Metal pipe for oil well and method for manufacturing metal pipe for oil well

Abstract

The oil well metal pipe disclosed herein can be tightened with a high torque even if it is large in diameter. The oil well metal pipe (1) disclosed herein comprises a pipe body (10) including a first end (10A) and a second end (10B). The pipe body (10) comprises a male buckle portion (40) formed at the first end (10A) and a female buckle portion (50) formed at the second end (10B). The male buckle portion (40) comprises a male buckle portion contact surface (400), the male buckle portion contact surface (400) comprising an external thread portion (41), and the female buckle portion (50) comprises a female buckle portion contact surface (500), the female buckle portion contact surface (500) comprising an internal thread portion (51). The oil well metal pipe (1) disclosed herein also comprises a resin coating (100) containing a resin, a solid lubricating powder and copper phthalocyanine on at least one of the male buckle portion contact surface (400) and the female buckle portion contact surface (500).

Description

Technical Field

[0001] The present disclosure relates to a metal pipe for oil well and a method for manufacturing the metal pipe for oil well. Background Art

[0002] In order to exploit oil fields and natural gas fields (hereinafter oil fields and natural gas fields are collectively referred to as "oil wells"), metal pipes for oil wells are used. Metal pipes for oil wells have threaded joints. Specifically, at the oil well exploitation site, multiple metal pipes for oil wells are connected to form an oil well pipe connection body represented by casing and pipeline. The oil well pipe connection body is formed by threading the metal pipes for oil wells together. There are cases where the oil well pipe connection body is inspected. In the case of inspection, the oil well pipe connection body is pulled up and the threads are returned. Then, the metal pipes for oil wells are removed from the oil well pipe connection body by threading and inspection. After the inspection, the metal pipes for oil wells are threadedly fastened to each other again and used as part of the oil well pipe connection body again.

[0003] The metal pipe for oil wells comprises a pin buckle part and a box buckle part. The pin buckle part has a pin buckle part contact surface including an external threaded part on the outer peripheral surface of the end of the metal pipe for oil wells. The box buckle part has a box buckle part contact surface including an internal threaded part on the inner peripheral surface of the end of the metal pipe for oil wells. In the present specification, the external threaded part and the internal threaded part are collectively referred to as "threaded part". In addition, there is a case where the pin buckle part contact surface also includes a pin buckle part non-threaded metal contact part, and the pin buckle part non-threaded metal contact part includes a pin buckle part sealing surface and a pin buckle part shoulder surface. Similarly, there is a case where the box buckle part contact surface also includes a box buckle part non-threaded metal contact part, and the box buckle part non-threaded metal contact part includes a box buckle part sealing surface and a box buckle part shoulder surface.

[0004] When the oil well metal pipe is threaded and returned, the pin contact surface and the box contact surface are repeatedly subjected to strong friction. Therefore, the pin contact surface and the box contact surface are prone to seizure (irreparable wear) when the thread is repeatedly tightened and returned. Therefore, sufficient durability against friction, that is, excellent wear resistance, is required for the oil well metal pipe.

[0005] Conventionally, in order to improve the wear resistance of metal pipes for oil wells, compound greases containing heavy metal powders, called dopants, have been used. The wear resistance of metal pipes for oil wells can be improved by applying compound grease to the contact surface of the pin part and / or the contact surface of the box part. However, heavy metal powders such as Pb, Zn, and Cu contained in the compound grease may have an impact on the environment. Therefore, it is desired to develop a metal pipe for oil wells that has excellent wear resistance even without using compound grease.

[0006] For example, International Publication No. 2014 / 042144 (Patent Document 1) and International Publication No. 2017 / 047722 (Patent Document 2) propose technologies for improving the wear resistance of metal pipes for oil wells.

[0007] The composition disclosed in Patent Document 1 is a composition for forming a solid coating on the surface of a threaded joint of a metal pipe for oil wells. The composition is a composition containing a powdered organic resin at least partially soluble in a bipolar aprotic solvent in a mixed solvent containing water and a bipolar aprotic solvent. In the composition, the powdered organic resin is present in a dissolved or dispersed state in the mixed solvent.

[0008] The composition disclosed in Patent Document 2 is a composition for forming a solid lubricating coating on a threaded joint of a metal pipe for oil wells. The composition contains a binder, a lubricating additive, a rust-proof additive, and a plasticizer.

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: International Publication No. 2014 / 042144

[0012] Patent Document 2: International Publication No. 2017 / 047722 Summary of the invention

[0013] Problem that the invention aims to solve

[0014] However, metal pipes for oil wells are used in various sizes (diameters). Therefore, it is desirable that the metal pipes for oil wells are not easily loosened regardless of the size of the metal pipes for oil wells. Here, a higher tightening torque is pre-set for large-diameter metal pipes for oil wells so that the fastened metal pipes for oil wells will not loosen.

[0015] In the case of tightening a large-diameter metal pipe for oil wells with a high torque, it is desired that the high torque performance is high. The high torque performance is high, which means that the shoulder friction torque is large. The shoulder friction torque means the difference between the yield torque at which a part of the metal pipe for oil wells yields and the shoulder torque at which the interference between the metal pipes for oil wells increases sharply. On the other hand, there is a case where the shoulder friction torque is small even if the technology disclosed in Patent Documents 1 and 2 is used. In this case, it is difficult to tighten a large-diameter metal pipe for oil wells with a high torque.

[0016] An object of the present disclosure is to provide an oil well metal pipe that can be fastened with a high torque even if the pipe has a large diameter, and a method for producing the oil well metal pipe.

[0017] Solutions for solving problems

[0018] The oil well metal pipe disclosed herein includes a pipe body including a first end portion and a second end portion.

[0019] The pipe body comprises:

[0020] a male buckle portion formed at the first end portion; and

[0021] a female buckle portion formed at the second end portion,

[0022] The pin buckle portion includes a pin buckle portion contact surface, and the pin buckle portion contact surface includes an external thread portion,

[0023] The box buckle portion includes a box buckle portion contact surface, and the box buckle portion contact surface includes an internal thread portion,

[0024] The oil well metal pipe further includes a resin coating containing resin, solid lubricating powder, and copper phthalocyanine on at least one of the pin portion contact surface and the box portion contact surface.

[0025] The method for manufacturing a metal pipe for oil well disclosed in the present invention comprises:

[0026] A step of preparing a metal pipe for oil wells, the metal pipe for oil wells having a pipe body including a pin portion and a box portion, the pin portion including a pin portion contact surface including an external thread portion, the box portion including a box portion contact surface including an internal thread portion;

[0027] A step of applying a composition containing a resin, a solid lubricating powder and copper phthalocyanine to at least one of the male buckle portion contact surface and the female buckle portion contact surface; and

[0028] A step of curing the applied composition to form a resin coating.

[0029] Effects of the Invention

[0030] The oil well metal pipe of the present disclosure can be fastened with a high torque even if the pipe has a large diameter. The oil well metal pipe manufacturing method of the present disclosure can manufacture the oil well metal pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a diagram showing the relationship between the number of rotations and the torque when the oil well metal pipe having a shoulder portion is tightened.

[0032] Figure 2A This is a graph showing the relationship between the content of copper phthalocyanine in the resin film and the high torque performance.

[0033] Figure 2B Yes means Figure 2A This is a partially enlarged view of a graph showing the relationship between the content of copper phthalocyanine in the resin coating and the high torque performance.

[0034] Figure 3 It is a structural diagram showing an example of the metal pipe for oil wells according to the present embodiment.

[0035] Figure 4 Yes means Figure 3 The illustrated partial cross-sectional view is a cross-sectional view of a coupling of a metal pipe for oil wells, taken along a section (longitudinal section) parallel to the pipe axis direction.

[0036] Figure 5 yes Figure 4 A cross-sectional view of a portion near a pin portion of the oil well metal pipe shown in FIG. 1 , parallel to the pipe axis direction of the oil well metal pipe.

[0037] Figure 6 yes Figure 4 A cross-sectional view of a portion near a box portion of the oil well metal pipe shown in the figure, parallel to the pipe axis direction of the oil well metal pipe.

[0038] Figure 7 It means Figure 4 A partial cross-sectional view of a section (longitudinal section) parallel to the pipe axis direction of a coupling for an oil well metal pipe according to another embodiment of the present invention.

[0039] Figure 8 This is a structural diagram of the integral oil well metal pipe according to the present embodiment.

[0040] Fig. 9 yes Figure 5 An enlarged view of the contact surface of the pin portion is shown.

[0041] Fig.10 yes Figure 6 An enlarged view of the contact surface of the female buckle portion is shown.

[0042] Fig.11 is with Fig. 9 An enlarged view of the contact surface of the male buckle portion of a different embodiment of the present invention.

[0043] Fig.12 is with Fig. 9 and Fig.11 An enlarged view of the contact surface of the male buckle portion of a different embodiment of the present invention.

[0044] Fig.13 is with Fig. 9 , Fig.11 and Fig.12 An enlarged view of the contact surface of the male buckle portion of a different embodiment of the present invention.

[0045] Fig.14This is a graph showing the relationship between the plating layer, the content of copper phthalocyanine, and the result of the Bowden test which is an index of wear resistance.

[0046] Fig.15 is with Fig.10 An enlarged view of the contact surface of the female buckle portion of a different embodiment of the present invention.

[0047] Fig.16 is with Fig. 9 , Fig.11 , Fig.12 and Fig.13 An enlarged view of the contact surface of the male buckle portion of a different embodiment of the present invention.

[0048] Fig.17 is with Fig. 9 , Fig.11 , Fig.12 , Fig.13 and Fig.16 An enlarged view of the contact surface of the male buckle portion of a different embodiment of the present invention.

[0049] Fig.18 is with Fig. 9 , Fig.11 , Fig.12 , Fig.13 , Fig.16 and Fig.17 An enlarged view of the contact surface of the male buckle portion of a different embodiment of the present invention.

[0050] Fig.19 It is a diagram for explaining the shoulder friction torque ΔT in the embodiment. DETAILED DESCRIPTION

[0051] Hereinafter, the present embodiment will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are denoted by the same reference numerals, and their description will not be repeated.

[0052] The present inventors have conducted various studies on the relationship between oil well metal pipes and tightening torque, and have obtained the following findings.

[0053] [High torque performance]

[0054] When oil well metal pipes are fastened to each other, an optimum torque for completing the fastening is determined in advance. Figure 1 This is a graph showing the relationship between the number of rotations and the torque when tightening the oil well metal pipe having a shoulder portion. Figure 1If the metal pipe for oil wells is threadedly tightened, the torque first rises slowly in proportion to the number of revolutions. If the thread is further tightened, the shoulders come into contact with each other. The torque at this time is called the shoulder torque Ts. If the thread is further tightened after the shoulder torque Ts is reached, the torque rises sharply in proportion to the number of revolutions. The tightening is completed when the torque reaches a predetermined value (tightening torque To). Under the tightening torque To, the metal sealing parts interfere with each other with appropriate surface pressure. In this case, the metal pipe for oil wells can obtain higher airtightness. If the thread is further excessively tightened after the tightening torque To is reached, the torque reaches the yield torque Ty, and a part of the male and female buckles yield. In this specification, the difference between the shoulder torque Ts and the yield torque Ty is called the shoulder friction torque ΔT.

[0055] In addition, as another form of oil well metal pipe, there is an oil well metal pipe having a wedge thread instead of a shoulder portion. In the case of such an oil well metal pipe having a wedge thread, the relationship between the number of revolutions and the torque of the oil well metal pipe is similar to that of the oil well metal pipe having a shoulder portion. Figure 1 .

[0056] Here, a wedge thread means a thread having the following structure. In the external thread portion of the wedge thread, as the screwing direction of the pin buckle portion proceeds, the width of the thread teeth gradually narrows along the helical line of the thread, and the width of the thread groove gradually widens along the helical line of the thread. Furthermore, in the internal thread portion of the wedge thread, as the screwing direction of the box buckle portion proceeds, the width of the thread groove gradually narrows along the helical line of the thread, and the width of the thread teeth gradually widens along the helical line of the thread. In the case of a metal pipe for oil wells having a wedge thread, as the thread is tightened, the load tooth side surfaces of the external thread portion and the internal thread portion, as well as the insertion tooth side surfaces, contact each other to produce locking (interference fit). The torque when locking occurs is also called locking torque or locking tooth side torque.

[0057] In this specification, unless otherwise specified, the locking torque and the shoulder torque are not distinguished, but are referred to as the shoulder torque Ts. In the case of a metal pipe for oil wells with a wedge thread, similarly to the case of a metal pipe for oil wells with a shoulder portion, if the thread is further tightened after reaching the shoulder torque Ts, the torque rises sharply in proportion to the number of revolutions. That is, under the shoulder torque Ts, the interference between the metal pipes for oil wells increases sharply. Then, if the thread is further tightened, the tightening torque To is reached. If the thread is further excessively tightened after reaching the tightening torque To, the yield torque Ty is reached, and a portion of the male and female buckles yield.

[0058] As described above, a higher tightening torque To is set for large-diameter metal pipes for oil wells. However, when the tightening torque To is set higher, there is a situation where a portion of the male buckle and the female buckle yields before the tightening torque To is reached, causing plastic deformation. If the shoulder friction torque ΔT is large, further thread tightening can be performed after the shoulder torque Ts is reached. Therefore, if the shoulder friction torque ΔT is large, even large-diameter metal pipes for oil wells can be tightened with a higher torque. In this case, the metal pipes for oil wells become less likely to loosen. Here, in this specification, high-torque performance means that the shoulder friction torque ΔT is large. In this specification, large-diameter metal pipes for oil wells mean metal pipes for oil wells with an outer diameter of 254 mm (10 inches) or more.

[0059] In order to increase the shoulder friction torque ΔT, it is effective to reduce the shoulder torque Ts or increase the yield torque Ty. However, it is generally known that the shoulder torque Ts and the yield torque Ty exhibit the same behavior. For example, in the case where the friction coefficient of the surface of the metal pipe for oil wells is reduced in order to reduce the shoulder torque Ts, not only the shoulder torque Ts is reduced, but also the yield torque Ty is reduced. In this case, there is a situation where a part of the male buckle part or the female buckle part yields before the tightening torque To is reached. In addition, in the case where the friction coefficient of the surface of the metal pipe for oil wells is increased in order to increase the yield torque Ty, not only the yield torque Ty increases, but also the shoulder torque Ts increases. In this case, there is a situation where the shoulder part does not contact even if the tightening torque To is reached.

[0060] Compared with normal to small diameter oil well metal pipes, large diameter oil well metal pipes are required to have higher high torque performance. Therefore, the inventors studied a method to improve high torque performance even for large diameter oil well metal pipes. As a result, the following findings were obtained.

[0061] Figure 2A This is a graph showing the relationship between the content of copper phthalocyanine in the resin film and the high torque performance. Figure 2A This is obtained from the results of Example 1 described later. In Example 1, a so-called large-diameter (outer diameter 273.05 mm (10.75 inches), wall thickness: 12.570 mm (0.495 inches)) oil well metal pipe was used.

[0062] Figure 2A The horizontal axis represents the content (mass %) of copper phthalocyanine in the resin film. Figure 2AThe vertical axis represents the shoulder friction torque ΔT. The shoulder friction torque ΔT is a relative value compared with the shoulder friction torque ΔT in the case of using the dopant specified in API (American Petroleum Institute) standard Bull 5A2 (1998) as 100. Figure 2A In the figure, a white circle mark (○) indicates that the resin coating contains copper phthalocyanine, and a black circle mark (●) indicates that the resin coating does not contain copper phthalocyanine.

[0063] Reference Figure 2A Compared with the case where the resin coating does not contain copper phthalocyanine, the shoulder friction torque ΔT is improved when the resin coating contains copper phthalocyanine. That is, when the resin coating contains copper phthalocyanine, the high torque performance is improved. In this case, even a large-diameter metal pipe for oil wells can be tightened with a higher torque.

[0064] Figure 2B This is a partially enlarged view of a graph showing the relationship between the content of copper phthalocyanine in the resin coating and the high torque performance. Figure 2B If the content of copper phthalocyanine in the resin coating is adjusted to 0.2 mass % or more, the high torque performance of the oil well metal pipe is further improved.

[0065] The main points of the metal pipe for oil well use and the method for producing the metal pipe for oil well use according to the present embodiment, which were completed based on the above findings, are as follows.

[0066] [1] A metal pipe for oil wells, wherein:

[0067] The oil well metal pipe comprises a pipe body including a first end portion and a second end portion.

[0068] The pipe body comprises:

[0069] a male buckle portion formed at the first end portion; and

[0070] a female buckle portion formed at the second end portion,

[0071] The pin buckle portion includes a pin buckle portion contact surface, and the pin buckle portion contact surface includes an external thread portion,

[0072] The box buckle portion includes a box buckle portion contact surface, and the box buckle portion contact surface includes an internal thread portion,

[0073] The oil well metal pipe further includes a resin coating containing resin, solid lubricating powder, and copper phthalocyanine on at least one of the pin portion contact surface and the box portion contact surface.

[0074] The metal pipe for oil wells of this embodiment has a resin coating containing copper phthalocyanine. Therefore, even a large-diameter metal pipe for oil wells can be tightened with a high torque. In addition, the metal pipe for oil wells of this embodiment can also be applied to metal pipes for oil wells of normal to small diameters. The metal pipe for oil wells of this embodiment can be tightened with a necessary and sufficient torque even when applied to metal pipes for oil wells of normal to small diameters.

[0075] [2] The metal pipe for oil wells according to [1], wherein:

[0076] The resin coating contains 0.2 to 30.0 mass % of copper phthalocyanine.

[0077] In this case, the high torque performance of the oil well metal pipe is further improved.

[0078] [3] The metal pipe for oil wells according to [2], wherein:

[0079] The resin coating contains:

[0080] 0.2-30.0 mass% copper phthalocyanine;

[0081] 60 to 90% by mass of the resin; and

[0082] 1 to 30% by mass of the solid lubricating powder.

[0083] [4] The metal pipe for oil wells according to [2] or [3], wherein:

[0084] The resin coating contains 0.2 to 9.0 mass % of copper phthalocyanine.

[0085] In this case, the oil well metal pipe has improved high torque performance and also improved wear resistance.

[0086] [5] The metal pipe for oil wells according to any one of [1] to [4], wherein

[0087] The oil well metal pipe further includes a plating layer between the resin coating and at least one of the pin portion contact surface and the box portion contact surface.

[0088] [6] The metal pipe for oil wells according to any one of [1] to [4], wherein

[0089] The oil well metal pipe further includes a chemical conversion coating between the resin coating and at least one of the pin portion contact surface and the box portion contact surface.

[0090] [7] The metal pipe for oil wells according to [5], wherein:

[0091] The oil well metal pipe further includes a chemical conversion film between the plating layer and the resin film.

[0092] [8] The metal pipe for oil wells according to any one of [1] to [7], wherein

[0093] The resin coating further contains an anti-rust pigment.

[0094] [9] The metal pipe for oil wells according to any one of [1] to [8], wherein

[0095] At least one of the pin portion contact surface and the box portion contact surface is a surface subjected to one or more treatments selected from the group consisting of sandblasting and pickling.

[0096]

[10] The metal pipe for oil wells according to any one of [1] to [9], wherein

[0097] The resin is at least one selected from the group consisting of epoxy resins, phenolic resins, acrylic resins, polyurethane resins, polyester resins, polyamideimide resins, polyamide resins, polyimide resins, and polyetheretherketone resins.

[0098]

[11] The metal pipe for oil wells according to any one of [1] to

[10] , wherein

[0099] The solid lubricating powder is one or more selected from the group consisting of graphite, zinc oxide, boron nitride, talc, molybdenum disulfide, tungsten disulfide, graphite fluoride, tin sulfide, bismuth sulfide, organic molybdenum, thiosulfate compounds and polytetrafluoroethylene.

[0100]

[12] The metal pipe for oil wells according to any one of [1] to

[11] , wherein

[0101] The male buckle part contact surface also includes a male buckle part sealing surface and a male buckle part shoulder surface,

[0102] The contact surface of the box buckle part also includes a box buckle part sealing surface and a box buckle part shoulder surface.

[0103]

[13] A method for manufacturing a metal pipe for oil wells according to [1], wherein:

[0104] The method for manufacturing the metal pipe for oil wells comprises:

[0105] A step of preparing a metal pipe for oil wells, the metal pipe for oil wells having a pipe body including a pin portion and a box portion, the pin portion including a pin portion contact surface including an external thread portion, the box portion including a box portion contact surface including an internal thread portion;

[0106] A step of applying a composition containing a resin, a solid lubricating powder and copper phthalocyanine to at least one of the male buckle portion contact surface and the female buckle portion contact surface; and

[0107] A step of curing the applied composition to form a resin coating.

[0108] Hereinafter, the oil well metal pipe according to the present embodiment will be described in detail.

[0109] [Structure of metal pipe for oil wells]

[0110] First, the structure of the metal pipe for oil wells of this embodiment is described. The metal pipe for oil wells has a known structure. The metal pipe for oil wells includes T&C type metal pipe for oil wells and integral type metal pipe for oil wells. Each type of metal pipe for oil wells is described in detail below.

[0111] [When the metal pipe 1 for oil well is of T&C type]

[0112] Figure 3 It is a structural diagram showing an example of the oil well metal pipe 1 according to the present embodiment. Figure 3 This is a structural diagram of a so-called T&C type (Threaded and Coupled) oil well metal pipe 1. Figure 3 The oil well metal pipe 1 includes a pipe body 10 .

[0113] The pipe body 10 extends in the pipe axis direction. The cross section of the pipe body 10 perpendicular to the pipe axis direction is circular. The pipe body 10 includes a first end 10A and a second end 10B. The first end 10A is an end on the opposite side of the second end 10B. Figure 3 In the illustrated T&C type oil well metal pipe 1, the pipe body 10 includes a pin pipe body 11 and a coupling 12. The coupling 12 is attached to one end of the pin pipe body 11. More specifically, the coupling 12 is fastened to one end of the pin pipe body 11 by threads.

[0114] Figure 4 Yes means Figure 3 The cross-sectional view of the coupling 12 of the oil well metal pipe 1 shown is a partial cross-sectional view of the cross section (longitudinal section) parallel to the pipe axis direction. Figure 3 and Figure 4 The pipe body 10 includes a pin 40 and a box 50. The pin 40 is formed at the first end 10A of the pipe body 10. The pin 40 is inserted into the box 50 of another oil well metal pipe 1 (not shown) during fastening, and is fastened to the box 50 of the other oil well metal pipe 1 by threads.

[0115] The box portion 50 is formed at the second end portion 10B of the pipe body 10. When fastening, the pin portion 40 of another oil well metal pipe 1 is inserted into the box portion 50 and fastened to the pin portion 40 of another oil well metal pipe 1 by threads.

[0116] [Regarding the structure of the male buckle portion 40]

[0117] Figure 5 yes Figure 4 The cross-sectional view of the vicinity of the pin portion 40 of the oil well metal pipe 1 is parallel to the pipe axis direction of the oil well metal pipe 1 . Figure 5 The dotted line portion in represents the structure of the box buckle portion 50 of another oil well metal pipe 1 when fastened to another oil well metal pipe 1. Figure 5 The pin 40 has a pin contact surface 400 on the outer peripheral surface of the first end 10A of the pipe body 10. The pin contact surface 400 is screwed into the box 50 of the other oil well metal pipe 1 when fastening with the other oil well metal pipe 1, and contacts the box contact surface 500 (described later) of the box 50.

[0118] The pin contact surface 400 includes at least an external thread portion 41 formed on the outer peripheral surface of the first end portion 10A. The pin contact surface 400 may further include a pin sealing surface 42 and a pin shoulder surface 43. Figure 5 In the embodiment, the male buckle shoulder surface 43 is arranged on the top end surface of the first end portion 10A, and the male buckle sealing surface 42 is arranged on the top end side of the first end portion 10A that is closer to the first end portion 10A than the external thread portion 41 in the outer peripheral surface of the first end portion 10A. That is, the male buckle sealing surface 42 is arranged between the external thread portion 41 and the male buckle shoulder surface 43. The male buckle sealing surface 42 is set to be conical. Specifically, on the male buckle sealing surface 42, in the long side direction (tube axis direction) of the first end portion 10A, the outer diameter gradually decreases as it moves from the external thread portion 41 toward the male buckle shoulder surface 43.

[0119] When fastening with another metal pipe 1 for oil wells, the male buckle sealing surface 42 contacts the female buckle sealing surface 52 (described later) of the female buckle 50 of the other metal pipe 1 for oil wells. More specifically, when fastening, the male buckle 40 is inserted into the female buckle 50 of the other metal pipe 1 for oil wells, whereby the male buckle sealing surface 42 contacts the female buckle sealing surface 52. Then, the male buckle 40 is further screwed into the female buckle 50 of the other metal pipe 1 for oil wells, whereby the male buckle sealing surface 42 contacts the female buckle sealing surface 52. Thus, when fastening, the male buckle sealing surface 42 contacts the female buckle sealing surface 52 to form a seal based on metal-metal contact. Therefore, in the metal pipes 1 for oil wells that are fastened to each other, the airtightness can be improved.

[0120] exist Figure 5In the embodiment, the male buckle shoulder surface 43 is arranged on the top end surface of the first end portion 10A. Figure 5 In the pin buckle part 40 shown, the external thread part 41, the pin buckle part sealing surface 42, and the pin buckle part shoulder surface 43 are arranged in the order from the center of the pipe body 10 toward the first end 10A. When fastening with another metal pipe 1 for oil wells, the pin buckle part shoulder surface 43 is opposite to and in contact with the female buckle part shoulder surface 53 (described later) of the female buckle part 50 of the other metal pipe 1 for oil wells. More specifically, when fastening, the pin buckle part 40 is inserted into the female buckle part 50 of the other metal pipe 1 for oil wells, whereby the pin buckle part shoulder surface 43 is in contact with the female buckle part shoulder surface 53. As a result, a higher torque can be obtained during fastening. In addition, the positional relationship between the pin buckle part 40 and the female buckle part 50 in the fastened state can be stabilized.

[0121] In addition, the pin part contact surface 400 of the pin part 40 includes at least the external threaded portion 41. That is, the pin part contact surface 400 may include the external threaded portion 41, and does not include the pin part sealing surface 42 and the pin part shoulder surface 43. Alternatively, the pin part contact surface 400 may include the external threaded portion 41 and the pin part shoulder surface 43, and does not include the pin part sealing surface 42. Alternatively, the pin part contact surface 400 may include the external threaded portion 41 and the pin part sealing surface 42, and does not include the pin part shoulder surface 43.

[0122] [Regarding the structure of the female buckle portion 50]

[0123] Figure 6 yes Figure 4 The cross-sectional view of the vicinity of the box portion 50 of the oil well metal pipe 1 is parallel to the pipe axis direction of the oil well metal pipe 1 . Figure 6 The dotted line portion in represents the structure of the male buckle portion 40 of another oil well metal pipe 1 when fastened to another oil well metal pipe 1. Figure 6 The box part 50 has a box part contact surface 500 on the inner peripheral surface of the second end portion 10B of the pipe body 10. The box part contact surface 500 is screwed into the pin part 40 of the other oil well metal pipe 1 when fastening with the other oil well metal pipe 1, and contacts the pin part contact surface 400 of the pin part 40.

[0124] The box portion contact surface 500 includes at least an internal thread portion 51 formed on the inner peripheral surface of the second end portion 10B. During fastening, the internal thread portion 51 meshes with the external thread portion 41 of the pin portion 40 of another oil well metal pipe 1.

[0125] The female buckle contact surface 500 may further include a female buckle sealing surface 52 and a female buckle shoulder surface 53. Figure 6In the embodiment, the box buckle portion sealing surface 52 is arranged on the inner peripheral surface of the second end portion 10B, which is closer to the pipe body 10 than the internal thread portion 51. That is, the box buckle portion sealing surface 52 is arranged between the internal thread portion 51 and the box buckle portion shoulder surface 53. The box buckle portion sealing surface 52 is set to be tapered. Specifically, in the box buckle portion sealing surface 52, in the long side direction (tube axis direction) of the second end portion 10B, the inner diameter gradually decreases as it moves from the internal thread portion 51 toward the box buckle portion shoulder surface 53.

[0126] When tightening with another metal pipe 1 for oil wells, the sealing surface 52 of the female buckle part contacts the sealing surface 42 of the male buckle part 40 of the other metal pipe 1 for oil wells. More specifically, when tightening, the male buckle part 40 of another metal pipe 1 for oil wells is screwed into the female buckle part 50, whereby the sealing surface 52 of the female buckle part contacts the sealing surface 42 of the male buckle part, and is further screwed in, whereby the sealing surface 52 of the female buckle part contacts the sealing surface 42 of the male buckle part. Thus, when tightening, the sealing surface 52 of the female buckle part contacts the sealing surface 42 of the male buckle part to form a seal based on metal-metal contact. Therefore, in the metal pipes 1 for oil wells that are tightened to each other, the airtightness can be improved.

[0127] The box buckle shoulder surface 53 is arranged on the pipe body 10 side relative to the box buckle sealing surface 52. That is, in the box buckle 50, the box buckle shoulder surface 53, the box buckle sealing surface 52, and the internal thread portion 51 are arranged in order from the center of the pipe body 10 toward the top of the second end portion 10B. When fastening with another metal pipe 1 for oil wells, the box buckle shoulder surface 53 is opposite to and in contact with the pin buckle shoulder surface 43 of the pin buckle 40 of the other metal pipe 1 for oil wells. More specifically, when fastening, the pin buckle 40 of another metal pipe 1 for oil wells is inserted into the box buckle 50, whereby the box buckle shoulder surface 53 is in contact with the pin buckle shoulder surface 43. As a result, a higher torque can be obtained during fastening. In addition, the positional relationship between the pin buckle 40 and the box buckle 50 in the fastened state can be stabilized.

[0128] The box contact surface 500 includes at least an internal thread portion 51. When tightened, the internal thread portion 51 of the box contact surface 500 of the box 50 corresponds to and contacts the external thread portion 41 of the pin contact surface 400 of the pin 40. The box sealing surface 52 corresponds to and contacts the pin sealing surface 42. The box shoulder surface 53 corresponds to and contacts the pin shoulder surface 43.

[0129] In the case where the pin part contact surface 400 includes the external threaded portion 41 and does not include the pin part sealing surface 42 and the pin part shoulder surface 43, the box part contact surface 500 includes the internal threaded portion 51 and does not include the box part sealing surface 52 and the box part shoulder surface 53. In the case where the pin part contact surface 400 includes the external threaded portion 41 and the pin part shoulder surface 43 and does not include the pin part sealing surface 42, the box part contact surface 500 includes the internal threaded portion 51 and the box part shoulder surface 53 and does not include the box part sealing surface 52. In the case where the pin part contact surface 400 includes the external threaded portion 41 and the pin part sealing surface 42 and does not include the pin part shoulder surface 43, the box part contact surface 500 includes the internal threaded portion 51 and the box part sealing surface 52 and does not include the box part shoulder surface 53.

[0130] The pin contact surface 400 may include a plurality of external threaded portions 41, a plurality of pin sealing surfaces 42, or a plurality of pin shoulder surfaces 43. For example, the pin shoulder surface 43, the pin sealing surface 42, the external threaded portion 41, the pin sealing surface 42, the pin shoulder surface 43, the pin sealing surface 42, and the external threaded portion 41 may be sequentially arranged on the pin contact surface 400 of the pin 40 from the top of the first end 10A toward the center of the pipe body 10. In this case, the internal threaded portion 51, the box sealing surface 52, the box shoulder surface 53, the box sealing surface 52, the internal threaded portion 51, the box sealing surface 52, and the box shoulder surface 53 may be sequentially arranged on the box contact surface 500 of the box 50 from the top of the second end 10B toward the center of the pipe body 10.

[0131] exist Figure 5 and Figure 6 The middle figure shows a so-called advanced joint: the pin part 40 includes an external threaded portion 41, a pin part sealing surface 42, and a pin part shoulder surface 43, and the box part 50 includes an internal threaded portion 51, a box part sealing surface 52, and a box part shoulder surface 53. However, as described above, it is also possible that the pin part 40 includes an external threaded portion 41 and does not include the pin part sealing surface 42 and the pin part shoulder surface 43. In this case, the box part 50 includes an internal threaded portion 51 and does not include the box part sealing surface 52 and the box part shoulder surface 53. Figure 7 1 is a diagram showing an example of a metal pipe 1 for oil wells, in which a pin portion 40 includes an external thread portion 41, excluding a pin portion sealing surface 42 and a pin portion shoulder surface 43, and a box portion 50 includes an internal thread portion 51, excluding a box portion sealing surface 52 and a box portion shoulder surface 53.

[0132] [When the metal pipe for oil well 1 is of integral type]

[0133] Figure 3 , Figure 4 and Figure 7The oil well metal pipe 1 shown is a so-called T&C type oil well metal pipe 1 in which the pipe body 10 includes a pin body 11 and a coupling 12. However, the oil well metal pipe 1 of this embodiment may not be a T&C type but an integral type.

[0134] Figure 8 1 is a structural diagram of an integral oil well metal pipe 1 according to the present embodiment. Figure 8 The integral type metal pipe for oil wells 1 includes a pipe body 10. The pipe body 10 includes a first end portion 10A and a second end portion 10B. The first end portion 10A is arranged on the side opposite to the second end portion 10B. As described above, in the T&C type metal pipe for oil wells 1, the pipe body 10 includes a male buckle portion pipe body 11 and a coupling 12. That is, in the T&C type metal pipe for oil wells 1, the pipe body 10 is formed by fastening two independent components (male buckle portion pipe body 11 and coupling 12). In contrast, in the integral type metal pipe for oil wells 1, the pipe body 10 is formed integrally.

[0135] The pin 40 is formed at the first end 10A of the pipe body 10. When fastening, the pin 40 is inserted into and screwed into the box 50 of another integral oil well metal pipe 1, and is fastened to the box 50 of another integral oil well metal pipe 1. The box 50 is formed at the second end 10B of the pipe body 10. When fastening, the pin 40 of another integral oil well metal pipe 1 is inserted into and screwed into the box 50, and is fastened to the pin 40 of another integral oil well metal pipe 1.

[0136] The structure of the male buckle part 40 of the integral oil well metal pipe 1 is Figure 5 The structure of the male buckle part 40 of the T&C type oil well metal pipe 1 shown in FIG. Figure 6 The structure of the female buckle portion 50 of the T&C type oil well metal pipe 1 shown is the same. Figure 8 In the embodiment, in the pin part 40, the pin part shoulder surface 43, the pin part sealing surface 42, and the external threaded portion 41 are arranged in this order from the top end of the first end 10A toward the center of the pipe body 10. Therefore, in the box part 50, the internal threaded portion 51, the box part sealing surface 52, and the box part shoulder surface 53 are arranged in this order from the top end of the second end 10B toward the center of the pipe body 10. However, like the pin part contact surface 400 of the pin part 40 of the T&C type oil well metal pipe 1, the pin part contact surface 400 of the pin part 40 of the integral type oil well metal pipe 1 only needs to include at least the external threaded portion 41. Also, like the box part contact surface 500 of the box part 50 of the T&C type oil well metal pipe 1, the box part contact surface 500 of the box part 50 of the integral type oil well metal pipe 1 only needs to include at least the internal threaded portion 51.

[0137] In short, the oil well metal pipe 1 of the present embodiment may be of a T&C type or of an integral type.

[0138] [Resin coating]

[0139] The oil well metal pipe 1 of the present embodiment includes a resin coating 100 on at least one of the pin portion contact surface 400 and the box portion contact surface 500 . Fig. 9 yes Figure 5 An enlarged view of the pin contact surface 400 is shown. Fig.10 yes Figure 6 FIG. 5 is an enlarged view of the female buckle portion contact surface 500. Fig. 9 and Fig.10 As shown in FIG. 1 , the oil well metal pipe 1 of the present embodiment may include the resin coating 100 on both the pin contact surface 400 and the box contact surface 500. However, the oil well metal pipe 1 of the present embodiment may include the resin coating 100 on only one of the pin contact surface 400 and the box contact surface 500. For example, in the case of Fig. 9 In the case where the male buckle portion contact surface 400 is provided with the resin coating 100, the female buckle portion contact surface 500 may not be provided with the resin coating 100. Fig.10 When the resin coating 100 is provided on the box contact surface 500, the resin coating 100 may not be provided on the pin contact surface 400. In other words, the oil well metal pipe 1 of the present embodiment has the resin coating 100 on the pin contact surface 400 and / or the box contact surface 500.

[0140] The resin coating 100 is a solid coating containing resin, solid lubricating powder and copper phthalocyanine. The resin and the solid lubricating powder can be selected independently. The resin, solid lubricating powder and copper phthalocyanine contained in the resin coating 100 of this embodiment are described in detail below.

[0141] [Resin]

[0142] The resin contained in the resin coating 100 of the present embodiment is not particularly limited. However, when the metal pipe 1 for oil wells is tightened, the surface of the resin coating 100 is cut to produce wear powder. Therefore, in order to stably obtain the wear resistance (film life) and high torque performance of the resin coating 100, it is preferred to use a resin with a high adhesion to the substrate and a moderate hardness. The resin with a high adhesion to the substrate and a moderate hardness is, for example, one or more selected from the group consisting of epoxy resin, phenolic resin, acrylic resin, polyurethane resin, polyester resin, polyamide-imide resin, polyamide resin, polyimide resin and polyetheretherketone resin.

[0143] Preferably, the resin is one or two selected from the group consisting of epoxy resins and acrylic resins.

[0144] The content of the resin in the resin coating 100 is, for example, 60 to 90% by mass. In this case, the moldability, wear resistance, and high torque performance of the resin coating 100 can be more stably improved. The lower limit of the content of the resin is preferably 62% by mass, more preferably 63% by mass, and further preferably 65% ​​by mass. The upper limit of the content of the resin is preferably 88% by mass, and more preferably 86% by mass.

[0145] [Solid Lubricant Powder]

[0146] The solid lubricating powder contained in the resin coating 100 of the present embodiment is not particularly limited. The solid lubricating powder is, for example, one or more selected from the group consisting of graphite, zinc oxide, boron nitride, talc, molybdenum disulfide, tungsten disulfide, graphite fluoride, tin sulfide, bismuth sulfide, organic molybdenum, thiosulfate compounds, and polytetrafluoroethylene.

[0147] Preferably, the solid lubricating powder is one or more selected from the group consisting of graphite, polytetrafluoroethylene, and molybdenum disulfide. More preferably, the solid lubricating powder is polytetrafluoroethylene.

[0148] The content of the solid lubricating powder in the resin coating 100 is, for example, 1 to 30% by mass. In this case, the moldability and wear resistance of the resin coating 100 can be more stably improved. The lower limit of the content of the solid lubricating powder is preferably 2% by mass, and more preferably 5% by mass. The upper limit of the content of the solid lubricating powder is preferably 25% by mass, and more preferably 20% by mass.

[0149] [Copper Phthalocyanine]

[0150] The resin coating 100 of this embodiment contains copper phthalocyanine. In the oil well metal pipe 1 of this embodiment, copper phthalocyanine is the most important substance required to exert high torque performance. 32 H 18 N8) and copper ions (Cu 2+ ) is a type of phthalocyanine complex formed by the coordination of copper phthalocyanine and copper phthalocyanine. The chemical formula of copper phthalocyanine is shown below.

[0151]

[0152] If copper phthalocyanine is contained in the resin coating 100, the high torque performance of the metal pipe for oil well 1 is improved. The reason for this is not clear in detail. However, it can be proved by the following examples that the shoulder friction torque ΔT, which is the difference between the yield torque Ty and the shoulder torque Ts, is increased by containing copper phthalocyanine in the resin coating 100 of the present embodiment. Therefore, the metal pipe for oil well 1 of the present embodiment can be tightened with a high torque even if it is large in diameter.

[0153] The content of copper phthalocyanine in the resin coating 100 of the present embodiment is not particularly limited. That is, if a small amount of copper phthalocyanine is contained in the resin coating 100, the effect of improving the high torque performance of the metal pipe for oil wells 1 can be obtained to some extent. The lower limit of the content of copper phthalocyanine in the resin coating 100 may be 0.1% by mass. On the other hand, if the content of copper phthalocyanine in the resin coating 100 is 0.2% by mass or more, the high torque performance of the metal pipe for oil wells 1 is further improved. Therefore, in the present embodiment, the lower limit of the content of copper phthalocyanine in the resin coating 100 is preferably 0.1% by mass, more preferably 0.2% by mass, and further preferably 0.4% by mass.

[0154] If the content of copper phthalocyanine in the resin coating 100 of the present embodiment is 30.0 mass % or less, the dispersibility of copper phthalocyanine is improved. Therefore, the preferred upper limit of the content of copper phthalocyanine in the resin coating 100 is 30.0 mass %. Furthermore, if the content of copper phthalocyanine in the resin coating 100 of the present embodiment is 9.0 mass % or less, not only the high torque performance but also the wear resistance of the oil well metal pipe 1 is improved. Therefore, the upper limit of the content of copper phthalocyanine in the resin coating 100 may be 9.0 mass %.

[0155] Based on the above, the upper limit of the content of copper phthalocyanine in the resin coating 100 of the present embodiment is preferably 30.0 mass %, more preferably 14.0 mass %, further preferably 12.0 mass %, further preferably 10.0 mass %, further preferably 9.0 mass %, further preferably 6.0 mass %.

[0156] [Abrasion resistance]

[0157] In the oil well metal pipe 1 of the present embodiment, if the upper limit of the content of copper phthalocyanine in the resin coating 100 is further adjusted, not only the high torque performance of the oil well metal pipe 1 but also the wear resistance is improved. This point is specifically described below using a table.

[0158] Table 1 shows the content of copper phthalocyanine in the resin coating 100 and the results of the Bowden test as an indicator of wear resistance. Table 1 is a partial excerpt of the results of Example 2 described later. In Example 2, a resin coating 100 containing copper phthalocyanine was formed on the surface of a steel plate of each test number with the content described in Table 1. Furthermore, a Bowden test was performed using steel plates of each test number on which the resin coating 100 was formed. In the Bowden test, a steel ball was made to slide on the surface of the resin coating 100 of the steel plate of each test number, and the friction coefficient was calculated. Table 1 shows the content of copper phthalocyanine in the resin coating 100 of each test number and the number of sliding times until the friction coefficient exceeds 0.3. In addition, the more sliding times until the friction coefficient exceeds 0.3, the higher the wear resistance.

[0159] [Table 1]

[0160] Table 1

[0161]

[0162] Referring to Table 1, when the content of copper phthalocyanine in the resin coating 100 is 0.2 to 9.0 mass %, the number of sliding times until the friction coefficient exceeds 0.3 increases compared to the case where the content of copper phthalocyanine in the resin coating 100 is 0.1 mass % and the case where the content of copper phthalocyanine in the resin coating 100 is 10.0 mass %. That is, when the content of copper phthalocyanine in the resin coating 100 is 0.2 to 9.0 mass %, not only the high torque performance of the metal pipe for oil well 1 is improved, but also the wear resistance is improved.

[0163] [Other ingredients]

[0164] The resin coating 100 of the present embodiment may also contain components other than the above components. Other components refer to, for example, one or more selected from the group consisting of a rust inhibitor, a corrosion inhibitor, and an antioxidant. The rust inhibitor is, for example, one or more selected from the group consisting of aluminum tripolyphosphate, aluminum phosphite, and calcium ion exchange silica. As the rust inhibitor, a commercially available water repellent may also be used.

[0165] The resin coating 100 of the present embodiment may be either a single layer or include multiple layers. "Including multiple layers" means that the resin coating 100 is stacked in more than two layers along the radial direction of the metal pipe 1 for oil wells. By repeatedly applying and curing the composition for forming the resin coating 100, the resin coating 100 can be stacked in more than two layers. The resin coating 100 may be formed directly on at least one of the male buckle contact surface 400 and the female buckle contact surface 500, or may be formed after the male buckle contact surface 400 and / or the female buckle contact surface 500 are subjected to the base treatment described later. In the case where the resin coating 100 includes multiple layers, either any one layer of the resin coating 100 may contain each component within the above range, or all of the multiple resin coatings 100 may contain each component within the above range. Preferably, the resin coating 100 includes a rust-proof resin coating. In the present embodiment, the rust-proof resin coating is an arbitrary structure. That is, in the oil well metal pipe 1 of the present embodiment, the rust-proof resin coating may not be formed. The rust-proof resin coating will be described in detail below.

[0166] [Rust-proof resin coating]

[0167] In the metal pipe for oil wells 1 of the present embodiment, a rust-proof resin coating may also be included in the resin coating 100 formed on at least one of the male buckle contact surface 400 and the female buckle contact surface 500. The rust-proof resin coating contains rust-proof pigment and acrylic silicone resin. The rust-proof pigment is, for example, one or more selected from the group consisting of aluminum tripolyphosphate, aluminum phosphite, zinc-rich primer (JIS K5552 (2010)) and micaceous iron oxide. The acrylic silicone resin can use commercially available acrylic silicone resin. Commercially available acrylic silicone resins are, for example, acrylic silicone resin ACRYDIC manufactured by DIC Corporation. When the resin coating 100 of the metal pipe for oil wells 1 contains the rust-proof resin coating 70, the corrosion resistance of the metal pipe for oil wells 1 is improved.

[0168] The content of the rust-proof pigment in the rust-proof resin coating is, for example, 5 to 30% by mass. The content of the acrylic silicone resin in the rust-proof resin coating is, for example, 50 to 80% by mass. In addition to the rust-proof pigment and the acrylic silicone resin, the rust-proof resin coating may also contain other components. For example, the other components are selected from one or more of the group consisting of a pigment, a defoamer, a leveling agent, and a fibrous filler. The content of the other components in the rust-proof resin coating is, for example, 0 to 20% by mass in total.

[0169] As described above, the rust-proof resin coating is included in the resin coating 100. Specifically, Fig.11 is with Fig. 9 An enlarged view of the male buckle contact surface 400 of another embodiment of the present invention. Fig.11The oil well metal pipe 1 includes a rust-proof resin coating 70 and an upper layer 60 of the resin coating 100 in the resin coating 100 formed on the male buckle contact surface 400. In this case, the upper layer 60 of the resin coating 100 contains resin, solid lubricating powder and copper phthalocyanine, and the rust-proof resin coating 70 as the lower layer of the resin coating 100 contains rust-proof pigment and acrylic silicone resin.

[0170] The arrangement of the rust-proof resin coating 70 in the oil well metal pipe 1 of the present embodiment is not limited to Fig.11 Although not shown in the figure, Fig.11 Similarly, the oil well metal pipe 1 may include the rust-proof resin coating 70 in the resin coating 100 formed on the box contact surface 500. The rust-proof resin coating 70 may include only the resin coating 100 formed on the pin contact surface 400, and not include the resin coating 100 formed on the box contact surface 500. The rust-proof resin coating 70 may include only the resin coating 100 formed on the box contact surface 500, not the resin coating 100 formed on the pin contact surface 400. The rust-proof resin coating 70 may include both the resin coating 100 formed on the pin contact surface 400 and the resin coating 100 formed on the box contact surface 500.

[0171] In the present embodiment, the rust-proof resin coating 70 may be included in the resin coating 100 formed on the plating layer described later, or in the resin coating 100 formed on the chemical conversion coating described later. That is, in the present embodiment, the rust-proof resin coating 70 may be formed on the male buckle portion contact surface 400, or on the female buckle portion contact surface 500, or on the plating layer described later, or on the chemical conversion coating described later.

[0172] The resin coating 100 may be disposed as the outermost layer on the pin contact surface 400 and / or the box contact surface 500. When the oil well metal pipe 1 is fastened, a liquid dopant may be further applied on the resin coating 100.

[0173] [Thickness of resin coating]

[0174] The thickness of the resin coating 100 is not particularly limited. The thickness of the resin coating 100 is, for example, 1 to 100 μm. In this case, the high torque performance of the oil well metal pipe 1 can be more stably improved. The lower limit of the thickness of the resin coating 100 is preferably 2 μm, more preferably 5 μm, and further preferably 10 μm. The upper limit of the thickness of the resin coating 100 is preferably 80 μm, more preferably 70 μm, further preferably 60 μm, and further preferably 50 μm.

[0175] [Measurement method of resin coating]

[0176] The thickness of the resin coating 100 is measured by the following method. The probe of the electromagnetic induction film thickness measuring instrument is brought into contact with the male buckle contact surface 400 or the female buckle contact surface 500 on which the resin coating 100 is formed. The probe has an electromagnet, and when the magnetic body is brought close, electromagnetic induction occurs, and its voltage changes depending on the distance between the probe and the magnetic body. The thickness of the resin coating 100 is calculated based on the change in the voltage. The measurement locations are 12 locations in the circumferential direction of the metal pipe 1 for oil wells (12 locations of 0°, 30°, 60°, 90°, 120°, 150°, 180°, 210°, 240°, 270°, 300°, and 330°). The arithmetic mean of the measurement results of the 12 locations is set as the thickness of the resin coating 100.

[0177] The resin coating 100 may be directly formed on the pin contact surface 400 or the box contact surface 500 in contact with the pin contact surface 400 or the box contact surface 500. The oil well metal pipe 1 may further include another coating between the pin contact surface 400 or the box contact surface 500 and the resin coating 100. The so-called other coating is, for example, one or more coatings selected from the group consisting of plating and chemical conversion coatings.

[0178] [Arbitrary structure]

[0179] [Plating]

[0180] The oil well metal pipe 1 of the present embodiment may further include a plating layer between at least one of the pin part contact surface 400 and the box part contact surface 500 and the resin coating 100. In the oil well metal pipe 1 of the present embodiment, the plating layer may have an arbitrary structure. That is, in the oil well metal pipe 1 of the present embodiment, the plating layer may not be formed.

[0181] Fig.12 is with Fig. 9 and Fig.11 An enlarged view of the male buckle contact surface 400 of a different embodiment of the present invention. Fig.12 In the embodiment, a plating layer 80 is disposed between the male buckle contact surface 400 and the resin coating 100. Specifically, Fig.12 In the embodiment, a plating layer 80 is formed on the male buckle contact surface 400, and a resin coating 100 is formed on the plating layer 80. However, the configuration of the plating layer 80 is not limited to Fig.12Although not shown in the figure, for example, a plating layer 80 may be arranged between the female buckle portion contact surface 500 and the resin coating 100. For example, a plating layer 80 may be arranged between the male buckle portion contact surface 400 and the resin coating 100, and neither the resin coating 100 nor the plating layer 80 may be arranged on the female buckle portion contact surface 500. For example, a plating layer 80 may be arranged between the male buckle portion contact surface 400 and the resin coating 100, and a plating layer 80 may be arranged between the female buckle portion contact surface 500 and the resin coating 100.

[0182] In this embodiment, a rust-proof resin coating 70 may be provided on the plating layer 80. Specifically, Fig.13 is with Fig. 9 , Fig.11 and Fig.12 An enlarged view of the male buckle contact surface 400 of another embodiment of the present invention. Fig.13 A plating layer 80 may be disposed between the male buckle contact surface 400 and the resin coating 100 , and the resin coating 100 may include the rust-proof resin coating 70 and the upper layer 60 of the resin coating 100 .

[0183] In the present embodiment, the type of the plating layer 80 is not particularly limited. The plating layer 80 is, for example, selected from the group consisting of a Zn plating layer, a Ni plating layer, a Cu plating layer, a Zn-Ni alloy plating layer, a Zn-Co alloy plating layer, and a Ni-W alloy plating layer. When the plating layer 80 is a Zn-Ni alloy plating layer, the chemical composition of the Zn-Ni alloy plating layer is, for example, 10 to 20% by mass of Ni; and the balance is Zn and impurities. When the plating layer 80 is a Cu plating layer, the chemical composition of the Cu plating layer includes, for example, Cu and impurities.

[0184] When the oil well metal pipe 1 of the present embodiment includes the plating layer 80 on the pin portion contact surface 400 and / or the box portion contact surface 500 , the wear resistance of the oil well metal pipe 1 is further improved.

[0185] Fig.14 This is a graph showing the relationship between the plating layer 80, the content of copper phthalocyanine, and the result of the Bowden test which is an index of wear resistance. Fig.14 It is obtained from Example 2 described later. Fig.14 The horizontal axis represents the content of copper phthalocyanine in the resin coating 100 . Fig.14 The vertical axis represents the number of sliding times until the friction coefficient exceeds 0.3. In Example 2, a steel ball was made to slide on the surface of a steel plate formed with a coating 80 and / or a resin coating 100, and the number of sliding times until the friction coefficient exceeds 0.3 was measured. The more sliding times until the friction coefficient exceeds 0.3, the higher the wear resistance. Fig.14In FIG. 1 , a white circle mark (⊂) indicates that no plating layer 80 is formed on the surface of the steel sheet, but only a resin coating 100 is formed. Fig.14 In FIG. 1 , a square mark (□) indicates that a Zn—Ni alloy plating layer is formed on the surface of the steel sheet and a resin coating 100 is formed on the Zn—Ni alloy plating layer. Fig.14 The oil well metal pipe 1 having the Zn-Ni alloy plating layer has a greater number of sliding times until the friction coefficient exceeds 0.3 than the oil well metal pipe 1 not having the plating layer 80. Thus, the wear resistance of the oil well metal pipe 1 having the plating layer 80 formed on the pin part contact surface 400 and / or the box part contact surface 500 is further improved.

[0186] [Thickness of the plating layer]

[0187] The thickness of the plating layer 80 is not particularly limited. The thickness of the plating layer 80 is, for example, 1 to 30 μm. In this case, the wear resistance of the oil well metal pipe 1 can be more stably improved. The lower limit of the thickness of the plating layer 80 is preferably 2 μm, more preferably 3 μm, and further preferably 4 μm. The upper limit of the thickness of the plating layer 80 is preferably 20 μm, and more preferably 10 μm.

[0188] [Method for measuring the thickness of the coating]

[0189] The thickness of the plating layer 80 is measured by the following method. The probe of the electromagnetic induction film thickness measuring instrument is brought into contact with the pin buckle contact surface 400 or the box buckle contact surface 500 on which the plating layer 80 is formed. The contact of the probe is performed on the portion of the pin buckle contact surface 400 or the box buckle contact surface 500 where the resin coating 100 is removed. The probe has an electromagnet, and when the magnetic body is brought close, electromagnetic induction occurs, and the voltage thereof changes depending on the distance between the probe and the magnetic body. The thickness of the plating layer 80 is obtained based on the change in the voltage. The measurement locations are 12 locations in the circumferential direction of the metal pipe for oil wells 1 (12 locations of 0°, 30°, 60°, 90°, 120°, 150°, 180°, 210°, 240°, 270°, 300°, and 330°). The arithmetic mean of the measurement results of the 12 locations is set as the thickness of the plating layer 80.

[0190] [Chemical conversion coating]

[0191] The oil well metal pipe 1 of the present embodiment may further include a chemical conversion coating between at least one of the pin portion contact surface 400 and the box portion contact surface 500 and the resin coating 100. In the oil well metal pipe 1 of the present embodiment, the chemical conversion coating may have an arbitrary structure. That is, in the oil well metal pipe 1 of the present embodiment, the chemical conversion coating may not be formed.

[0192] Fig.15 is with Fig.10 An enlarged view of the contact surface 500 of the female buckle portion of the present embodiment. Fig.15 In the embodiment, a chemical conversion film 90 is disposed between the female buckle portion contact surface 500 and the resin film 100. Specifically, Fig.15 In the embodiment, a chemical conversion film 90 is formed on the female buckle portion contact surface 500, and a resin film 100 is formed on the chemical conversion film 90. However, the configuration of the chemical conversion film 90 is not limited to Fig.15 Although not shown in the figure, for example, the chemical conversion coating 90 may be arranged between the male buckle portion contact surface 400 and the resin coating 100, and neither the resin coating 100 nor the chemical conversion coating 90 may be arranged on the female buckle portion contact surface 500. Alternatively, for example, the chemical conversion coating 90 may be arranged between the male buckle portion contact surface 400 and the resin coating 100, and the chemical conversion coating 90 may be arranged between the female buckle portion contact surface 500 and the resin coating 100.

[0193] In this embodiment, a rust-proof resin coating 70 may be further provided on the chemical conversion coating 90. Specifically, Fig.16 is with Fig. 9 , Fig.11 , Fig.12 and Fig.13 An enlarged view of the male buckle contact surface 400 of another embodiment of the present invention. Fig.16 A chemical conversion coating 90 may be disposed between the male buckle contact surface 400 and the resin coating 100 , and the resin coating 100 includes the rust-proof resin coating 70 and the upper layer 60 of the resin coating 100 .

[0194] The pin part contact surface 400 and the box part contact surface 500 of the present embodiment may further include both the plating layer 80 and the chemical conversion film 90 . Fig.17 is with Fig. 9 , Fig.11 , Fig.12 , Fig.13 and Fig.16 An enlarged view of the male buckle contact surface 400 of a different embodiment of the present invention. Fig.17 In the embodiment, the plating layer 80 is arranged on the pin contact surface 400, the chemical conversion film 90 is arranged on the plating layer 80, and the resin film 100 is arranged on the chemical conversion film 90. That is, when the plating layer 80 is provided, the oil well metal pipe 1 has the chemical conversion film 90 between the plating layer 80 and the resin film 100.

[0195] The arrangement of the plating layer 80 and the chemical conversion film 90 in the oil well metal pipe 1 of the present embodiment is not limited to Fig.17However, in the case where the plating layer 80 and the chemical conversion film 90 are arranged between the male buckle part contact surface 400 and the resin film 100, the chemical conversion film 90 may be arranged on the plating layer 80, and the resin film 100 may be arranged on the chemical conversion film 90. In addition, in the case where the plating layer 80 is not arranged between the male buckle part contact surface 400 and the resin film 100, the chemical conversion film 90 may be arranged on the male buckle part contact surface 400, and the resin film 100 may be arranged on the chemical conversion film 90. Similarly, in the case where the plating layer 80 and the chemical conversion film 90 are provided between the female buckle part contact surface 500 and the resin film 100, the chemical conversion film 90 may be arranged on the plating layer 80, and the resin film 100 may be arranged on the chemical conversion film 90. In addition, when the plating layer 80 is not provided between the female buckle contact surface 500 and the resin coating 100 , the chemical conversion coating 90 may be disposed on the female buckle contact surface 500 , and the resin coating 100 may be disposed on the chemical conversion coating 90 .

[0196] In the present embodiment, when the plating layer 80 and the chemical conversion film 90 are further provided, the rust-proof resin film 70 may be provided on the chemical conversion film 90. Specifically, Fig.18 is with Fig. 9 , Fig.11 , Fig.12 , Fig.13 , Fig.16 and Fig.17 An enlarged view of the male buckle contact surface 400 of another embodiment of the present invention. Fig.18 Alternatively, a plating layer 80 may be disposed on the male buckle contact surface 400 , a chemical conversion coating 90 may be disposed on the plating layer 80 , a resin coating 100 may be disposed on the chemical conversion coating 90 , and the resin coating 100 may include a rustproof resin coating 70 and an upper layer 60 of the resin coating 100 .

[0197] In the present embodiment, the type of chemical conversion film 90 is not particularly limited. The chemical conversion film 90 is, for example, selected from the group consisting of a phosphate chemical conversion film, an oxalate chemical conversion film, a borate chemical conversion film, and a chromate film. From the viewpoint of the adhesion of the resin film 100, a phosphate chemical conversion film is preferred. Here, the phosphate refers to, for example, one or more selected from the group consisting of manganese phosphate, zinc phosphate, iron manganese phosphate, or zinc calcium phosphate. The chemical conversion film 90 may also be a chromate film. The chromate film can be formed by a known method. The chromate film preferably does not contain hexavalent chromium.

[0198] In the case where the chemical conversion coating 90 is provided on the pin contact surface 400 and / or the box contact surface 500 of the metal pipe for oil wells 1 of the present embodiment, the wear resistance of the metal pipe for oil wells 1 is further improved. The chemical conversion coating 90 improves the adhesion of the resin coating 100 thereon by the anchoring effect. Thus, the wear resistance of the metal pipe for oil wells 1 is improved. Referring to Example 3 described later, the metal pipe for oil wells 1 having the chemical conversion coating 90 has a greater number of sliding times until the friction coefficient exceeds 0.3 than the metal pipe for oil wells 1 not having the chemical conversion coating 90. In this way, the wear resistance of the metal pipe for oil wells 1 having the chemical conversion coating 90 formed on the pin contact surface 400 and / or the box contact surface 500 is further improved.

[0199] The oil well metal pipe 1 of this embodiment only needs to have the resin coating 100 on at least one of the pin part contact surface 400 and the box part contact surface 500. As described above, the arrangement of the plating layer 80, the chemical conversion coating 90, and the rust-proof resin coating 70 may be the same or different on the pin part contact surface 400 and the box part contact surface 500. The oil well metal pipe 1 may further have other coatings as needed.

[0200] [Substrate treatment]

[0201] At least one of the pin contact surface 400 and the female contact surface 500 of the oil well metal pipe 1 of the present embodiment may be a surface to which a base treatment has been applied. That is, in the present embodiment, the base treatment is an arbitrarily implemented process, and both the pin contact surface 400 and the female contact surface 500 may not be surfaces to which a base treatment has been applied. In the case of implementation, the base treatment is, for example, one or more selected from the group consisting of sandblasting and pickling. If the base treatment is implemented, the surface roughness of the pin contact surface 400 and / or the female contact surface 500 is improved. Therefore, the adhesion of the resin coating 100, the plating layer 80 and / or the chemical conversion coating 90 formed thereon is improved. As a result, the wear resistance of the oil well metal pipe 1 is improved.

[0202] [Chemical composition of the tube body]

[0203] The chemical composition of the pipe body 10 of the oil well metal pipe 1 of this embodiment is not particularly limited. The oil well metal pipe 1 of this embodiment is characterized by the resin coating 100. Therefore, in this embodiment, the steel type of the pipe body 10 of the oil well metal pipe 1 is not particularly limited.

[0204] The pipe body 10 can be formed of, for example, carbon steel, stainless steel, and alloys. That is, the metal pipe for oil wells can be a steel pipe composed of an Fe-based alloy or an alloy pipe represented by a Ni-based alloy pipe. Here, the steel pipe is, for example, a low-alloy steel pipe, a martensitic stainless steel pipe, a duplex stainless steel pipe, etc. On the other hand, among alloy steels, high-alloy steels such as Ni-based alloys and duplex stainless steels containing alloy elements such as Cr, Ni, and Mo also have high corrosion resistance. Therefore, if the above-mentioned high-alloy steel is used as the pipe body 10, excellent corrosion resistance can be obtained in a corrosive environment containing hydrogen sulfide, carbon dioxide, etc.

[0205] [Manufacturing method]

[0206] Hereinafter, a method for manufacturing the oil well metal pipe 1 according to the present embodiment will be described.

[0207] The method for producing the oil well metal pipe 1 of the present embodiment includes a preparation step, a coating step, and a curing step. The curing step is performed after the coating step.

[0208] [Preparation process]

[0209] In the preparation process, the oil well metal pipe 1 having the pipe body 10 including the pin part 40 including the pin part contact surface 400 including the external thread part 41 and the box part 50 including the box part contact surface 500 including the internal thread part 51 is prepared. As described above, the oil well metal pipe 1 of the present embodiment has a known structure. That is, in the preparation process, the oil well metal pipe 1 having a known structure may be prepared.

[0210] [Coating process]

[0211] In the coating step, a composition containing a resin, a solid lubricating powder, and copper phthalocyanine is coated on at least one of the male buckle contact surface 400 and the female buckle contact surface 500. The composition is a composition for forming the above-mentioned resin coating 100. The composition contains a resin, a solid lubricating powder, and copper phthalocyanine. The composition for forming the resin coating 100 is the same as the composition of the above-mentioned resin coating 100 except for the solvent.

[0212] The solvent-free composition can be produced, for example, by heating a resin to a molten state, adding a solid lubricating powder and copper phthalocyanine, and kneading the mixture. A powder mixture obtained by mixing all the components in a powder form may be used as the composition.

[0213] The solvent-based composition can be produced, for example, by the following method: dissolving or dispersing the resin, solid lubricating powder and copper phthalocyanine in a solvent and mixing them. The solvent is, for example, water, alcohol and an organic solvent. The solvent may contain a trace amount of a surfactant. The proportion of the solvent is not particularly limited. The proportion of the solvent can be adjusted to give the composition an appropriate viscosity according to the coating method. The proportion of the solvent is, for example, 40 to 60% by mass when the sum of all components other than the solvent is regarded as 100% by mass.

[0214] The method of applying the composition on the male buckle contact surface 400 and / or the female buckle contact surface 500 is not particularly limited and may be a known method. In the case of a solvent-free composition, for example, the composition can be applied to the male buckle contact surface 400 and / or the female buckle contact surface 500 using a hot melt method. In the hot melt method, the composition is heated to melt the resin to form a low-viscosity flow state. The composition in the flow state is sprayed from a spray gun with a temperature maintenance function. The method of applying the composition to the male buckle contact surface 400 and / or the female buckle contact surface 500 may also be brushing and dipping instead of spraying. In addition, it is preferred that the heating temperature of the composition is set to a temperature 10 to 50°C higher than the melting point of the resin.

[0215] In the case of a solvent-based composition, for example, the composition in a solution state can be applied to the male buckle contact surface 400 and / or the female buckle contact surface 500 by spraying. In this case, the viscosity of the composition is adjusted so that it can be sprayed under normal temperature and pressure. The method of applying the composition to the male buckle contact surface 400 and / or the female buckle contact surface 500 can also be brushing, dipping, etc. instead of spraying.

[0216] [Curing process]

[0217] In the curing process, the applied composition is cured to form a resin coating 100. In the case of a solvent-free composition, the composition applied on at least one of the male buckle contact surface 400 and the female buckle contact surface 500 is cooled, thereby the molten composition is cured to form a solid resin coating 100. In this case, the cooling method is not particularly limited and can be a known method. The cooling method is, for example, natural atmospheric cooling and air cooling. In the case of a solvent-based composition, the composition applied on at least one of the male buckle contact surface 400 and the female buckle contact surface 500 is dried, thereby the composition is cured to form a solid resin coating 100. In this case, the drying method is not particularly limited and can be a known method. The drying method is, for example, natural drying, low-temperature air drying, and vacuum drying. In addition, in the case where the resin is a thermosetting resin, the composition can also be cured by a thermal curing treatment to form a solid resin coating 100.

[0218] Through the above-described manufacturing steps, the oil well metal pipe 1 of the present embodiment can be manufactured.

[0219] [Optional manufacturing process]

[0220] The manufacturing method of the oil well metal pipe 1 of this embodiment may further include any one or more of the following steps: a plating forming step, a chemical conversion treatment step, a rustproof resin coating forming step, and a base treatment step. The above steps are all arbitrary steps. Therefore, the above steps may not be performed.

[0221] [Plating layer forming process]

[0222] The method for manufacturing the oil well metal pipe 1 of the present embodiment may further include a plating forming step before the coating step. When the plating forming step is performed, the plating layer 80 is formed on at least one of the pin portion contact surface 400 and the box portion contact surface 500 .

[0223] The method for forming the plating layer 80 is not particularly limited and may be a known method. The plating layer 80 may be formed by either electroplating or chemical plating. For example, in the case of forming a Zn-Ni alloy plating layer by electroplating, the plating bath contains zinc ions and nickel ions. The composition of the plating bath preferably contains zinc ions: 1 to 100 g / L, and nickel ions: 1 to 50 g / L. The conditions for electroplating are, for example, a plating bath pH of 1 to 10, a plating bath temperature of 20 to 60°C, and a current density of 1 to 100 A / dm 2 , and treatment time: 0.1 to 50 minutes. For example, when forming a Cu plating layer by electroplating, it can be implemented by a known method.

[0224] [Chemical conversion treatment process]

[0225] The method for manufacturing the oil well metal pipe 1 of the present embodiment may further include a chemical conversion treatment step before the coating step. When the chemical conversion treatment step is performed, a chemical conversion film 90 is formed on at least one of the pin contact surface 400 and the box contact surface 500 .

[0226] The method of chemical conversion treatment is not particularly limited and can be a known method. The chemical conversion treatment is, for example, selected from the group consisting of phosphate chemical conversion treatment, oxalate chemical conversion treatment, borate chemical conversion treatment and chromate treatment. As a treatment liquid for chemical conversion treatment, an acidic phosphate chemical conversion treatment liquid for conventional galvanized materials can be used. As a treatment liquid, for example, a zinc phosphate-based chemical conversion treatment containing 1 to 150 g / L of phosphate ions, 3 to 70 g / L of zinc ions, 1 to 100 g / L of nitrate ions, and 0 to 30 g / L of nickel ions can be used. As a treatment liquid, a manganese phosphate-based chemical conversion treatment liquid commonly used for metal pipes 1 for oil wells can also be used. As a treatment liquid, a commercially available chromate treatment liquid can also be used. The liquid temperature of the treatment liquid is, for example, room temperature to 100°C. The treatment time of the chemical conversion treatment can be appropriately set according to the desired film thickness, for example, 0.5 to 15 minutes. In order to promote the formation of the chemical conversion film 90, surface adjustment can also be performed before the chemical conversion treatment. Surface conditioning means immersion in an aqueous solution for surface conditioning containing colloidal titanium. When a chemical conversion treatment step is performed, it is preferred that after the chemical conversion treatment, water washing or hot water washing is performed and then drying is performed.

[0227] Furthermore, as described above, in the oil well metal pipe 1 of the present embodiment, the chemical conversion coating 90 is formed on any one of the pin portion contact surface 400, the box portion contact surface 500, and the plating layer 80. That is, in the method for manufacturing the oil well metal pipe 1 of the present embodiment, when both the plating layer forming step and the chemical conversion treatment step are performed, the chemical conversion treatment step is performed after the plating layer forming step, and then the coating step is performed.

[0228] [Rust-proof resin coating forming process]

[0229] The method for manufacturing the oil well metal pipe 1 of the present embodiment may further include a rust-proof resin coating forming step before the coating step. When the rust-proof resin coating forming step is performed, the rust-proof resin coating 70 is formed on at least one of the pin contact surface 400, the box contact surface 500, the plating layer 80, and the chemical conversion coating 90.

[0230] The method for forming the rust-proof resin coating 70 is not particularly limited, and may be a known method. The rust-proof resin coating 70 can be formed, for example, by the following method: a composition containing a rust-proof pigment and an acrylic silicone resin is applied to at least one of the male buckle contact surface 400, the female buckle contact surface 500, the plating layer 80, and the chemical conversion coating 90, and the composition is cured. The coating method is not particularly limited, and may be spraying, brushing, and dipping. The composition used to form the rust-proof resin coating 70 may contain a solvent. The composition of the composition used to form the rust-proof resin coating 70, excluding the solvent, is the same as the composition of the rust-proof resin coating 70 described above. The curing method is, for example, natural drying, low-temperature air drying, and heating drying.

[0231] Furthermore, as described above, in the oil well metal pipe 1 of the present embodiment, the rust-proof resin coating 70 is formed on any one of the pin portion contact surface 400, the box portion contact surface 500, the plating layer 80, and the chemical conversion coating 90. That is, in the method for manufacturing the oil well metal pipe 1 of the present embodiment, when the plating layer forming step, the chemical conversion treatment step, and the rust-proof resin coating forming step are all performed, the plating layer forming step, the chemical conversion treatment step, and the rust-proof resin coating forming step are performed in this order, and thereafter the coating step is performed.

[0232] [Substrate treatment process]

[0233] The manufacturing method of the metal pipe for oil well 1 of the present embodiment may also include a base treatment step before the coating step. In the case of implementing a coating forming step, the manufacturing method of the metal pipe for oil well 1 may also include a base treatment step before the coating forming step. In the case of implementing a chemical conversion treatment step, the manufacturing method of the metal pipe for oil well 1 may also include a base treatment step before the chemical conversion treatment step. In the case of implementing a rust-proof resin coating forming step, the manufacturing method of the metal pipe for oil well 1 may also include a base treatment step before the rust-proof resin coating forming step. In the base treatment step, for example, pickling treatment and / or sandblasting treatment are implemented. In addition, alkaline degreasing treatment may also be performed.

[0234] When pickling treatment is performed, the pin contact surface 400 and / or the box contact surface 500 are immersed in a strong acid solution such as sulfuric acid, hydrochloric acid, nitric acid, hydrofluoric acid, or a mixture of the above acids to improve the surface roughness of the pin contact surface 400 and / or the box contact surface 500. When sandblasting is performed, for example, sandblasting is performed by mixing sandblasting materials (abrasives) and compressed air and projecting them onto the pin contact surface 400 and / or the box contact surface 500. In this case, the surface roughness of the pin contact surface 400 and / or the box contact surface 500 is improved.

[0235] In addition, the above-mentioned plating layer forming step, chemical conversion treatment step and base treatment step may be performed in the same manner or in different manners on the pin buckle part contact surface 400 and the box buckle part contact surface 500. In addition, the above-mentioned treatment may be performed only on the pin buckle part contact surface 400 or only on the box buckle part contact surface 500.

[0236] The above steps can produce the oil well metal pipe 1 of this embodiment. However, the above production method is an example of a production method of the oil well metal pipe 1 of this embodiment, and the present invention is not limited to this production method. The oil well metal pipe 1 of this embodiment can also be produced by other methods.

[0237] Example 1

[0238] In Example 1, a resin coating 100 was formed on the pin contact surface 400 or the box contact surface 500 of the oil well metal pipe 1, and high torque performance and wear resistance were evaluated. Specifically, in Example 1, an oil well metal pipe VAM21 (registered trademark) HT (outer diameter 273.05 mm (10.75 inches), wall thickness: 12.570 mm (0.495 inches)) manufactured by Nippon Steel Corporation was used. The steel type of the oil well metal pipe is SM2535M110 steel (C≤0.03%, Si:≤0.50%, Mn≤1.0%, Cu≤1.5%, Ni:29.5-36.5%, Cr:24.0-27.0%, balance: Fe and impurities).

[0239] A coating layer and a resin coating including a rust-proof resin coating are appropriately formed on the contact surface of the female buckle of test numbers 1 to 12, and oil well metal pipes including a male buckle and a female buckle of test numbers 1 to 12 are prepared. The formed coating layer is indicated in the "Coating" column in Table 2. The "-" in the "Coating" column in Table 2 means that no coating layer is formed. In addition, the thickness of the formed coating layer is 8 μm. The thickness of the coating layer is measured by using an electromagnetic film thickness meter SDM-picoR manufactured by Sanko Electronics Research Institute Co., Ltd. and the above-mentioned method. In the "Rust-proof Resin Coating" column in Table 2, it is indicated whether a rust-proof resin coating is formed. The "formed" in the "Rust-proof Resin Coating" column in Table 2 means that a rust-proof resin coating is formed. The "-" in the "Rust-proof Resin Coating" column in Table 2 means that no rust-proof resin coating is formed. In addition, the formed rust-proof resin coating is the same as the rust-proof resin coating of test number 32 and test number 33 of Example 4 described later.

[0240] Furthermore, the "Resin Coating" column in Table 2 indicates whether a resin coating is formed. The "formed" in the "Resin Coating" column in Table 2 means that a resin coating is formed. The "-" in the "Resin Coating" column in Table 2 means that a resin coating is not formed. In addition, in test numbers 1 to 9 and test numbers 11 to 12, the thickness of the formed resin coating is 20 μm. In test number 10, the thickness of the resin coating is 20 μm except for the thickness of the rust-proof resin coating. The thickness of the resin coating is measured by using an electromagnetic film thickness meter SDM-picoR manufactured by Sanko Electronics Laboratories Co., Ltd. and the above-mentioned method. In test numbers 2 to 9 and test numbers 11 to 12, the resin coating is formed on the surface of the above-mentioned plating layer.

[0241] In addition, in test number 1, no plating layer is formed. Therefore, in test number 1, a resin coating is directly formed on the contact surface of the female buckle. Furthermore, in test number 10, an upper layer of a resin coating is formed on the rust-proof resin coating. That is, in test number 10, the resin coating is multilayered. For each test number, the content of copper phthalocyanine in the formed resin coating is shown in Table 2. In addition, the formed resin coating also contains 1 to 30% by mass of polytetrafluoroethylene (PTFE) as a solid lubricating powder, and the remainder contains epoxy resin as a resin. The "-" in the "Content of Copper Phthalocyanine" column in Table 2 means that no resin coating is formed or copper phthalocyanine is not contained in the formed resin coating. In addition, in test number 12, the formed resin coating does not contain copper phthalocyanine. In test number 12, the resin coating contains 8.6% by mass of Cr2O3 instead of copper phthalocyanine. The resin coating of Test No. 12 further contains 1 to 30% by mass of polytetrafluoroethylene (PTFE) as solid lubricating powder, and the remainder contains epoxy resin as resin.

[0242] [Table 2]

[0243] Table 2

[0244]

[0245] [Female buckle contact surface]

[0246] [Plating layer forming process]

[0247] As shown in Table 2, a Zn-Ni alloy plating layer was formed by electroplating on the contact surface of the female buckle portion of test numbers 2 to 9 and test numbers 11 to 12. The plating bath used was DAIN ZIN ALLOY N-PL (trademark) manufactured by Yamato Chemical Industry Co., Ltd. The thickness of the Zn-Ni alloy plating layer was 8 μm. The thickness of the plating layer was measured by using an electromagnetic film thickness meter SDM-picoR manufactured by Sanko Electronics Laboratories Co., Ltd. and the above-mentioned method. The electroplating conditions were as follows: plating bath pH: 6.5, plating bath temperature: 25°C, current density: 2A / dm 2 , and treatment time: 18 minutes. The composition of the Zn-Ni alloy plating layer is Zn: 85% and Ni: 15%. A trivalent chromate coating is further formed on the obtained Zn-Ni alloy plating layer. The treatment liquid used to form the trivalent chromate coating is DAIN CHROMATE TR-02 manufactured by Yamato Chemical Co., Ltd. The conditions for the chemical conversion treatment are bath temperature: 25°C, pH: 4.0, and treatment time 50 seconds.

[0248] [Coating process and curing process]

[0249] As shown in Table 2, a resin coating is formed on the contact surface of the female buckle part of test numbers 1 to 12. In test numbers 2 to 9, 11 and 12, a resin coating is formed on the contact surface of the female buckle part where the plating layer is formed. In test number 1, a resin coating is directly formed on the contact surface of the female buckle part. In test number 10, an upper layer of the resin coating is formed on the rust-proof resin coating. A composition for forming a resin coating is sprayed on the contact surface of the female buckle part, the Zn-Ni alloy plating layer, or the rust-proof resin coating, and cured. As described above, in the composition, the components other than the solvent contain polytetrafluoroethylene particles and copper phthalocyanine, and the remainder is epoxy resin. The composition also contains a solvent. The solvent used is a mixed solution of water, alcohol and a surfactant. After the composition was sprayed on the Zn-Ni alloy plating layer on the surface of the female buckle part, a heat curing treatment was performed at 210°C for 20 minutes to form a resin coating. In Test No. 12, copper phthalocyanine was not used, but 8.6 mass % of Cr2O3 was used instead.

[0250] [Pin contact surface]

[0251] Mechanical polishing was performed on the pin contact surfaces of test numbers 1 to 12. That is, as shown in Table 2, no plating layer or resin coating was formed on the pin contact surfaces of test numbers 1 to 12.

[0252] [High torque performance evaluation]

[0253] The shoulder friction torque ΔT was measured using oil well metal pipes with pin and box contact surfaces of test numbers 1 to 12. Specifically, the tightening torque value was gradually increased at a tightening speed of 10 rpm, and the test was terminated when the material yielded. The torque was measured during thread tightening, and a Fig.19 Torque diagram shown. Fig.19 Ts in it means shoulder torque. Fig.19 The MTV in means the torque value where the line segment L intersects the torque diagram. The line segment L is a straight line having the same slope as the slope of the linear area in the torque diagram after the shoulder, and having 0.2% more rotation speed than the linear area. Usually, when the shoulder friction torque is measured, Ty (yield torque Ty) is used. However, in this embodiment, the yield torque Ty (the boundary between the linear area and the nonlinear area in the torque diagram after the shoulder) is unclear. Therefore, the MTV is specified using the line segment L. The difference between MTV and Ts is set to the shoulder friction torque ΔT. For the shoulder friction torque ΔT, the shoulder friction torque ΔT when the API standard dopant is used is set to 100 and is calculated as a relative value. The results are shown in the "High Torque Performance" column in Table 2.

[0254] [Repeated tightening test]

[0255] Using oil well metal pipes with male and female contact surfaces of test numbers 1 to 12, repeated tightening tests were performed with a tightening torque of 53800 Nm. Tightening was performed until irreparable wear of the threaded portion (external threaded portion and / or internal threaded portion) or wear of the metal seal portion occurred. The results are shown in the "M&B times (times)" column in Table 2. The "-" in the "M&B times (times)" column in Table 2 indicates that repeated tightening tests were not performed.

[0256] [Evaluation results]

[0257] Referring to Table 2, the oil well metal pipes of test numbers 1 to 10 have a resin coating containing resin, solid lubricating powder and copper phthalocyanine on at least one of the pin contact surface and the box contact surface. Therefore, the shoulder friction torque ΔT of test numbers 1 to 10 is 100 or more, showing excellent high torque performance.

[0258] Furthermore, in the oil well metal pipes of Test No. 1 and Test Nos. 3 to 10, the content of copper phthalocyanine in the resin coating was 0.2 to 30.0 mass %. Therefore, the oil well metal pipes of Test No. 1 and Test Nos. 3 to 10 had a higher shoulder friction torque ΔT than Test No. 2 in which the content of copper phthalocyanine was less than 0.2 mass %.

[0259] On the other hand, in the oil well metal pipe of test number 11, a resin coating containing resin and solid lubricating powder was formed on the contact surface of the box portion, but the resin coating did not contain copper phthalocyanine. As a result, the shoulder friction torque ΔT was 65, and the high torque performance was low.

[0260] In the oil well metal pipe of test number 12, a resin coating containing resin and solid lubricant powder is formed on the contact surface of the box portion, but the resin coating does not contain copper phthalocyanine but contains Cr2O3 instead. As a result, the shoulder friction torque ΔT is 90, and the high torque performance is low.

[0261] Example 2

[0262] In Example 2, a resin coating was formed on the surface of a steel plate simulating a metal pipe for oil wells, and the wear resistance was evaluated. Specifically, in Example 2, a cold-rolled steel plate (chemical composition: C≤0.15%, Mn≤0.60%, P≤0.100%, S≤0.050%, balance: Fe and impurities) was used.

[0263] The plating layers shown in Table 3 were appropriately formed on the surfaces of the steel sheets of test numbers 13 to 21. The "plating layer" column in Table 3 indicates the formed plating layer. The "-" in the "plating layer" column in Table 3 means that no plating layer is formed. In addition, the thickness of the formed plating layer is 8 μm. A resin coating is formed on the surfaces of the steel sheets of test numbers 13 to 17 and test number 21. In test numbers 18 to 20, a resin coating is formed on the formed plating layer. In addition, the thickness of the formed resin coating is 20 μm. The thickness of the resin coating was measured using an electromagnetic film thickness meter SDM-picoR manufactured by Sanko Electronics Research Institute Co., Ltd., and the average value of the thickness at 9 points on the same evaluation surface was set as the thickness of the resin coating. Furthermore, the content of copper phthalocyanine in the formed resin coating is shown in Table 3. In addition, the formed resin coating also contains 1 to 30% by mass of polytetrafluoroethylene (PTFE) as a solid lubricating powder, and the remainder contains epoxy resin as a resin. The “-” in the “Content of copper phthalocyanine” column in Table 3 means that the formed resin film does not contain copper phthalocyanine.

[0264] [Table 3]

[0265] Table 3

[0266]

[0267] [Plating layer forming process]

[0268] A Zn-Ni alloy coating was formed on the surface of the steel plates of test numbers 18 to 20 by electroplating. The plating bath used was DAIN ZIN ALLOY N-PL (trademark) manufactured by Yamato Kasei Co., Ltd. The thickness of the Zn-Ni alloy coating was 8 μm. The thickness of the coating was measured using an electromagnetic film thickness meter SDM-picoR manufactured by Sanko Electronics Laboratories, Ltd., and the average thickness at 9 points on the same evaluation surface was taken as the thickness of the coating. The electroplating conditions were: bath pH: 6.5, bath temperature: 25°C, current density: 2 A / dm 2 , and treatment time: 18 minutes. The composition of the Zn-Ni alloy plating layer is Zn: 85% and Ni: 15%. A trivalent chromate coating is further formed on the obtained Zn-Ni alloy plating layer. The treatment liquid used to form the trivalent chromate coating is DAIN CHROMATE TR-02 manufactured by Yamato Chemical Co., Ltd. The conditions for the chemical conversion treatment are bath temperature: 25°C, pH: 4.0, and treatment time 50 seconds.

[0269] [Coating process and curing process]

[0270] A resin coating was formed on the surface of the steel plates of test numbers 13 to 21. Specifically, a composition for forming a resin coating was applied to the surface of the steel plates of test numbers 13 to 21 by a rod coater and cured. In the composition, components other than the solvent include solid lubricating particles and copper phthalocyanine, and the remainder is resin. In test numbers 13 to 21, epoxy resin was used as the resin. In test numbers 13 to 21, polytetrafluoroethylene particles were used as solid lubricating particles. The content of copper phthalocyanine is shown in Table 3. The composition also contains a solvent. A mixed solution of water, alcohol and a surfactant was used as the solvent. In the case where a plating layer is present, for the case where there is no plating layer on the plating layer (or the chemical conversion film thereon), after the composition was applied to the surface of the steel plate by a rod coater, a heat curing treatment was performed at 210°C for 20 minutes to form a resin coating.

[0271] [Bowden test]

[0272] The Bowden test was carried out using steel plates with test numbers 13 to 21 formed with resin coatings, and the wear resistance was evaluated. Specifically, a steel ball was slid on the surface of the resin coating of test numbers 13 to 21, and the friction coefficient was calculated. The diameter of the steel ball was 3 / 16 inch, and the chemical composition was equivalent to SUJ2 of the JIS standard. The load was 3 kgf (Hertzian surface pressure: average 1.56 GPa). The sliding width was 10 mm, and the sliding speed was 4 mm / sec. The sliding was carried out without oiling and at room temperature. The friction coefficient μ of the steel ball during sliding was measured, and the number of sliding times (reciprocating times, i.e., one reciprocating sliding in a range of 10 mm was counted as "1 time") until the friction coefficient μ exceeded 0.3 (equivalent to the friction coefficient between the resin coating and the steel ball) was measured. The test used a Bowden-type adhesion sliding tester manufactured by Kobelco Seisakusho (Co., Ltd.). The results are shown in the column of the number of sliding times until the friction coefficient exceeds 0.3 in Table 3.

[0273] [Evaluation results]

[0274] Referring to Table 3, the steel plates of test numbers 13 to 20 have a resin coating containing resin, solid lubricating powder and copper phthalocyanine on the surface. Referring to Table 3, the content of copper phthalocyanine in the resin coating formed on the steel plates of test numbers 14 to 16 and test numbers 18 to 20 is 0.2 to 9.0% by mass. As a result, the steel plates of test numbers 14 to 16 and test numbers 18 to 20 have a larger number of sliding times until the friction coefficient exceeds 0.3 than the steel plates of test number 21 in which the resin coating does not contain copper phthalocyanine, and test number 13 and test number 17 in which the content of copper phthalocyanine in the resin coating is outside the range of 0.2 to 9.0% by mass. That is, excellent wear resistance is shown.

[0275] Example 3

[0276] In Example 3, a resin coating was formed on the surface of a steel plate simulating an oil well metal pipe, and the wear resistance was evaluated in the same manner as in Example 2. Specifically, in Example 3, a cold-rolled steel plate (chemical composition: C≤0.15%, Mn≤0.60%, P≤0.100%, S≤0.050%, balance: Fe and impurities) was used.

[0277] The plating layers shown in Table 4 were appropriately formed on the surfaces of the steel sheets of test numbers 22 to 31. The "plating layer" column in Table 4 shows the formed plating layer. The "-" in the "plating layer" column in Table 4 means that no plating layer was formed. In addition, the thickness of the formed plating layer was 8 μm. The thickness of the plating layer was measured using an electromagnetic film thickness meter SDM-picoR manufactured by Sanko Electronics Laboratory Co., Ltd., and the average value of the thickness at 9 points on the same evaluation surface was set as the thickness of the plating layer. Chemical conversion films were formed on the surfaces of the steel sheets of test numbers 22 to 29 and test number 31. The "chemical conversion film" column in Table 4 shows the formed chemical conversion film. Table 5 shows the chemical conversion treatment liquid, treatment temperature and treatment time used for the formation of films A to D in the chemical conversion films in the "chemical conversion film" column. In addition, "trivalent chromate" in the "chemical conversion film" column in Table 4 means that a trivalent chromate film is formed. The trivalent chromate film will be described later.

[0278] [Table 4]

[0279] Table 4

[0280]

[0281] [Table 5]

[0282] Table 5

[0283]

[0284] A resin coating is formed on the plating layer or the chemical conversion coating of test numbers 22 to 31. In addition, the thickness of the formed resin coating is 20 μm. The thickness of the resin coating is measured using an electromagnetic film thickness meter SDM-picoR manufactured by Sanko Electronics Research Institute Co., Ltd., and the average value of the thickness at 9 points on the same evaluation surface is set as the thickness of the resin coating. In addition, the formed resin coating contains copper phthalocyanine in the content shown in Table 4, and also contains 1 to 30% by mass of polytetrafluoroethylene (PTFE) as a solid lubricating powder, and the remainder contains epoxy resin as a resin.

[0285] [Plating layer forming process]

[0286] A Zn-Ni alloy coating was formed on the surface of the steel plates of test number 30 and test number 31 by electroplating. The plating bath used was DAIN ZIN ALLOY N-PL (trademark) manufactured by Yamato Chemical Industry Co., Ltd. The thickness of the Zn-Ni alloy coating was 8 μm. The thickness of the coating was measured using an electromagnetic film thickness meter SDM-picoR manufactured by Sanko Electronics Laboratories, Ltd., and the average thickness at 9 points on the same evaluation surface was taken as the thickness of the coating. The electroplating conditions were: bath pH: 6.5, bath temperature: 25°C, current density: 2A / dm2 , and treatment time: 18 minutes. The composition of the Zn-Ni alloy plating layer is Zn: 85% and Ni: 15%.

[0287] [Chemical conversion film forming step]

[0288] A chemical conversion film was formed on the surface of the steel sheet or the plated layer of test numbers 22 to 29 and test number 31. Specifically, the chemical conversion treatment liquids described in Table 5 were used as the chemical conversion treatment liquids for the films A to D. DAIN CHROMATE TR-02 manufactured by Yamato Chemical Industry Co., Ltd. was used as the treatment liquid for forming the trivalent chromate film. The conditions for the chemical conversion treatment of the films A to D are as described in Table 5. The conditions for the chemical conversion treatment for forming the trivalent chromate film were bath temperature: 25°C, pH: 4.0, and treatment time 50 seconds.

[0289] [Coating process and curing process]

[0290] A resin coating is formed on the surface of the plating layer or chemical conversion film of test numbers 22 to 31. Specifically, a composition for forming a resin coating is applied to the surface of the plating layer or chemical conversion film of test numbers 22 to 31 by a rod coater and cured. In the composition, components other than the solvent include solid lubricating particles and copper phthalocyanine, and the remainder is resin. In test numbers 22 to 31, epoxy resin is used as the resin. In test numbers 22 to 31, polytetrafluoroethylene particles are used as solid lubricating particles. The content of copper phthalocyanine is shown in Table 4. The composition also contains a solvent. A mixed solution of water, alcohol and a surfactant is used as the solvent. In the case where a chemical conversion film is present, for the case where there is no chemical conversion film on the chemical conversion film, the composition is applied to the plating layer by a rod coater, and then a heat curing treatment is performed at 210°C for 20 minutes to form a resin coating.

[0291] [Pin-on-disc test]

[0292] The wear resistance was evaluated using a pin-disc type sliding tester using the steel plates of test numbers 22 to 31 formed with a resin coating. Specifically, the rotating disk was rotated at 100 rpm while the steel plates of test numbers 22 to 31 attached to the rotating disk were pressed with 60 N against a steel ball. The rotation direction of the rotating disk was set to only one direction. In addition, the sliding of the steel ball relative to the resin coating caused by the rotation of the rotating disk was carried out without oiling and at room temperature. The friction coefficient μ of the steel ball during sliding was measured, and the sliding distance (m) until the friction coefficient μ exceeded 0.6 (equivalent to the friction coefficient between the resin coating and the steel ball) was measured. The results are shown in the column of sliding distance until the friction coefficient exceeds 0.6 in Table 4.

[0293] [Evaluation results]

[0294] Referring to Table 4, the steel plates of test numbers 22 to 31 have a resin coating containing resin, solid lubricating powder and copper phthalocyanine on the surface. Referring to Table 4, the content of copper phthalocyanine in the resin coating formed on the steel plates of test numbers 22 to 31 is 0.2 to 9.0% by mass. As a result, the sliding distance until the friction coefficient exceeds 0.6 is long. That is, excellent wear resistance is shown.

[0295] The steel plates of test numbers 22 to 29 and test number 31 have a chemical conversion film under the resin film. As a result, the sliding distance until the friction coefficient exceeds 0.6 is longer than that of the steel plate of test number 30 which does not have a chemical conversion film under the resin film. That is, it shows more excellent wear resistance.

[0296] The steel sheets of test numbers 22 to 29 had coatings A to D as chemical conversion coatings. As a result, the sliding distance until the friction coefficient exceeded 0.6 was longer than that of the steel sheet of test number 31 having a trivalent chromate coating as a chemical conversion coating. That is, they showed more excellent wear resistance.

[0297] Example 4

[0298] In Example 4, a resin coating was formed on the surface of a steel plate simulating a metal pipe for oil wells, and the wear resistance was evaluated. Specifically, in Example 4, a cold-rolled steel plate (chemical composition: C≤0.15%, Mn≤0.60%, P≤0.100%, S≤0.050%, balance: Fe and impurities) was used.

[0299] The steel sheets of test numbers 32 to 34 were provided with a resin coating including a rust-proof resin coating or a resin coating as shown in Table 6. The "formed" in the rust-proof resin coating column of Table 6 indicates that a rust-proof resin coating was formed on the steel sheet surface. The "-" in the rust-proof resin coating column of Table 6 indicates that a rust-proof resin coating was not formed on the steel sheet surface.

[0300] [Table 6]

[0301] Table 6

[0302]

[0303] [Rust-proof resin coating forming process]

[0304] A rust-proof resin coating is formed on the surface of the steel plates of test number 32 and test number 33. The composition for forming the rust-proof resin coating contains 8% by mass of rust-proof pigment and 70% by mass of acrylic silicone resin. The composition for forming the rust-proof resin coating also contains a solvent. The composition for forming the rust-proof resin coating was sprayed onto the surfaces of the steel plates of test number 32 and test number 33, and cured by natural drying. The thickness of the rust-proof resin coating of test number 32 is 13 μm, and the thickness of the rust-proof resin coating of test number 33 is 11 μm. The thickness of the rust-proof resin coating was measured using an electromagnetic film thickness meter SDM-picoR manufactured by Sanko Electronics Laboratories Co., Ltd., and the average value of the thickness at 9 points on the same evaluation surface was set as the thickness of the resin coating.

[0305] [Coating process and curing process]

[0306] For test numbers 32 and 33, an upper layer of a resin coating was formed on the surface of the rust-proof resin coating. For test number 34, a resin coating was formed on the surface of a steel plate. Specifically, a composition for forming a resin coating was applied on the surface of the steel plates of test numbers 32 to 34 or on the surface of the rust-proof resin coating using a rod coater, and then cured. In the composition, components other than the solvent include solid lubricating particles and copper phthalocyanine, and the remainder is resin. Epoxy resin was used as the resin. Polytetrafluoroethylene particles were used as the solid lubricating particles. The content of copper phthalocyanine is shown in Table 6. The composition also contains a solvent. A mixed solution of water, alcohol, and a surfactant was used as the solvent. In the case where there is a rust-proof resin coating, for the case where there is no rust-proof resin coating on the rust-proof resin coating, the composition was applied on the surface of the steel plate using a rod coater, and then heat-cured at 210°C for 20 minutes to form a resin coating. The formed resin film contains 1 to 30% by mass of polytetrafluoroethylene (PTFE) as solid lubricating powder, and the remainder contains epoxy resin as resin.

[0307] In addition, the thickness of the resin coating of test number 32 is 35.5 μm, the thickness of the resin coating of test number 33 is 33.0 μm, and the thickness of the resin coating of test number 34 is 26.8 μm. In addition, as described above, the resin coatings of test numbers 32 and 33 include rust-proof resin coatings. That is, the thickness of the upper layer of the resin coating of test number 32 is 22.5 μm, and the thickness of the upper layer of the resin coating of test number 33 is 22.0 μm. The thickness of the resin coating was measured using an electromagnetic film thickness meter SDM-picoR manufactured by Sanko Electronics Laboratories, Ltd., and the average value of the thickness at 9 points on the same evaluation surface was set as the thickness of the resin coating.

[0308] [Salt spray test]

[0309] A salt spray test (SST) was conducted using steel plates with test numbers 32 to 34 formed with a resin coating. The salt spray test was conducted using a salt dry-wet combined cycle tester CY90 manufactured by Suga Testing Instruments Co., Ltd. The salt spray test was conducted in accordance with JIS Z 2371 (2015). The test conditions were: spray NaCl concentration 5±0.5%, spray volume 1.5±0.5mL / h / 80cm 2 , temperature 35±2°C, pH 6.5-7.2 during the test. In this example, the time when the resin film swells is defined as the rust time. The rust time (hours) obtained for each test number is shown in Table 6.

[0310] [Evaluation results]

[0311] Referring to Table 6, the steel sheets of test numbers 32 to 34 have a resin coating containing a resin, a solid lubricating powder, and copper phthalocyanine on the surface.

[0312] The steel sheets of test numbers 32 and 33 had a rust-proof resin coating in the resin coating. As a result, the time until rusting was longer than that of the steel sheet of test number 34 which did not have a rust-proof resin coating in the resin coating. That is, excellent corrosion resistance was shown.

[0313] The embodiments of the present disclosure have been described above. However, the above embodiments are merely examples for implementing the present disclosure. Therefore, the present disclosure is not limited to the above embodiments, and the above embodiments can be appropriately modified within the scope of the present disclosure.

[0314] Description of Reference Numerals

[0315] 1 Metal pipe for oil wells

[0316] 10 Tube body

[0317] 10A 1st end

[0318] 10B 2nd end

[0319] 11 Male buckle body

[0320] 12 Coupling

[0321] 40 Male buckle

[0322] 41 External thread

[0323] 42 Male buckle sealing surface

[0324] 43 Shoulder surface of male buckle

[0325] 50 Female buckle

[0326] 51 Internal thread

[0327] 52 Female buckle sealing surface

[0328] 53 Shoulder surface of female buckle

[0329] 70 Anti-rust resin coating

[0330] 80 Plating

[0331] 90 Chemical conversion coating

[0332] 100 Resin coating

[0333] 400 Male contact surface

[0334] 500 Female buckle contact surface

Claims

1. A metal pipe for oil wells, wherein: The oil well metal pipe comprises a pipe body including a first end portion and a second end portion. The pipe body comprises: a male buckle portion formed at the first end portion; and a female buckle portion formed at the second end portion, The pin buckle portion includes a pin buckle portion contact surface, and the pin buckle portion contact surface includes an external thread portion, The box buckle portion includes a box buckle portion contact surface, and the box buckle portion contact surface includes an internal thread portion, The oil well metal pipe further includes a resin coating containing resin, solid lubricating powder, and copper phthalocyanine on at least one of the pin portion contact surface and the box portion contact surface.

2. The metal pipe for oil wells according to claim 1, wherein: The resin coating contains 0.2 to 30.0 mass % of copper phthalocyanine.

3. The metal pipe for oil wells according to claim 2, wherein: The resin coating contains: 0.2-30.0 mass% copper phthalocyanine; 60 to 90% by mass of the resin; and 1 to 30% by mass of the solid lubricating powder.

4. The metal pipe for oil wells according to claim 2, wherein: The resin coating contains 0.2 to 9.0 mass % of copper phthalocyanine.

5. The metal pipe for oil wells according to claim 3, wherein: The resin coating contains 0.2 to 9.0 mass % of copper phthalocyanine.

6. The metal pipe for oil wells according to claim 1, wherein: The oil well metal pipe further includes a plating layer between the resin coating and at least one of the pin portion contact surface and the box portion contact surface.

7. The metal pipe for oil wells according to claim 2, wherein: The oil well metal pipe further includes a plating layer between the resin coating and at least one of the pin portion contact surface and the box portion contact surface.

8. The metal pipe for oil wells according to claim 3, wherein: The oil well metal pipe further includes a plating layer between the resin coating and at least one of the pin portion contact surface and the box portion contact surface.

9. The metal pipe for oil wells according to claim 4, wherein: The oil well metal pipe further includes a plating layer between the resin coating and at least one of the pin portion contact surface and the box portion contact surface.

10. The metal pipe for oil wells according to claim 5, wherein: The oil well metal pipe further includes a plating layer between the resin coating and at least one of the pin portion contact surface and the box portion contact surface.

11. The metal pipe for oil wells according to claim 1, wherein: The oil well metal pipe further includes a chemical conversion coating between the resin coating and at least one of the pin portion contact surface and the box portion contact surface.

12. The metal pipe for oil wells according to claim 2, wherein: The oil well metal pipe further includes a chemical conversion coating between the resin coating and at least one of the pin portion contact surface and the box portion contact surface.

13. The metal pipe for oil well according to claim 3, wherein: The oil well metal pipe further includes a chemical conversion coating between the resin coating and at least one of the pin portion contact surface and the box portion contact surface.

14. The metal pipe for oil wells according to claim 4, wherein: The oil well metal pipe further includes a chemical conversion coating between the resin coating and at least one of the pin portion contact surface and the box portion contact surface.

15. The metal pipe for oil wells according to claim 5, wherein: The oil well metal pipe further includes a chemical conversion coating between the resin coating and at least one of the pin portion contact surface and the box portion contact surface.

16. The metal pipe for oil wells according to claim 6, wherein: The oil well metal pipe further includes a chemical conversion film between the plating layer and the resin film.

17. The metal pipe for oil wells according to claim 7, wherein: The oil well metal pipe further includes a chemical conversion film between the plating layer and the resin film.

18. The metal pipe for oil well according to claim 8, wherein: The oil well metal pipe further includes a chemical conversion film between the plating layer and the resin film.

19. The metal pipe for oil wells according to claim 9, wherein: The oil well metal pipe further includes a chemical conversion film between the plating layer and the resin film.

20. The metal pipe for oil wells according to claim 10, wherein: The oil well metal pipe further includes a chemical conversion film between the plating layer and the resin film.

21. The metal pipe for oil wells according to any one of claims 1 to 20, wherein The resin coating further contains an anti-rust pigment.

22. The metal pipe for oil wells according to any one of claims 1 to 20, wherein At least one of the pin portion contact surface and the box portion contact surface is a surface subjected to one or more treatments selected from the group consisting of sandblasting and pickling.

23. The metal pipe for oil wells according to any one of claims 1 to 20, wherein The resin is at least one selected from the group consisting of epoxy resins, phenolic resins, acrylic resins, polyurethane resins, polyester resins, polyamideimide resins, polyamide resins, polyimide resins, and polyetheretherketone resins.

24. The metal pipe for oil wells according to any one of claims 1 to 20, wherein The solid lubricating powder is one or more selected from the group consisting of graphite, zinc oxide, boron nitride, talc, molybdenum disulfide, tungsten disulfide, graphite fluoride, tin sulfide, bismuth sulfide, organic molybdenum, thiosulfate compounds and polytetrafluoroethylene.

25. The metal pipe for oil wells according to any one of claims 1 to 20, wherein The male buckle part contact surface also includes a male buckle part sealing surface and a male buckle part shoulder surface, The contact surface of the box buckle part also includes a box buckle part sealing surface and a box buckle part shoulder surface.

26. A method for manufacturing a metal pipe for oil wells according to claim 1, wherein: The method for manufacturing the metal pipe for oil wells comprises: A step of preparing a metal pipe for oil wells, the metal pipe for oil wells having a pipe body including a pin portion and a box portion, the pin portion including a pin portion contact surface including an external thread portion, the box portion including a box portion contact surface including an internal thread portion; A step of applying a composition containing a resin, a solid lubricating powder and copper phthalocyanine to at least one of the male buckle part contact surface and the female buckle part contact surface; and A step of curing the applied composition to form a resin coating.

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