EA045795B1 - METAL PIPE FOR OIL WELL AND METHOD OF ITS MANUFACTURE - Google Patents

Description

Technical field

The invention relates to a metal pipe for an oil well and a method for its manufacture.

Prior Art

Metal oil well pipe is used for drilling oil and natural gas fields (hereinafter collectively referred to as oil wells). A metal pipe for an oil well has a threaded connection. In particular, at an oil well drilling site, a plurality of metal oil well tubing is connected to form an integrated body of oilfield tubular products, a typical example of which is casing or tubing. An integrated body of oilfield tubular products is formed by screwing metal oil well pipes together. Inspections are sometimes carried out on integrated oilfield tubular bodies. During inspection, the integrated body of oilfield tubular products is pulled and loosened. The metal oil well tubing is then separated from the integrated oilfield tubular body by unscrewing and inspected. After inspection, the metal oil well tubing is reattached to each other, and the metal oil well tubing is reused as part of an integrated body of oil field tubular products.

A metal pipe for an oil well contains a nipple and a coupling. The nipple includes a nipple contact surface including a male threaded portion formed on an outer peripheral surface of an end portion of a metal oil well pipe. The coupling comprises a coupling contact surface comprising an internally threaded portion formed on an inner peripheral surface of an end portion of a metal oil well pipe. In this specification, the male threaded portion and the female threaded portion may be collectively referred to as threaded portions. It should be appreciated that in some cases the pin contact surface may also comprise a non-threaded metal contact portion comprising a pin sealing surface and a pin thrust surface. Likewise, in some cases, the coupling contact surface may also comprise a non-threaded metal contact portion comprising a coupling sealing surface and a coupling thrust surface.

The contact surface of the pin and the contact surface of the coupling repeatedly experience strong friction when making and unscrewing the metal oil well pipe. Accordingly, during repeated screwing and unscrewing, scoring (irremovable scoring) will occur on the contact surfaces of the pin and coupling. Accordingly, a metal pipe for an oil well must have sufficient resistance to friction, i.e. have excellent resistance to scuffing.

Until now, compound lubricating greases containing heavy metal powder, called additives, have been used to improve the scuffing resistance of metal oil well pipes. Applying a compound grease to the contact surface of the pin and/or coupling can improve the galling resistance of metal oil well pipe. However, heavy metal powders such as Pb, Zn and Cu contained in compound lubricating greases may have an environmental impact. Therefore, it is necessary to develop a metal pipe for oil wells that has excellent scuffing resistance even without the use of compound grease.

A technology for improving the scuffing resistance of metal oil well pipe is proposed, for example, in International Application Publication WO2014/042144 (Patent Document 1) and International Application Publication WO2017/047722 (Patent Document 2). The composition disclosed in Patent Document 1 is a composition for forming a hard coating on the surface of a threaded joint of a metal oil well pipe. The composition contains, in a mixed solvent containing water and a dipolar aprotic solvent, a powdered organic polymer that is at least partially dissolved in the dipolar aprotic solvent. In the composition, the powdered organic polymer is present in a dissolved or dispersed state in a mixed solvent. The composition disclosed in Patent Document 2 is a composition for forming a solid lubricating coating on a threaded joint of a metal oil well pipe. The composition contains a binder, a lubricant additive, an anti-corrosion additive and a plasticizer.

List of materials cited

Patent documents

Patent Document 1: International Application Publication No. WO2014/042144

Patent Document 2: International Application Publication No. WO2017/047722

The essence of the invention

Technical challenge

In this regard, different sizes (diameters) are used for the metal pipe for an oil well. Therefore, it is desirable that the metal oil well pipes screwed together are difficult to unscrew, regardless of the large or small size of the metal oil well pipe. In this regard, a high tightening torque is preset for the large-diameter oil well metal pipe so that the oil well metal pipes screwed together do not come loose.

In the case of making up metal pipes for large diameter oil well with high torque, the high torque characteristic of the tightening is required to be high. The phrase high torque characteristic is high means that, in other words, the torque at the thrust resistance is high. The term resistance torque means the difference between the yield torque, at which one part of the threaded connection is plastically deformed, and the thrust torque, at which the interference between the threaded connections increases rapidly. On the other hand, even when applying the technologies disclosed in Patent Document 1 and Patent Document 2, in some cases the torque at the thrust resistance is low. In this case, it is difficult to screw together metal pipes for large diameter oil well with high torque.

An object of the present disclosure is to provide a metal oil well pipe that can be screwed with high torque even when the metal oil well pipe has a large diameter, and a method for manufacturing the same.

The solution of the problem

A metal pipe for an oil well according to the present invention includes: a pipe main body comprising a first end portion and a second end portion, the pipe main body including a nipple formed on the first end portion and a coupling formed on the second end portion;

the nipple includes a nipple contact surface including a male thread portion; and the coupling includes a coupling contact surface including a female thread portion;

the metal oil well pipe further comprises a polymer coating comprising a polymer, a solid lubricating powder and copper phthalocyanine on or over at least one of a pin contact surface and a coupling contact surface.

The method for manufacturing a metal pipe for an oil well according to the present invention contains the following steps:

preparing a metal pipe for an oil well, the metal pipe for an oil well comprising a pipe main body comprising a nipple comprising a pin contact surface comprising a male threaded portion, and a coupling comprising a coupling contact surface comprising a female threaded portion;

applying a composition containing a polymer, a solid lubricating powder and copper phthalocyanine to at least one surface of the pin contact surface and the coupling contact surface; and curing the composition applied to form the polymer coating.

Technical results of the invention

The metal oil well pipe according to the present invention can be screwed with high torque even if the metal oil well pipe has a large diameter. The method for manufacturing a metal pipe for an oil well according to the present invention can produce the above metal pipe for an oil well.

Brief description of drawings

In fig. 1 is a graph illustrating the relationship between the number of revolutions of a metal oil well pipe having a stop section and the screwing torque of the metal oil well pipe.

In fig. 2A is a graph illustrating the relationship between copper phthalocyanine content in a polymer coating and high torque performance.

In fig. 2B is an enlarged portion of a graph illustrating the relationship between the copper phthalocyanine content of the polymer coating and the high torque performance shown in FIG. 2A.

In fig. 3 is a diagram illustrating one example of a metal pipe for an oil well according to this embodiment of the invention.

In fig. 4 is a partial sectional view (longitudinal section) parallel to the pipe axis direction of the coupling pipe of the metal oil well pipe shown in FIG. 3.

In fig. 5 is a sectional view parallel to the axis direction of the metal oil well pipe shown in FIG. 4, illustrating a portion near a nipple of a metal oil well pipe.

In fig. 6 is a sectional view parallel to the axis direction of the metal oil well pipe shown in FIG. 4, illustrating a portion near the coupling of a metal pipe for an oil well.

In fig. 7 is a partial sectional view (longitudinal section) parallel to the direction

- 2 045795 pipe axis of a metal pipe coupling for an oil well according to this embodiment of the invention, different from FIG. 4.

In fig. 8 is a diagram illustrating an integral type metal pipe for an oil well according to this embodiment of the invention.

In fig. 9 is an enlarged view of the contact surface of the pin shown in FIG. 5.

In fig. 10 is an enlarged view of the contact surface of the coupling shown in FIG. 6.

In fig. 11 is an enlarged view of the contact surface of a pin according to this embodiment of the invention, different from FIG. 9.

In fig. 12 is an enlarged view of the contact surface of a pin according to this embodiment of the invention, different from FIG. 9 and fig. eleven.

In fig. 13 is an enlarged view of the contact surface of a pin according to this embodiment of the invention, different from FIG. 9, fig. 11 and fig. 12.

In fig. 14 is a graph illustrating the relationship between the metallized layer and the results of the Bowden test in terms of scuff resistance.

In fig. 15 is an enlarged view of the contact surface of the coupling according to this embodiment of the invention, different from FIG. 10.

In fig. 16 is an enlarged view of the contact surface of a pin according to this embodiment of the invention, different from FIG. 9, fig. 11, fig. 12 and fig. 13.

In fig. 17 is an enlarged view of the contact surface of a pin according to this embodiment of the invention, different from FIG. 9, fig. 11, fig. 12, fig. 13 and fig. 16.

In fig. 18 is an enlarged view of the contact surface of a pin according to this embodiment of the invention, different from FIG. 9, fig. 11, fig. 12, fig. 13, fig. 16 and fig. 17.

In fig. 19 is a graph explaining the behavior of the torque ΔΤ with the stop resistance taking into account examples.

Description of Embodiments of the Invention

Below, an embodiment of the invention will be described in detail with reference to the drawings. The same reference symbols will be used throughout the drawings for the same or similar parts, and the disclosure will not be repeated.

The inventors of the present invention have conducted various studies on the relationship between oil well metal pipe and tightening torque. As a result, the inventors of the present invention came to the following conclusions.

High torque characteristic

When screwing together metal pipes for an oil well, the optimal torque to complete the screwing is determined in advance. In fig. 1 is a graph illustrating the relationship between the number of revolutions of a metal oil well pipe having a stop section and the screwing torque of the metal oil well pipe. As shown in FIG. 1, when screwing metal pipes for an oil well together, first the torque increases moderately and in proportion to the number of revolutions. As make-up continues, the stop sections come into contact with each other. The torque that occurs at this time is called the thrust torque Ts. After reaching the stop torque Ts, as make-up continues, the torque quickly increases in proportion to the number of revolutions. Make-up is completed at the point in time when the torque reaches a predetermined value (tightening torque To). When the tightening torque is applied, the sections of the metal seal interact with each other with a corresponding pressure between the surfaces. In this case, high gas tightness is achieved with respect to metal pipes for an oil well. Once the tightening torque T is reached, if the metal oil well pipes are continued to be screwed together excessively, the torque at the yield point will be reached and part of the nipple and coupling will be deformed. In this disclosure, the difference between the abutment torque Ts and the yield stress torque Ty is referred to as the abutment resistance torque ΔΤ.

It should be noted that another form of metal pipe for an oil well is available in a pipe with a wedge-shaped threaded profile and without a stop section. In the case of this type of tapered metal oil well pipe, similar to the metal oil well pipe having an abutment portion, the relationship between the number of revolutions of the metal oil well pipe and the tightening torque is also shown in FIG. 1.

As used herein, the term wedge thread means a thread having the structure described below. On the male thread wedge section portion, in the direction in which the pin is screwed in, the top width of the male thread portion gradually decreases along the helix thread line, and the groove width of the male thread portion gradually increases along the helix thread line. And also on the wedge-shaped threaded profile part with internal threads, in the direction in which the coupling is screwed, the groove width of the internal threaded part gradually decreases along the helical thread line, and the width of the top of the internal threaded part gradually increases along the helical thread line. In the case of a metal oil well pipe with a wedge threaded profile, as the screwing process progresses, the supporting sides of the male thread part and the female thread part contact each other, and the embedded sides of the male thread part and the internal thread part contact each other, and locking (pressure fit). Locking torque is also called locking torque or locked side torque. In the present specification, unless otherwise indicated, no distinction is made between the locking torque and the thrust torque, and the term thrust torque Ts is used to refer to them. In the case of a metal oil well pipe having a wedge-shaped threaded profile, similarly to an oil well metal pipe having a stop portion, after reaching the stop torque Ts, if make-up continues, the torque will increase rapidly in proportion to the number of revolutions. Those. At the torque Ts of the stop, the interaction between the threaded connections increases rapidly. If make-up is continued, the tightening torque T will be reached. Once the tightening torque To is reached, if we continue to screw together the metal oil well pipes excessively, the torque Tu at the yield point will be reached and part of the nipple and coupling will be deformed.

As described above, for large-diameter metal oil well pipes, a high tightening torque is set. However, in the case where the tightening torque To is set to a high value, in some cases, before the tightening torque To is reached, part of the pin and coupling is deformed and plastic deformation occurs. If the torque AT at the stop resistance is high, you can continue making up after reaching the torque Ts of the stop. Therefore, if the torque AT at the abutment resistance is high, high torque make-up can be carried out even in the case of large-diameter metal oil well pipes. In this case, it will be difficult for the metal oil well pipes to loosen the connection. In the present description, the term high high torque characteristic means that the torque AT at the thrust resistance is high. As used herein, the term large diameter oil well metal pipe means a metal oil well pipe with an outer diameter of 254 mm (10 inches) or more.

To increase the torque AT at the stop resistance, it is useful to reduce the torque Ts of the stop or increase the torque Tu at the yield point. However, it is known that, in general, the thrust torque Ts and the torque Tu at the yield point demonstrate the same dynamics. For example, if the surface friction coefficient of a metal oil well pipe is reduced to reduce the thrust torque Ts, the yield stress torque Ty is also reduced. In this situation, sometimes part of the pin or coupling becomes deformed before reaching the tightening torque. In addition, if the surface friction coefficient of the oil well metal pipe is increased to increase the yield stress torque Ty, the thrust torque Ts is also increased. In this situation, sometimes the stop sections may not contact each other even after reaching the tightening torque To.

Compared with normal and small diameter metal pipes for oil wells, large diameter metal pipes for oil wells also require increased high torque performance. Therefore, the inventors of the present invention conducted research on methods for improving the high torque characteristic even in the case of a large diameter metal pipe for an oil well. As a result, the inventors of the present invention came to the following conclusions. In fig. 2A is a graph illustrating the relationship between copper phthalocyanine content in a polymer coating and high torque performance. The graph in Fig. 2A was obtained based on the results of Example 1 disclosed below. In Example 1, a so-called large diameter metal oil well pipe (with an outer diameter of 273.05 mm (10.75 inch) and a wall thickness of 12.570 mm (0.495 inch)) was used.

Abscissa in Fig. 2A represents the content (wt.%) of copper phthalocyanine in the polymer coating. The ordinate in Fig. 2A represents the torque AT at the abutment resistance. The torque AT at thrust resistance was determined as a relative value compared to the torque AT at thrust resistance when the additive specified in API (American Petroleum Institute) BUL 5A2 (1998) was used, and its value was taken to be 100. In FIG. . 2A, the white circle (O) indicates that the polymer coating contained copper phthalocyanine, and the black circle (®) indicates that no copper phthalocyanine was contained in the polymer coating.

As shown in FIG. 2A, the thrust torque AT increased when the polymer coating contained copper phthalocyanine compared to the case when the polymer coating

- 4 045795 did not contain copper phthalocyanine. That is, if the polymer coating contains copper phthalocyanine, the torque characteristic increases. In this case, it is possible to make up even large-diameter metal pipes for an oil well with high torque.

In fig. 2B is an enlarged portion of a graph illustrating the relationship between copper phthalocyanine content of a polymer coating and high torque performance. As shown in FIG. 2B, if the content of copper phthalocyanine in the resin coating is 0.2 wt% or more, the high torque characteristic of the oil well metal pipe continues to increase.

The essence of the oil well metal pipe and the manufacturing method thereof according to the present embodiment, established based on the above results, is disclosed below.

1. A metal pipe for an oil well, containing:

a pipe main body comprising a first end portion and a second end portion, wherein the pipe main body includes a nipple formed on the first end portion and a coupling formed on the second end portion;

the nipple includes a nipple contact surface including a male thread portion; and the coupling includes a coupling contact surface including a female thread portion;

the metal oil well pipe further comprises a polymer coating containing a polymer, a solid lubricating powder and copper phthalocyanine on or over at least one surface of a pin contact surface and a coupling contact surface.

The metal oil well pipe according to the present embodiment contains a resin coating containing copper phthalocyanine. Thus, even if the metal oil well pipe has a large diameter, it can be made up with a large torque. It should be noted that the oil well metal pipe according to the present embodiment also refers to the normal and small diameter oil well metal pipe. Even in the case where the oil well metal pipe according to the present embodiment is a normal and small diameter oil well metal pipe, it is possible to make up with a necessary and sufficient torque.

2. A metal pipe for an oil well according to claim 1, in which the polymer coating contains from 0.2 to 30.0 wt.% copper phthalocyanine.

In this case, the high torque characteristic of the oil well metal pipe continues to increase.

3. A metal pipe for an oil well according to claim 2, in which the polymer coating contains from 0.2 to 30.0 wt.% copper phthalocyanine, from 60 to 90 wt.% polymer, and from 1 to 30 wt.% solid lubricant powder.

4. A metal pipe for an oil well according to claim 2 or 3, in which the polymer coating contains from 0.2 to 9.0 wt.% copper phthalocyanine.

In this case, the galling resistance of the metal oil well pipe is increased in addition to the high torque characteristic.

5. A metal pipe for an oil well according to any one of claims 1 to 4, further comprising a metallized layer between at least the contact surface of the nipple or the contact surface of the coupling and the polymer coating.

6. The metal oil well pipe according to any one of claims 1 to 4, further comprising a chemical conversion layer between at least a pin contact surface or a coupling contact surface and a polymer coating.

7. The metal pipe for an oil well according to claim 5, further comprising a layer obtained by chemical conversion between the metallized layer and the polymer coating.

8. A metal pipe for an oil well according to any one of claims 1-7, in which the polymer coating additionally contains an anti-corrosion filler.

9. The metal oil well pipe according to any one of claims 1 to 8, wherein at least one of the pin contact surface and the coupling contact surface is a surface subjected to one or more treatments from the group consisting of blasting and etching.

10. The metal oil well pipe according to any one of claims 1 to 9, wherein the polymer is one or more types selected from the group consisting of epoxy resin, phenolic resin, acrylic resin, urethane resin, polyester resin, polyamide imide resin, polyamide resin, polyimide resin and polyetheretherketone resin.

11. The metal pipe for an oil well according to any one of claims 1 to 10, wherein the solid lubricating powder is one or more substances from the group consisting of graphite,

- 5 045795 zinc oxide, boron nitride, talc, molybdenum disulfide, tungsten disulfide, graphite fluoride, tin sulfide, bismuth sulfide, organic molybdenum, thiosulfate compounds and polytetrafluoroethylene.

12. The metal oil well pipe according to any one of claims 1 to 11, wherein the pin contact surface further comprises a pin sealing surface and a pin abutment surface, and the coupling contact surface further comprises a coupling sealing surface and a coupling abutment surface.

13. A method for manufacturing a metal pipe according to claim 1, including the following steps:

preparing a metal pipe for an oil well, the metal pipe for an oil well comprising a pipe main body comprising a nipple comprising a pin contact surface comprising a male threaded portion, and a coupling comprising a coupling contact surface comprising a female threaded portion;

applying a composition containing a polymer, a solid lubricating powder and copper phthalocyanine to at least one surface of the pin contact surface and the coupling contact surface; and curing the composition applied to form the polymer coating.

Next, a metal oil well pipe according to an embodiment of the invention will be described in detail.

Construction of a metal pipe for an oil well

First, a structure of a metal pipe for an oil well according to the present embodiment will be disclosed. A metal pipe for an oil well has a well-known design. Available types of metal oil well pipes are metal oil well pipe with thread and coupling and integral type metal oil well pipe. Each type of metal pipe for an oil well will be discussed in detail below.

An embodiment in which the oil well metal pipe 1 is a threaded and coupling type

In fig. 3 is a diagram illustrating one example of a metal pipe 1 for an oil well according to this embodiment of the invention. In fig. 3 is a diagram illustrating a metal oil well pipe 1 of the so-called threaded coupling type. As shown in FIG. 3, the metal oil well pipe 1 includes a pipe main body 10.

The pipe main body 10 extends in the direction of the pipe axis. The cross section perpendicular to the pipe axis direction of the pipe main body 10 has a circular shape. The pipe main body 10 includes a first end portion 10A and a second end portion 10B. The first end portion 10A is an end portion on the side opposite to the second end portion 10B. In the metal oil well pipe 1 of the threaded and coupling type shown in FIG. 3, the pipe main body 10 includes a tubular nipple body 11 and a coupling 12. The coupling 12 is attached at one end of the tubular nipple body 11. In particular, the coupling 12 is screwed onto a thread at one end of the tubular nipple body 11.

In fig. 4 is a partial sectional view (longitudinal section) parallel to the pipe axis direction of the coupling 12 of the metal oil well pipe 1 shown in FIG. 3. As shown in FIG. 3 and fig. 4, the pipe main body 10 includes a nipple 40 and a coupling 50. The nipple 40 is formed on the first end portion 10A of the pipe main body 10. When making up, the nipple 40 is inserted into the coupling 50 of another metal oil well pipe 1 (not shown) and screwed into the coupling 50 of the other metal oil well pipe 1.

The coupling 50 is formed on the second end portion 10B of the pipe main body 10. When making up, a nipple 40 of the other metal oil well pipe 1 is inserted into the coupling 50, and the coupling 50 is screwed onto the nipple 40 of the other metal oil well pipe 1.

Nipple design 40

In fig. 5 is a sectional view of a portion adjacent to nipple 40 of the metal oil well pipe 1 shown in FIG. 4, namely, a sectional view along the axis of a metal pipe 1 for an oil well. The dotted line in Fig. 5 shows a structure of a coupling 50 of another metal oil well pipe in the case of screwing together the metal oil well pipe 1 with another metal oil well pipe 1. As shown in FIG. 5, the nipple 40 includes a nipple contact surface 400 on an outer peripheral surface of the first end portion 10A of the pipe main body 10. When making up with another metal oil well pipe 1, the pin contact surface 400 is screwed into the coupling 50 of the other metal oil well pipe 1, and it contacts the contact surface 500 (to be disclosed below) of the coupling 50.

The pin contact surface 400 includes at least a male thread portion 41,

- 6 045795 formed on the outer peripheral surface of the first end portion 10A. The pin contact surface 400 may further comprise a pin sealing surface 42 and a pin abutment surface 43 . In fig. 5, the pin abutment surface 43 is located on the front end surface of the first end portion 10A and on the outer peripheral surface of the first end portion 10A, the pin sealing surface 42 is located further on the front end surface of the first end portion 10A than the male thread portion 41. In other words, the pin sealing surface 42 is located between the male thread portion 41 and the pin abutment surface 43. The sealing surface 42 of the nipple has a conical shape. Specifically, the outer diameter of the pin sealing surface 42 gradually decreases from the male thread portion 41 to the pin abutment surface 43 in the longitudinal direction (pipe axis direction) of the first end portion 10A. When made up with another metal oil well pipe 1, the sealing surface 42 of the pin contacts the sealing surface 52 (to be disclosed below) of the coupling 50 of the other metal oil well pipe 1. In particular, during make-up, when the nipple 40 is inserted into the coupling 50 of another metal oil well pipe 1, the sealing surface 42 of the pin is in contact with the sealing surface 52 of the coupling. Therefore, when the nipple 40 continues to be screwed into the coupling 50 of the other metal oil well pipe 1, the sealing surface 42 of the nipple is in close contact with the sealing surface 52 of the coupling. Due to this, during make-up, the pin sealing surface 42 is in close contact with the coupling sealing surface 52 to thereby form a metal-to-metal seal. In this way, it is possible to improve the gas tightness in each oil well screwed metal pipe 1.

In fig. 5, a nipple sealing surface 43 is located on the front end surface of the first end portion 10A. In other words, in nipple 40 in FIG. 5, the male thread portion 41, the nipple sealing surface 42 and the nipple thrust surface 43 are arranged sequentially in this order from the center of the pipe main body 10 to the first end portion 10 A. When screwing with another metal oil well pipe 1, the nipple thrust surface 43 is located opposite the abutment surface 53 (to be disclosed below) of the coupling 50 of the other metal oil well pipe 1 and contacts it. Specifically, during make-up, the pin abutment surface 43 contacts the pin abutment surface 53 as a result of insertion of the pin 40 into the coupling 50 of the other metal oil well pipe 1. In this way, high torque can be achieved during make-up. In addition, the positional relationship between the nipple 40 and the coupling 50 in the make-up position can be stabilized.

It should be taken into account that the contact surface 400 of the nipple 40 includes at least a portion 41 with an external thread. In other words, the pin contact surface 400 includes a male thread portion 41 and does not necessarily include a pin sealing surface 42 and a pin thrust surface 43. The pin contact surface 400 may include a male thread portion 41 and a pin abutment surface 43 and does not necessarily include a pin sealing surface 42 . The pin contact surface 400 may include a male thread portion 41 and a pin sealing surface 42 and does not necessarily include a pin abutment surface 43 .

Coupling design 50

In fig. 6 is a sectional view of a portion adjacent to the coupling 50 of the metal oil well pipe 1 shown in FIG. 4, i.e. cross-sectional view along the axis of a metal pipe 1 for an oil well. The dotted line in Fig. 6 shows the structure of a nipple 40 of another metal oil well pipe 1 in the case of screwing the metal oil well pipe 1 with another metal oil well pipe 1. As shown in FIG. 6, the coupling 50 includes a coupling contact surface 500 on the inner peripheral surface of the second end portion 10B of the pipe main body 10. When making up with another metal oil well pipe 1, the coupling contact surface 500 contacts the contact surface 400 of the nipple 40 of the other metal oil well pipe 1 when the nipple 40 is screwed into the coupling 50. The coupling contact surface 500 includes at least a female thread portion 51 , formed on the inner peripheral surface of the second end portion 10B. When screwed together, the female thread portion 51 engages with the male thread portion 41 of the nipple 40 of the other metal oil well pipe 1. The coupling contact surface 500 may further comprise a coupling sealing surface 52 and a coupling thrust surface 53 . In fig. 6, on the inner peripheral surface of the second end portion 10B, the coupling sealing surface 52 is located further from the center of the pipe main body 10 than the female thread portion 51. In other words, the coupling sealing surface 52 is located between the female thread portion 51 and the coupling thrust surface 53. The sealing surface 52 of the coupling has a conical shape. Specifically, the inner diameter of the coupling sealing surface 52 gradually decreases from the internal thread portion 51 to the coupling abutment surface 53 in the longitudinal direction (pipe axis direction) of the second end portion 10B.

When screwing with another metal pipe 1 for an oil well, the sealing

- 7 045795 the surface 52 of the coupling is in contact with the sealing surface 42 of the nipple 40 of another metal pipe 1 for the oil well. Specifically, during make-up, when the nipple 40 of the other metal oil well pipe 1 is screwed into the coupling 50, the coupling sealing surface 52 is in contact with the nipple sealing surface 42, and when the nipple 40 is screwed further, the coupling sealing surface 52 is in close contact with the sealing surface 42 nipple Due to this, during make-up, the coupling sealing surface 52 is in close contact with the pin sealing surface 42 to thereby form a metal-to-metal seal. In this way, it is possible to improve the gas tightness in each oil well screwed metal pipe 1.

The coupling abutment surface 53 is located further on the side of the pipe main body 10 than the coupling sealing surface 52. In other words, in the coupling 50, the coupling abutment surface 53, the coupling sealing surface 52 and the internal thread portion 51 are arranged sequentially in that order from the center of the pipe main body 10 to the front end of the second end portion 10B. When making up with another metal oil well pipe 1, the abutment surface 53 of the coupling is located opposite the abutment surface 43 of the nipple 40 of the other metal oil well pipe 1 and is in contact with it. Specifically, during make-up, the coupling abutment surface 53 contacts the nipple abutment surface 43 as a result of insertion of the nipple 40 into the coupling 50 of the other metal oil well pipe 1. In this way, high torque can be achieved during make-up. In addition, the positional relationship between the nipple 40 and the coupling 50 in the make-up position can be stabilized.

The coupling contact surface 500 includes at least a female thread portion 51. When fastening is performed, the female thread portion 51 of the contact surface 500 of the coupling 50 contacts the male thread portion 41 of the contact surface 400 of the pin 40 such that the female thread portion 51 corresponds to the male thread portion 41. The coupling sealing surface 52 contacts the pin sealing surface 42 such that the coupling sealing surface 52 matches the pin sealing surface 42. The coupling abutment surface 53 contacts the pin abutment surface 43 such that the coupling abutment surface 53 corresponds to the pin abutment surface 43. In the case where the pin contact surface 400 includes a male thread portion 41 and does not include a pin sealing surface 42 and a nipple abutment surface 43, the coupling contact surface 500 includes an internal thread portion 51 and does not include a coupling sealing surface 52 and a coupling abutment surface 53. In the case where the pin contact surface 400 includes a male thread portion 41 and a pin abutment surface 43 and does not include a pin sealing surface 42, the coupling contact surface 500 includes an internal thread portion 51 and a coupling abutment surface 53 and does not include a coupling sealing surface 52. In the case where the pin contact surface 400 includes a male thread portion 41 and a pin sealing surface 42 and does not include a pin abutment surface 43, the coupling contact surface 500 includes an internal thread portion 51 and a coupling sealing surface 52 and does not include a coupling abutment surface 53.

The pin contact surface 400 may include a plurality of male thread portions 41, a plurality of pin sealing surfaces 42, and a plurality of pin abutment surfaces 43. For example, the nipple abutment surface 43, the nipple sealing surface 42, the male thread portion 41, the nipple sealing surface 42, the nipple abutment surface 43, the nipple sealing surface 42, and the male thread portion 41 may be arranged in that order on the contact surface 400 of the nipple 40 in a direction from the front end of the first end portion 10A to the center of the pipe main body 10. In this case, the internal thread portion 51, the coupling sealing surface 52, the coupling abutment surface 53, the coupling sealing surface 52, the internal thread portion 51, the coupling sealing surface 52, and the coupling abutment surface 53 may be arranged in that order on the coupling contact surface 500 50 in a direction from the front end of the second end portion 10B to the center of the pipe main body 10.

In fig. 5 and fig. 6 depicts a so-called best connection in which pin 40 includes a male thread portion 41, a pin sealing surface 42, and a nipple thrust surface 43, and coupling 50 includes a female thread portion 51, a coupling sealing surface 52, and a coupling thrust surface 53. However, as disclosed above, pin 40 may include a male thread portion 41 and does not necessarily include a pin sealing surface 42 and a pin stop surface 43. In this case, the coupling 50 includes an internal thread portion 51 and does not include a coupling sealing surface 52 and a coupling thrust surface 53. In fig. 7 is a view illustrating one example of a metal oil well pipe 1 in which the nipple 40 includes a male thread portion 41 and does not include a nipple sealing surface 42 and a nipple thrust surface 43, and the coupling 50 includes an internal thread portion 51 and does not include a sealing surface. a coupling surface 52 and a coupling thrust surface 53.

A variant in which the oil well metal pipe 1 is an integral type

- 8 045795

The metal pipe 1 for an oil well shown in FIG. 3, fig. 4 and fig. 7 is a so-called threaded coupling type oil well metal pipe 1, in which the pipe main body 10 includes a nipple tubular body 11 and a coupling 12. However, the oil well metal pipe 1 according to this embodiment may be an integral type instead of a threaded and coupling type.

In fig. 8 is a diagram illustrating a metal pipe 1 for an integral type oil well according to this embodiment of the invention. As shown in FIG. 8, the integral type oil well metal pipe 1 includes a pipe main body 10. The pipe main body 10 includes a first end portion 10A and a second end portion 10B. The first end portion 10A is located on the side opposite the second end portion 10B. As disclosed above, in the threaded and coupler type oil well metal pipe 1, the pipe main body 10 includes a nipple tubular body 11 and a coupler 12. In other words, in the threaded and coupler type oil well metal pipe 1, the pipe main body 10 formed by screwing together two separate elements (tubular body 11 of the nipple and coupling 12). On the contrary, in the integral type oil well metal pipe 1, the pipe main body 10 is formed in a permanent manner.

The nipple 40 is formed on the first end portion 10A of the pipe main body 10. When making up, the nipple 40 is inserted and screwed into the coupling 50 of another metal integral oil well pipe 1, and thus screwed into the coupling 50 of another metal integral oil well pipe 1. The coupling 50 is formed on the second end portion 10B of the pipe main body 10. When making up, the nipple 40 of the other integral type metal oil well pipe 1 is inserted and screwed into the coupling 50, thereby screwing the coupling 50 with the nipple 40 of the other metal oil well pipe 1. The structure of the nipple 40 of the integral type oil well metal pipe 1 is the same as the structure of the nipple 40 of the threaded coupling type oil well metal pipe 1 shown in FIG. 5. Likewise, the structure of the metal pipe coupling 50 for the integral type oil well is the same as the structure of the metal pipe coupling 50 for the threaded and coupling type oil well shown in FIG. 6. It should be noted that in FIG. 8, the nipple abutment surface 43, the nipple sealing surface 42, and the male thread portion 41 in the nipple 40 are arranged in this order from the front end of the first end portion 10A toward the center of the pipe main body 10. Thus, the internal thread portion 51, the coupling sealing surface 52, and the coupling abutment surface 53 in the coupling 50 are arranged in this order from the front end of the second end portion 10B toward the center of the pipe main body 10. However, similar to the contact surface 400 of the nipple 40 of the metal oil well pipe 1 of the threaded and coupling type, it is sufficient that the contact surface 400 of the nipple 40 of the metal oil well pipe 1 contains at least a male thread portion 41. In addition, similarly to the contact surface 500 of the coupling 50 of the metal oil well pipe 1 of the threaded and coupling type, it is sufficient that the contact surface 500 of the coupling 50 of the metal oil well pipe 1 contains at least a portion 51 with an internal thread.

Briefly, the metal oil well pipe 1 according to this embodiment may be a threaded coupling type or an integral type.

Polymer coating

The metal oil well pipe 1 according to this embodiment of the invention includes a polymer coating 100 on or over at least a nipple contact surface 400 or a coupling contact surface 500. In fig. 9 is an enlarged view of the contact surface 400 of the pin shown in FIG. 5. In FIG. 10 is an enlarged view of the contact surface 500 of the clutch shown in FIG. 6. As shown in FIG. 9 and fig. 10, the metal oil well pipe 1 according to this embodiment may include a polymer coating 100 on or over both the nipple contact surface 400 and the coupling contact surface 500. However, a configuration in which the metal oil well pipe 1 according to this embodiment includes a resin coating 100 on or over only the nipple contact surface 400 or only the coupling contact surface 500 may also be applied. For example, when a polymer coating 100 is provided on or over the pin contact surface 400, as shown in FIG. 9, the polymer coating 100 should not be applied to or over the coupling contact surface 500. In addition, when the polymer coating 100 is provided on or over the coupling contact surface 500, as shown in FIG. 10, no resin coating should be applied to the pin contact surface 400. In other words, the metal oil well pipe 1 according to this embodiment includes a resin coating 100 on the nipple contact surface 400 and/or the coupling contact surface 500.

- 9 045795

The polymer coating 100 is a hard coating containing a polymer, a solid lubricating powder, and copper phthalocyanine. The polymer and solid lubricating powder can be selected separately. Next, the resin, solid lubricating powder and copper phthalocyanine contained in the resin coating 100 according to this embodiment will be described in detail.

Polymer

The polymer contained in the polymer coating 100 according to this embodiment is not particularly limited. However, when screwing together the metal oil well pipe 1, the surface of the resin coating 100 is scratched and abrasive powder is generated. Thus, for stable wear resistance (coating life) of the polymer coating 100 and high torque characteristics, it is preferable to use a polymer with high adhesion to the substrate and medium hardness. The high-adhesion, medium-hardness polymer is, for example, one or more polymers selected from the group consisting of epoxy resin, phenolic resin, acrylic resin, urethane resin, polyester resin, polyamide imide resin, polyamide resin, polyimide resin, and polyetheretherketone resin . Preferably, the polymer is one or two polymers selected from the group consisting of epoxy resin and acrylic resin. The polymer content of the polymer coating 100 is, for example, from 60 to 90 wt.%. In this case, the ductility, scuff resistance, and high torque characteristic of the resin coating 100 can be increased more stably. The lower limit of polymer content is preferably 62 wt%, more preferably 63 wt% and even more preferably 65 wt%. The upper limit of the polymer content is preferably 88 wt.% and more preferably 86 wt.%.

Solid lubricating powder

The solid lubricating powder contained in the resin coating 100 according to this embodiment is not particularly limited. The solid lubricating powder is, for example, one or more substances 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 . 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.

The content of solid lubricating powder in the polymer coating 100 is, for example, from 1 to 30 wt.%. In this case, the ductility and scuff resistance of the resin coating 100 can be increased more steadily. The lower limit of the solid lubricating powder content is preferably 2 wt% and more preferably 5 wt%. The upper limit of the solid lubricating powder content is preferably 25 wt%, and more preferably 20 wt%.

Copper phthalocyanine

The resin coating 100 according to the present embodiment contains copper phthalocyanine. In the metal oil well pipe 1 according to the present embodiment, copper phthalocyanine is the most important substance for achieving high torque characteristics. Copper phthalocyanine is one type of phthalocyanine complex in which phthalocyanine (C ₃₂ H ₁₈ N ₈ ) is combined with copper ions (Cu ²⁺ ). The chemical formula of copper phthalocyanine is given below.

If copper phthalocyanine is contained in the resin coating 100, the high torque characteristic of the oil well metal pipe 1 is increased. The details of the reason for the increase in high torque characteristic are not clear. However, the examples disclosed below confirm that as a result of the presence of copper phthalocyanine in the resin coating 100 according to this embodiment, the abutment resistance torque ΔΤ, which is the difference between the yield stress torque Ty and the abutment torque Ts, increases. Thus, even when the metal oil well pipe 1 according to this embodiment has a larger diameter, the metal oil well pipe 1 can be screwed with high torque.

The content of copper phthalocyanine in the resin coating 100 according to this embodiment is not particularly limited. That is, even when a small amount of copper phthalocyanine

- 10 045795 is contained in the resin coating 100, the effect of increasing the high torque characteristic of the metal oil well pipe 1 is achieved to a certain extent. The lower limit of copper phthalocyanine content in the polymer coating 100 may be 0.1 wt%. On the other hand, if the content of copper phthalocyanine in the resin coating 100 is 0.2 wt% or more, the high torque characteristic of the oil well metal pipe 1 continues to increase. Accordingly, in this embodiment, the lower limit of the content of copper phthalocyanine in the polymer coating 100 is preferably 0.1 wt%, more preferably 0.2 wt%, and even more preferably -0.4 wt%.

If the content of copper phthalocyanine in the resin coating 100 according to this embodiment is 30.0 wt% or less, the dispersity of copper phthalocyanine is increased. Accordingly, the preferred upper limit of copper phthalocyanine content in the polymer coating 100 is 30.0 wt%. Moreover, if the content of copper phthalocyanine in the resin coating 100 according to this embodiment is 9.0 wt% or less, in addition to the high torque characteristic, the scuffing resistance of the oil well metal pipe 1 is also improved. Thus, the upper limit of the copper phthalocyanine content in the polymer coating 100 may be 9.0 wt%.

Thus, the upper limit of the content of copper phthalocyanine in the resin coating 100 according to this embodiment is preferably 30.0 wt%, more preferably 14.0 wt%, even more preferably 12.0 wt%, even more preferably - 10.0 wt.%, even more preferably 9.0 wt.% and even more preferably 6.0 wt.%.

Scuff Resistance

In the oil well metal pipe 1 according to this embodiment, if the upper limit of the copper phthalocyanine content of the resin coating 100 is further adjusted, in addition to the high torque characteristic, the scoring resistance of the oil well metal pipe 1 is also increased. Further, the content will be disclosed in more detail with reference to the table.

In table 1 shows the copper phthalocyanine content of polymer coatings 100 and the results of the Bowden test as an indicator of resistance to scuffing. Table 1 was obtained by extracting some results from Example 2, which will be disclosed below. In example 2, polymer coating 100 with the copper phthalocyanine content shown in table. 1 was formed on the surface of the steel plate in each of the tests. Bowden tests were carried out using steel plates with the corresponding test number, which were coated with polymer coating 100. During Bowden tests, a steel ball was moved over the surface of polymer coating 100 on a steel plate with the corresponding test number and the coefficient of friction was determined. The content of copper phthalocyanine in the polymer coating 100 and the number of slips until the coefficient of friction exceeds 0.3 for each test number are shown in Table. 1. It should be taken into account that a higher number of slips before the coefficient of friction reaches a value of 0.3 means a higher resistance to scuffing.

Table 1

Test number Copper phthalocyanine content Number of slips until the friction coefficient exceeds 0.3 13 0.1 wt% 510 14 0.5 wt% 647 15 2.0 wt% 524 16 5.0 wt% 531 17 10.0 wt% 55 21 - 511

As shown in table. 1, if the content of copper phthalocyanine in the polymer coating 100 is from 0.2 to 9.0 wt.%, the number of slips until the coefficient of friction exceeds the value of 0.3 increases compared with the content of copper phthalocyanine in the polymer coating 100 in the amount of 0.1 wt. .% or 10.0 wt.%. That is, if the content of copper phthalocyanine in the resin coating 100 is from 0.2 to 9.0 wt%, not only the high torque performance but also the scuffing resistance of the metal oil well pipe 1 is increased.

Other components

The polymer coating 100 according to this embodiment may also contain components other than those disclosed above. The other components are, for example, one or more types selected from the group consisting of an anticorrosive additive, an antiseptic additive and an antioxidant additive. The anti-corrosion additive is, for example, one or more substances selected from the group consisting of aluminum tripolyphosphate, aluminum phosphite and calcium ion-exchange silica. As an anti-corrosion

- 11 045795 water-repellent additive available on the market can be used.

The resin coating 100 according to this embodiment may be formed from a single layer or may comprise multiple layers. The term multilayer refers to a state in which the resin coating 100 is applied in two or more layers in the radial direction of the metal oil well pipe 1. The polymer coating 100 may be applied and formed in two or more layers by repeated application and curing of the composition to form the polymer coating 100. The polymer coating 100 may be directly formed on at least the pin contact surface 400 or the coupling contact surface 500 or may be formed after pre-treatment of the pin contact surface 400 and/or the coupling contact surface 500, disclosed below. If the polymer coating 100 contains multiple layers, any of the plurality of layers of the polymer coating 100 may contain corresponding components in the above ranges, or all of the multiple layers of the polymer coating 100 may contain corresponding components in the above ranges. Preferably, the polymer coating 100 contains an anti-corrosion polymer coating. In this embodiment, the anti-corrosion polymer coating is an optional component. That is, the anti-corrosion polymer coating may not be applied to the metal oil well pipe 1 according to this embodiment. Next, the anti-corrosion polymer coating will be disclosed.

Anti-corrosion polymer coating

The metal oil well pipe 1 according to this embodiment may include an anti-corrosion resin coating in the resin coating 100 formed on or over at least the nipple contact surface 400 or the coupling contact surface 500. The anti-corrosion polymer coating contains anti-corrosion filler and acrylic silicone resin. The anti-corrosion filler is, for example, one or more substances selected from the group consisting of aluminum tripolyphosphate, aluminum phosphite, zinc-rich primer (JIS K5552 (2010)) and mica iron oxide. As the acrylic silicone resin, a commercially available acrylic silicone resin can be used. A commercially available acrylic silicone resin is, for example, an acrylic silicone resin with the trade name ACRYDIC manufactured by DIC Corporation. If the resin coating 100 of the metal oil well pipe 1 contains the anti-corrosion resin coating 70, the corrosion resistance of the metal oil well pipe 1 is increased.

The content of the anti-corrosion filler in the anti-corrosion polymer coating is, for example, from 5 to 30 wt.%. The content of the acrylic silicone resin in the anti-corrosion resin coating is, for example, 50 to 80% by weight. The anti-corrosion polymer coating may contain other components in addition to the anti-corrosion filler and acrylic silicone resin. Examples of other components contain one or more types selected from the group consisting of filler, antifoam additive, leveling agent, and fiber filler. The content of other components in the anti-corrosion polymer coating is, for example, only from 0 to 20% by weight.

As stated above, the resin coating 100 includes an anti-corrosion resin coating. In particular, in FIG. 11 is an enlarged view of a pin contact surface 400 according to this embodiment, different from FIG. 9. As shown in FIG. 11, the metal oil well pipe 1 includes an anti-corrosion resin coating 70 and a top layer 60 of the resin coating 100 in the resin coating 100 formed on or over the pin contact surface 400. In this case, the top layer 60 of the resin coating 100 contains a polymer, solid lubricating powder and copper phthalocyanine, and the anti-corrosion resin coating 70 as the bottom layer of the resin coating 100 contains an anti-corrosion filler and an acrylic silicone resin.

In the metal oil well pipe 1 according to this embodiment, the location where the anti-corrosion resin coating 70 is provided is not limited to the location in the example shown in FIG. 11. Although not shown in the drawings, similar to that illustrated in FIG. 11, the metal oil well pipe 1 may include an anti-corrosion polymer coating 70 in the polymer coating 100 formed on or over the coupling contact surface 500. Also, the anti-corrosion polymer coating 70 may only be contained in the polymer coating 100 formed on or over the pin contact surface 400, and may not be contained in the polymer coating 100 formed on or over the coupling contact surface 500. In addition, the anti-corrosion polymer coating 70 may not be contained in the polymer coating 100 formed on or over the pin contact surface 400, and may only be contained in the polymer coating 100 formed on or over the coupling contact surface 500. In addition, the anti-corrosion polymer coating 70 may be contained in both a polymer coating 100 formed on or over the pin contact surface 400 and a polymer coating 100 formed on or over the coupling contact surface 500.

In this embodiment, the anti-corrosion polymer coating 70 may be contained in a polymer coating 100 formed on a metallized layer, disclosed below, or in a polymer coating 100 formed on a chemical conversion layer, disclosed below. That is, in this embodiment, the anti-corrosion resin coating 70 may be formed on the pin contact surface 400, the coupling contact surface 500, the metallized layer disclosed below, or the chemical conversion layer disclosed below.

The polymer coating 100 may be formed as the outermost layer on the pin contact surface 400 and/or the coupling contact surface 500. When screwing together a metal pipe 1 for an oil well, a liquid lubricant may be additionally applied to the polymer coating 100.

Thickness of polymer coating

The thickness of the resin coating 100 is not particularly limited. The thickness of the polymer coating 100 is, for example, from 1 to 100 microns. In this case, the high torque characteristic of the oil well metal pipe 1 can be increased more stably. The lower limit of the thickness of the polymer coating 100 is preferably 2 μm, more preferably 5 μm, and even more preferably 10 μm. The upper limit of the thickness of the polymer coating 100 is preferably 80 μm, more preferably 70 μm, even more preferably 60 μm, and even more preferably 50 μm.

Method for measuring polymer coating

The thickness of the polymer coating 100 is measured in the following manner. The probe of the electromagnetic induction film thickness measuring instrument is brought into contact with a pin contact surface 400 or a coupling contact surface 500 on which a polymer coating 100 is formed. The probe is equipped with an electromagnet, and when a magnetic object approaches it, electromagnetic induction occurs and its voltage changes by depending on the distance between the probe and the magnetic object. The thickness of the polymer coating 100 is determined by the change in voltage. Measurements are carried out at twelve places (at 0°, 30°, 60°, 90°, 120°, 150°, 180°, 210°, 240°, 270°, 300° and 330°) in the circumferential direction of metal pipe 1 for oil well. The arithmetic average of the measurement results at twelve locations is the thickness of the polymer coating 100. The polymer coating 100 may be formed on the pin contact surface 400 or the coupling contact surface 500 in direct contact with the pin contact surface 400 or the coupling contact surface 500. The metal oil well pipe 1 may also include another coating between the nipple contact surface 400 or the coupling contact surface 500 and a polymer coating 100. The other coating has, for example, one or more types of coating selected from the group consisting of a metallized layer and a layer obtained through chemical conversion.

Optional Components

Metallized layer

The metal oil well pipe 1 according to this embodiment may include a metallized layer between at least the nipple contact surface 400 or the coupling contact surface 500 and the resin coating 100. In the metal oil well pipe 1 according to this embodiment, the metallized layer is an optional component. Thus, in the metal oil well pipe 1 according to this embodiment, a metallized layer may not be formed. In fig. 12 is an enlarged view of a pin contact surface 400 according to this embodiment, different from FIG. 9 and fig. 11. In FIG. 12, a metallized layer 80 is provided between the pin contact surface 400 and the polymer coating 100. Specifically, in FIG. 12, a metallized layer 80 is formed on the pin contact surface 400, and a resin layer 100 is formed on the metallized layer 80. However, the location at which the metallized layer 80 is provided is not limited to the location shown in FIG. 12. Although not shown in the drawings, for example, a metallized layer 80 may be provided between the coupling contact surface 500 and the polymer coating 100. For example, a metallized layer 80 may be provided between the pin contact surface 400 and the polymer coating 100, when it is not necessary that the resin coating 100 and the metallized layer 80 be provided on the coupling contact surface 500. For example, a metallized layer 80 may be provided between the pin contact surface 400 and the polymer coating 100, and a metallized layer 80 may also be provided between the coupling contact surface 500 and the polymer coating 100.

In this embodiment, the anti-corrosion resin coating 70 is formed on the metallized layer 80. In FIG. 13 shows the contact surface on an enlarged scale

- 13 045795

A nipple 400 according to this embodiment of the invention, different from FIG. 9, fig. 11 and fig. 12. As shown in FIG. 13, a metallized layer 80 may be provided between the pin contact surface 400 and the resin coating 100, and further, the anti-corrosion resin coating 70 and the top layer 60 of the resin coating 100 may be contained in the resin coating 100.

In the present embodiment, the kind of metallized layer 80 is not particularly limited. As an example, the metallized layer 80 is selected from the group consisting of a zinc metallized layer, a nickel metallized layer, a copper metallized layer, a Zn-Ni alloy metallized layer, a Zn-Co alloy metallized layer, and a Ni-W alloy metallized layer. In the case where the metallized layer 80 is a Zn-Ni alloy metallized layer, the chemical composition of the Zn-Ni alloy metallized layer includes, for example, 10 to 20 wt.% Ni, and the rest is Zn and impurities. In the case where the metallized layer 80 is a copper metallized layer, the chemical composition of the copper metallized layer includes, for example, Cu and impurities.

When the metal oil well pipe 1 according to this embodiment includes a metallized layer 80 on the nipple contact surface 400 and/or on the coupling contact surface 500, the scuffing resistance of the metal oil well pipe 1 is further increased.

In fig. 14 is a graph illustrating the relationship between the metallized layer 80, copper phthalocyanine content and Bowden test results in terms of scuff resistance. The graph in Fig. 14 was obtained based on Example 2 disclosed below. Abscissa in Fig. 14 represents the copper phthalocyanine content of the resin coating 100. The ordinate in FIG. 14 represents the number of slips before the friction coefficient exceeds 0.3. In Example 2, a steel ball was moved over the surface of a steel plate on which a metallized layer 80 and/or a polymer coating 100 was formed, and the number of slides until the coefficient of friction exceeded a value of 0.3 was measured. A higher number of slips before the coefficient of friction reaches 0.3 means higher resistance to scuffing. In fig. 14, the white circle (O) indicates that only the resin coating 100 is formed on the surface of the steel plate, and the metallized layer 80 is not formed. In fig. 14, a square (□) indicates that a Zi-Ni alloy metallized layer and a resin coating 100 are formed on the surface of the steel plate. As shown in FIG. 14, for a metal pipe 1 for an oil well with a metallized layer of Zn-Ni alloy, the number of slips until the friction coefficient exceeds the value of 0.3 is large compared to the metal pipe 1 for an oil well without a metallized layer of 80. Thus, the resistance to the formation of metal scoring oil well pipe 1 with a metallized layer 80 on the nipple contact surface 400 and/or on the coupling contact surface 500 is further increased.

Metallized layer thickness

The thickness of the metallized layer 80 is not particularly limited. The thickness of the metallized layer 80 is, for example, from 1 to 30 μm. In this case, the scuffing resistance of the metal oil well pipe 1 can be increased more steadily. The lower limit of the thickness of the metallized layer 80 is preferably 2 μm, more preferably 3 μm, and even more preferably 4 μm. The upper limit of the thickness of the metallized layer 80 is preferably 20 µm and more preferably 10 µm.

Method for measuring the thickness of the metallized layer

The thickness of the metallized layer 80 is measured in the following manner. The probe of the electromagnetic induction film thickness measuring instrument is brought into contact with a pin contact surface 400 or a coupling contact surface 500 on which a metallized layer 80 is formed. The probe is brought into contact with a pin contact surface 400 or a coupling contact surface 500 at a location where the polymer coating has been removed. 100. The probe is equipped with an electromagnet and when a magnetic object approaches it, electromagnetic induction occurs and its voltage changes depending on the distance between the probe and the magnetic object. The thickness of the metallized layer 80 is determined by the change in voltage. Measurements are carried out at twelve places (at 0°, 30°, 60°, 90°, 120°, 150°, 180°, 210°, 240°, 270°, 300° and 330°) in the circumferential direction of metal pipe 1 for oil well. The arithmetic mean of the measurement results at twelve places is the thickness of the metallized layer 80.

Chemical conversion layer

The metal oil well pipe 1 according to this embodiment may further comprise a chemical conversion layer between at least the nipple contact surface 400 or the coupling contact surface 500 and the resin coating 100. In the metal oil well pipe 1 according to this embodiment The chemical conversion layer is an optional component. Those. in the metal oil well pipe 1 according to this embodiment

- 14 045795 the layer obtained by chemical conversion may not be formed.

In fig. 15 is an enlarged view of a coupling contact surface 500 according to this embodiment, different from FIG. 10. In FIG. 15, a chemical conversion layer 90 is provided between the coupling contact surface 500 and the resin coating 100. Specifically, in FIG. 15, the chemical conversion layer 90 is formed on the coupling contact surface 500, and the resin layer 100 is formed on the chemical conversion layer 90. However, the location at which the chemical conversion layer 90 is provided is not limited to the location shown in FIG. 15. Although not shown in the drawings, as an example, a chemical conversion layer 90 may be provided between the pin contact surface 400 and the polymer coating 100, and neither the polymer coating 100 nor the chemical conversion layer 90 conversions should not be provided on the coupling contact surface 500. For example, a chemical conversion layer 90 may be provided between the pin contact surface 400 and the polymer coating 100, and a chemical conversion layer 90 may also be provided between the coupling contact surface 500 and the polymer coating 100.

Moreover, in this embodiment, the anti-corrosion resin coating 70 is provided on the chemical conversion layer 90. In particular, in FIG. 16 is an enlarged view of a pin contact surface 400 according to this embodiment, different from FIG. 9, fig. 11, fig. 12 and fig. 13. As shown in FIG. 16, a chemical conversion layer 90 may be provided between the pin contact surface 400 and the resin coating 100, and further, the anti-corrosion resin coating 70 and the top layer 60 of the resin coating 100 may be included in the resin coating 100.

In addition, the pin contact surface 400 and the coupling contact surface 500 according to this embodiment may include a metallized layer 80 and a chemical conversion layer 90. In fig. 17 is an enlarged view of a pin contact surface 400 according to this embodiment, different from FIG. 9, fig. 11, fig. 12, fig. 13 and fig. 16. In FIG. 17, a metallized layer 80 is provided on the pin contact surface 400, a chemically converted layer 90 is provided on the metallized layer 80, and a resin coating 100 is provided on the chemically converted layer 90. Thus, when the metal oil well pipe 1 includes a metallized layer 80, the metal oil well pipe 1 contains a chemical conversion layer 90 between the metallized layer 80 and the polymer coating 100.

In the metal oil well pipe 1 according to this embodiment, although the locations at which the metallized layer 80 and the chemical conversion layer 90 are provided are not limited to the example in FIG. 17, when the metallized layer 80 and the chemical conversion layer 90 are provided between the pin contact surface 400 and the resin coating 100, the chemical conversion layer 90 may be provided on the metallized layer 80, and the resin coating 100 may be provided on layer 90 obtained by chemical conversion. In addition, when a metallized layer 80 is not provided between the pin contact surface 400 and the resin coating 100, a chemical conversion layer 90 may be provided on the pin contact surface 400, and a resin coating 100 may be provided on the chemical conversion layer 90. conversions. Similarly, when the metal oil well pipe 1 includes a metallized layer 80 and a chemical conversion layer 90 between the coupling contact surface 500 and the polymer coating 100, the chemical conversion layer 90 may be provided on the metallized layer 80 and the polymer coating the coating 100 may be provided on the layer 90 obtained by chemical conversion. In addition, when the metal oil well pipe 1 does not include a metallized layer 80 between the coupling contact surface 500 and the resin coating 100, the chemical conversion layer 90 may be provided on the coupling contact surface 500, and the resin coating 100 may be provided on layer 90 obtained by chemical conversion.

In this embodiment, when the metal oil well pipe 1 includes a metallized layer 80 and a chemical conversion layer 90, an anti-corrosion resin coating 70 is provided on the chemical conversion layer 90. In particular, in FIG. 18 is an enlarged view of a pin contact surface 400 according to this embodiment, different from FIG. 9, fig. 11, fig. 12, fig. 13, fig. 16 and fig. 17. As shown in FIG. 18, a metallized layer 80 may be provided on the pin contact surface 400, a chemical conversion layer 90 may be provided on the metallized layer 80, a resin coating 100 may be provided on the chemical conversion layer 90, and further, the anti-corrosion polymer coating 70 and the top layer 60 of the polymer coating 100 may be included in the polymer coating 100.

In the present embodiment, the kind of layer 90 obtained by chemical conversion is not particularly limited. The chemical conversion layer 90 is, by way of example, selected from the group consisting of phosphate conversion layers, oxalate conversion layers, borate conversion layers, and a chromate coating. From the point of view of the adhesive ability of the polymer coating 100, treatment by chemical phosphate conversion is preferred. In this case, the phosphate is, for example, one or more types selected from the group consisting of manganese phosphate, zinc phosphate, manganese-iron phosphate or calcium-zinc phosphate. The chemical conversion layer 90 may be a chromate coating. The chromate coating can be formed by a well known process. The chromate coating should preferably not contain hexavalent chromium.

When the chemical conversion layer 90 is provided on the pin contact surface 400 and/or on the coupling contact surface 500 of the metal oil well pipe 1 according to this embodiment, the durability of the metal oil well pipe 1 is further increased. The chemical conversion layer 90 increases the adhesive ability of the polymer coating 100 provided thereon through an anchoring effect. Due to this, the resistance of the metal pipe 1 for an oil well to the formation of scuffing increases. According to Example 3 disclosed below, the number of slides before the coefficient of friction exceeds 0.3 is greater for the oil well metal pipe 1 containing the chemical conversion layer 90 than for the oil well metal pipe 1 not containing the chemical conversion layer 90. through chemical conversion. Thus, the scoring resistance of the metal oil well pipe 1 with the chemical conversion layer 90 on the nipple contact surface 400 and/or the coupling contact surface 500 is further increased.

It is sufficient that the metal oil well pipe 1 according to this embodiment contains a polymer coating 100 on at least the nipple contact surface 400 or the coupling contact surface 500. With regard to the arrangement of the metallized layer 80, the chemical conversion layer 90, and the anti-corrosion resin coating 70 as disclosed above, they may be arranged similarly on the pin contact surface 400 and the coupling contact surface 500, or may be arranged differently on the contact surface 400 nipple and contact surface 500 coupling. The metal oil well pipe 1 may also contain other coatings as required.

Preliminary processing

In the metal oil well pipe 1 according to this embodiment, at least the nipple contact surface 400 or the coupling contact surface 500 may be a surface to be pretreated. Thus, in this embodiment, pretreatment is an optional process, and the pin contact surface 400 and the coupling contact surface 500 may not be the surface to be pretreated. If pre-treatment is performed, it is, for example, one or more types selected from the group consisting of blasting and etching. When performing pre-treatment, the roughness of the pin contact surface 400 and/or the coupling contact surface 500 increases. Thus, the adhesive ability of the polymer coating 100, the metallized layer 80 and/or the chemical conversion layer 90 formed thereon is increased. As a result, the resistance of the metal oil well pipe 1 to scuffing increases.

Chemical composition of the pipe main body

The main body 10 of the metal oil well pipe 1 according to this embodiment is not particularly limited. A component of the oil well metal pipe 1 according to this embodiment is a resin coating 100. Thus, in this embodiment, the type of steel of the main body 10 of the oil well metal pipe 1 is not particularly limited.

The pipe main body 10 may be formed, for example, from carbon steel, stainless steel, alloy steel and the like. Accordingly, the oil well metal pipe may be a Fe-based alloy steel pipe or an alloy steel 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, and a duplex stainless steel pipe. At the same time, among alloy steels, high alloy steels such as Ni alloy and duplex stainless steels containing alloying elements such as Cr, Ni and Mo have high corrosion resistance. Thus, by using these high-alloy steels as the main pipe body 10, excellent corrosion resistance is achieved in a corrosive environment containing hydrogen sulfide, carbon dioxide, and the like.

Preparation method

A method for manufacturing a metal pipe 1 for an oil well according to the present embodiment is disclosed below. The method for manufacturing a metal oil well pipe 1 according to the present embodiment includes a preparation process, an application process, and a curing process. The curing process is carried out after the application process.

Preparatory process

In the preparation process, a metal oil well pipe 1 is prepared having a main pipe body 10 containing a nipple 40 containing a nipple contact surface 400 containing a male thread portion 41 and a coupling 50 containing a coupling contact surface 500 containing a female thread portion 51 . As disclosed above, the metal oil well pipe 1 according to the present embodiment has a generally known structure. In other words, in the preparatory process it is sufficient to prepare a metal pipe 1 for an oil well having a well-known design.

Application process

During the application process, a composition comprising a polymer, a solid lubricating powder and copper phthalocyanine is applied to at least a pin contact surface 400 or a coupling contact surface 500. The composition is a composition for forming the above polymer coating 100. The composition contains a polymer, a solid lubricating powder and copper phthalocyanine. The composition for forming the polymer coating 100 is the same as for the polymer coating 100 disclosed above, excluding the solvent.

The solvent-free composition can be prepared, for example, by heating the polymer to a molten state, adding solid lubricating powder, copper phthalocyanine and mixing them. The composition can be prepared from a mixture of powders by mixing all the components in powder form.

The solvent composition can be prepared, for example, by melting or dispersing a polymer, a solid lubricating powder and copper phthalocyanine in a solvent and mixing them. The solvent is, for example, water, alcohol or an organic solvent. The solvent may contain a small amount of surfactant. The proportion of solvent is not particularly limited. It is enough to adjust the proportion of solvent to a certain viscosity according to the application method. The proportion of solvent is, for example, in the range from 40 to 60 wt.%, if the total amount of all components except solvent is taken as 100 wt.%. The method of applying the composition to the pin contact surface 400 and/or to the coupling contact surface 500 is not particularly limited, and a well-known method can be used. In the case of a solvent-free composition, for example, the composition can be applied to the pin contact surface 400 and/or the coupling contact surface 500 by a hot melt coating process. During the hot melt application process, the composition is heated to melt the polymer to transform the composition into a low-viscosity liquid state. The composition in a liquid state can be applied with a spray gun with a temperature maintenance function. Instead of spray application, another method, such as brushing or dipping, may be used as a method of applying the composition to the pin contact surface 400 and/or the coupling contact surface 500. It should be taken into account that the temperature to which the composition is heated preferably exceeds the melting point of the polymer by an amount in the range from 10 to 50°C.

In the case of a solvent composition, for example, the composition as a solution is applied to the pin contact surface 400 and/or the coupling contact surface 500 by spraying. In this case, the viscosity of the composition must be controlled so that it can be applied by spraying the coating in an environment at normal temperature and normal pressure. Instead of spray application, another method, such as brushing or dipping, may be used as a method of applying the composition to the pin contact surface 400 and/or the coupling contact surface 500.

Curing process

During the curing process, the applied composition hardens to form a polymer coating 100. In the case of a solvent-free composition, by cooling the composition applied to at least the pin contact surface 400 or the coupling contact surface 500, the composition in the molten state hardens and a solid is formed. polymer coating 100. In this case, the cooling method is not particularly limited, and a well-known method can be used. Examples of the cooling method include atmospheric cooling and air cooling. In the case of a solvent composition, by drying the composition applied to at least the pin contact surface 400 or the coupling contact surface 500, the composition hardens and a solid polymer coating 100 is formed. In this case, the drying method is not particularly limited and it is possible to use a well known method. The drying method is, for example, natural drying, low temperature air drying or vacuum drying. In addition, if the polymer is a thermoset polymer, the hard polymer coating 100 can be formed by curing the composition by performing a heat-hardening process.

The metal oil well pipe 1 according to this embodiment is manufactured by the above processes.

Optional process

The method for manufacturing a metal oil well pipe 1 according to this embodiment may further include one or more processes of a metallized layer forming process, a chemical conversion process, an anti-corrosion resin coating forming process, and a pre-treatment process. All other processes are optional. Therefore, these processes may not run.

The process of formation of a metallized layer

The method for manufacturing a metal oil well pipe 1 according to the present embodiment may further include a process of forming a metallized layer before the deposition process. When the metallized layer forming process is completed, the metallized layer 80 is formed on at least the pin contact surface 400 or the coupling contact surface 500.

The method of forming the metallized layer 80 is not particularly limited, and a well-known method can be used. Formation of the metallized layer 80 may be accomplished by electrodeposition or by chemical reduction. For example, in the case of forming a metallized layer of a Zn-Ni alloy by electrodeposition, the electroplating bath contains zinc ions and nickel ions. The composition of the galvanic bath should preferably include zinc ions in an amount from 1 to 100 g/l; and nickel ions in an amount from 1 to 50 g/l. Conditions for electrodeposition are, for example, the following: pH in the plating bath from 1 to 10, temperature in the plating bath from 20 to 60°C; current density from 1 to 100 A/dm ² and treatment duration from 0.1 to 50 minutes. For example, when forming a copper metallized layer by electrodeposition, a well-known method can be used.

Chemical conversion process

The method for manufacturing a metal oil well pipe 1 according to the present embodiment may further comprise a chemical conversion process before the deposition process. When the chemical conversion process is performed, the chemical conversion layer 90 is formed on at least the pin contact surface 400 or the coupling contact surface 500.

The chemical conversion method is not particularly limited and may be a well-known method. The chemical conversion is exemplified from the group consisting of phosphate chemical conversion, oxalate chemical conversion, borate chemical conversion, and chromate treatment. As a chemical conversion solution, an ordinary acid solution can be used for chemical conversion treatment of phosphates for galvanized products. As a solution for chemical conversion treatment, for example, a zinc phosphate solution containing 1 to 150 g/L phosphate ions, 3 to 70 g/L zinc ions, 1 to 100 g/L nitrate ions, and 0 to 30 g/l nickel ions. Also, manganese phosphate solutions commonly used for oil well metal pipes 1 can be used as the chemical conversion solution. A commercially available chromate treatment solution can also be used as the treatment solution. The temperature of the treatment solution is, for example, in the range from normal temperature to 100°C. The chemical conversion time can be set accordingly depending on the required coating thickness and, for example, can be from 0.5 to 15 minutes. To facilitate the formation of the chemical conversion layer 90, surface modification may be performed prior to the chemical conversion treatment. Surface modification refers to a treatment that involves immersion in an aqueous solution containing colloidal titanium to modify the surface. If chemical conversion is carried out, it is preferable to rinse with water or warm water before drying.

It should be noted that, as disclosed above, in the metal oil well pipe 1 according to this embodiment of the invention, the chemical conversion layer 90 is formed on the nipple contact surface 400, the coupling contact surface 500 and the metallized layer 80. That is, in the method manufacturing a metal pipe 1 for an oil well according to this embodiment, when performing the metallized layer forming process and chemical conversion, the chemical conversion is performed after the metallized layer forming process, and then the deposition process is performed.

The process of forming an anti-corrosion polymer layer

- 18 045795

The method for manufacturing a metal oil well pipe 1 according to the present embodiment may further comprise a process of forming an anti-corrosion resin layer before the application process. When the anti-corrosion resin coating forming process is performed, the anti-corrosion resin coating 70 is formed on at least the pin contact surface 400, the coupling contact surface 500, the metallized layer 80 and the chemical conversion layer 90.

The method of forming the anti-corrosion resin layer 70 is not particularly limited, and a well-known method can be used. The anti-corrosion polymer coating 70 can be formed, for example, by applying a composition containing an anti-corrosion filler and an acrylic silicone resin to at least the pin contact surface 400, the coupling contact surface 500, the metallized layer 80 and the chemical conversion layer 90 and curing compositions. The application method is not particularly limited and may be spray, brush or dip application. The composition for forming the anti-corrosion polymer coating 70 may contain a solvent. The composition for forming the anti-corrosion resin coating 70 is the same as that for the anti-corrosion resin coating 70 disclosed above, excluding the solvent. The curing method is, for example, natural drying, low temperature air drying or heat drying.

It should be noted that, as disclosed above, in the metal oil well pipe 1 according to this embodiment, an anti-corrosion resin coating 70 is formed on the nipple contact surface 400, the coupling contact surface 500, the metallized layer 80 and the chemical conversion layer 90. Those. in the method for manufacturing a metal oil well pipe 1 according to this embodiment, when performing the process of forming a metallized layer, chemical conversion and forming an anti-corrosion resin coating, these coatings are carried out in this order, and then the deposition process is carried out.

Pre-treatment process

The method for manufacturing a metal oil well pipe 1 according to the present embodiment may further comprise a pre-treatment process before the deposition process. If a metallized layer forming process is to be carried out, the method for manufacturing a metal pipe 1 for an oil well may comprise a pre-treatment process before the metallized layer forming process. If a chemical conversion process is to be carried out, the method for manufacturing a metal pipe 1 for an oil well may comprise a pre-treatment process before the chemical conversion process. If the anti-corrosion resin coating forming process is to be carried out, the method for manufacturing the metal oil well pipe 1 may comprise a pre-treatment process before the anti-corrosion resin coating forming process. In the pre-treatment process, for example, etching and/or blasting are carried out. In addition, alkaline degreasing can be carried out.

In etching, for example, the pin contact surface 400 and/or the coupling contact surface 500 is immersed in a solution of a strong acid, such as sulfuric acid, hydrochloric acid, nitric acid, hydrofluoric acid, or a mixture thereof, thereby increasing the roughness of the contact surface 400 and/or contact surface 500 of the coupling. In blasting, for example, sandblasting is performed in which an abrasive material is mixed with compressed air and the resulting mixture is applied to a pin contact surface 400 and/or a coupling contact surface 500. In this case, the roughness of the pin contact surface 400 and/or the coupling contact surface 500 increases.

It should be noted that in view of the above process of forming the metallized layer, chemical conversion and pre-treatment, the pin contact surface 400 and the coupling contact surface 500 may be subjected to the same or different processes. In addition, the processes can be carried out only on the contact surface 400 of the pin or only on the contact surface 500 of the coupling.

The metal oil well pipe 1 according to this embodiment is manufactured using the above processes. However, the manufacturing method disclosed above is one example of the manufacturing method of the metal oil well pipe 1 according to this embodiment, and this embodiment is not limited to the manufacturing method disclosed above. The metal pipe 1 for the oil well according to this embodiment can also be manufactured by another method.

Example 1

In Example 1, a resin coating 100 was formed on a pin contact surface 400 or a coupling contact surface 500 of a metal oil well pipe 1, and the high torque performance and scuffing resistance were evaluated. In particular, in

- 19 045795 example 1, a metal pipe for an oil well with a trade name was used

VAM21 (Registered Trademark) HT manufactured by NIPPON STEEL CORPORATION (outer diameter: 273.05 mm (10.75 in.), wall thickness: 12.570 mm (0.495 in.)). Steel grade of metal pipe for oil well SM2535-M110 (C < 0.03%, Si < 0.50%, Mn < 1.0%, Cu < 1.5%, Ni from 29.5 to 36.5%, Cr from 24.0 to 27.0%, other Fe and impurities).

For Tests 1-12, a metallized layer and an anti-corrosion resin coating included in the polymer coating were properly formed on the coupling contact surface to prepare metal oil well pipes containing the nipple and coupling of Tests 1-12. The formed metallized layers are shown in the Metallized Layer column in Table. 2. Icon - in the Metallized layer column in the table. 2 means that the metallized layer has not been formed. The thickness of each formed metallized layer was 8 μm. The thickness of the metallized layer was measured using the method described above using an electromagnetic film thickness measuring instrument SDM-picoR manufactured by Sanko Electronic Laboratory Co., Ltd. Whether an anti-corrosion polymer coating has been formed is indicated in the Anti-corrosion polymer coating column in Table. 2. The term Formation in the Anti-corrosion polymer coating column in the table. 2 means that the anti-corrosion polymer coating has been formed. The icon is in the Anti-corrosion polymer coating column in the table. 2 means that the anti-corrosion polymer coating has not been formed. It should be noted that the anti-corrosion polymer coating that was formed was the same as the anti-corrosion polymer coating in Tests 32 and 33 in Example 4 disclosed below.

Whether a polymer coating has been formed is indicated in the Polymer coating column in the table. 2. The term Formation in the Polymer coating column in the table. 2 means the polymer coating has been formed. The icon is in the Polymer coating column in the table. 2 means no polymer coating has been formed. It should be noted that in each of tests 1-9 and 11-12, the thickness of each polymer coating that was formed was 20 microns. In Test 10, the thickness of the polymer coating was 20 μm, excluding the thickness of the anti-corrosion polymer coating. The thickness measurement of the polymer coating was carried out by the method described above using an electromagnetic film thickness measuring device SDM-picoR manufactured by Sanko Electronic Laboratory Co., Ltd. In each of Tests 2-9 and 11, 12, a polymer coating was formed on the surface of the above metallized layer.

In Test 1, no metallized layer was formed. Thus, in Test 1, a polymer coating was formed directly on the coupling contact surface. In Test 10, a polymer coating was formed on an anti-corrosion polymer coating. Thus, in Test 10, the polymer coating contained multiple layers. The content of copper phthalocyanine in the corresponding polymer coatings that were formed is shown in table. 2. It should be noted that the polymer coatings that were formed also contained from 1 to 30 wt.% polytetrafluoroethylene (PTFE) as a solid lubricating powder, and the other substances consisted of epoxy resin as a polymer. The icon is in the Copper phthalocyanine content column in the table. 2 means that no resin coating was formed or that copper phthalocyanine was not contained in the resin coating that was formed. It should be noted that in Test 12, the polymer coating formed did not contain copper phthalocyanine. In Test 12, the polymer coating contained 8.6 wt.% Cr ₂ O ₃ instead of copper phthalocyanine. The polymer coating in Test 12 also contained from 1 to 30 wt.% polytetrafluoroethylene (PTFE) as a solid lubricating powder, and the other substances consisted of epoxy resin as a polymer.

- 20 045795

table 2

Test number Metallized layer Anti-corrosion polymer coating Polymer coating Copper phthalocyanine content High torque characteristic Quantity of M&V 1 Nipple contact surface - - - - 120 - Coupling contact surface - - Formation 10.0 wt% 2 Nipple contact surface - - - - 110 8 Coupling contact surface ZnNi alloy - Formation 0.1 wt% 3 Nipple contact surface - - - - 120 eleven Coupling contact surface ZnNi alloy - Formation 0.2 wt% 4 Nipple contact surface - - - - 127 10 Coupling contact surface ZnNi alloy - Formation 0.4 wt% 5 Nipple contact surface - - - - 138 14 Coupling contact surface ZnNi alloy - Formation 1.0 wt% 6 Nipple contact surface - - - - 120 12 Coupling contact surface ZnNi alloy - Formation 4.0 wt% 7 Nipple contact surface - - - - 125 eleven Coupling contact surface ZnNi alloy - Formation 10.0 wt% 8 Nipple contact surface - - - - 132 6 Coupling contact surface ZnNi alloy - Formation 20.0 wt% 9 Nipple contact surface - - - - 128 6 Coupling contact surface ZnNi alloy - Formation 30.0 wt% 10 Nipple contact surface - - - - 130 - Coupling contact surface - Formation Formation 10.0 wt% eleven Nipple contact surface - - - - 65 8 Coupling contact surface ZnNi alloy - Formation - 12 Nipple contact surface - - - - 90 10 Coupling contact surface ZnNi alloy - Formation (CggOz: 8.6 wt%)

Coupling contact surface

The process of formation of a metallized layer

As shown in table. 2, a metallized Zn-Ni alloy layer was formed by electrodeposition on the coupling contact surface in Tests 2-9, 11, 12. DAIN Zinalloy N-PL (trade name), manufactured by Daiwa Fine Chemicals Co., Ltd., was used as the plating bath. The thickness of the metallized layer of the Zn-Ni alloy was 8 μm. The thickness of the metallized layer was measured using the method described above using an electromagnetic film thickness measuring instrument SDM-picoR manufactured by Sanko Electronic Laboratory Co., Ltd. The conditions for electrodeposition were as follows: pH in the plating bath 6.5, temperature in the plating bath 25°C; current density 2 A/dm and treatment duration 18 min. The metallized layer of the Zn-Ni alloy had the following composition: Zn 85% and Ni 15%. In addition, a trivalent chromate coating was formed on the resulting Zn-Ni alloy metallized layer. The treatment solution for forming the trivalent chromate coating was DAIN Chromate TR-02 from Daiwa Fine Chemicals Co., Ltd. The chemical conversion conditions were as follows: bath temperature 25°C, pH 4.0, and treatment duration 50 s.

Application process and curing process

- 21 045795

As shown in table. 2, a polymer coating was formed on the coupling contact surface in Tests 1-12. In Tests 2-9, 11, 12, a polymer coating was formed on the contact surface of the coupling, on which a metallized layer was formed. In Test 1, a polymer coating was formed directly on the coupling contact surface. In Test 10, a top layer of polymer coating was formed on an anti-corrosion polymer coating. The composition for forming a polymer coating was applied by spraying onto the contact surface of the coupling, onto a metallized layer of a Zn-Ni alloy or onto an anti-corrosion polymer coating and cured. As disclosed above, the components of the composition other than the solvent were polytetrafluoroethylene particles and copper phthalocyanine, and the rest were epoxy resin. The composition also contained a solvent. A solution of a mixture of water, alcohol and surfactant was used as a solvent. After spraying the composition onto the metallized Zn-Ni alloy layer on the surface of the coupling, a thermal curing process was carried out for 20 minutes at a temperature of 210°C to form a polymer coating. In Test 12, copper phthalocyanine was not used and Cr ₂ O ₃ was used instead at 8.6 wt%.

Nipple contact surface

The contact surface of the pin in Tests 1-12 was subjected to machine grinding. That is, as shown in table. 2, the metallized layer and polymer coating were not formed on the pin contact surface in Tests 1-12.

High Torque Characteristic Evaluation

The thrust torque AT was measured using a metal oil well pipe having a pin contact surface and a coupling contact surface of each of Tests 1-12. In particular, at a make-up speed of 10 rpm, the tightening torque value was gradually increased, and the test ended when the material acquired flow properties. The torque during make-up was measured and the torque diagram shown in FIG. 19. Reference symbols Ts in FIG. 19 indicate the torque of the stop. The MTV reference symbols in FIG. 19 indicate the torque value at which the linear segment L and the torque graph intersect. Linear segment L is a straight line that has the same slope as the slope of the linear region of the after-stop torque graph and for which the RPM is 0.2% greater than the above linear region. Typically YT (yield torque) is used when measuring torque at abutment resistance. However, in this example, the torque Ty at the yield point (the boundary between the linear region and the nonlinear region in the post-stop torque diagram) was indistinguishable. Therefore, MTV was determined using the linear segment L. The difference between MTV and Ts was taken as the torque at the thrust resistance AT. The torque AT at abutment resistance was determined as a relative value compared to the torque AT at abutment resistance when an additive according to the API standard was used, and its value was taken to be 100. The results are shown in the High Torque Characteristic column in Table 1. 2.

Cyclic make-up tests

Cyclic make-up tests using a torque of 53,800 Nm were performed using a metal oil well pipe having a pin contact surface and a coupling contact surface from Tests 1-12. Screwing was carried out until the formation of burrs that cannot be repaired on the threaded part (the part with external threads and/or the part with internal threads) or until the formation of burrs on the part of the metal seal. The results are shown in the Amount of M&W column in the table. 2. Icon - in the Quantity of M&V column in the table. 2 means that cyclic make-up tests were not carried out.

Evaluation results

As shown in table. 2, the metal oil well pipes of Tests 1-10 contained a polymer coating containing a polymer, solid lubricating powder and copper phthalocyanine on at least one of the pin contact surface or the coupling contact surface. Therefore, the thrust resistance torque ΔΤ for each of Tests 1 to 10 was 100 or more, which means excellent high torque performance.

In addition, in the metal oil well pipes in Tests 1, 3-10, the content of copper phthalocyanine in the polymer coating ranged from 0.2 to 30.0 wt%. In addition, the abutment torque ΔΤ of the metal oil well pipes in Tests 1, 3-10 was further increased compared with Tests 2 in which the copper phthalocyanine content was less than 0.2 wt%. On the other hand, in the metal oil well pipe in Test 11, although a resin coating containing a resin and a solid lubricating powder was formed on the coupling contact surface, the resin coating did not contain copper phthalocyanine. As a result, the torque ΔΤ at the stop resistance was 65, and therefore

- 22 045795 high torque characteristic was low. In the metal oil well pipe in Test 12, although a polymer coating containing a polymer and a solid lubricating powder was formed on the coupling contact surface, the polymer coating did not contain copper phthalocyanine and instead contained Cr ₂ O ₃ . As a result, the torque ΔΤ at the stop resistance was 90, and therefore the high torque characteristic was low.

Example 2

In Example 2, a polymer coating was formed on the surface of steel plates simulating a metal oil well pipe and the resistance to scuffing was evaluated. In particular, in example 2, cold-rolled steel plates were used (chemical composition: C < 0.15%, Mn < 0.60%, P < 0.100%, S < 0.050%, and the rest Fe and impurities).

The metallized layers shown in table. 3 were properly formed on the surfaces of the steel plates in Tests 13-21. The formed metallized layers are shown in the Metallized Layer column in Table. 3. Icon - in the Metallized layer column in the table. 3 means that the metallized layer has not been formed. The thickness of each formed metallized layer was 8 μm. A polymer coating was formed on the surfaces of the steel plates in Tests 13-17 and 21. In Tests 18-20, a polymer coating was formed on the metallized layer that was formed. The thickness of each formed polymer coating was 20 μm. The thickness measurement of the resin coating was carried out by the method disclosed above using an electromagnetic film thickness measuring instrument SDM-picoR manufactured by Sanko Electronic Laboratory Co., Ltd., and the average thickness value at nine points on one evaluation surface was taken as the thickness of the resin coating. In addition, the content of copper phthalocyanine in the polymer coatings that were formed is shown in Table. 3. It should be taken into account that the polymer coatings that were formed also contained 1-30 wt.% polytetrafluoroethylene (PTFE) as a solid lubricating powder, and the other substances consisted of epoxy resin as a polymer. The icon is in the Copper phthalocyanine content column in the table. 3 means that copper phthalocyanine was not contained in the polymer coating that was formed.

Table 3

Test number Metallized layer Copper phthalocyanine content Number of slips until the friction coefficient exceeds 0.3 13 - 0.1 wt% 510 14 - 0.5 wt% 647 15 - 2.0 wt% 524 16 - 5.0 wt% 531 17 - 10.0 wt% 55 18 Metallized layer of Zn-Ni alloy 0.5 wt% 743 19 Metallized layer of Zn-Ni alloy 2.0 wt% 660 20 Metallized layer of Zn-Ni alloy 5.0 wt% 609 21 - - 511

The process of formation of a metallized layer

A metallized Zn-Ni alloy layer was formed by electrodeposition on the surface of a steel plate in each of Tests 18-20. DAIN Zinalloy N-PL (trade name), manufactured by Daiwa Fine Chemicals Co., Ltd., was used as the plating bath. The thickness of the metallized layer of the Zn-Ni alloy was 8 μm. The thickness measurement of the metallized layer was carried out by the method disclosed above using an electromagnetic film thickness measuring instrument SDM-picoR manufactured by Sanko Electronic Laboratory Co., Ltd., and the average value of the thickness at nine points on one evaluation surface was taken as the thickness of the metallized layer. The conditions for electrodeposition were as follows: pH in the plating bath 6.5, temperature in the plating bath 25°C; current density 2 A/dm ² and treatment duration 18 minutes. The metallized layer of the Zn-Ni alloy had the following composition: Zn 85% and Ni 15%. In addition, a trivalent chromate coating was formed on the resulting Zn-Ni alloy metallized layer. The treatment solution for forming the trivalent chromate coating was DAIN Chromate TR-02 from Daiwa Fine Chemicals Co., Ltd. The chemical conversion conditions were as follows: bath temperature 25°C, pH 4.0, and treatment duration 50 seconds.

Application process and curing process

A polymer coating was formed on the surfaces of the steel plates in each of Tests 13-21. Specifically, the resin coating forming composition was applied to the surface of the steel plate in each of Tests 13 to 21 using a rod device and was cured. Components of the composition other than the solvent were solid particles

- 23 045795 lubricants and copper phthalocyanine, and other things - polymer. Epoxy resin was used as the polymer in Tests 13-21. Polytetrafluoroethylene particles were used as solid lubricant particles in Tests 13-21. The content of copper phthalocyanine is shown in table. 3. The composition also contained a solvent. A solution of a mixture of water, alcohol and a surfactant was used as a solvent. In the presence of a metallized layer, the composition was applied with a rod device to the metallized layer (or on a layer obtained by chemical conversion formed on it), and in the absence of a metallized layer, the composition was applied with a rod device to the surface of the steel plate, and then the thermal curing process was carried out at 210°C for 20 minutes to form a polymer coating.

Bowden tests

Bowden tests were carried out using steel plates in Tests 13-21, which were coated with a polymer and evaluated for resistance to scoring. Specifically, a steel ball was made to slide over the surface of a polymer coating in Tests 13-21 and the coefficient of friction was determined. The steel ball had a diameter of 3/16 inch and a chemical composition similar to SUJ2 specified in the JIS standard. The load was 3 kgf (Hertzian contact pressure: average 1.56 GPa). The sliding width was set to 10 mm and the sliding speed to 4 mm/s. Sliding was carried out without lubrication at room temperature. We measured the coefficient of friction μ of the steel ball during sliding and the number of slides (the number of completed cycles, i.e., each time the steel ball rolled back and forth over an area of 10 mm, counted at one time) until the coefficient of friction μ exceeded 0.3 (equivalent to the coefficient of friction between the polymer coating and the steel ball). A Bowden stick-slip testing apparatus manufactured by Shinko Engineering Co., Ltd. was used for testing. The results are presented in the column Number of slips before the friction coefficient exceeds the value of 0.3 in the table. 3.

Evaluation results

As shown in table. 3, the steel plates from Tests 13-20 contained a polymer coating containing polymer, solid lubricating powder and copper phthalocyanine on the surface. As shown in table. 3, in the resin coating formed on the steel plate in each of Tests 14-16 and 18-20, the copper phthalocyanine content ranged from 0.2 to 9.0 wt%. As a result, for the steel plates in Tests 14-16 and 18-20, the number of slips before the coefficient of friction exceeded 0.3 was high compared to the steel plate in Tests 21, in which the polymer coating did not contain copper phthalocyanine, and with the steel plates in Tests 13 and 17, in which the copper phthalocyanine content of the polymer coating was outside the range of 0.2 to 9.0 wt.%. Those. Excellent scuff resistance has been demonstrated.

Example 3

In example 3, similar to example 2, a polymer coating was formed on the surface of steel plates simulating a metal pipe for an oil well, and resistance to scuffing was assessed. In particular, in Example 3, cold-rolled steel plates were used (chemical composition: C < 0.15%, Mn < 0.60%, P < 0.100%, S < 0.050%, balance: Fe and impurities).

The metallized layers shown in table. 4 were properly formed on the surfaces of the steel plates in Tests 22-31. The formed metallized layers are shown in the Metallized Layer column in Table. 4. Icon - in the Metallized layer column in the table. 4 means that the metallized layer has not been formed. The thickness of each formed metallized layer was 8 μm. The thickness measurement of the metallized layer was carried out by the method disclosed above using an electromagnetic film thickness measuring instrument SDM-picoR manufactured by Sanko Electronic Laboratory Co., Ltd., and the average value of the thickness at nine points on one evaluation surface was taken as the thickness of the metallized layer. The chemical conversion layer was formed on the surface of the steel plate in Tests 22 to 29 and 31. The formed chemical conversion layer is shown in the Chemical conversion layer column in Table 1. 4. The chemical conversion solution, temperature and treatment time used to form coatings A-D, among the chemical conversion layers in the Chemical conversion layer column are presented in Table. 5. It should be taken into account that the term trivalent chromate in the Layer column obtained by chemical conversion in the table. 4 means that a trivalent chromate coating has been formed. The trivalent chromate coating is disclosed below.

- 24 045795

Table 4

Test number Metallized layer Layer obtained by chemical conversion Copper phthalocyanine content Sliding distance until the friction coefficient exceeds 0.6 (m) 22 - Coating A 0.5 wt% 153.4 23 - Coating A 2.0 wt% 155.8 24 - Coating B 0.5 wt% 193.5 25 - Coating B 2.0 wt% 201.0 26 - Coating C 0.5 wt% 143.9 27 - Coating C 2.0 wt% 151.2 28 - Coating D 0.5 wt% 362.5 29 - Coating D 2.0 wt% 375.8 thirty Metallized layer of Zn-Ni alloy - 2.0 wt% 108.8 31 Metallized layer of Zn-Ni alloy Trivalent chromate 2.0 wt% 121.5

Table 5

Coating A Coating B Coating C Coating D Chemical conversion solution System Zinc Phosphate System Zinc Phosphate System Zinc Phosphate System Manganese Phosphate System Free acidity 7.5 h/10 ml 0.6 b/w ml 1.9 b/w ml 7.5 h/10 ml Total acidity 45.0 h/10 ml 22.0 h/10 ml 12.2 b/w ml 24.4 b/w ml Processing temperature 80°С 40°C 60°C 90°C Processing time 10 min. 2 minutes. 2 minutes. 5 minutes.

The polymer coating was formed on the metallized or chemically converted layer in Tests 22-31. The thickness of each formed polymer coating was 20 μm. The thickness measurement of the resin coating was carried out by the method disclosed above using an electromagnetic film thickness measuring instrument SDM-picoR manufactured by Sanko Electronic Laboratory Co., Ltd., and the average thickness value at nine points on one evaluation surface was taken as the thickness of the resin coating. It should be taken into account that the polymer coatings that were formed contained copper phthalocyanine in the amount indicated in the table. 4, and also contained from 1 to 30 wt.% polytetrafluoroethylene (PTFE) as a solid lubricating powder, and the other substances consisted of epoxy resin as a polymer.

The process of formation of a metallized layer

A metallized Zn-Ni alloy layer was formed by electrodeposition on the surface of a steel plate in each of Tests 30-31. DAIN Zinalloy N-PL (trade name), manufactured by Daiwa Fine Chemicals Co., Ltd., was used as the plating bath. The thickness of the metallized layer of the Zn-Ni alloy was 8 μm. The thickness measurement of the metallized layer was carried out by the method disclosed above using an electromagnetic film thickness measuring instrument SDM-picoR manufactured by Sanko Electronic Laboratory Co., Ltd., and the average value of the thickness at nine points on one evaluation surface was taken as the thickness of the metallized layer. The conditions for electrodeposition were as follows: pH in the plating bath 6.5, temperature in the plating bath 25°C; current density 2 A/dm ² and treatment duration 18 minutes. The metallized layer of Zn-Ni alloy had the following composition: Zn in the amount of 85% and Ni in the amount of 15%.

The process of forming a layer obtained through chemical conversion

The chemical conversion layer was formed on the surface of the steel plate or the metallized layer in Tests 22-29 and 31. In particular, the chemical conversion solutions listed in Table. 5 were used as chemical conversion solutions for AD coatings. The treatment solution for forming the trivalent chromate coating was DAIN Chromate TR-02 from Daiwa Fine Chemicals Co., Ltd. The chemical conversion conditions for coatings A-D were as specified in Table 5. The chemical conversion conditions for forming the trivalent chromate coating were as follows: bath temperature 25°C, pH 4.0 and treatment duration 50 seconds.

Application process and curing process

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A polymer coating was formed on the surface of the metallized or chemical conversion layer in Tests 22-31. Specifically, the resin coating forming composition was applied to the surface of the metallized layer or the chemical conversion layer of Tests 22-31 by a rod device and was cured. The components of the composition other than the solvent were solid lubricant particles and copper phthalocyanine, and the rest were polymer. Epoxy resin was used as the polymer in Tests 22-31. Polytetrafluoroethylene particles were used as solid lubricant particles in Tests 22-31. The content of copper phthalocyanine is shown in table. 4. The composition also contained a solvent. A solution of a mixture of water, alcohol and surfactant was used as a solvent. In the presence of a layer obtained by chemical conversion, the composition was applied by a rod device to the layer obtained by chemical conversion, and in the absence of a layer obtained by chemical conversion, the composition was applied by a rod device to the metallized layer, and then the thermal curing process was carried out at 210°C in for 20 minutes to form a polymer coating.

Pin-disk tests

Resistance to scuffing was assessed using a pin-disk friction and wear test machine using steel plates from Tests 22-31 on which a polymer coating had been formed. Specifically, the steel plate from each of Tests 22-31 was fixed to a rotating disk, and the rotating disk was rotated at a speed of 100 rpm while the steel ball remained pressed against the rotating disk with a force of 60 N. The rotation of the disk was set only in one direction. It should be taken into account that due to the rotation of the disk, the sliding of the steel ball relative to the polymer coating was carried out without lubrication at room temperature. The coefficient of friction μ of the steel ball during sliding and the sliding distance (m) until the coefficient of friction μ exceeded 0.6 (equivalent to the coefficient of friction between the polymer coating and the steel ball) were measured. The results are presented in the column Sliding distance before the friction coefficient exceeds 0.6 in the table. 4.

Evaluation results

As shown in table. 4, the steel plates from Tests 22-31 contained a polymer coating containing polymer, solid lubricating powder and copper phthalocyanine on the surface. As shown in table. 4, in the resin coating formed on the steel plates in Tests 22-31, the copper phthalocyanine content ranged from 0.2 to 9.0 wt%. As a result, the sliding distance before the friction coefficient exceeded 0.6 was large. Those. Excellent scuff resistance has been demonstrated.

The steel plates in Tests 22-29 and 31 contained a chemical conversion layer as a polymer coating substrate. As a result, compared with the steel plate from Test 30, which did not contain the chemical conversion layer as a substrate for the resin coating, the sliding distance before the friction coefficient exceeded 0.6 was longer. Those. better resistance to scuffing has been demonstrated. The steel plates in Tests 22-29 contained coatings A-D as a chemical conversion layer. As a result, compared to the steel plate from Test 31, which contained a trivalent chromate coating, the sliding distance before the coefficient of friction exceeded 0.6 was even greater. Those. better resistance to scuffing has been demonstrated.

Example 4

In Example 4, a polymer coating was formed on the surface of steel plates simulating a metal oil well pipe and the resistance to scuffing was evaluated. In particular, in example 4, cold-rolled steel plates were used (chemical composition: C < 0.15%, Mn < 0.60%, P < 0.100%, S < 0.050%, the rest Fe and impurities). An anti-corrosion polymer coating containing a polymer coating, or a polymer coating, as shown in Table. 6 were formed on the surfaces of the steel plate in Tests 32-34. The term Formation in the Anti-corrosion polymer coating column in the table. 6 means that the anti-corrosion polymer coating has been formed on the surface of the steel plate. The symbol is in the Anti-corrosion polymer coating column in the table. 6 means that the anti-corrosion resin coating has not been formed on the surface of the steel plate.

Table 6

Test number Anti-corrosion polymer coating Copper phthalocyanine content Corrosion development period (h) 32 Formation 0.5 wt% 1006< 33 Formation 2.0 wt% 1006< 34 - 2.0 wt% 768

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The process of forming an anti-corrosion polymer layer

An anti-corrosion resin coating was formed on the surfaces of steel plates in Tests 32, 33. The composition for forming an anti-corrosion resin coating contained an anti-corrosion filler in an amount of 8 wt.% and an acrylic silicone resin in an amount of 70 wt.%. The composition for forming an anti-corrosion polymer coating also contained a solvent. The composition for forming an anti-corrosion polymer coating was applied to the surface of the steel plate from Tests 32,33 by spraying and was cured by natural drying. The thickness of the anti-corrosion polymer coating from Test 32 was 13 microns. The thickness of the anti-corrosion polymer coating from Test 33 was 11 microns. Measurement of the thickness of the anti-corrosion resin coating was carried out by the method disclosed above using an electromagnetic film thickness measuring instrument SDM-picoR manufactured by Sanko Electronic Laboratory Co., Ltd., and the average value of the thickness at nine points on one evaluation surface was taken as the thickness of the anti-corrosion resin coating .

Application process and curing process

The top resin coating layer was formed on the surface of the anti-corrosion resin coating of Tests 32, 33. The resin coating was formed on the surface of the steel plate of Test 34. Specifically, the resin coating forming composition was applied to the surface of the steel plate or the surface of the anti-corrosion resin coating of Tested 32-34 using a rod device and was cured. The components of the composition other than the solvent were solid lubricant particles and copper phthalocyanine, and the rest was a polymer. Epoxy resin was used as a polymer. Polytetrafluoroethylene particles were used as solid lubricant particles. The content of copper phthalocyanine is shown in table. 6. The composition also contained a solvent. A solution of a mixture of water, alcohol and surfactant was used as a solvent. In the presence of an anti-corrosion polymer coating, the composition was applied with a rod device to the anti-corrosion polymer coating, and in the absence of an anti-corrosion polymer coating, the composition was applied with a rod device to the surface of the steel plate, and then the thermal curing process was carried out at 210°C for 20 minutes to form a polymer coating. The polymer coatings that were formed also contained 1-30 wt.% polytetrafluoroethylene (PTFE) as a solid lubricating powder, and the other substances consisted of epoxy resin as a polymer.

The polymer coating thickness from Test 32 was 35.5 μm, the polymer coating thickness from Test 33 was 33.0 μm, and the polymer coating thickness from Test 34 was 26.8 μm. It should be noted that the polymer coating from Tests 32 and 33 contained an anti-corrosion polymer coating. Thus, the thickness of the top layer of polymer coating from Test 32 was 22.5 μm, and the thickness of the top layer of polymer coating from Test 33 was 22.0 μm. The thickness measurement of the resin coating was carried out by the method disclosed above using an electromagnetic film thickness measuring instrument SDM-picoR manufactured by Sanko Electronic Laboratory Co., Ltd., and the average thickness value at nine points on one evaluation surface was taken as the thickness of the resin coating.

Salt chamber tests

Salt chamber tests were carried out using steel plates in Tests 32-34, which were coated with a polymer coating. For salt chamber testing, a device with the trade name Combined Cyclic Corrosion Test Instrument CY90 manufactured by Suga Test Instruments Co., Ltd. was used. Salt chamber testing complied with JIS Z 2371 (2015). The test conditions were as follows: NaCl concentration in the spray 5±0.5%, spray amount 1.5±0.5 ml/h/80 ^cm2 , temperature 35±2°C, pH during testing 6.5-7, 2. In this example, the period before swelling of the polymer coating was taken as the period of corrosion development. The periods of corrosion development are indicated in table. 6.

Evaluation results

As shown in table. 6, the steel plates from Tests 32-34 contained a polymer coating containing polymer, solid lubricating powder and copper phthalocyanine on the surface.

The steel plates from Tests 32 and 33 contained an anti-corrosion polymer coating in the polymer coating. As a result, the period until corrosion developed was longer compared to the steel plate from Test 34, which did not contain the anti-corrosion polymer coating in the polymer coating. Those. Excellent resistance to corrosion has been demonstrated.

An embodiment of the present invention has been disclosed above. However, the above embodiment is one example of the present invention. Accordingly, the present invention is not limited to the above-described embodiment, and the above-mentioned embodiment may be suitably modified.

Claims (11)

not within the scope without departing from the spirit of the present invention. List of reference designations 1 metal pipe for oil well, 10 Pipe main body, 10 A First end part, 10V Second end part, 11 Tubular nipple body, 12 Coupling coupling, 40 Nipple, 41 Part with external thread, 42 Nipple sealing surface, 43 Nipple thrust surface, 50 coupling, 51 Part with internal thread, 52 Coupling sealing surface, 53 Clutch thrust surface, 70 Anti-corrosion polymer coating, 80 Metallized layer, 90 The layer obtained by chemical conversion, 100 Polymer coating, 400 Nipple contact surface, 500 Contact surface of the coupling. CLAIM 1. A metal pipe for an oil well, comprising: a pipe main body containing a first end portion and a second end portion; wherein the pipe main body includes a nipple formed on the first end portion and a coupling formed on the second end portion; neither the pin comprises a pin contact surface including a male thread portion; the coupling includes a coupling contact surface including a female thread portion; the metal oil well pipe further comprises a polymer coating comprising a polymer, a solid lubricating powder and copper phthalocyanine on or over at least one of the pin contact surfaces and the coupling contact surface. 2. A metal pipe for an oil well according to claim 1, in which the polymer coating contains from 0.2 to 30.0 wt.% copper phthalocyanine. 3. A metal pipe for an oil well according to claim 2, in which the polymer coating contains from 0.2 to 30.0 wt.% copper phthalocyanine, from 60 to 90 wt.% polymer, and from 1 to 30 wt.% solid lubricant powder. 4. A metal pipe for an oil well according to claim 2 or 3, in which the polymer coating contains from 0.2 to 9.0 wt.% copper phthalocyanine. 5. A metal pipe for an oil well according to any one of claims 1 to 4, further comprising a metallized layer between at least the contact surface of the nipple or the contact surface of the coupling and the polymer coating. 6. The metal pipe for an oil well according to any one of claims 1 to 4, further comprising a layer obtained by chemical conversion between at least the contact surface of the nipple or the contact surface of the coupling and the polymer coating. 7. The metal pipe for an oil well according to claim 5, further comprising a layer obtained by chemical conversion between the metallized layer and the polymer coating. 8. A metal pipe for an oil well according to any one of claims 1-7, in which the polymer coating additionally contains an anti-corrosion filler. 9. The metal oil well pipe according to any one of claims 1 to 8, wherein at least one of the pin contact surface and the coupling contact surface is a surface subjected to one or more treatments from the group consisting of blasting and etching. 10. The metal oil well pipe according to any one of claims 1 to 9, wherein the polymer is one or more types selected from the group consisting of epoxy resin, phenolic resin, acrylic resin, urethane resin, polyester resin, polyamide imide resin, polyamide resin, polyimide resin and polyetheretherketone resin. 11. The metal oil well pipe according to any one of claims 1 to 10, wherein the solid lubricating powder is one or more substances from the group consisting of graphite, -