Welding method for thin-wall pipeline

Abstract

The invention provides a welding method for a thin-wall pipeline, and relates to the technical field of pipeline welding, the welding method for the thin-wall pipeline comprises the following steps: (1) forming a groove in the welding surface of a to-be-welded part; and (2) backing welding and filling welding are conducted on the two to-be-welded parts. According to the welding method for the thin-wall pipeline, two welding gun movement modes are adopted, and penetration of the root is achieved through backing welding; a better weld bead appearance is achieved through filling welding, and surface welding defects are avoided; compared with an existing manual bottoming and mechanical welding filling process, station replacement after manual argon tungsten-arc welding bottoming is omitted, and continuous operation can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of pipeline welding, and in particular to a welding method for thin-walled pipelines. Background Art

[0002] The construction and installation of nuclear power plants involves extensive welding of prefabricated pipes, with thin-walled stainless steel pipes comprising a significant portion of these welds. Due to the thin wall thickness, deformation can easily occur during material transportation and preparation, leading to various misalignments during the weld assembly process. Conventional construction necessitates manual welding, which is relatively inefficient.

[0003] Due to the large number of thin-wall welds, there is a high demand for manual welders. However, the training cycle for thin-wall nuclear-grade manual welders is approximately one to two years. After certification, they need a year of adaptation to nuclear-grade products to maintain a high pass rate. The conventional training rate for thin-wall nuclear-grade manual welders is no longer sufficient to meet the current accelerated pace of nuclear power construction. Summary of the Invention

[0004] The purpose of the present invention is to provide a welding method for thin-walled pipes to alleviate the technical problems in the construction and installation of nuclear power plants, such as the need for a large number of pipe welding, low manual welding efficiency, long welder training cycle, and inability to keep up with the pace of nuclear power construction.

[0005] The present invention provides a welding method for thin-walled pipes, wherein the welding method comprises the following steps: (1) Create a groove on the welding surface of the workpiece to be welded; (2) Perform base welding and filler welding on the two parts to be welded.

[0006] In an optional embodiment, in step (1), the groove angle α is 37.5°±2.5°.

[0007] In an optional embodiment, in step (2), the conditions of the base welding include: peak current 95-110A, base current 40-60A, peak wire feeding speed 500-600mm / min, base wire feeding speed 350-550mm / min, welding speed 30-35mm / min, duty cycle 50-60%, and pulse period 900-1000ms.

[0008] In an optional embodiment, in step (2), the filling welding conditions include: peak current 95-125A, base current 35-60A, peak wire feeding speed 500-700mm / min, base wire feeding speed 300-600mm / min, welding speed 45-55mm / min, duty cycle 50-60%, and pulse period 500-600ms.

[0009] In an optional embodiment, during the filling welding process, the oscillation width is 5-7 mm. In an optional embodiment, in step (2), the two parts to be welded are paired without leaving a gap, and arc welding is started from the upper end of the parts to be welded, first welding the vertical downward position along the weld seam, and then welding the vertical upward position. In an optional embodiment, the part to be welded is a stainless steel thin-wall pipe, and the wall thickness of the stainless steel thin-wall pipe is 3-6 mm.

[0010] In an optional embodiment, in step (2), after the parts to be welded are assembled, they are placed flat in the 5G position; a TIG caliper-type mechanized welding machine is set up, and the left and right sides are adjusted to align the tungsten electrode with the center of the weld; the height of the welding gun is adjusted, and the arc starting height is controlled to lower the tungsten electrode to 2-3 mm below the bottom of the groove to be welded. In an optional embodiment, the parts to be welded have no blunt edges.

[0011] The welding method for thin-walled pipes provided by the present invention adopts two welding gun movement modes. Through the base welding, the root penetration is achieved; the filling welding achieves a better weld appearance and avoids surface welding defects; compared with the current manual base plus mechanized welding and filling process, the station replacement after manual tungsten inert gas arc welding is eliminated, and continuous operation is possible. BRIEF DESCRIPTION OF THE DRAWINGS In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0012] Figure 1 A schematic structural diagram of the groove of a workpiece to be welded in a welding method for thin-walled pipes provided in an embodiment of the present invention; Figure 2 A schematic structural diagram of a pair of parts to be welded in a welding method for thin-walled pipes provided in an embodiment of the present invention; Figure 3 A schematic structural diagram of the distribution of weld beads between two parts to be welded in a welding method for thin-walled pipes provided by an embodiment of the present invention; Figure 4 A schematic structural diagram of the welding positions of two parts to be welded in a welding method for thin-walled pipes provided in an embodiment of the invention.

[0013] Icon: 100-parts to be welded; 200-base weld; 300-filling weld. DETAILED DESCRIPTION

[0014] The terms "first", "second", "third", etc. are only used to distinguish and describe, and do not indicate the order of arrangement, nor can they be understood as indicating or implying relative importance.

[0015] Furthermore, terms such as "horizontal," "vertical," and "overhanging" do not necessarily imply that a component must be absolutely horizontal or overhanging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but rather that it can be slightly tilted.

[0016] In the description of this application, it should be noted that the terms "inside", "outside", "left", "right", "up", "down", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are the directions or positional relationships in which the product of the application is usually placed when in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limitations on this application.

[0017] In the description of this application, unless otherwise clearly specified and limited, the terms "set", "install", "connected" and "connect" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be a connection between the internal parts of two elements.

[0018] The technical solution of this application will be clearly and completely described below with reference to the accompanying drawings.

[0019] Reference Figure 1-Figure 4 The present invention provides a welding method for thin-walled pipes, wherein the welding method comprises the following steps: (1) A groove is formed on the welding surface of the workpiece 100 to be welded; (2) Perform base welding and filler welding on the two parts to be welded 100.

[0020] In some embodiments, in a welding method for thin-walled pipes, grooves are provided on both surfaces of two parts 100 to be welded, the two parts 100 to be welded are aligned, and then base welding and filler welding are performed.

[0021] Two welding gun movement modes are adopted according to the distribution of welds. The welding gun for base welding does not swing, which is convenient for achieving root penetration. However, the welding operator needs to fine-tune the welding gun position according to the actual working conditions during the process. The filling welding adopts swing welding to achieve better weld appearance and avoid surface welding defects. Compared with the current manual base welding plus mechanized welding filling process, it eliminates the need for station replacement after manual tungsten inert gas arc welding base welding and can operate continuously. The fully mechanized welding process is stable, the welding efficiency is high, the back of the weld has good penetration, and the one-time ray pass rate far exceeds that of traditional manual tungsten inert gas arc welding.

[0022] Reference Figure 1 In an optional embodiment, in step (1), the groove angle α is 37.5°±2.5°.

[0023] The groove angle α of the workpiece 100 to be welded is between 35° and 40°. The welding method for thin-walled pipes can realize single-sided welding and double-sided forming fully mechanized welding; it can achieve stable double-sided welding penetration, stable welding quality, high welding efficiency, effectively solve the shortage of manual welding personnel, reduce labor intensity, and improve the working environment.

[0024] In an optional embodiment, in step (2), the conditions of the base welding include: peak current 95-110A, base current 40-60A, peak wire feeding speed 500-600mm / min, base wire feeding speed 350-550mm / min, welding speed 30-35mm / min, duty cycle 50-60%, and pulse period 900-1000ms.

[0025] In an optional embodiment, in step (2), the filling welding conditions include: peak current 95-125A, base current 35-60A, peak wire feeding speed 500-700mm / min, base wire feeding speed 300-600mm / min, welding speed 45-55mm / min, duty cycle 50-60%, and pulse period 500-600ms.

[0026] In an optional embodiment, during the filling welding process, the oscillation width is 5-7 mm. In some embodiments, reference Figure 3 The bottom weld 200 is located below the filling weld 300. The bottom weld is performed first, and then the filling weld is performed. During the filling weld, the welding gun swings, that is, the filling weld adopts swing welding, and the swing width is 5-7mm. The filling weld adopts swing welding to facilitate the realization of a better weld appearance and avoid surface welding defects.

[0027] In an optional embodiment, in step (2), the two parts to be welded 100 are paired without leaving a gap, and arc welding is started from the upper end of the parts to be welded 100, and the vertical downward position is welded first along the weld seam, and then the vertical upward position is welded. In an optional embodiment, the workpiece 100 to be welded is a stainless steel thin-walled pipe, and the wall thickness of the stainless steel thin-walled pipe is 3-6 mm.

[0028] In an optional embodiment, in step (2), after the 100 pieces to be welded are paired, they are placed flat in the 5G position; a TIG caliper-type mechanized welding machine is set up, and the left and right sides are adjusted to align the tungsten electrode with the center of the weld; the height of the welding gun is adjusted, and the arc starting height is controlled to lower the tungsten electrode to 2-3 mm below the bottom of the groove to be welded. That is, two parts to be welded 100 are placed horizontally, and the pipeline is fixedly welded horizontally; TIG welding (Tungsten InertGas Welding) is also called non-melting inert gas shielded arc welding.

[0029] In an optional embodiment, the workpiece 100 to be welded has no blunt edges.

[0030] In some embodiments, the blunt edge refers to the un-grooved straight edge portion retained along the root of the joint groove when the weldment is beveled. When the weldment 100 is beveled, the weldment 100 has no blunt edge; when the two weldments 100 are paired, there is no gap between the two weldments 100; when welding, arc welding is started from the 12 o'clock direction of the pipe groove, and the vertical downward position is welded first along the weld seam, and then the vertical upward position is welded; during the welding process, attention is paid to the change in arc height, and corresponding adjustments are made in time. When welding to the joint, the wire feed is turned off and the arc is gradually extinguished.

[0031] Reference Figure 4 , the downward direction is from 12 o'clock, moving towards 3 o'clock, and then moving towards 6 o'clock; the upward direction is from 6 o'clock, moving towards 9 o'clock, and then moving towards 12 o'clock. When the workpiece 100 to be welded has no blunt edges, the groove processing speed of the workpiece 100 to be welded is faster, and there is no gap between the two workpieces 100 to be welded, which can achieve stable double-sided welding, stable welding quality, high welding efficiency, effectively solving the shortage of manual welding personnel, reducing labor intensity, and improving the working environment.

[0032] The welding method for thin-walled pipes provided by the present invention adopts two welding gun movement modes. Through the base welding, the root penetration is achieved; the filling welding achieves a better weld appearance and avoids surface welding defects; compared with the current manual base plus mechanized welding and filling process, the station replacement after manual tungsten inert gas arc welding is eliminated, and continuous operation is possible. Although nuclear power installation units have optimized the process of manual primer and mechanized welding filling, this process requires back and forth transportation and changing workstations during construction, resulting in lower efficiency compared to full manual welding. Therefore, the fully mechanized stainless steel thin-wall welding process has become a key technology for pipeline welding construction in nuclear power plant construction.

[0033] The welding method for thin-walled pipes provided by the present invention realizes fully mechanical welding of stainless steel thin walls, thereby solving the problems of a large number of thin-walled pipe welds in the current nuclear power construction process, a shortage of manual welders for pipe welding, and a relatively low efficiency of the welding method of manual welding primer plus mechanized welding filling.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than 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 they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A welding method for thin-walled pipes, wherein: The welding method The method comprises the following steps: (1) A groove is formed on the welding surface of the workpiece (100) to be welded; (2) Perform base welding and filler welding on the two parts to be welded (100).

2. The welding method for thin-walled pipes according to claim 1, characterized in that: In step (1), the groove angle α is 37.5°±2.5°.

3. The welding method for thin-walled pipes according to claim 1, characterized in that: In step (2), the conditions for the base welding include: peak current 95-110A, base current 40-60A, peak wire feeding speed 500-600mm / min, base wire feeding speed 350-550mm / min, welding speed 30-35mm / min, duty cycle 50-60%, and pulse period 900-1000ms.

4. The welding method for thin-walled pipes according to claim 1, characterized in that: In step (2), the filling welding conditions include: peak current 95-125A, base current 35-60A, peak wire feeding speed 500-700mm / min, base wire feeding speed 300-600mm / min, welding speed 45-55mm / min, duty cycle 50-60%, and pulse period 500-600ms.

5. The welding method for thin-walled pipes according to claim 1, characterized in that: During the filling welding process, the swing width is 5-7mm.

6. The welding method for thin-walled pipes according to claim 1, characterized in that: In step (2), the two parts to be welded (100) are paired without leaving any gap, and arc welding is started from the upper end of the parts to be welded (100), and the vertical downward position is welded first along the weld seam, and then the vertical upward position is welded.

7. The welding method for thin-walled pipes according to claim 1, characterized in that: in, The part (100) to be welded is a stainless steel thin-wall pipe, and the wall thickness of the stainless steel thin-wall pipe is 3-6 mm.

8. The welding method for thin-walled pipes according to claim 1, characterized in that: In step (2), after the parts to be welded (100) are assembled, they are placed flat at the 5G position; a TIG caliper-type mechanized welding machine is set up, and the left and right sides are adjusted to align the tungsten electrode with the center of the weld; the height of the welding gun is adjusted, and the arc starting height is controlled to lower the tungsten electrode to 2-3 mm below the bottom of the groove to be welded.

9. The welding method for thin-walled pipes according to claim 1, characterized in that: The parts to be welded (100) have no blunt edges.

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