A bimetallic composite pipe and end treatment method

Abstract

The present application belongs to the technical field of double-metal composite pipe, and particularly relates to a double-metal composite pipe end processing method. A stepped support plug is placed inside the pipe end, and axial extension of the corrosion-resistant alloy section of the double-metal composite pipe end is performed on the surface of the support plug by means of surfacing welding. The large end of the support plug is provided with a small gap fit, which effectively ensures the coaxiality of the surfacing alloy section and the pipe body, and the small end is provided with a large gap, which effectively ensures that the inner wall of the axially extended alloy section after the support plug is removed by turning is made of corrosion-resistant alloy. The present application eliminates the process of first turning the carbon steel base pipe layer of the pipe end, effectively guarantees the quality of the surfacing corrosion-resistant alloy section, improves the surfacing efficiency of the corrosion-resistant alloy, and is suitable for double-metal composite pipes of any wall thickness and double-metal composite pipes with corrosion-resistant alloy layers of any thickness.

Description

Technical Field

[0001] This invention pertains to bimetallic composite pipe technology, specifically relating to a bimetallic composite pipe and an end treatment method. Background Technology

[0002] Bimetallic composite pipes are typically composed of a carbon steel layer and a corrosion-resistant alloy layer. The carbon steel layer serves as the load-bearing structure, while the corrosion-resistant layer provides corrosion resistance. Due to their superior cost-effectiveness and excellent corrosion resistance compared to pure corrosion-resistant alloy pipes, bimetallic composite pipes are increasingly used in energy exploration, development, and transportation (oil, natural gas, coalbed methane), as well as in water supply and drainage systems for public works projects. However, ensuring the corrosion resistance of the pipe ends during connection is a significant factor limiting the application of bimetallic pipe fittings. For example, when using threaded connections, how to ensure corrosion resistance at the threaded joints? When using welded connections, how to ensure corrosion resistance at the weld seams? Currently, a common method for addressing corrosion resistance in threaded connections of bimetallic composite pipes is to machine the carbon steel layer at the pipe end and then weld an additive manufacturing process using a corrosion-resistant alloy of the same material as the inner corrosion-resistant alloy layer, creating a corrosion-resistant alloy layer of a certain axial length and thickness on the pipe end face. In production practice, when the inner corrosion-resistant alloy layer is thin, especially less than 1 mm, when corrosion-resistant alloy is applied to the surface of the inner corrosion-resistant alloy layer, the inner corrosion-resistant alloy is prone to forming molten holes, making effective corrosion-resistant alloy application impossible. Summary of the Invention

[0003] This invention proposes a bimetallic composite pipe and an end treatment method to solve the problem in the prior art that when corrosion-resistant alloy is applied to the surface of the inner corrosion-resistant alloy layer, the inner corrosion-resistant alloy is prone to forming molten holes, making effective corrosion-resistant alloy application impossible.

[0004] To achieve the above objectives, the present invention proposes the following technical solution:

[0005] A method for treating the end of a bimetallic composite pipe includes the following steps:

[0006] Step 1: Insert the large end of the support plug into the inner hole of the composite pipe end, with the small end of the support plug facing outwards;

[0007] Step 2: Using the small end of the support plug as a reference, axially extend a section of length at the end of the composite pipe to form a corrosion-resistant alloy section;

[0008] Step 3: Remove the support plug to make the inner diameter of the corrosion-resistant alloy growth section match the inner diameter of the composite pipe.

[0009] Step 4: Process the outer surface of the corrosion-resistant alloy section to make the outer diameter of the corrosion-resistant alloy section consistent with the outer diameter of the composite pipe.

[0010] Preferably, in step 2, the same alloy material as the corrosion-resistant alloy layer material on the inner wall of the composite pipe is used to axially grow the pipe end of the composite pipe.

[0011] Preferably, in step 2, the pipe end of the composite pipe is axially augmented by welding.

[0012] Preferably, in step 3, the support plug is removed by machining.

[0013] Preferably, the support plug is made of carbon steel and has a stepped axial shape on its outer surface.

[0014] Preferably, the nominal outer diameter of the large end of the support plug is the inner diameter of the composite pipe, with a tolerance of -0.1-0 mm;

[0015] The nominal outer diameter of the small end of the support plug is the inner diameter of the composite pipe, with a tolerance of -0.5 to 0.3 mm.

[0016] Preferably, the large end cylindrical section of the support plug has rounded chamfers at both ends, with a length of 18-10mm, and the small end cylindrical section of the support plug has a length of 3-20mm.

[0017] Preferably, in step 1, after the support plug is placed into the composite tube, the shoulders of the large and small ends are flush with the ends of the composite tube.

[0018] Preferably, in step 2, the small end of the support plug is used as a support, and the entire wall thickness is welded on the entire end face of the tube by laser welding, and then extended axially.

[0019] A bimetallic composite tube, wherein the bimetallic composite tube is manufactured by the aforementioned bimetallic composite tube end processing method.

[0020] The advantages of this invention are:

[0021] This invention proposes a method for treating the end of a bimetallic composite pipe. A stepped support plug is placed inside the pipe end, and the corrosion-resistant alloy section at the end of the bimetallic composite pipe is axially extended by welding onto the surface of the support plug. The large end of the support plug uses a small clearance fit, effectively ensuring the coaxiality of the welded alloy section and the pipe body. The small end uses a large clearance, effectively ensuring that the inner wall of the axially extended alloy section is corrosion-resistant alloy after the support plug is removed by machining. This invention eliminates the need for pre-machining of the carbon steel base layer at the pipe end, effectively ensures the quality of the welded corrosion-resistant alloy section, and improves the welding efficiency of the corrosion-resistant alloy. It is applicable to bimetallic composite pipes of any wall thickness and bimetallic composite pipes with any thickness of corrosion-resistant alloy layer. Attached Figure Description

[0022] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0023] Figure 1 This is a schematic flowchart of a bimetallic composite pipe end processing method according to an embodiment of the present invention;

[0024] Figure 2 A schematic diagram of the pipe end structure of a bimetallic composite pipe end treatment process provided in an embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of a support plug structure for a bimetallic composite tube end treatment process provided in one embodiment of the present invention.

[0026] Wherein: 1 is the outer layer of the bimetallic composite pipe; 2 is the inner wall of the bimetallic composite pipe; 3 is the support plug; 3-1 is the large end cylindrical section; 3-2 is the small end cylindrical section; and 4 is the corrosion-resistant alloy section. Detailed Implementation

[0027] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0028] The following detailed description is exemplary and intended to provide further detailed explanation of the invention. Unless otherwise specified, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this invention is for describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention.

[0029] Example 1:

[0030] Please see Figure 1 As shown, the present invention provides a method for treating the end of a bimetallic composite pipe, comprising the following steps:

[0031] Step 1: Using a small gap assembly method, insert the large end 3-1 of the support plug 3 into the inner hole of the composite pipe end, with the small end 3-2 of the support plug facing outwards.

[0032] Step 2: Using the small end 3-2 of the support plug as a base, and employing the same alloy as the corrosion-resistant alloy layer 2 on the inner wall of the composite pipe, axially extend the pipe end of the composite pipe by welding to form a corrosion-resistant alloy section 4.

[0033] Step 3: Remove the support plug 3 by machining so that the inner diameter of the corrosion-resistant alloy section 4 is consistent with the inner diameter of the composite pipe.

[0034] Step 4: The outer surface of the corrosion-resistant alloy section 4 is machined to make the outer diameter of the corrosion-resistant alloy section 4 consistent with the outer diameter of the composite pipe.

[0035] In one specific embodiment, the bimetallic composite pipe, such as Figure 2 As shown, the outer layer 1 of the bimetallic composite pipe is made of carbon steel, and the inner wall 2 of the bimetallic composite pipe is made of corrosion-resistant metal.

[0036] In one specific embodiment, the support plug 3 is made of carbon steel, as shown, with a stepped shaft-like outer surface. The nominal outer diameter of the large end 3-1 is the inner diameter of the composite pipe with a tolerance of -0.1-0 mm, and the nominal outer diameter of the small end 3-2 is the inner diameter of the composite pipe with a tolerance of -0.5-0.3 mm.

[0037] like Figure 3 As shown, the large end cylindrical section 3-1 of the support plug has rounded chamfers at both ends and a length of 18-10mm. The small end cylindrical section 3-2 of the support plug has a length of 3-20mm, and its specific length depends on the design requirements.

[0038] In one specific embodiment, the support plug 3 is a hollow tube, and the wall thickness of the small-end cylindrical section 3-2 is greater than 1.2 mm.

[0039] In one specific embodiment, after the support plug 3 is inserted into the composite tube, the shoulders of the large and small ends are flush with the ends of the composite tube.

[0040] In one specific embodiment, the small end 3-2 of the support plug 3 is used as a support, and the entire wall thickness is welded on the entire end face of the tube body by laser welding, and then extended axially.

[0041] In one specific embodiment, the bimetallic tube may also have an outer layer of corrosion-resistant alloy layer 2 and an inner layer of carbon steel base tube 1.

[0042] In one specific embodiment, the support plug 3 may also be a solid bar.

[0043] In one specific embodiment, the material of the support plug 3 may also be the same alloy as the bimetallic corrosion-resistant alloy layer or other metallic materials.

[0044] In one specific embodiment, the carbon steel substrate 1 and the corrosion-resistant alloy layer 2 of the bimetallic composite pipe can be metallurgically bonded or mechanically bonded.

[0045] The present invention provides a bimetallic composite tube, which is manufactured based on the above-described bimetallic composite tube end operation method.

[0046] Bimetallic composite pipes are composed of a carbon steel base layer and a corrosion-resistant alloy layer. The corrosion-resistant alloy layer provides corrosion protection, while the carbon steel base layer provides sufficient load-bearing capacity. Therefore, the structure typically features a thicker carbon steel layer and a thinner corrosion-resistant alloy layer. When connecting pipes, alloying treatment is often performed at the pipe ends to ensure corrosion resistance at the joint. In existing technologies, the alloying treatment of bimetallic composite pipe ends often involves machining off the carbon steel and welding a corrosion-resistant alloy of the same material onto the surface of the corrosion-resistant alloy layer. In production practice, when the corrosion-resistant alloy layer is thin, welding additive corrosion-resistant alloy onto its surface can easily cause the inner corrosion-resistant alloy layer to melt through, creating holes and making it impossible to effectively perform additive welding on the surface of the corrosion-resistant alloy layer.

[0047] This invention provides an innovative bimetallic composite pipe end-treatment process. A stepped support plug is placed inside the pipe end, and the corrosion-resistant alloy section of the bimetallic composite pipe end is axially extended by welding onto the surface of the support plug. The large end of the support plug uses a small clearance fit, effectively ensuring the coaxiality of the welded alloy section and the pipe body. The small end uses a large clearance, effectively ensuring that the inner wall of the axially extended alloy section is corrosion-resistant alloy after the support plug is removed by machining. This invention eliminates the need for pre-machining of the carbon steel base layer at the pipe end, effectively ensures the quality of the welded corrosion-resistant alloy section, and improves the welding efficiency of the corrosion-resistant alloy. It is applicable to bimetallic composite pipes of any wall thickness and bimetallic composite pipes with any thickness of corrosion-resistant alloy layer.

[0048] As is known from common technical knowledge, this invention can be implemented through other embodiments that do not depart from its spirit or essential characteristics. Therefore, the disclosed embodiments described above are merely illustrative in all respects and are not the only ones. All modifications within the scope of this invention or its equivalents are included in this invention.

[0049] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0050] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0051] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0052] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for treating the end of a bimetallic composite pipe, characterized in that, Includes the following steps: Step 1: Insert the large end of the support plug into the inner hole of the composite pipe end, with the small end of the support plug facing outwards; Step 2: Using the small end of the support plug as a reference, axially extend a section of length at the end of the composite pipe to form a corrosion-resistant alloy section; Step 3: Remove the support plug to make the inner diameter of the corrosion-resistant alloy growth section match the inner diameter of the composite pipe. Step 4: Process the outer surface of the corrosion-resistant alloy section to make the outer diameter of the corrosion-resistant alloy section consistent with the outer diameter of the composite pipe; The support plug is made of carbon steel and has a stepped shaft-like outer surface. The nominal outer diameter of the large end of the support plug is the inner diameter of the composite pipe, with a tolerance of -0.1 to 0 mm; The nominal outer diameter of the small end of the support plug is the same as the inner diameter of the composite pipe, with a tolerance of -0.5 to 0.3 mm. The large end cylindrical section of the support plug has rounded chamfers at both ends and a length of 10-18mm, while the small end cylindrical section of the support plug has a length of 3-20mm. The large end of the support plug adopts a small clearance fit to ensure the coaxiality of the welded alloy section and the tube body, while the small end adopts a large clearance to ensure that the inner wall of the axially extended alloy section is a corrosion-resistant alloy after the support plug is removed by machining.

2. The bimetallic composite pipe end treatment method as described in claim 1, characterized in that, In step 2, the same alloy material as the corrosion-resistant alloy layer material on the inner wall of the composite pipe is used to axially grow the pipe end of the composite pipe.

3. The bimetallic composite pipe end treatment method as described in claim 1, characterized in that, In step 2, the pipe ends of the composite pipe are axially augmented using a welding method.

4. The bimetallic composite pipe end treatment method as described in claim 1, characterized in that, In step 3, the support plug is removed by machining.

5. The bimetallic composite pipe end treatment method as described in claim 1, characterized in that, In step 1, after the support plug is placed into the composite tube, the shoulders of the large and small ends are flush with the ends of the composite tube.

6. The bimetallic composite pipe end treatment method as described in claim 1, characterized in that, In step 2, using the small end of the support plug as support, full-wall-thickness welding is performed on the entire end face of the tube body by laser welding, and then extended axially.

7. A bimetallic composite pipe, characterized in that, The bimetallic composite tube is manufactured by the bimetallic composite tube end treatment method according to any one of claims 1-6.

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