Ni alloy plating layer forming step, Cu-Sn-Zn alloy plating layer forming step, and is performed in the order of the solid lubricating coating layer forming step.
[0109]
　[Surface Roughness forming step]
　The surface roughness-forming step, the at least one contact surface 130, 140 of the pin 13 and box 14, to form a certain surface roughness. The surface roughness forming step, a specific surface roughness by blasting with blasting device.
[0110]
　Blasting, pursuant to JIS Z0310 (2016), may be a known method. For example, sand blasting, shot blasting, and the like grit blasting. For example, in the sandblasting, projected onto the contact surfaces 130, 140 as a mixture of blasting material and (abrasive) and compressed air. The blasting can be increased surface roughness of the contact surfaces 130 and 140. 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.
[0111]
　Depending on the object, by adjusting the abrasive grain type and size, spraying pressure, the projection angle, the distance between the nozzle, and the time zone, it is possible to obtain a desired specific surface roughness. Be about the size of the abrasive grains 100 mesh, it is possible to obtain a specific surface roughness relatively easily present invention. In this way the pipe threaded joint surface, the specific surface roughness is formed. Specific surface roughness, arithmetic average roughness Ra of 1 ~ 8 [mu] m, and a maximum height roughness Rz is 10 ~ 40 [mu] m.
[0112]
　[Zn-Ni alloy plating layer 21 forming
　step] The Zn-Ni alloy plating layer 21 formation step, the contact surface 130, 140 forming a specific surface roughness, the Zn-Ni alloy plating layer 21 made of Zn-Ni alloy Form. Zn-Ni alloy plating layer 21 is formed by electroplating. Electroplating, the plating bath containing zinc ions and nickel ions, at least one contact surface 130, 140 of the pin 13 and box 14 forming the surface roughness was immersed, carried out by energizing. The plating bath can be used commercially available ones. The plating bath preferably, zinc ion: 1 ~ 100g / L and nickel ions: 1 ~ 50g / L is contained. Conditions of the electroplating can be appropriately set. Conditions of electroplating, for example, plating bath pH: 1 ~ 10, the plating bath temperature: 10 ~ 60 ° C., a current density: 1 ~ 100A / dm 2 , and the processing time: 0.1-30 minutes.
[0113]
　[Cu-Sn-Zn alloy plating layer 22 forming
　step] In the Cu-Sn-Zn alloy plating layer 22 formation step, on the Zn-Ni alloy plating layer 21, Cu-Sn-Zn alloy consisting of Cu-Sn-Zn alloy forming a plating layer 22. Cu-Sn-Zn alloy plating layer 22 is formed by electroplating. Electroplating of copper ions, the pin 13 and box 14 in a plating bath containing tin and zinc ions, and immersing the contact surfaces 130 and 140 forming a Zn-Ni alloy plating layer 21 is carried out by energizing. The plating bath preferably, copper ions: 1 ~ 50g / L, tin ions: 1 ~ 50g / L and zinc ions: 1 ~ 50g / L is contained. Conditions of the electroplating can be appropriately set. Conditions of electroplating, for example, plating bath pH: 1 ~ 14, the plating bath temperature: 10 ~ 60 ° C., a current density: 1 ~ 100A / dm 2 , and the processing time: 0.1 to 40 minutes.
[0114]
　[Solid lubricating coating layer 23 forming
　step] After the Cu-Sn-Zn alloy plating layer 22 formation step, carrying out the solid lubricating coating layer 23 formation step. The solid lubricating coating layer 23 forming step includes a coating step and curing step. The coating step, on Cu-Sn-Zn alloy plating layer 22 is coated with a composition as described above. The solidification step, and solidifying the applied composition on the contact surfaces 130 and 140 to form a solid lubricant coating layer 23.
[0115]
　First, to produce a composition. The composition of solvent-free, for example, by heating the binder to a molten state, lubricant additives, can be prepared by kneading with the addition of anti-rust additives and plasticizers. All components of the powder mixture obtained by mixing a powder or as a composition. Solvent-based compositions, for example, can be prepared in a solvent, a binder, lubricant additives, by mixing by dissolving or dispersing the rust-preventive agents and plasticizers.
[0116]
　[Coating Step]
　In the coating step is applied to the contact surfaces 130, 140 of the composition in a known manner. For solvent-free composition can be applied to the composition using a hot melt method. The hot melt method, to melt the binder by heating the composition to a fluid 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 binder in the composition. Coating method, instead of the spray coating, or a brushing and dipping. The heating temperature of the composition is preferably 10 to the 50 ° C. above the melting point of the binder. When applying the composition, at least one contact surface 130, 140 of the pin 13 and box 14 which the composition is applied, it is preferable to heat higher than the melting point of the base temperature. Thereby it is possible to obtain a good coverage. For solvent-based composition, the composition became a solution state is applied to the contact surfaces 130 and 140 by spray coating or the like. In this case, the composition, under normal temperature and normal pressure environments, to adjust the viscosity to allow spray application.
[0117]
　[Solidification step]
　In solidifying step, and solidifying the applied composition on the contact surfaces 130 and 140 to form a solid lubricant coating layer 23. For solvent-free composition, by cooling the composition applied to the contact surfaces 130 and 140, the solid lubricant coating layer 23 is formed the composition of the molten and solidified. Cooling method can be carried out in known manner. Cooling method, for example, an air cooling and air cooling. For solvent-based composition, by drying the applied composition to contact surfaces 130 and 140, the solid lubricant coating layer 23 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. 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, the opposite surface (the outer surface of the steel pipe 11 or coupling 12 in the case of box 14, in the case of the pin 13 the inner surface of the steel pipe 11) of the contact surfaces 130 and 140 indirectly cooled. This can suppress the deterioration due to rapid cooling of the solid lubricating coating layer 23.
[0118]
　The pin 13 or box 14 composition has been applied, it may be dried by heating. Heat drying can be carried out using a commercially available hot-air drying apparatus. Thus, the composition is cured, the solid lubricant coating layer 23 is formed on the Cu-Sn-Zn alloy plating layer 22. Conditions of heat drying, taking into account the boiling point and melting point of each component contained in the composition can be appropriately set.
[0119]
　[Formation of a solid corrosion protective coating (trivalent chromate treatment)]
　As described above, the pin 13 and at least one contact surface 130, 140 of the box 14, a surface roughness-forming step, Zn-Ni alloy plating layer 21 formation step, Cu -sn-Zn alloy plating layer 22 formation step, and then carrying out solid lubricating coating layer 23 formation step, a specific surface roughness, Zn-Ni alloy plating layer 21, Cu-Sn-Zn alloy plating layer 22 and the solid lubricant film to form a layer 23.
[0120]
　On the other hand, for the other contact surface 130, 140 of the pin 13 and box 14, the specific surface roughness, the Zn-Ni alloy plating layer 21, Cu-Sn-Zn alloy plating layer 22 and the solid lubricant coating layer 23 formed may be, the plating layer and / or the solid corrosion protective coating may be formed. Hereinafter, the other contact surface 130 and 140, the case of forming a solid corrosion protective coating consisting of Zn-Ni alloy plating layer 21 and the chromate film.
[0121]
　In this case, to implement the above-described electroplating process, to form a Zn-Ni alloy plating layer 21. After the electroplating process, to implement a trivalent chromate treatment to form a solid corrosion protective coating. The trivalent chromate treatment, is a film (chromate film) chromate trivalent chromium. Chromate film formed by the trivalent chromate treatment suppresses white rust on the surface of the Zn-Ni alloy plating layer 21. This improves the product appearance. Trivalent chromate treatment can be carried out in a known manner. For example, the pin 13 and at least one contact surface 130, 140 of the box 14 is immersed in a chromate treatment solution, or sprayed coating the chromate treatment solution to contact the surface 130, 140. Thereafter rinsing the contact surfaces 130 and 140. The contact surfaces 130, 140 immersed in a chromate treatment solution may be washed with water after the energization. The chromating solution is applied to the contact surfaces 130 and 140, may be dried by heating. Processing conditions trivalent chromate can be appropriately set.
[0122]
　[Background process]
　manufacturing method optionally, a surface roughness-forming step, includes a surface treatment step prior to Zn-Ni alloy plating layer 21 forming step and Cu-Sn-Zn alloy plating layer 22 forming step it may be. Surface treatment step is, for example, a pickling and alkaline degreasing. The surface treatment step, cleaning the oil or the like adhering to the contact surfaces 130 and 140.
Example
[0123]
　Hereinafter, the embodiment will be described. 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 means mass%.
[0124]
　In this embodiment, a VAM21 (registered trademark) manufactured by Nippon Steel Sumitomo Metals Corporation. VAM21 (R) outer diameter: 24.448cm (9-5 / 8 inches), a pipe thread joint thick 1.199cm (0.472 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.
[0125]
　To the pin surface and the box surface of each test number was performed finished by machine grinding. Thereafter, the test numbers shown in Table 2 and Table 3 were carried out blasting. Blasting is carried out sandblasting (abrasive Mesh100), roughened. Arithmetic mean roughness Ra and the maximum height roughness Rz of each test number was as shown in Table 2 and Table 3. Arithmetic mean roughness Ra and the maximum height roughness Rz was measured in accordance with JIS B0601 (2013). The measurement of the arithmetic average roughness Ra and the maximum height roughness Rz, using 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, and the acquired data number 1024 × 1024.
[0126]
[Table 2]

[0127]
[table 3]

[0128]
　Then, Zn-Ni alloy plating layer shown in Table 2 and Table 3, Cu-Sn-Zn alloy plating layer, to form a solid lubricant coating layer and / or the solid corrosion protective coating was prepared pin and box of each test number .
[0129]
　Each Zn-Ni alloy plating layer, Cu-Sn-Zn alloy plating layer, the method of forming the solid lubricating coating and solid corrosion protective coating was as follows. Each Zn-Ni alloy plating layer, Cu-Sn-Zn alloy plating layer, the hardness and thickness of the solid lubricating coating and solid corrosion protective coating was as shown in Table 2 and Table 3. Incidentally, the solid lubricating coating formed on the box surface of the test No. 12 is very soft, the micro Vickers hardness could not be measured.
[0130]
　Test No. 1]
　In Test No. 1, to pin surface, to implement the Zn-Ni alloy plating by electroplating, to form a Zn-Ni alloy plating layer. Zn-Ni alloy plating bath was used trade name dyne Jin alloy N-PL manufactured by Daiwa Kasei Co., Ltd.. Conditions of electroplating, the plating bath pH: 6.5, the plating bath temperature: 25 ° C., a current density: 2A / dm 2 , and the treatment time were: 18 min. The composition of the Zn-Ni alloy plating layer, Zn: 85% and Ni: was 15%. Furthermore, the obtained Zn-Ni alloy plating layer was formed on the solid corrosion protective coating was performed trivalent chromate treatment. Trivalent chromate treatment solution, was used trade name dyne chromate TR-02 manufactured by Daiwa Kasei Co., Ltd.. Trivalent chromate treatment conditions, the bath pH: 4.0, bath temperature: 25 ° C., and treatment time was 50 seconds.
[0131]
　To box surface by blasting, to form a surface roughness of the rough arithmetic average as shown in Table 2 (Ra) and maximum height roughness Rz. Blasting was sandblasting (abrasive grains Mesh100). Similar to the pin in the box surface having a surface roughness to form a Zn-Ni alloy plating layer. On the Zn-Ni alloy plating layer, and carrying out the Cu-Sn-Zn alloy plating by electroplating, to form a Cu-Sn-Zn alloy plating layer. Cu-Sn-Zn alloy plating bath, using the plating bath manufactured by Nihon Kagaku Sangyo Co., Ltd.. Cu-Sn-Zn alloy plating layer was formed by electroplating. Conditions of electroplating, the plating bath pH: 14, the plating bath temperature: 45 ° C., a current density: 2A / dm 2 and the treatment time were: 40 min. The composition of the Cu-Sn-Zn alloy plating layer, Cu: 60%, Sn: 30%, Zn: was 10%. Further, on the Cu-Sn-Zn alloy plating layer was applied to the solid lubricating coating-forming composition. Solid lubricating coating composition for forming an epoxy resin (22%), PTFE particles (10%), the solvent (total 18%), water (40%) and other additives (including pigment) (10%) It contained. After the solid lubricating coating-forming composition is sprayed onto, dried by heating for 5 minutes at 90 ° C., to form a solid lubricating coating layer.
[0132]
　Test No. 2]
　In Test No. 2, with respect to the pin surface to form a Zn-Ni alloy plating layer by electroplating. Zn-Ni alloy plating bath was used trade name dyne Jin alloy N-PL manufactured by Daiwa Kasei Co., Ltd.. Conditions of electroplating, the plating bath pH: 6.5, the plating bath temperature: 25 ° C., a current density: 2A / dm 2 , and the treatment time were: 18 min. The composition of the Zn-Ni alloy plating layer, Zn: 85% and Ni: was 15%. The Zn-Ni alloy plating layer, like the pins of the test No. 1 was performed trivalent chromate treatment.
[0133]
　For box surface, similar to the box test No. 1, the surface roughness, Zn-Ni alloy plating layer to form a Cu-Sn-Zn alloy plating layer. On the Cu-Sn-Zn alloy plating layer was applied to the solid lubricating coating-forming composition. Solid lubricating coating composition for forming a polyamide-imide resin (22%), PTFE particles (5%), the solvent (total 18%), water (40%), other additives (including pigment) (15%) It contained. After the solid lubricating coating-forming composition is sprayed onto, dried by heating for 5 minutes at 90 ° C., to form a solid lubricating coating layer.
[0134]
　Test No. 3]
　In Test No. 3, the respective pin and box, similar to the box test No. 1, to form a surface roughness and Zn-Ni alloy plating layer and the Cu-Sn-Zn alloy plating layer. In box, Cu-Sn-Zn alloy plating bath, a plating bath made by Nihon Kagaku Sangyo Co., electroplating conditions, the plating bath pH: 14, the plating bath temperature: 45 ° C., a current density: 2A / Dm 2 and, processing time: was 40 minutes. On the Cu-Sn-Zn alloy plating layer of the pin and box, coated with solid lubricant coating layer forming composition. Solid lubricating coating composition for forming an epoxy resin (22%), PTFE particles (10%), the solvent (total 18%), water (40%) and other additives (including pigment) (10%) It contained. After the solid lubricating coating-forming composition was sprayed and dried by heating for 5 minutes at 90 ° C.. After heating and drying, further subjected to curing treatment for 20 minutes at 210 ° C., to form a solid lubricating coating layer.
[0135]
　[Test No. 4]
　In Test No. 4, with respect to the pin, like the box Test No. 1, to form a surface roughness by carrying out blasting. On the pin to form a surface roughness, to implement the Zn-Ni alloy plating by electroplating, to form a Zn-Ni alloy plating layer. Zn-Ni alloy plating bath was used trade name dyne Jin alloy N-PL manufactured by Daiwa Kasei Co., Ltd.. Conditions of electroplating, the plating bath pH: 6.5, the plating bath temperature: 25 ° C., a current density: 2A / dm 2 , and the treatment time were: 18 min. The composition of the Zn-Ni alloy plating layer, Zn: 85% and Ni: was 15%. On the Zn-Ni alloy plating layer, and carrying out the Cu-Sn-Zn alloy plating by electroplating, to form a Cu-Sn-Zn alloy plating layer. Cu-Sn-Zn alloy plating bath, using the plating bath manufactured by Nihon Kagaku Sangyo Co., Ltd.. Cu-Sn-Zn alloy plating layer was formed by electroplating. Conditions of electroplating, the plating bath pH: 14, the plating bath temperature: 45 ° C., a current density: 2A / dm 2 and the treatment time were: 40 min. The composition of the Cu-Sn-Zn alloy plating layer, Cu: 60%, Sn: 30%, Zn: was 10%. Further, on the Cu-Sn-Zn alloy plating layer was applied to the solid lubricating coating-forming composition. Solid lubricating coating composition for forming an epoxy resin (22%), PTFE particles (10%), the solvent (total 18%), water (40%) and other additives (including pigment) (10%) It contained. After the solid lubricating coating-forming composition is sprayed onto, dried by heating for 5 minutes at 90 ° C., to form a solid lubricating coating layer. For box, similar to the pins of the test No. 1, to form a Zn-Ni alloy plating layer, it was performed trivalent chromate treatment.
[0136]
　[Test No. 5]
　In Test No. 5, with respect to the pin, as the pin of the test No. 1, to form a Zn-Ni alloy plating layer, was performed trivalent chromate treatment. For box, similar to the box test No. 1, the surface roughness, Zn-Ni alloy plating layer, and to form a Cu-Sn-Zn alloy plating layer. On the Cu-Sn-Zn alloy plating layer was applied to the solid lubricating coating-forming composition. Solid lubricating layer coating composition is an epoxy resin (22%), PTFE particles (10%), the solvent (total 18%), water (40%) and other additives (including pigment) (10%) It contained. After the solid lubricating coating-forming composition was sprayed and dried by heating for 5 minutes at 90 ° C.. After heating and drying, further subjected to curing treatment for 20 minutes at 190 ° C., to form a solid lubricating coating layer.
[0137]
　Test No. 6]
　In Test No. 6, with respect to the pin, as the pin of the test No. 1, to form a Zn-Ni alloy plating layer, was performed trivalent chromate treatment. For box, under the same conditions as in box test No. 1, the surface roughness, Zn-Ni alloy plating layer, and to form a solid lubricating coating layer. That is, except that was not formed Cu-Sn-Zn alloy plating layer with respect to the box was the same as Test No. 1.
[0138]
　Test No. 7]
　In Test No. 7, with respect to the pin, as the pin of the test No. 1, to form a Zn-Ni alloy plating layer, was performed trivalent chromate treatment. For box, similar to the box test No. 1, the surface roughness, Cu-Sn-Zn alloy plating layer, and to form a solid lubricating coating layer. That is, except that did not form Zn-Ni alloy plating layer with respect to the box was the same as Test No. 1.
[0139]
　[Test No. 8]
　In Test No. 8, with respect to the pin, as the pin of the test No. 1, to form a Zn-Ni alloy plating layer, was performed trivalent chromate treatment. For boxes, the surface roughness formation process, Cu-Sn-Zn alloy plating layer forming step, Zn-Ni alloy plating layer forming step, and the order of the solid lubricating coating layer forming step was carried out each step. Implementation conditions of each step were the same as in box Test No. 1. That is, for the box, by replacing the positions of the Zn-Ni alloy plating layer and the Cu-Sn-Zn alloy plating layer of boxes Test No. 1, to form each layer. In Test No. 8, the original Zn-Ni alloy plating layer Cu-Sn-Zn alloy plating layer at positions where the to be formed is formed, the position should originally Cu-Sn-Zn alloy plating layer is formed, Zn- Ni alloy plating layer was formed. Therefore, in Table 3, in the column of Zn-Ni alloy plating layer for Cu-Sn-Zn alloy plating layer, in the column of the Cu-Sn-Zn alloy plating layer described for Zn-Ni alloy plating layer.
[0140]
　[Test No. 9]
　In Test No. 9, with respect to the pin, as the pin of the test No. 1, to form a Zn-Ni alloy plating layer, was performed trivalent chromate treatment. For box, under the same conditions as in box test No. 1, Zn-Ni alloy plating layer, Cu-Sn-Zn alloy plating layer, and to form a solid lubricating coating layer. That for the box, it did not form a surface roughness of Test No. 1.
[0141]
　Test No. 10]
　In Test No. 10, with respect to the pin, as the pin of the test No. 1, to form a Zn-Ni alloy plating layer, was performed trivalent chromate treatment. For box, similar to the box test No. 1, the surface roughness, Zn-Ni alloy plating layer to form a Cu-Sn-Zn alloy plating layer. On the Cu-Sn-Zn alloy plating layer was applied to the solid lubricating coating-forming composition. Solid lubricating coating composition for forming an epoxy resin (22%), MoS 2 particles (10%), the solvent (total 18%), water (40%) and other additives (including pigment) (10%) It contained. After the solid lubricating coating-forming composition is sprayed onto, dried by heating for 5 minutes at 90 ° C., to form a solid lubricating coating layer.
[0142]
　Test No. 11]
　In Test No. 11, with respect to the pin, as the pin of the test No. 1, to form a Zn-Ni alloy plating layer, was performed trivalent chromate treatment. For box, similar to the box test No. 1, the surface roughness, Zn-Ni alloy plating layer to form a Cu-Sn-Zn alloy plating layer. On the Cu-Sn-Zn alloy plating layer was applied to the solid lubricating coating-forming composition. Solid lubricating coating composition for forming a polyamide-imide resin (22%), graphite particles (10%), the solvent (total 18%), water (40%) and other additives (including pigment) (10%) It contained. After the solid lubricating coating-forming composition is sprayed onto, dried by heating for 5 minutes at 90 ° C., to form a solid lubricating coating layer.
[0143]
　Test No. 12]
　In Test No. 12, with respect to the pin surface, to implement the Zn-Ni alloy plating by electroplating, to form a Zn-Ni alloy plating layer. Zn-Ni alloy plating bath was used trade name dyne Jin alloy N-PL manufactured by Daiwa Kasei Co., Ltd.. Conditions of electroplating, the plating bath pH: 6.5, the plating bath temperature: 25 ° C., a current density: 2A / dm 2 , and the treatment time were: 18 min. The composition of the Zn-Ni alloy plating layer, Zn: 85% and Ni: was 15%. Furthermore, the obtained Ni-Zn alloy plating layer was formed on the solid corrosion protective coating was performed trivalent chromate treatment. Trivalent chromate treatment solution, was used trade name dyne chromate TR-02 manufactured by Daiwa Kasei Co., Ltd.. Trivalent chromate treatment conditions, the bath pH: 4.0, bath temperature: 25 ° C., and treatment time was 50 seconds.
[0144]
　To box surface by blasting, to form a surface roughness of the rough arithmetic mean of as shown in Table 3 (Ra) and maximum height roughness Rz. Blasting was sandblasting (abrasive grains Mesh100). Similar to the pin in the box surface having a surface roughness to form a Zn-Ni alloy plating layer. On the Zn-Ni alloy plating layer, and carrying out the Cu-Sn-Zn alloy plating by electroplating, to form a Cu-Sn-Zn alloy plating layer. Cu-Sn-Zn alloy plating bath, using the plating bath manufactured by Nihon Kagaku Sangyo Co., Ltd.. Cu-Sn-Zn alloy plating layer was formed by electroplating. Conditions of electroplating, the plating bath pH: 14, the plating bath temperature: 45 ° C., a current density: 2A / dm 2 and the treatment time were: 40 min. The composition of the Cu-Sn-Zn alloy plating layer, Cu: 60%, Sn: 30%, Zn: was 10%. Further, on the Cu-Sn-Zn alloy plating layer was applied to the solid lubricating coating-forming composition. Solid lubricating coating composition for forming polyethylene homopolymer (CLARIANT Co. COWAX　TM PE520: 9%), carnauba wax (15%), zinc stearate (15%), the liquid polyalkyl methacrylate (RohMax Inc. VISCOPLEX TM　6-950,5%), corrosion inhibitor (LUBRIZOL Corporation ALOX　TM 606: 40%), fluorinated graphite (3.5%), zinc oxide (1%), titanium dioxide (5%), bismuth trioxide (5%), silicone (manufactured by Ciba-Gerigy Inc.) (polydimethylsiloxane, 1%) and antioxidants (IRGANOX TM　L150: 0.3%,　IRGAFOS TM 168: contained 0.2%). The method of coating a solid lubricating coating-forming composition were as follows. The solid lubricating coating-forming composition was heated to 0.99 ° C. with a stirrer with a tank in a molten state, it was preheated to 130 ° C. by also induction heating box surface which was carried out the surface treatment. Using a spray gun having a spray head of retaining heat, after the solid lubricating coating-forming composition in a molten state was sprayed, then cooled to form a solid lubricating coating layer.
[0145]
　[Fastening performance]
　fastening performance was evaluated for seizure resistance and the torque on shoulder resistance [Delta] T '.
[0146]
　[Seizure resistance evaluation test]
　seizure resistance was evaluated by two types of repeated concluded test. Evaluation test by hand tight, and a resistance to misalignment resistance evaluation test.
[0147]
　[Hand Tight by Evaluation Test]
　using a pin and box of the test Nos. 1 to test No. 12, the hand tight (state fastened by human power), entered into initial engagement until the screw engages. After the conclusion of a hand tight, repeat the back screw tightening and screw with power tongs, it was to evaluate the seizure resistance. The return screw tightening and screw each performed once, it was observed visually pin surface and the box surface. By visual observation, it was confirmed the occurrence of the seizure. Is a very minor seizure, if possible recovery, and continue the test and repair the seizure flaws. Without causing with unrecoverable baked was measured the number of times that could return screw tightening and screw. The results are shown in "hand tight" column of Table 4. In Table 4, "20 <" means that the number of times that could return screw tightening and screw exceeds 20 times.
[0148]
　[Resistant misalignment Evaluation Test]
　using a pin and box of the test Nos. 1 to Test No. 12, without hand tight was concluded from the beginning in the power tongs. Therefore, repeated back screw tightening and screw involving misalignment was evaluated resistance to misalignment resistance. The crossing angle θ of misalignment was 5 °. Tightening rate of return screwing and screw 10 rpm, the tightening torque was 42.8kN · m. The return screw tightening and screw each performed once, it was observed visually pin surface and the box surface. By visual observation, it was confirmed the occurrence of the seizure. Is a very minor seizure, if possible recovery, and continue the test and repair the seizure flaws. Without causing with unrecoverable baked was measured the number of times that could return screw tightening and screw. The results are shown in Table 4. In Table 4, "20 <" means that the number of times that could return screw tightening and screw exceeds 20 times.
[0149]
[Table 4]

[0150]
　'Measurement Test Torque on shoulder resistance [Delta] T]
　with the pin and box of the test Nos. 1 to test No. 12, the torque on shoulder resistance [Delta] T' was measured. Specifically, the tightening speed 10 rpm, a screw tightening tightening torque 42.8kN · m was performed. The torque was measured when the screw tightening, created a torque chart as shown in FIG. Ts in FIG. 6 represents a shouldering torque. MTV in FIG. 6 represents the line segment L, and the torque value and the torque chart meet. Line segment L has the same slope as the slope of the linear region in the torque chart after shouldering, rotational speed compared to the same linear area is 0.2% more linear. Usually, when measuring torque on shoulder resistance [Delta] T 'uses Ty (yield torque). However, in this embodiment, the yield torque (in the torque chart after shouldering, the boundary between the linear region and the nonlinear region) was unclear. Therefore, by using a line segment L, it defined the MTV. The difference between MTV and the Ts, and the torque on shoulder resistance ΔT '. Torque on shoulder resistance [Delta] T 'is the numerical value when using the API standard doping instead of a solid lubricating coating layer of Test No. 1 as the criterion (100), it was determined as a relative value. The results are shown in Table 4.
[0151]
　The API standard dope, a screw compound grease for oil well pipes manufactured in compliance with API Bul 5A2. The composition of the API standard dope the grease as a substrate, graphite powder: 18 ± 1.0%, lead powder: 30.5 ± 0.6%, and copper flakes: 3.3 is defined to contain ± 0.3% ing. Incidentally, in this component range, screw compounding grease OCTG is understood to have an equivalent performance.
[0152]
　Corrosion Resistance
　[salt spray test]
　to the test Nos. 1 to Test No. 12 of the box surface was to salt spray test. Salt spray test was conducted according to the method described in JIS Z2371 (2015). The size of the test piece is 70 mm × 150 mm, the thickness was 1 mm. Red rust on the surface of the test piece for each test number was measured times caused by visual observation. The results are shown in Table 4. The test time was up to 4000 hours. If rust occurs more than 1500 hours, it is determined that there is no problem in corrosion resistance during long-term storage.
[0153]
　[Evaluation Result]
　With reference to Tables 2 to 4, the pipe threaded joint for Test Nos. 1 to Test No. 5, the at least one contact surface of the pin and box, the arithmetic average roughness Ra of 1 to 8 [mu] m and a maximum, height roughness Rz is 10 ~ 40 [mu] m in surface roughness, Zn-Ni alloy plating layer, Cu-Sn-Zn alloy plating layer, and had a solid lubricating coating layer. Further, each layer of the stacking order was also appropriate. Therefore, even if there is a hand-tight, even if accompanied by misalignment, repeated back screw tightening and screw 10 times, galling did not occur, showing excellent seizure resistance. Furthermore, the torque on shoulder resistance [Delta] T 'exceeds 100. Furthermore, results of the salt spray test is "no rust 4,000 hours" and showed excellent corrosion resistance.
[0154]
　Box surface of the test Nos. 1 to Test No. 3, the hardness of the solid lubricant coating layer was 15 or more in Vickers. Therefore, seizure resistance was higher in comparison with the test number 5.
[0155]
　On the other hand, the box surface of a test number 6 did not form a Cu-Sn-Zn alloy plating layer. Therefore, seizure resistance was low.
[0156]
　Box surface of the test numbers 7 did not form a Zn-Ni alloy plating layer. Therefore, seizure resistance was low. Moreover, in the salt spray test, rust occurred after 500 hours (pitching), the corrosion resistance was low.
[0157]
　Box surface of the test numbers 8, stacking sequence of the Zn-Ni alloy plating layer and the Cu-Sn-Zn alloy plating layer was reversed. Therefore, seizure resistance was low. Moreover, in the salt spray test, rust occurred after 750 hours (pitching), the corrosion resistance was low.
[0158]
　Box surface of the test number 9, was not carried out the blast processing. Therefore, both the arithmetic average roughness Ra and the maximum height roughness Rz is less than the scope of the present invention, galling resistance was low.
[0159]
　Box surface of the test number 10, the solid lubricant coating layer did not contain a fluorine resin particles. Therefore, the torque on shoulder resistance [Delta] T 'is less than 100.
[0160]
　Box surface of the test number 11, the solid lubricant coating layer did not contain a fluorine resin particles. Therefore, the torque on shoulder resistance [Delta] T 'is less than 100.
[0161]
　Box surface of the test number 12, the composition of the solid lubricating coating layer did not contain any epoxy resin and a polyamide-imide resin. Therefore, the torque on shoulder resistance [Delta] T 'is less than 100. Presumably because the coefficient of friction of the solid lubricant coating layer was low.
[0162]
　It has been described an embodiment of the present invention. However, the above-described embodiment is merely an example for implementing the present invention. Accordingly, the present invention is not limited to the embodiments described above, it can be implemented by changing the above-described embodiments without departing from the scope and spirit thereof as appropriate.
DESCRIPTION OF SYMBOLS
[0163]
　3,13 Pin
　14 Box
　15 externally threaded section
　16 and 19 the metal seal part
　17, 18 the shoulder portion
　20 the internal thread portion
　21 Zn-Ni alloy plating layer
　22 Cu-Sn-Zn alloy plating layer
　23 solid lubricating coating layer
　130, 140 contact surfaces

WE claims

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 portion,
at least one of said contact surfaces of the pin and the box has an arithmetic mean roughness Ra 1 ~ 8 [mu] m and a maximum height roughness Rz, has a surface roughness of 10 ~ 40 [mu] m,
　a threaded joint for the tube, on the contact surface with the surface roughness consists of Zn-Ni alloy and Zn-Ni alloy plating layer,
　the Zn-Ni alloy plating layer, a Cu-Sn-Zn alloy plating layer consisting of Cu-Sn-Zn alloy,
　the Cu-Sn-Zn alloy plating layer, a solid lubricant and a coating layer,
　the solid lubricant coating layer is at least one element selected from the group consisting of an epoxy resin and a polyamide-imide resin, and a fluorine-containing resin particles, a screw joint for a tube hand.
[Requested item 2]
　A pipe thread joint according to claim 1,
　wherein the Zn-Ni hardness of the alloy plating layer is more than 300 micro-Vickers, and the thickness of the Zn-Ni alloy plating layer is 5 ~ 20 [mu] m, pipe threads joint.
[Requested item 3]
　A pipe thread joint according to claim 1 or claim 2,
　wherein the Cu-Sn-Zn hardness of the alloy plating layer is micro-Vickers at 500 or more and a thickness of the Cu-Sn-Zn alloy plating layer is 5 ~ 20 [mu] m, pipe threaded joint.
[Requested item 4]
　A pipe thread joint according to any one of claims 1 to 3,
　wherein the solid lubricant film 15 to hardness in micro-Vickers of layer 25, and the thickness of the solid lubricating coating is 10 - is 40 [mu] m, pipe threaded joint.
[Requested item 5]
　A pipe thread joint according to any one of claims 1 to 4,
　wherein the fluorine resin particles, polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexa hexafluoropropylene copolymer (4.6 fluoride), is selected tetrafluoroethylene-ethylene copolymer, polyvinylidene fluoride (2 fluorinated), and from the group consisting of polychlorotrifluoroethylene (trifluoride) one or two or more kinds, pipe threaded joint.
[Requested item 6]
　A method of manufacturing 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 portion,
　the manufacturing method of the pipe threaded joint, the pin and the at least one of the contact surfaces of the box,
　a step of arithmetic average roughness Ra of 1 ~ 8 [mu] m, and a maximum height roughness Rz to form a surface roughness of 10 ~ 40 [mu] m by blasting,
　forming the surface roughness after the steps of forming a Zn-Ni alloy plating layer consisting of Zn-Ni alloy by electroplating,
　after formation of the Zn-Ni alloy plating layer, a Cu-Sn-Zn alloy by electroplating Cu-Sn forming a -Zn alloy plating layer,
　after forming the Cu-Sn-Zn alloy plating layer, and forming a solid lubricating coating, it pipe Method of manufacturing a Flip joints.