Method for processing external thread end of bimetal composite pipe

Abstract

The invention discloses a machining method for an external thread end of a bimetal composite pipe. The machining method comprises the following steps that the bimetal composite pipe is taken; the outer wall of the bimetal composite pipe is an outer-layer carbon steel pipe body, the inner wall of the bimetal composite pipe is an inner-layer corrosion-resistant alloy pipe body, and the outer-layer carbon steel pipe body at one end of the bimetal composite pipe is subjected to taper cutting treatment to form a taper cutting section; the end part of one end of the taper cutting section is subjected to external upsetting treatment; the end part of one end of the taper cutting section subjected to external upsetting treatment is subjected to local quenching and tempering heat treatment to form a pipe end cylindrical section; and the outer wall of the end, provided with the pipe end cylindrical section, of the bimetal composite pipe is subjected to thread machining treatment to form pipe body external threads, and machining is completed. According to the machining method for the outer thread end of the bimetal composite pipe, the machining procedures of the composite pipe are effectively reduced, production efficiency is improved, and production cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of thread processing technology and relates to a method for processing the external thread end of a bimetallic composite pipe. Background Technology

[0002] Bimetallic composite pipes, due to their excellent corrosion resistance of the inner layer, are increasingly used in the exploration and development of energy resources such as oil, natural gas, and coalbed methane. For example, they are used to manufacture oil casing to stabilize the wellbore and create oil and gas channels. However, the corrosion resistance between the pipe body and the coupling at the threaded connection of bimetallic pipe fittings is a significant factor limiting their application. This includes potential difference corrosion between the surface substrate and the inner corrosion-resistant alloy layer of the bimetallic pipe, and potential difference corrosion between the pipe body and the coupling material. Currently, the common method for addressing the threaded connection of bimetallic composite pipes is to weld the same corrosion-resistant alloy material onto the pipe end and the coupling surface, ensuring that both the pipe body and the coupling connection use the same corrosion-resistant alloy material. This increases the cost of the threaded connection, adds manufacturing steps, and reduces production efficiency.

[0003] In summary, existing technologies suffer from high costs and low efficiency in applying corrosion-resistant alloys to bimetallic composite pipe threaded connections. Summary of the Invention

[0004] The purpose of this invention is to provide a method for processing the external thread end of a bimetallic composite pipe, which solves the problems of high cost and low efficiency of welding corrosion-resistant alloys to the threaded connection part of bimetallic composite pipes in the prior art.

[0005] The technical solution adopted in this invention is a method for processing the external thread end of a bimetallic composite pipe, comprising the following steps:

[0006] S1. Take a bimetallic composite pipe;

[0007] The outer wall of the bimetallic composite pipe is an outer layer of carbon steel pipe, and the inner wall of the bimetallic composite pipe is an inner layer of corrosion-resistant alloy pipe.

[0008] S2. The outer carbon steel pipe body at one end of the bimetallic composite pipe is tapered and cut to form a tapered section.

[0009] S3. Apply external thickening and upsetting treatment to one end of the tapered cutting section;

[0010] S4. After local tempering heat treatment of one end of the tapered cutting section after external thickening and upsetting, a cylindrical section of the tube end is formed.

[0011] S5. After threading the outer wall of one end of the cylindrical section on the bimetallic composite pipe, external threads are formed on the pipe body, and the machining is completed.

[0012] The invention is further characterized by:

[0013] The types of bimetallic composite pipes include bimetallic composite oil pipes, externally thickened bimetallic metallurgical composite oil pipes, externally thickened bimetallic metallurgical composite sleeves, and solid bimetallic metallurgical composite sleeves.

[0014] The wall thickness of the inner corrosion-resistant alloy tube is 0.8mm-1.2mm.

[0015] The taper of the tapered cutting section is 1:(12-15), and the cutting thickness of the tapered cutting section is 2.5mm-3.5mm.

[0016] After being subjected to external upsetting, the inner and outer diameters of the two end faces of the bimetallic composite pipe are the same.

[0017] The cylindrical section at the pipe end is formed by the rheological transformation of the inner layer of corrosion-resistant alloy pipe body metal at the end.

[0018] The cylindrical section at the pipe end has the same inner diameter as the bimetallic composite pipe, while the outer diameter of the cylindrical section at the pipe end is smaller than that of the bimetallic composite pipe.

[0019] The axial length of the cylindrical section at the pipe end is 2.0mm-2.5mm, and the wall thickness of the cylindrical section at the pipe end is 2.5mm-3.0mm.

[0020] The external thread of the pipe is located at the end of the cylindrical section of the pipe end, near the bimetallic composite pipe.

[0021] The beneficial effects of this invention are: compared with the method of applying corrosion-resistant alloy welding to the end face, this invention improves the corrosion resistance of the pipe body and the threaded connection of the coupling, and achieves the corrosion resistance integrity of the entire pipe string. It is a key technology for using bimetallic pipes in oil casing applications. This invention does not require the application of corrosion-resistant alloy welding to form a corrosion-resistant alloy layer at the pipe end, effectively reducing the processing steps of composite pipes, improving production efficiency, and reducing production costs. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the bimetallic composite tube before processing in this invention;

[0023] Figure 2 This is a schematic diagram of the structure in the processing of the bimetallic composite tube in this invention;

[0024] Figure 3 This is a schematic diagram of the structure of the bimetallic composite tube after external thickening and upsetting treatment in this invention;

[0025] Figure 4 This is a schematic diagram of the structure of the bimetallic composite tube after processing in this invention.

[0026] In the figure, 1 is the bimetallic composite pipe body; 101 is the outer carbon steel pipe body; 102 is the inner corrosion-resistant alloy pipe body; 103 is the tapered cutting section; 104 is the external thread of the pipe body; and 105 is the cylindrical section at the pipe end. Detailed Implementation

[0027] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0028] The method for machining the external thread end of a bimetallic composite pipe includes the following steps:

[0029] S1, take as Figure 1 The bimetallic composite tube 1 shown;

[0030] The outer wall of the bimetallic composite pipe 1 is an outer carbon steel pipe body 101, and the inner wall of the bimetallic composite pipe 1 is an inner corrosion-resistant alloy pipe body 102.

[0031] S2. After taper cutting of the outer carbon steel tube body 101 at one end of the bimetallic composite tube 1, it forms the following... Figure 2 The tapered cutting section 103 is shown.

[0032] S3. The end of the tapered cutting section 103 is subjected to external thickening and upsetting treatment;

[0033] S4, for example Figure 3 The tapered cutting section 103 shown is subjected to local tempering heat treatment at one end to form a cylindrical section 105 at the end of the tube end.

[0034] S5. After threading the outer wall of one end of the cylindrical section 105 on the bimetallic composite pipe 1, it forms the following... Figure 4 The external thread 104 on the pipe shown is now complete.

[0035] The bimetallic composite pipe 1 includes various pipe types such as bimetallic composite tubing, externally thickened bimetallic metallurgical composite tubing, externally thickened bimetallic metallurgical composite casing, and solid bimetallic metallurgical composite casing. The inner corrosion-resistant alloy pipe body 102 has a wall thickness of 0.8mm-1.2mm. The taper of the tapered cutting section 103 is 1:12-15, and the cutting thickness of the tapered cutting section 103 is 2.5mm-3.5mm. After external thickening and upsetting, the inner and outer diameters of both end faces of the bimetallic composite pipe 1 are the same. The cylindrical end section 105 is formed by the rheological transformation of the inner corrosion-resistant alloy pipe body 102 at the end.

[0036] The cylindrical section 105 at the pipe end has the same inner diameter as the bimetallic composite pipe 1, but its outer diameter is smaller than that of the bimetallic composite pipe 1. The axial length of the cylindrical section 105 is 2.0mm-2.5mm, and its wall thickness is 2.5mm-3.0mm. An external thread 104 is located at the end of the cylindrical section 105 closest to the bimetallic composite pipe 1.

[0037] This invention employs a low-cost, special external upsetting and thickening process for processing external threads. Compared to internal alloy thickening processes such as laser cladding and welding, this reduces production costs and improves production efficiency. The external upsetting and thickening process linearly increases the thickness of the internal alloy layer at the end. After thread processing, a cylindrical section 105 of the same material and thickness as the inner layer of the composite pipe is formed at the external thread end of the pipe. After thread connection, a metal sealing surface is formed between the cylindrical section 105 and the inner layer of the composite pipe end face inside the female thread. Since the cylindrical section and the inner layer of the composite pipe are made of the same material, galvanic corrosion between metals caused by contact sealing of different materials is avoided, which not only improves the sealing performance of the connection but also increases its service life.

[0038] Example 1

[0039] This embodiment proposes a method for machining the external thread end of a bimetallic composite pipe, including the following steps:

[0040] S1, take as Figure 1 The bimetallic composite tube 1 shown;

[0041] The outer wall of the bimetallic composite pipe 1 is an outer carbon steel pipe body 101, and the inner wall of the bimetallic composite pipe 1 is an inner corrosion-resistant alloy pipe body 102.

[0042] S2. After taper cutting of the outer carbon steel tube body 101 at one end of the bimetallic composite tube 1, it forms the following... Figure 2 The tapered cutting section 103 is shown.

[0043] S3. The end of the tapered cutting section 103 is subjected to external thickening and upsetting treatment;

[0044] S4, for example Figure 3 The tapered cutting section 103 shown is subjected to local tempering heat treatment at one end to form a cylindrical section 105 at the end of the tube end.

[0045] S5. After threading the outer wall of one end of the cylindrical section 105 on the bimetallic composite pipe 1, it forms the following... Figure 4 The external thread 104 on the pipe shown is now complete.

[0046] Example 2

[0047] This embodiment proposes a method for machining the external thread end of a bimetallic composite pipe, including the following steps:

[0048] S1, take as Figure 1 The bimetallic composite tube 1 shown;

[0049] The outer wall of the bimetallic composite pipe 1 is an outer carbon steel pipe body 101, and the inner wall of the bimetallic composite pipe 1 is an inner corrosion-resistant alloy pipe body 102.

[0050] S2. After taper cutting of the outer carbon steel tube body 101 at one end of the bimetallic composite tube 1, it forms the following... Figure 2 The tapered cutting section 103 is shown.

[0051] S3. The end of the tapered cutting section 103 is subjected to external thickening and upsetting treatment;

[0052] S4, for example Figure 3 The tapered cutting section 103 shown is subjected to local tempering heat treatment at one end to form a cylindrical section 105 at the end of the tube end.

[0053] S5. After threading the outer wall of one end of the cylindrical section 105 on the bimetallic composite pipe 1, it forms the following... Figure 4 The external thread 104 on the pipe shown is now complete.

[0054] The bimetallic composite pipe 1 is a bimetallic composite oil pipe. The inner corrosion-resistant alloy pipe body 102 has a wall thickness of 0.8 mm. The taper of the tapered cutting section 103 is 1:12, and the cutting thickness of the tapered cutting section 103 is 2.5 mm. After external thickening and upsetting, the inner and outer diameters of the two end faces of the bimetallic composite pipe 1 are the same. The cylindrical section 105 at the pipe end is formed by the rheological transformation of the inner corrosion-resistant alloy pipe body 102 at the end.

[0055] Example 3

[0056] This embodiment proposes a method for machining the external thread end of a bimetallic composite pipe, including the following steps:

[0057] S1, take as Figure 1 The bimetallic composite tube 1 shown;

[0058] The outer wall of the bimetallic composite pipe 1 is an outer carbon steel pipe body 101, and the inner wall of the bimetallic composite pipe 1 is an inner corrosion-resistant alloy pipe body 102.

[0059] S2. After taper cutting of the outer carbon steel tube body 101 at one end of the bimetallic composite tube 1, it forms the following... Figure 2 The tapered cutting section 103 is shown.

[0060] S3. The end of the tapered cutting section 103 is subjected to external thickening and upsetting treatment;

[0061] S4, for example Figure 3 The tapered cutting section 103 shown is subjected to local tempering heat treatment at one end to form a cylindrical section 105 at the end of the tube end.

[0062] S5. After threading the outer wall of one end of the cylindrical section 105 on the bimetallic composite pipe 1, it forms the following... Figure 4 The external thread 104 on the pipe shown is now complete.

[0063] The bimetallic composite pipe 1 is a thickened bimetallic metallurgical composite oil pipe. The inner corrosion-resistant alloy pipe body 102 has a wall thickness of 1.2 mm. The taper of the tapered cutting section 103 is 1:15, and the thickness of the tapered cutting section 103 is 3.5 mm. After the thickened and upset treatment, the inner and outer diameters of the two end faces of the bimetallic composite pipe 1 are the same. The cylindrical section 105 at the pipe end is formed by the rheological transformation of the inner corrosion-resistant alloy pipe body 102 at the end.

[0064] Example 4

[0065] This embodiment proposes a method for machining the external thread end of a bimetallic composite pipe, including the following steps:

[0066] S1, take as Figure 1 The bimetallic composite tube 1 shown;

[0067] The outer wall of the bimetallic composite pipe 1 is an outer carbon steel pipe body 101, and the inner wall of the bimetallic composite pipe 1 is an inner corrosion-resistant alloy pipe body 102.

[0068] S2. After taper cutting of the outer carbon steel tube body 101 at one end of the bimetallic composite tube 1, it forms the following... Figure 2 The tapered cutting section 103 is shown.

[0069] S3. The end of the tapered cutting section 103 is subjected to external thickening and upsetting treatment;

[0070] S4, for example Figure 3 The tapered cutting section 103 shown is subjected to local tempering heat treatment at one end to form a cylindrical section 105 at the end of the tube end.

[0071] S5. After threading the outer wall of one end of the cylindrical section 105 on the bimetallic composite pipe 1, it forms the following... Figure 4 The external thread 104 on the pipe shown is now complete.

[0072] The bimetallic composite pipe 1 has a pipe body type including a flat bimetallic metallurgical composite sleeve. The inner corrosion-resistant alloy pipe body 102 has a wall thickness of 1.0 mm. The taper of the tapered cutting section 103 is 1:13.5, and the cutting thickness of the tapered cutting section 103 is 3.0 mm. After external thickening and upsetting, the inner and outer diameters of the two end faces of the bimetallic composite pipe 1 are the same. The cylindrical section 105 at the pipe end is formed by the rheological transformation of the inner corrosion-resistant alloy pipe body 102 at the end.

Claims

1. A method for machining the external thread end of a bimetallic composite pipe, characterized in that, Includes the following steps: S1. Take the bimetallic composite pipe (1); The outer wall of the bimetallic composite pipe (1) is an outer carbon steel pipe body (101), and the inner wall of the bimetallic composite pipe (1) is an inner corrosion-resistant alloy pipe body (102). S2. The outer carbon steel pipe body (101) at one end of the bimetallic composite pipe (1) is tapered and cut to form a tapered section (103). S3. The end of the tapered cutting section (103) is subjected to external thickening and upsetting treatment; S4. After local tempering heat treatment of one end of the tapered cutting section (103) after external thickening and upsetting, a cylindrical section (105) is formed at the end of the tube. S5. After threading the outer wall of one end of the cylindrical section (105) on the bimetallic composite pipe (1), the external thread (104) of the pipe body is formed, and the processing is completed.

2. The method for processing the external thread end of a bimetallic composite pipe according to claim 1, characterized in that, The bimetallic composite pipe (1) has the following pipe body types: bimetallic composite oil pipe, externally thickened bimetallic metallurgical composite oil pipe, externally thickened bimetallic metallurgical composite sleeve, and flat bimetallic metallurgical composite sleeve.

3. The method for processing the external thread end of a bimetallic composite pipe according to claim 1, characterized in that, The wall thickness of the inner corrosion-resistant alloy tube (102) is 0.8mm-1.2mm.

4. The method for processing the external thread end of a bimetallic composite pipe according to claim 1, characterized in that, The taper of the tapered cutting section (103) is 1:(12-15), and the cutting thickness of the tapered cutting section (103) is 2.5mm-3.5mm.

5. The method for processing the external thread end of a bimetallic composite pipe according to claim 1, characterized in that, The inner and outer diameters of the two end faces of the bimetallic composite pipe (1) after the external thickening and upsetting treatment are the same.

6. The method for processing the external thread end of a bimetallic composite pipe according to claim 1, characterized in that, The cylindrical section (105) at the pipe end is formed by the metal rheology of the inner corrosion-resistant alloy pipe body (102) at the end.

7. The method for processing the external thread end of a bimetallic composite pipe according to claim 1, characterized in that, The cylindrical section (105) at the pipe end has the same inner diameter as the bimetallic composite pipe (1), and the outer diameter of the cylindrical section (105) at the pipe end is smaller than that of the bimetallic composite pipe (1).

8. The method for processing the external thread end of a bimetallic composite pipe according to claim 1, characterized in that, The axial length of the cylindrical section (105) at the pipe end is 2.0mm-2.5mm, and the wall thickness of the cylindrical section (105) at the pipe end is 2.5mm-3.0mm.

9. The method for processing the external thread end of a bimetallic composite pipe according to claim 1, characterized in that, The external thread (104) of the tube is located at one end of the cylindrical section (105) of the tube end, near the bimetallic composite tube (1).

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