A high-frequency pulse argon arc welding root welding process for a bimetal composite pipe

Abstract

This invention provides a high-frequency pulsed argon arc welding root welding process for bimetallic composite pipes. The root welding process includes a suitable inner cladding thinning bevel design, welding process parameters, and a high-frequency pulsed arc control method. This invention not only ensures good mechanical properties, appearance, and corrosion resistance at the root of the bimetallic composite pipe, but also allows for a slower heating rate at the pipe end and a shorter cooling time during welding, thereby significantly improving welding efficiency.

Description

Technical Field

[0001] This invention relates to the field of welding construction for surface pipelines in oil and gas fields, and more specifically, to a high-frequency pulse argon arc welding root welding process for bimetallic composite pipes. Background Technology

[0002] Bimetallic composite pipes are composite pipes made of carbon steel or low-alloy steel as the base pipe, with a thin layer of corrosion-resistant alloy lining the inner surface. This special structure combines the pressure resistance of carbon steel and the corrosion resistance of stainless steel, along with a relatively low price advantage. During the welding process of bimetallic composite pipes, special attention must be paid to the selection of the welding sequence and welding process to ensure the strength and corrosion resistance of the welded joint.

[0003] The root weld of bimetallic composite pipes is a weak point in the pipeline, and its quality directly affects the strength and toughness of the pipeline. Defects in the weld, such as cracks or slag inclusions, will reduce the pipeline's load-bearing capacity and increase the risk of leakage or breakage during operation. Bimetallic composite pipes typically consist of a base layer and a cladding layer. The cladding material usually has excellent corrosion resistance. If the root weld quality is poor, the cladding material may be damaged at the weld, thereby reducing the pipeline's corrosion resistance. Summary of the Invention

[0004] The purpose of this invention is to address at least one of the aforementioned deficiencies in the prior art. For example, the purpose of this invention is to provide a high-frequency pulsed argon arc welding root welding process for bimetallic composite pipes.

[0005] To achieve the above objectives, the present invention provides a high-frequency pulsed argon arc welding root welding process for bimetallic composite pipes. The root welding process includes a bevel form for appropriate inner cladding thinning, welding process parameters, and a high-frequency pulsed arc control method.

[0006] Optionally, the bevel type includes: the bevel thickness of the root weld area is 1.2mm-2.5mm, and the bevel blunt edge length is 1.2mm-2.0mm; the blunt edge and the outer bevel are transitioned by a rounded chamfer.

[0007] Alternatively, the radius of the chamfered arc is R2.4mm-R3.2mm.

[0008] Optionally, the blunt edges at both ends of the bevel are paired without gaps and the maximum gap is ≤0.5mm, and the misalignment is controlled to ≤1.5mm.

[0009] Alternatively, the bimetallic composite pipe may include a carbon steel base layer and a corrosion-resistant alloy layer.

[0010] Alternatively, the transition section between the blunt edge and the outer bevel of the bevel, as well as the blunt edge, is located in the corrosion-resistant alloy layer; the outer bevel is located in the carbon steel base layer.

[0011] Optionally, the welding process parameters include: high-frequency pulsed argon arc welding for root welding, with a pulse frequency of 2kHz-3kHz, a peak welding current of 200A-250A, a base current of 100A-125A, and a welding speed of 10cm / min-20cm / min.

[0012] Alternatively, the high-frequency pulse arc control method employs arc waveform control and tracking technology.

[0013] Alternatively, the arc waveform control and tracking technology can be implemented in the following ways:

[0014] Generate the required electric arc pulse waveform;

[0015] The position and state of the electric arc are monitored in real time using an arc sensor;

[0016] The collected arc signals are filtered and amplified to extract key information reflecting weld parameters.

[0017] The generation of the required arc pulse waveform includes adjusting the peak value, base value, pulse frequency, and pulse width of the pulse current.

[0018] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:

[0019] 1. This invention systematically develops and manufactures a high-frequency pulsed argon arc welding process and supporting equipment for bimetallic composite pipe root welding, realizing low heat input and rapid welding of bimetallic composite pipe roots.

[0020] 2. In addition to ensuring good mechanical properties, appearance and corrosion resistance of the root weld of bimetallic composite pipe, the present invention can also slow down the heating rate of the pipe end and shorten the cooling time of the welding process, thereby greatly improving the welding efficiency. Attached Figure Description

[0021] The above and other objects and / or features of the present invention will become clearer from the following description taken in conjunction with the accompanying drawings, in which:

[0022] Figure 1 The bevel form for thinning the inner cladding layer in the high-frequency pulse argon arc welding root welding process of the bimetallic composite pipe of the present invention is shown.

[0023] Figure 2 The example shows the welded joint design;

[0024] Figure 3 The sequence of weld beads in the example is shown.

[0025] Figure label:

[0026] 1-Bevel thickness of the root weld area; 2-Bevel blunt edge length; 3-Rounded chamfer; 4-Carbon steel base layer; 5-Corrosion resistant alloy layer. Detailed Implementation

[0027] In the following, a high-frequency pulsed argon arc welding root welding process for bimetallic composite pipes according to the present invention will be described in detail with reference to exemplary embodiments.

[0028] Existing conventional DC TIG welding involves high heat input during root welding of composite pipes in all positions, which easily leads to quality problems such as weld concavity. While the existing low-frequency pulse TIG welding technology would improve weld quality, conventional low-frequency TIG welding suffers from poor weld surface quality and low welding speed. Therefore, it is necessary to develop newer high-frequency pulse TIG welding process parameters and supporting control technologies and equipment to improve the process.

[0029] Exemplary embodiments

[0030] This exemplary embodiment provides a high-frequency pulsed argon arc welding root welding process for bimetallic composite pipes. The root welding process includes a bevel form for appropriate inner cladding thinning, welding process parameters, and a high-frequency pulsed arc control method.

[0031] In this embodiment, as Figure 1 As shown, the bevel form includes: the bevel thickness 1 of the root welding area is 1.2mm-2.5mm, the bevel blunt edge length 2 is 1.2mm-2.0mm; the blunt edge and the outer bevel are transitioned by a rounded chamfer 3.

[0032] In this embodiment, the radius of the chamfer is R2.4mm-R3.2mm.

[0033] In this embodiment, the blunt edges at both ends of the bevel are paired without gaps and the maximum gap is ≤0.5mm, and the misalignment is controlled to be ≤1.5mm.

[0034] The purpose of selecting the above parameters is to form a thin plate butt joint in the root weld area, which is beneficial to ensure the root weld penetration of high-frequency argon arc welding and improve the root weld welding speed.

[0035] In this embodiment, the bimetallic composite pipe includes a carbon steel base layer 4 and a corrosion-resistant alloy layer 5.

[0036] In this embodiment, the transition section between the blunt edge and the outer bevel, as well as the blunt edge, is located in the corrosion-resistant alloy layer; the outer bevel is located in the carbon steel base layer.

[0037] In this embodiment, the welding process parameters include: high-frequency pulsed argon arc welding for root welding, pulse frequency of 2kHz-3kHz, peak welding current of 200A-250A, base current of 100A-125A, and welding speed of 10cm / min-20cm / min.

[0038] Among them, when performing root welding with low-frequency pulse argon arc welding, the pulse frequency is 10Hz-40Hz, the peak welding current is 120-150A, the base current is 60-80A, and the welding speed is about 8cm / min.

[0039] In this embodiment, the high-frequency pulse arc control method adopts arc waveform control tracking technology, while general DC or low-frequency argon arc welding adopts the traditional arc voltage feedback tracking mode.

[0040] In this embodiment, the arc waveform control and tracking technology is implemented in the following ways:

[0041] Generate the required electric arc pulse waveform;

[0042] The position and state of the electric arc are monitored in real time using an arc sensor;

[0043] The collected arc signals are filtered and amplified to extract key information reflecting weld parameters.

[0044] In this embodiment, generating the required arc pulse waveform includes adjusting the peak value, base value, pulse frequency, and pulse width of the pulse current.

[0045] Among them, pulsed arc has better stability and controllability, which can reduce fluctuations and interference in the welding process, making the welding process more stable and the weld quality more consistent.

[0046] Example

[0047] When using this invention patent in engineering, the ends of the bimetallic composite pipes are first processed into a bevel shape with a thinner inner cladding layer as designed in this invention. The ends of two processed bimetallic composite pipes that meet the size requirements are then joined together, and the maximum gap and misalignment control are inspected to ensure that they meet the requirements of this invention.

[0048] The arc control tracking technology designed according to the present invention is used to set the arc control mode of the welding machine during the welding process.

[0049] The welding process parameters (pulse peak time, base time, welding peak current, base current, pulse peak time, base time, welding speed) during the welding process are set according to this invention to complete the entire welding construction process.

[0050] Welding was performed on the inner wall of an L360QS ERNiCrMo-3 composite pipe (diameter: φ=168.3mm; wall thickness: base layer 8mm, cladding layer 3mm). The joint design is as follows: Figure 2 As shown, the weld sequence is as follows Figure 3 As shown, the welding parameters are shown in Tables 1 and 2.

[0051] Table 1 Welding Layers

[0052]

[0053] Table 2 Welding parameters

[0054]

[0055] Although the present invention has been described above in conjunction with exemplary embodiments and accompanying drawings, those skilled in the art should understand that various modifications can be made to the above embodiments without departing from the spirit and scope of the claims.

Claims

1. A high-frequency pulsed argon arc welding root welding process for bimetallic composite pipes, characterized in that, The root welding process includes a suitable bevel form for thinning the inner cladding layer, welding process parameters, and a high-frequency pulsed arc control method.

2. The high-frequency pulse argon arc welding root welding process for bimetallic composite pipes according to claim 1, characterized in that, The bevel type includes: the bevel thickness of the root weld area is 1.2mm-2.5mm, and the bevel blunt edge length is 1.2mm-2.0mm; the blunt edge and the outer bevel are transitioned by a rounded chamfer.

3. The high-frequency pulse argon arc welding root welding process for bimetallic composite pipes according to claim 2, characterized in that, The radius of the chamfered arc is R2.4mm-R3.2mm.

4. The high-frequency pulse argon arc welding root welding process for bimetallic composite pipes according to claim 2, characterized in that, The blunt edges at both ends of the bevel are paired without gaps, with a maximum gap of ≤0.5mm and misalignment controlled to ≤1.5mm.

5. The high-frequency pulse argon arc welding root welding process for bimetallic composite pipes according to claim 1, characterized in that, The bimetallic composite pipe comprises a carbon steel base layer and a corrosion-resistant alloy layer.

6. The high-frequency pulse argon arc welding root welding process for bimetallic composite pipes according to claim 1, characterized in that, The transition section between the blunt edge and the outer bevel of the bevel, and the blunt edge is located in the corrosion-resistant alloy layer; the outer bevel is located in the carbon steel base layer.

7. The high-frequency pulse argon arc welding root welding process for bimetallic composite pipes according to claim 1, characterized in that, The welding process parameters include: high-frequency pulsed argon arc welding for root welding, pulse frequency of 2kHz-3kHz, peak welding current of 200A-250A, base current of 100A-125A, and welding speed of 10cm / min-20cm / min.

8. The high-frequency pulse argon arc welding root welding process for bimetallic composite pipes according to claim 1, characterized in that, The high-frequency pulse arc control method employs arc waveform control and tracking technology.

9. The high-frequency pulse argon arc welding root welding process for bimetallic composite pipes according to claim 8, characterized in that, The arc waveform control and tracking technology is implemented in the following ways: Generate the required electric arc pulse waveform; The position and state of the electric arc are monitored in real time using an arc sensor; The collected arc signals are filtered and amplified to extract key information reflecting weld parameters.

10. The high-frequency pulse argon arc welding root welding process for bimetallic composite pipes according to claim 9, characterized in that, The generation of the required arc pulse waveform includes adjusting the peak value, base value, pulse frequency, and pulse width of the pulse current.

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