Welding structure of large-diameter pipeline

Abstract

The welding structure comprises a first pipeline and a second pipeline which are arranged in a butt joint mode, a V-shaped groove is formed in the butt joint position of the pipe wall of the first pipeline and the pipe wall of the second pipeline, an opening of the V-shaped groove faces the interior of the pipeline, and a ceramic gasket is arranged outside the V-shaped groove. The bottom layer, the filling layer and the covering layer are sequentially welded in the V-shaped groove in an FCAW-G welding mode; according to the welding structure of the large-diameter pipeline, the FCAW-G welding technology is applied to welding of the large-diameter pipeline, and the quality requirements of relevant welding preparation specifications are completely met. The CO2 single-side welding of the ceramic lining greatly improves the welding efficiency and obtains a good economic effect in practical application.

Description

Technical Field

[0001] The utility model belongs to the technical field of large-diameter pipeline welding, and in particular relates to a welding structure of a large-diameter pipeline. Background Art

[0002] The statements herein merely provide background art related to the present invention and do not necessarily constitute prior art.

[0003] With the development of modern welding technology and the advancement of science and technology, flux-cored CO2 gas shielded welding (FCAW-G for short) has been widely promoted and applied in various welding fields such as construction, bridges, chemical machinery, new energy, etc. due to its high welding productivity, high deposition efficiency, fast deposition speed and significant protection effect.

[0004] The welding of large-diameter pipes is usually achieved by welding tools due to their large diameter. For example, Chinese utility model patent CN215846235U discloses a large-diameter pipe welding tool. By placing the two sections of pipes to be welded on a roller, the pipes slowly move along the welding direction according to the rotation speed parameters set by the roller, thereby achieving the welding of large-diameter pipes. However, in the construction of large-diameter drain pipes, due to limited on-site construction conditions, welding tools and submerged arc automatic welding cannot be used for welding. If ordinary double-sided welding is used, it will not only lead to a long welding time and low production efficiency, but also continuous welding cannot be performed due to the long weld. Especially during construction in winter, the temperature is low and the interlayer temperature cools quickly, which is very easy to produce hardened structure, and the welding strength cannot be guaranteed. Utility Model Content

[0005] The utility model aims to provide a welding structure for large-diameter pipelines, which is proposed for the application of a ceramic liner FCAW-G welding method on large-diameter pipelines, thereby improving the welding efficiency and welding length of large-diameter pipelines.

[0006] In order to achieve the above purpose, the utility model is implemented through the following technical solutions:

[0007] In the first aspect, an embodiment of the utility model provides a welding structure of a large-diameter pipeline, comprising a first pipeline and a second pipeline that are butt-jointed, a V-shaped groove is provided at the butt joint position of the pipe walls of the first pipeline and the second pipeline, the opening of the V-shaped groove faces the inside of the pipeline, a ceramic liner is arranged outside the V-shaped groove, and a base layer, a filling layer and a cover layer are welded in sequence in the V-shaped groove using the FCAW-G welding method.

[0008] As a further technical solution, the angle of the V-shaped groove is 55-65°.

[0009] As a further technical solution, the ceramic liner includes a first ceramic liner and a second ceramic liner, and the first ceramic liner is arranged inside the second ceramic liner.

[0010] As a further technical solution, the cross section of the first ceramic liner is in an inverted trapezoidal shape, and the second ceramic liner is provided with a groove corresponding to the first ceramic liner.

[0011] As a further technical solution, the upper surfaces of the first ceramic liner and the second ceramic liner are both arranged in close contact with the outer wall surfaces of the first pipe and the second pipe.

[0012] As a further technical solution, the second ceramic liner is fixed to the inner wall surfaces of the first pipe and the second pipe by means of a fixing adhesive strip.

[0013] As a further technical solution, the base layer, the filling layer and the cover layer, the base layer has a conical cross-section, and the filling layer and the cover layer have a fan-shaped cross-section.

[0014] As a further technical solution, the base layer, filling layer and cover layer are made of the same welding wire.

[0015] As a further technical solution, the FCAW-G welding method uses carbon dioxide as a shielding gas, and the purity of the carbon dioxide gas is greater than 99.5%.

[0016] As a further technical solution, the butt clearance between the first pipe and the second pipe is 2-4 mm, and the misalignment between the first pipe and the second pipe is less than 1 mm.

[0017] The beneficial effects of the above-mentioned embodiments of the utility model are as follows:

[0018] The welding structure of the large-diameter pipe provided by the utility model can realize the forced forming of the back side in the double-sided forming of single-sided welding through the ceramic liner, that is, a supporting material is added to the back of the weld to make the back have good weld forming. The liner supports the metal molten pool and prevents the arc from burning through and forcing the back side of the weld to be formed, ensuring sufficient penetration during welding and ensuring that the root of the weld is melted through. Using the ceramic liner as a welding processing aid will make the weld strong, beautiful, crack-resistant, tough and have stable mechanical properties, which can effectively improve the welding quality, reduce welding costs, and save corporate expenses.

[0019] The utility model provides a welding structure for a large-diameter pipeline, which is provided with a plurality of welding layers such as a cover layer, a filling layer and a base layer. The plurality of welding layers adopt the same welding wire, which ensures a good bonding degree between adjacent welding layers and improves the quality and strength of the weld.

[0020] The welding structure of large-diameter pipelines provided by the utility model applies FCAW-G welding process to large-diameter pipeline welding, which fully meets the quality requirements of relevant welding preparation specifications. Ceramic lining CO2 single-sided welding greatly improves welding efficiency and obtains good economic effects in practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention.

[0022] Figure 1 It is a schematic diagram of the welding structure of a large-diameter pipeline of the utility model;

[0023] Figure 2 It is a schematic diagram of the V-shaped groove of the utility model.

[0024] The schematic diagram is for illustrative purposes only;

[0025] Among them, 1. the first pipeline; 2. the second pipeline; 3. the first ceramic liner; 4. the second ceramic liner; 5. the base layer; 6. the first filling layer; 7. the second filling layer; 8. the cover layer; 9. the welding gun; 10. the welding wire; 11. the V-shaped groove. DETAILED DESCRIPTION

[0026] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0027] Example 1

[0028] In a typical implementation of the present invention, Figure 1 and Figure 2 As shown, a welding structure of a large-diameter pipeline is provided, including a first pipeline 1 and a second pipeline 2 that are butt-jointed, a V-shaped groove 11 is provided at the butt joint position of the pipe walls of the first pipeline 1 and the second pipeline 2, the V-shaped groove 11 opens toward the inside of the pipeline, a ceramic liner is provided outside the V-shaped groove, and a base layer 5, a filling layer and a cover layer 8 are welded in sequence in the V-shaped groove 11 by using the FCAW-G welding method.

[0029] In this embodiment, the angle of the V-shaped groove is 55-65°, preferably 60°, and the size of the groove is selected according to the thickness of the pipe wall.

[0030] In this embodiment, the ceramic liner includes a first ceramic liner 3 and a second ceramic liner 4, wherein the first ceramic liner 3 is arranged inside the second ceramic liner 4, further, the cross section of the first ceramic liner 3 is inverted trapezoidal, the second ceramic liner 4 is provided with a groove corresponding to the first ceramic liner, and the upper surfaces of the first ceramic liner 3 and the second ceramic liner 4 are both arranged in close contact with the outer wall surfaces of the first pipe 1 and the second pipe 2. The ceramic liner can effectively absorb and disperse heat, reduce the thermal stress of the welding part, and thus prevent the occurrence of thermal damage and deformation. At the same time, the two layers of ceramic liners can also prevent the entry of oxygen, reduce the oxidation reaction during welding, and improve the welding quality.

[0031] In this embodiment, the ceramic liner is sintered by preparing a variety of ceramic raw materials and flux, and has the characteristics of fire resistance, non-deformation, high strength, etc. It is mainly suitable for single-sided welding of flat, vertical and horizontal butt joints of general steel structures, that is, single-sided welding and double-sided forming at one time.

[0032] In this embodiment, the second ceramic liner 3 is fixed to the inner wall surfaces of the first pipe and the second pipe by means of a fixing adhesive strip.

[0033] In this embodiment, the base layer 5, the filling layer and the cover layer 7, the base layer 5 has a conical cross section, and the filling layer and the cover layer have a fan-shaped cross section. This welding layer structure can increase the contact area between adjacent welding layers and improve the strength of the weld. The filling layer can be provided with multiple layers according to the wall thickness of the pipeline, such as a first filling layer 6 and a second filling layer 7 in this embodiment.

[0034] In this embodiment, the base layer, filling layer and cover layer are made of the same welding wire to ensure a good bonding degree between adjacent welding layers.

[0035] In this embodiment, the FCAW-G welding method uses carbon dioxide as the shielding gas, and the purity of the carbon dioxide gas is greater than 99.5%.

[0036] In this embodiment, the butt clearance between the first pipe and the second pipe is 2-4 mm to ensure full penetration, and the misalignment between the first pipe and the second pipe is less than 1 mm, so that better weld formation and welding quality can be obtained.

[0037] The welding process of the welding structure of the large-diameter pipe of the utility model is described in detail below in conjunction with a specific embodiment:

[0038] 1. Preparation before welding:

[0039] The base material is Q235B φ2200×14mm pipe, machined with 60° V-shaped groove (such as Figure 1As shown), ceramic liner, welding machine NBC-500, welding material E71 T-1Cφ1.2. CO2 is selected as the shielding gas, firstly, it matches the welding material requirements, and secondly, carbon dioxide has better protection and economy. The purity of carbon dioxide gas used in welding is >99.5%.

[0040] 2. Cleaning the groove:

[0041] Clean the rust, oil stains, and debris within 20mm on both sides of the groove to reveal the metallic luster.

[0042] 3. Pairing:

[0043] Use the assembly tool to adjust the misalignment and the gap between the two ends. The gap between the two ends should be within 2-4mm to ensure full penetration. The misalignment is 0-1mm. In order to obtain better weld formation and welding quality, a special assembly tool is used inside the pipeline instead of positioning welding. When using the welding tool, it should be clamped and fixed firmly. When the welding base welding is completed, the welding residue of the tool should be removed and polished in time.

[0044] 4. Welding parameter selection is shown in Table 1:

[0045] Table 1 Welding parameters

[0046]

[0047] 5. Welding pipelines according to Figure 1 Arrangement is carried out. During welding, the welding wire 10 in the welding gun 9 extends out 2mm. The welders adopt uphill welding and two-person symmetrical welding. During welding, "backflow" is prohibited to ensure welding quality.

[0048] During welding, pay attention to the following:

[0049] (1) The welding of the base layer is the key technology of the single-sided welding and double-sided forming welding operation. In order to ensure the quality of the back weld, the ceramic pad on the back should be even and firm. When welding the base, a relatively high welding current should be used as much as possible to ensure the penetration depth and keep the arc continuous. During the operation, the welding rod should be moved smoothly and evenly. Improper operation may cause the back of the weld to be unfused or not fully penetrated.

[0050] (2) Since the ceramic liner is not conductive, the welding speed should not be too fast. When the arc is broken, it should be restarted from two-thirds of the arc pit.

[0051] (3) When welding with uphill welding, pay attention to the backward tilt angle of the welding wire. Due to the arc force, the molten metal moves to the tail of the molten pool, which is conducive to the direct heating of the base material at the bottom of the molten pool by the arc. The arc penetration ability is increased, the fusion of the back weld is improved, and the molten width and excess height of the back weld are increased. The opposite is true for forward tilt welding. Therefore, the backward tilt angle of the welding wire is usually controlled to be 10-20°. Pay attention to the cleaning of the welding slag between each layer. Use a grinder to remove the welding slag before continuing welding. The temperature between welding layers should be less than 300℃.

[0052] The mechanical analysis of the weld obtained in the above specific implementation is as follows:

[0053] The chemical composition of the deposited metal through spectral testing is shown in Table 2:

[0054] Table 2 Metal chemical composition

[0055]

[0056] The mechanical properties of the weld are shown in Table 3:

[0057] Table 3 Mechanical properties of weld

[0058]

[0059] The test shows that the above welding structure fully meets the quality requirements of the relevant welding preparation specifications. The key points of the CO2 single-sided welding process of ceramic liner are to control the current, voltage and welding speed and ensure that the welded ceramic liner is well attached to the back of the workpiece. CO2 single-sided welding of ceramic liner has greatly improved the welding efficiency and achieved good economic results in practical applications.

[0060] The above description is only the preferred embodiment of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A welding structure for a large-diameter pipeline, characterized in that: The invention comprises a first pipeline and a second pipeline which are butt-jointed, wherein a V-shaped groove is provided at the butt joint position of the pipe walls of the first pipeline and the second pipeline, the opening of the V-shaped groove faces the inside of the pipeline, a ceramic liner is provided outside the V-shaped groove, and a base layer, a filling layer and a cover layer are welded in sequence in the V-shaped groove by using FCAW-G welding method.

2. The welding structure of a large-diameter pipeline according to claim 1, characterized in that: The angle of the V-shaped groove is 55-65°.

3. The welding structure of a large-diameter pipeline according to claim 1, characterized in that: The ceramic liner includes a first ceramic liner and a second ceramic liner, wherein the first ceramic liner is disposed inside the second ceramic liner.

4. The welding structure of a large-diameter pipeline according to claim 3, characterized in that: The cross section of the first ceramic liner is in an inverted trapezoidal shape, and the second ceramic liner is provided with a groove corresponding to the first ceramic liner.

5. The welding structure of a large-diameter pipeline according to claim 3, characterized in that: The upper surfaces of the first ceramic liner and the second ceramic liner are both arranged in close contact with the outer wall surfaces of the first pipe and the second pipe.

6. The welding structure of a large-diameter pipeline according to claim 3, characterized in that: The second ceramic liner is fixed to the inner wall surfaces of the first pipe and the second pipe by means of a fixing adhesive strip.

7. The welding structure of a large-diameter pipeline according to claim 1, characterized in that: The base layer, the filling layer and the cover layer, the base layer has a conical cross section, and the filling layer and the cover layer have a fan-shaped cross section.

8. The welding structure of a large-diameter pipeline according to claim 7, characterized in that: The base layer, filling layer and cover layer are made of the same welding wire.

9. The welding structure of a large-diameter pipeline according to claim 1, characterized in that: The FCAW-G welding method uses carbon dioxide as a protective gas, and the purity of the carbon dioxide gas is greater than 99.5%.

10. The welding structure of a large-diameter pipeline according to claim 1, characterized in that: The butt clearance between the first pipe and the second pipe is 2-4 mm, and the misalignment between the first pipe and the second pipe is less than 1 mm.

Images