Argon filling method for backing argon arc welding of large-diameter pipeline to prevent back oxidation

Abstract

The argon filling method comprises the following steps that (1) water-soluble paper is attached to the front face of a welded junction, an arc-shaped inflation cover matched with the pipeline is fixed to the back face of the welded junction, a stainless steel net is arranged on the opening portion, connected with the welded junction, of the arc-shaped inflation cover, and the arc-shaped inflation cover is filled with stainless steel wires; an inflation interface is arranged on the arc-shaped inflation cover; (2) the arc-shaped inflation cover is inflated with argon through an inflation connector, and the flow of the inflated argon is 4-12 L / min; and (3) after the arc-shaped inflation cover is filled with argon, a small amount of water-soluble paper on the front face of the welded junction is uncovered, and backing welding is started. Before backing welding of a welded junction is started, the inflation cover is filled with argon, deposited metal in the welding process is isolated from air through the argon, oxidation of the welded junction is avoided, meanwhile, the cover is only filled with argon, the using amount of the argon is small, continuous manual movement is not needed after installation, labor can be reduced, the cost can be saved, and meanwhile the safety of argon filling operation can be guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of pipeline welding, in particular to an argon filling method for argon arc welding of large-diameter pipelines to prevent back oxidation. Background Art

[0002] At present, nickel alloy pipes and stainless steel pipes are widely used in various types of petrochemical equipment. Since nickel alloy and stainless steel pipes are easily oxidized during welding construction, when argon arc welding is used for base welding, the front of the weld is generally protected by the welding torch spraying argon gas, and the high-temperature weld metal on the back of the weld is easily exposed to air and oxidized, and argon gas needs to be filled to protect the back. For large-diameter prefabricated welds with a diameter greater than or equal to DN600 in prefabrication plants, the first method is to use sponge plugging on both sides; the second method is to arrange operators inside the pipeline to hold movable argon filling tools and move synchronously with the front welding arc. The first method uses sponge plugging. Due to the large diameter and long pipe, a large amount of argon is required, which is costly; the second method requires additional operators to climb into the pipeline and work synchronously with the base welding, which has high labor costs, high temperature inside the pipe, poor working environment, and safety risks in confined space operations. Therefore, it is necessary to design an argon filling structure to solve the problems of large argon consumption, high labor costs, and operational safety risks. Summary of the invention

[0003] The present invention solves the technical problems existing in the known technology and provides an argon filling method for argon arc welding of large-diameter pipelines to prevent back oxidation, which can reduce the amount of argon gas used, reduce labor, and ensure the safety of argon filling operations.

[0004] The technical solution adopted by the present invention to solve the technical problems existing in the known technology is: an argon filling method for argon arc welding of large-diameter pipelines to prevent back oxidation, the steps are as follows: 1) sticking water-soluble paper on the front of the weld, fixing an arc-shaped inflatable hood that matches the pipeline on the back of the weld, the mouth of the arc-shaped inflatable hood connecting the weld is provided with a stainless steel mesh, stainless steel wire is filled in the arc-shaped inflatable hood, and an inflation interface is provided on the arc-shaped inflatable hood; 2) filling argon into the arc-shaped inflatable hood through the inflation interface, and the flow rate of the argon filling is 4-12L / min; 3) after the arc-shaped inflatable hood is filled with argon, uncover a small amount of water-soluble paper on the front of the weld and start the base welding.

[0005] There are multiple arc-shaped inflatable hoods, which are evenly distributed along the circumference and supported by radial brackets. The radial brackets are provided with support rods corresponding to the arc-shaped inflatable hoods one by one. The support rods adopt a telescopic structure, and the arc-shaped inflatable hood is provided with fixed support positioning grooves that match the support rods.

[0006] There are two arc-shaped inflatable hoods, and the radial support is composed of a telescopic rod.

[0007] The mesh diameter of the stainless steel mesh is 3-4 mm.

[0008] The diameter of the steel wire of the stainless steel mesh is 1-2 mm.

[0009] The arc-shaped inflatable hood is made of stainless steel thin plates.

[0010] The groove width of the arc-shaped inflatable hood is 150-200mm.

[0011] The height of the arc-shaped inflatable hood is 40-60 mm.

[0012] The advantages and positive effects of the present invention are: by filling the inflatable hood with argon before the start of the weld base welding, the argon isolates the deposited metal in the welding process from the air, thereby avoiding the oxidation of the weld, and at the same time, the structure only fills the hood with argon, the amount of argon is small, and after installation, there is no need for manual continuous movement, which can reduce labor and save costs, and at the same time, the safety of the argon filling operation can be ensured. In addition, the present invention has a simple structure, is easy to manufacture and use, and has a low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of the application of the present invention;

[0014] Figure 2 This is a schematic diagram of the structure of the tooling used in the present invention.

[0015] In the figure: 1, welding joint; 2-1, 2-2 are arc-shaped inflation hoods; 3, radial bracket; 4, inflation interface; 5, fixed support positioning groove. DETAILED DESCRIPTION

[0016] In order to further understand the content, features and effects of the present invention, the following embodiments are given as examples and described in detail with reference to the accompanying drawings:

[0017] See also Figure 1 and Figure 2 , a method for filling argon to prevent back oxidation during argon arc welding of large-diameter pipelines, the steps are as follows:

[0018] 1) A water-soluble paper is pasted on the front of the weld 1, and an arc-shaped inflatable cover 2-1, 2-2 that matches the pipeline is fixed on the back of the weld 1. The opening of the arc-shaped inflatable cover 2-1, 2-2 connected to the weld 1 is provided with a stainless steel mesh, and stainless steel wire is filled in the arc-shaped inflatable cover 2-1, 2-2. An inflatable interface 4 is provided on the arc-shaped inflatable cover 2-1, 2-2;

[0019] 2) Argon is charged into the arc-shaped charging covers 2-1 and 2-2 through the charging interface 4, and the flow rate of the charging argon is 4-12 L / min;

[0020] 3) After the arc-shaped inflatable hoods 2-1 and 2-2 are filled with argon gas, peel off a small amount of water-soluble paper on the front of the weld and start the base welding.

[0021] In this embodiment, there are multiple arc-shaped inflatable hoods 2-1 and 2-2, which are evenly distributed along the circumference and supported by radial brackets 3. The radial brackets 3 are provided with support rods corresponding to the arc-shaped inflatable hoods 2-1 and 2-2 one by one. The support rods are of a telescopic structure, and fixed support positioning grooves 5 that match the support rods are provided on the arc-shaped inflatable hoods 2-1 and 2-2. Preferably, there are two arc-shaped inflatable hoods 2-1 and 2-2, and the radial brackets 3 are composed of a telescopic rod, which has a simple structure and is easy to use. One set can be arranged during welding, and then moved to the next welding position after welding is completed; or several sets can be evenly arranged along the weld to cover the entire weld.

[0022] Preferably, the mesh diameter of the stainless steel mesh is 3-4 mm; the wire diameter of the stainless steel mesh is 1-2 mm. The arc-shaped inflatable hoods 2-1 and 2-2 are made of stainless steel sheets. The groove width of the arc-shaped inflatable hoods 2-1 and 2-2 is 150-200 mm; the height of the arc-shaped inflatable hoods 2-1 and 2-2 is 40-60 mm; the length is determined according to the length of the weld and the number of arc-shaped inflatable hoods.

[0023] Although the preferred embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments, which are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can make many forms without departing from the scope of protection of the present invention and the claims, all of which fall within the scope of protection of the present invention.

Claims

1. A method for filling argon to prevent back oxidation during argon arc welding of large-diameter pipelines, characterized in that: Here are the steps: 1) A water-soluble paper is pasted on the front of the weld, and an arc-shaped inflatable cover that matches the pipeline is fixed on the back of the weld. A stainless steel mesh is provided at the mouth of the arc-shaped inflatable cover that connects with the weld, stainless steel wire is filled in the arc-shaped inflatable cover, and an inflatable interface is provided on the arc-shaped inflatable cover; 2) Fill the arc-shaped inflatable hood with argon gas through the inflatable interface, and the flow rate of the inflatable argon gas is 4-12L / min; 3) After the arc-shaped inflatable hood is filled with argon gas, peel off a small amount of water-soluble paper on the front of the weld and start the base welding.

2. The argon filling method for argon arc welding of large-diameter pipelines to prevent back oxidation according to claim 1 is characterized in that: There are multiple arc-shaped inflatable hoods, which are evenly distributed along the circumference and supported by radial brackets. The radial brackets are provided with support rods corresponding to the arc-shaped inflatable hoods one by one. The support rods adopt a telescopic structure, and the arc-shaped inflatable hood is provided with fixed support positioning grooves that match the support rods.

3. The argon filling method for argon arc welding of large-diameter pipelines to prevent back oxidation according to claim 2, characterized in that: There are two arc-shaped inflatable hoods, and the radial support is composed of a telescopic rod.

4. The argon filling method for argon arc welding of large-diameter pipelines to prevent back oxidation according to claim 1, characterized in that: The mesh diameter of the stainless steel mesh is 3-4 mm.

5. The argon filling method for argon arc welding of large-diameter pipelines to prevent back oxidation according to claim 1, characterized in that: The diameter of the steel wire of the stainless steel mesh is 1-2 mm.

6. The argon filling method for argon arc welding of large-diameter pipelines to prevent back oxidation according to claim 1, characterized in that: The arc-shaped inflatable hood is made of stainless steel thin plates.

7. The argon filling method for argon arc welding of large-diameter pipelines to prevent back oxidation according to claim 1, characterized in that: The groove width of the arc-shaped inflatable hood is 150-200mm.

8. The argon filling method for argon arc welding of large-diameter pipelines to prevent back oxidation according to claim 1, characterized in that: The height of the arc-shaped inflatable hood is 40-60 mm.

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