THREADED END OF A TUBULAR COMPONENT PROVIDED WITH A COATING COMPRISING A ZINC-CHROMIUM ALLOY

Abstract

A threaded end of a tubular component is for drilling and/or operating a hydrocarbon well, transporting oil and gas, transporting or storing hydrogen, carbon capture or geothermal energy, comprising at least one thread extending over its outer or inner peripheral surface, wherein the thread is coated with a layer comprising a zinc-chromium (ZnCr) alloy in which zinc (Zn) is the predominant element by weight, relative to the total weight of the alloy. A process for preparing a threaded end, as defined above, includes at least one electrodeposition, on the surface of the thread of the end, of an aqueous composition comprising one or more zinc salts, one or more chromium salts, one or more electrolytes and one or more surfactants.

Claims

1. A threaded end of a tubular component, comprising at least one thread extending over its outer or inner peripheral surface, wherein the thread is coated with a layer comprising a zinc-chromium (ZnCr) alloy in which zinc (Zn) is the predominant element by weight, relative to the total weight of the alloy, and wherein the tubular component is suitable for drilling and/or operating a hydrocarbon well, transporting oil and gas, transporting or storing hydrogen, carbon capture or geothermal energy.

2. The threaded end of a tubular component according to claim 1, wherein the content of zinc (Zn) is greater than 50% by weight, relative to the total weight of the zinc-chromium alloy.

3. The threaded end of a tubular component according to claim 1, wherein the content of chromium (Cr) is greater than or equal to 3% by weight, relative to the total weight of the zinc-chromium alloy.

4. The threaded end of a tubular component according to claim 1, wherein the content of chromium (Cr) varies from 20% to 30% by weight, relative to the total weight of the zinc-chromium alloy.

5. The threaded end of a tubular component according to claim 1, wherein the layer comprising a zinc-chromium (ZnCr) alloy is electrodeposited.

6. The threaded end of a tubular component according to claim 1, wherein the layer comprising a zinc-chromium (ZnCr) alloy has a thickness ranging from 4 to 20 m.

7. The threaded end of a tubular component according to claim 1, wherein the tubular component further comprises at least one non-threaded portion coated with the layer comprising a zinc-chromium (ZnCr) alloy.

8. The threaded end of a tubular component according to claim 7, wherein the non-threaded portion comprises a stop and/or a sealing seat.

9. The threaded end of a tubular component according to claim 1, wherein the threaded end is made of steel.

10. A process for preparing a threaded end of a tubular component as defined in claim 1, comprising at least one electrodeposition of an aqueous composition comprising one or more zinc salts, one or more chromium salts, one or more electrolytes and one or more surfactants on a surface of the thread of said end.

11. The process according to claim 10, further comprising a preparation of the surface to be coated.

12. A tubular component for drilling and/or operating a hydrocarbon well, transporting oil and gas, transporting or storing hydrogen, carbon capture or geothermal energy, comprising a threaded end according to claim 1.

13. The tubular component according to claim 12, wherein the tubular component is of the male type and has at least one thread (3) extending over an outer peripheral surface.

14. The tubular component according to claim 12, wherein the tubular component is of the female type and has at least one thread (4) extending over an inner peripheral surface.

15. A tubular threaded joint comprising a threaded end of a male-type tubular component having a thread extending over its outer peripheral surface and a threaded end of a female-type tubular component having at least one thread extending over its inner peripheral surface, which are screwed into one another, wherein at least one of the threaded ends is according to claim 1.

16. The process according to claim 11, wherein the preparation of the surface to be coated comprises a mechanical treatment or a sandblasting process.

Description

[0167] Features of the invention are explained in greater detail in the following description, with reference to the appended drawings.

[0168] FIG. 1 is a schematic view of a joint resulting from the joining, by screwing together, of two tubular components.

[0169] FIG. 2 is an enlarged view of the boxed area A from FIG. 1.

[0170] FIG. 3 is a detailed view of the cooperation between the threads of two assembled tubular components.

[0171] FIG. 4 is a detailed view of a connection element (thread) according to the invention covered with a zinc-chromium coating in accordance with the invention.

[0172] FIG. 5 is a diagram comparing the appearance time of a layer of white rust of intensity 2 and intensity 3, after exposure to a salt spray test, on the surface of a zinc-nickel (ZnNi) coating and the surface of a zinc-chromium (ZnCr) coating in accordance with the invention.

[0173] FIG. 6 is a diagram comparing the time for complete coverage by a layer of white rust of intensity 2, after exposure to a salt spray test, of the surface of a zinc-nickel (ZnNi) coating and of the surface of a zinc-chromium (ZnCr) coating in accordance with the invention.

[0174] The threaded joint shown in FIG. 1 comprises a first tubular component with an axis of revolution 9 and a male end 1 and a second tubular component with an axis of revolution 9 and a female end 2. The two ends 1 and 2 each terminate in an end surface oriented radially with respect to the axis 9 of the threaded joint and are respectively provided with threaded portions 3 and 4 which cooperate with each other for mutual assembly by screwing together of the two components. The threaded portions 3 and 4 may be of the trapezoidal thread type or other type. In the example shown, the threaded portions have threads with tapering profiles at the respective ends of the threaded portions. These tapering profiles extend over a part of the axial extent of the threaded portion. In particular, a part of the threaded portion with a tapering profile 10 does not cooperate with a complementary thread.

[0175] Furthermore, as shown in FIG. 2, metal/metal sealing surfaces (seats) 5, 6 intended to be in leaktight close contact against one another after assembly by screwing together of the two threaded components, are formed respectively on the male and female ends in the vicinity of the threaded portions 3, 4. Finally, the male end 1 terminates in an end surface 7 which abuts against a corresponding surface 8 formed on the female end 2 when the two ends are screwed into one another, The surfaces 7 and 8 are referred to as stops.

[0176] In FIG. 3, the detail of a thread of a threaded portion is shown. Each thread thus comprises a load flank 11 forming an angle 12 of between 5 and +5 relative to the normal N of the connection axis 10. The load flank is connected by a crest 13 to an assembly flank 14. In particular, the connection shown is such that, in the final position of the assembly, the load flanks of the male threaded portion 3 are in contact with the corresponding load flanks of the female threaded portion 4.

[0177] FIG. 4 shows the male end 1 of a tubular component, of which the threaded portion 3 and sealing surface 5 (seat) are covered with a coating 15 as defined in the invention, that is to say, a zinc-chromium coating comprising a zinc-chromium (ZnCr) alloy in which zinc (Zn) is the predominant element by weight, relative to the total weight of the alloy.

[0178] Preferably, the coating 15 has a chromium content ranging from 20% to 30% by weight, more preferentially ranging from 25% to 30% by weight, and a zinc content ranging from 70% to 80% by weight, more preferentially ranging from 70% to 75% by weight, relative to the total weight of the alloy.

Exemplary Embodiment

[0179] A thread made of L80 grade carbon steel is electroplated, as described above, with a semi-bright metal coating comprising a zinc-chromium (ZnCr) alloy having a chromium content of 27% by weight relative to the total weight of the alloy.

[0180] The semi-bright zinc-chromium coating was obtained from an aqueous composition containing 75 g/l of glycine.

[0181] The zinc-chromium coating is compared with zinc-nickel (ZnNi) coatings, in which zinc is the predominant element by weight, having various weight contents of nickel ranging from 10% to 18% by weight. The percentage by weight is calculated relative to the total weight of the alloy.

[0182] The coatings were subjected to tribological tests (scratch test and Bowden test) in order to determine the critical load for which peeling of the coatings (plastic deformation) is observed, the initial coefficient of friction and the number of cycles that the coatings are capable of withstanding.

[0183] The coatings were also subjected to a salt spray test to determine their anti-corrosion performance.

Scratch Test

[0184] The experimental conditions use a tungsten carbide ball which is applied to the coatings and moved with an increasing load ranging from 10 N to 260 N, with a speed of movement of the ball of 4.20 mm/s, a duration of 2.38 seconds, a ball size of 5 mm and a track length of 10 mm.

The Scratch Test Results are Shown in Table 1

Results

TABLE-US-00001 TABLE 1 % by weight Critical load (N) of the metal element ZnCr X in the alloy (ZnX) ZnNi (semi-bright) 10 250 14 209 18 149 27 170

[0185] The results of the scratch tests described in Table 1 show that the semi-bright zinc-chromium coating withstands loads at least as high as those withstood by zinc-nickel coatings having a nickel content ranging from 10% to 18% by weight relative to the total weight of alloy.

Bowden Test

[0186] In order to evaluate the lubricating properties (coefficient of friction) of the surface of the coating, a commercially available Bowden friction tester (Shinko Engineering Co., Ltd.) was used. In the Bowden friction tester, a tungsten carbide ball was moved back and forth in a straight line on a coating formed on a steel sheet while a load was applied to the ball.

[0187] The coefficient of friction was measured from the frictional force and the pressure load at that time.

Procedure

[0188] The tungsten carbide ball is applied to the coatings and moved with a pressing load of 30 N and 100 N, with a speed of movement of the ball of 4.20 mm/s, a duration of 2.38 seconds, a ball size of 5 mm and a track length of 10 mm.

[0189] The initial coefficient of friction was determined to evaluate the lubricating properties of the coating.

[0190] The number of cycles (number of passes of the ball over the surface) was measured for each coating to evaluate their abrasion resistance.

[0191] The results are indicated in Tables 2 and 3 below.

Bowden TestResult for a 30 N Load

TABLE-US-00002 TABLE 2 Initial coefficient Endurance % by weight of friction (number of cycles) of the metal element X ZnCr ZnCr in the alloy (ZnX) ZnNi (semi-bright) ZnNi (semi-bright) 10 14 0.5-0.6 300 18 0.4-0.5 500 27 0.3-0.4 500

[0192] The Bowden test described in Table 2 shows that for a load of 30 N, the initial coefficients of friction are lower for a zinc-chromium coating according to the invention than for zinc-nickel coatings.

[0193] In addition, the zinc-chromium coating exhibits an endurance at least as high as the zinc-nickel coatings for a load of 30 N.

Bowden TestResult for a 100 N Load

TABLE-US-00003 TABLE 3 Endurance % by weight (number of cycles) of the metal element X ZnCr in the alloy (ZnX) ZnNi (semi-bright) 10 <100 14 <100 18 100-150 27 250

[0194] The Bowden test carried out for a load of 100 N, described in Table 3, shows that the zinc-chromium coating according to the invention has a higher endurance than that of the zinc-nickel coatings.

[0195] As a result, the zinc-chromium coating according to the invention has better wear resistance than the zinc-nickel coatings in which the nickel content varies from 10% to 18% by weight.

[0196] As a result, the more the load is increased, the more the zinc-chromium (ZnCr) coating according to the invention exhibits improved endurance, namely therefore a higher wear resistance, compared with a zinc-nickel (ZnNi) coating.

Salt Spray Test

[0197] The corrosion tests consisted of a neutral salt spray test carried out in a climatic chamber under the following conditions: 35 C. with a 50 g/l saline solution having a density of between 1.029 and 1.036 at 25 C., a pH of between 6.5 and 7.2 at 25 C. and collected at an average rate of 1.5 ml/h.

[0198] During this test, the appearance of red rust and white rust was evaluated.

Anti-Corrosion PerformanceAppearance of Red Rust

[0199] The appearance of red rust is evaluated by determining, in ascending order, the degree of rusting Re which corresponds to the percentage of rusted surface area relative to the total surface area.

[0200] Intact samples without red rusting must then meet class Re0 of the ISO 9227 standard after exposure.

[0201] The results are indicated in Table 4 below.

TABLE-US-00004 TABLE 4 Red rust after salt spray test Coating over a period of 504 hours ZnNi with 14% nickel - 10 m Re1 ZnCr (1) with 27% chromium - 5 m Re0 ZnCr (1) with 27% chromium - 10 m Re1 ZnCr (1) with 27% chromium - 15 m Re1

[0202] The degree of rusting, in ascending order from Re0 to Re2 after exposure corresponds to the rusted surface area relative to the total surface area.

[0203] In accordance with this degree of rusting: [0204] Re0=0% rusting of the total surface area, [0205] Re1=0.05% rusting of the total surface area, [0206] Re2=0.5% rusting of the total surface area, [0207] Re6=40%-50% rusting of the total surface area.

[0208] Table 4 thus shows that the zinc-chromium (ZnCr) coatings perform at least as well against the appearance of red rust as a zinc-nickel coating.

Anti-Corrosion PerformanceAppearance of White Rust

[0209] The presence of white rust corresponds to the oxidation of the coating, in particular the oxidation of zinc, and is evaluated by measuring, after exposure to salt spray, its appearance time and its time for total coverage of the surface of the coating.

[0210] After exposure to salt spray, the intensity of the layer of white rust covering the coatings classified in the following ascending order: [0211] white rust of intensity 1 corresponding to a layer of white rust that is thin and light, which can also be referred to as bloom, [0212] white rust of intensity 2 corresponding to a layer of white rust that is in the form of crystals, [0213] white rust of intensity 3 corresponding to a layer of white rust that is very dense.

Appearance Time of White Rust

[0214] FIG. 5 compares the appearance time of a layer of white rust of intensity 2 and intensity 3 after exposure to the salt spray test, on the surface of a zinc-nickel coating [ZnNi with 14% by weight of nickel and a thickness of 10 m] and on the surface of a zinc-chromium coating [ZnCr with 27% by weight of chromium and a thickness of 5 m].

[0215] FIG. 5 shows a rapid appearance of a layer of white rust of intensity 2 on the surface of the zinc-nickel coating [ZnNi with 14% by weight nickel and a thickness of 10 m], starting at 24 hours, whereas a layer of white rust of intensity 2 appears only after 170 hours on the surface of a zinc-chromium coating [ZnCr with 27% by weight of chromium and a thickness of 5 m].

[0216] FIG. 5 also shows the rapid appearance of a layer of white rust of intensity 3 on the zinc-nickel coating [ZnNi with 14% by weight nickel and a thickness of 10 m], starting at 24 hours, whereas a layer of white rust of intensity 3 appears only after 336 hours for a zinc-chromium coating [ZnCr with 27% by weight of chromium and a thickness of 5 m].

Time for Total Coverage of the Surface of the Coating by White Rust

[0217] FIG. 6 compares the time for complete coverage of the surface of a zinc-nickel coating [ZnNi with 14% by weight of nickel and a thickness of 10 m] and of a zinc-chromium coating [ZnCr with 27% by weight of chromium and a thickness of 5 m] by a layer of white frost of intensity 2.

[0218] FIG. 6 shows that the time for complete coverage of the surface of the zinc-nickel coating [ZnNi with 14% by weight of nickel and a thickness of 10 m] by a layer of white rust of intensity 2 is 24 hours, whereas this time for coverage by this same layer is 336 hours for a zinc-chromium coating [ZnCr with 27% by weight of chromium and a thickness of 5 m].

CONCLUSION

[0219] The results show that the zinc-chromium (ZnCr) coatings according to the invention have better performance in terms of appearance of white rust compared to a zinc-nickel (ZnNi) coating.

[0220] This results in better adhesion of the layers deposited subsequently on the zinc-chromium coatings.