JP3541166B2 - Pipe joining method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pipe joining method for joining two butted ends of two pipes whose end faces are joined to each other, and more particularly to a pipe joining method that can be suitably implemented in pipeline laying work.
[0002]
[Prior art]
The pipeline is constructed by laying a plurality of conduits at the laying site with their end faces butting each other, and the butted portions of the respective conduits are welded by various welding methods. In such a pipeline, a pipe having a large diameter is used to transport a fluid such as a gas in a large volume, and a thick pipe is used to transport the fluid at a high pressure. Therefore, in order to construct a pipeline quickly, it is necessary to join the butt portions at high speed, and various welding methods such as a MAG welding method, a TIG welding method, a laser welding method, and an electron beam welding method can be made at high speed. It has been devised. In particular, since the electron beam welding method is a method capable of high-speed welding of thick plates, an apparatus for using this electron beam welding method for butt welding of pipelines has been developed.
[0003]
Japanese Patent Laid-Open No. 52-26331 discloses a method in which a joint of a material to be welded is melted halfway through the thickness of the material to be welded by each electron beam from two electron beam emitting devices. Is disclosed.
[0004]
Japanese Patent Application Laid-Open No. 55-128384 discloses a method of welding the outer surface side of a material to be welded by electron beam welding first, and then shifting the inner surface side of the material to be welded by electron beam welding after shifting for a certain time. Is disclosed.
[0005]
Japanese Patent Application Laid-Open No. Sho 56-119679 discloses a method of welding by irradiating the butt surfaces of two metal bodies simultaneously with electron beams from both sides.
[0006]
[Problems to be solved by the invention]
As described above, the electron beam welding method is a method capable of high-speed welding. However, when welding is performed by irradiating an electron beam upwardly, that is, vertically upward, a butting portion called a backside bead or the like. It is difficult to form an extra bank that swells on the outer peripheral surface side. In other words, in the upward welding position, the condition tolerance for forming the back bead is small, and due to a slight error in the groove gap of the butt portion, the back bead needs to be repaired after electron beam welding, and the conduit High-speed construction of construction is hindered. Moreover, the mechanism for decompressing the inner side and the outer side of the abutting portion is required, and the configuration of the welding apparatus becomes complicated.
[0007]
The prior arts disclosed in JP-A-52-26331, JP-A-55-128384, and JP-A-56-119679 all require a mechanism for decompressing the outside of the tube. To do.
[0008]
In addition, since the bead width formed by the electron beam welding method is narrowed, the bead has a shape projecting sharply from the butt portion toward the inside of the conduit. Therefore, this bead becomes a flow resistance of the fluid in the pipe, and the fluid may cause a pressure loss. Further, during the ultrasonic test of the welded portion, a strong reflected wave is returned at the protruding portion of the bead, which may hinder accurate inspection.
[0009]
Accordingly, an object of the present invention is to provide a method for joining pipes, which can join two pipes whose end faces are butted against each other at a high speed.
[0010]
Another object of the present invention is to provide a method for joining pipes that can form a bead with as little flow resistance as possible in the pipe.
[0011]
[Means for Solving the Problems]
The present invention described in claim 1 is a method for joining pipes, in which the butted portions of two pipes whose end faces are butted against each other are joined.
By the first welding means for welding under atmospheric pressure, the outer peripheral surface side region of the butted portion is welded over the entire circumference,
Next, the second welding means for irradiating and welding an electron beam under reduced pressure irradiates the electron beam from the inner side of the tube toward the inner peripheral surface of the butt portion, and thereby the inner peripheral surface side region of the butt portion is formed. A pipe joining method characterized by welding all around the circumference.
[0012]
According to the present invention, first, the outer peripheral surface side region of the butt portion is welded over the entire circumference by the first welding means that performs welding in a state where the welding atmosphere is under atmospheric pressure. Thus, since the bead width of the formed bead is increased by the first welding means that does not depressurize the welding atmosphere, a back bead is reliably formed in the outer peripheral surface side region of the butt portion. As the first welding means, a welding means other than an electron beam welding means capable of welding without reducing the welding atmosphere can be employed. For example, an arc welding means, a gas welding means, a laser welding means, or the like can be used. Can be adopted.
[0013]
Next, the second welding means for irradiating and welding an electron beam under reduced pressure irradiates the electron beam from the inner side of the tube toward the inner peripheral surface of the butt portion, and thereby the inner peripheral surface side region of the butt portion is formed. Weld all around. That is, since the electron beam welding means is employed as the second welding means, the inner peripheral surface side region of the butt portion can be welded at a high speed. Moreover, since the outer peripheral surface side area | region of the butt | matching part is welded over the perimeter by the 1st welding means, the inner side and the outer side of the butt | matching part are interrupted | blocked airtightly, and, thereby, an inner peripheral surface side area | region by the 2nd welding means , It is only necessary to depressurize only the inside of the butt portion, and there is no need to depressurize the outside.
[0014]
According to a second aspect of the present invention, in the configuration according to the first aspect, after the inner peripheral surface side region of the butt portion is welded by the second welding means, toward the bead formed on the inner peripheral surface side, In this method, the electron beam is irradiated with energy lower than that in the welding of the inner peripheral surface region.
[0015]
According to the present invention, the bead on the inner peripheral surface side formed by the second welding means is irradiated with an electron beam having a lower energy than that during welding of the inner peripheral surface side region, such as a defocused electron beam. The surface of the bead is partially melted and smoothed. Therefore, with this smooth bead, the resistance of the fluid flow in the pipe is reduced as much as possible, and the pressure loss is also reduced. Furthermore, there is no obstacle to nondestructive inspection such as ultrasonic inspection.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram showing a welding apparatus 1 that realizes a pipe joining method according to an embodiment of the present invention. First, the configuration of the welding apparatus 1 will be described with reference to FIG. The welding apparatus 1 includes a clamp unit 4 that fixes two pipes 2a and 2b, a first welding unit 18 that welds an outer peripheral surface side region 30 of a butted portion 5 of the two tubes 2a and 2b, and a butted portion 5. The second welding means 19 for welding the inner peripheral surface side region 31 and the groove forming means 11 for forming the groove portion 25 in the outer peripheral surface side region 31 of the butt portion 5.
[0017]
The clamping means 4 is inserted into the two annular ring members 8a and 8b and these ring members 8a and 8b from the outer peripheral surface side (upper side in FIG. 1) to the inner side in the diameter line direction (lower side in FIG. 1). And a plurality of clamp bolts 10 mounted across the two ring members 8a and 8b. End portions of two pipes 2a and 2b laid substantially horizontally are inserted into the ring members 8a and 8b, and the end surfaces 12 are abutted against each other. Thereafter, the straight circle straightening bolt 9 is screwed into the inside of the tubes 2a and 2b in the diameter line direction (downward in FIG. 1), thereby correcting the respective tubes 2a and 2b into a perfect circle shape. The tubes 2a and 2b are fixed so that the tube shafts 13a and 13b are coaxial.
[0018]
The first welding means 18 has a laser output head 7, and this laser output head 7 is disposed on the outer side 24 of the abutting portion 5 with the laser emission port 14 facing the outer peripheral surface 16 of the abutting portion 5. Centering on a tube axis 13 common to the tubes 2a and 2b, the tube 2a and 2b are provided so as to be movable along the outer periphery of the tubes 2a and 2b. The laser output head 7 emits a laser beam 20 from the laser emission port 14 toward the outer peripheral surface 16 of the butting portion 5. As the laser beam 20, a pulse laser such as a YAG laser or a continuous wave laser such as a carbon dioxide gas laser is used.
[0019]
The second welding means 19 has an electron beam output head 6, and this electron beam output head 6 is disposed on the inner side 23 of the abutting portion 5 with the beam exit 15 facing the inner peripheral surface 17 of the abutting portion 5. It arrange | positions and it is provided so that a movement along the inner periphery of the pipe | tubes 2a and 2b centering | focusing on the pipe axis 13 common to the pipe | tubes 2a and 2b. The electron beam output head 6 emits an electron beam 21 from the beam emission port 15 toward the inner peripheral surface 17 of the butting portion 5.
[0020]
The groove forming means 11 is disposed on the outer side 24 of the abutting portion 5 with the groove forming portion 22 opposed to the outer peripheral surface 16 of the abutting portion 5, and is centered on the tube shaft 13 common to the tubes 2 a and 2 b. As described above, the pipes 2a and 2b are provided so as to be movable along the outer circumference.
[0021]
Next, with reference to FIG. 2 to FIG. 9, a method for joining pipes according to the present invention will be described. FIG. 2 is a diagram for explaining the pipe joining method of the present invention, FIG. 3 is a flowchart of the pipe joining method of the present invention, FIG. 4 is a diagram showing step s1, and FIG. FIG. 6 is a diagram showing step s3, FIG. 7 is a diagram showing step s4, FIG. 8 is a diagram showing step s5, and FIG. 9 is a diagram showing step s6. .
[0022]
First, in step s1, as shown in FIG. 4, the two pipes 2a and 2b to be joined are laid substantially horizontally with their pipe shafts 13a and 13b being coaxial, and the pipes 2a and 2b are respectively laid horizontally. The end faces 12 are butted against each other, and the pipes 2 a and 2 b are fixed by the clamping means 4.
[0023]
Next, in step s2, as shown in FIG. 5, the groove forming means 11 is moved along the outer periphery of the tubes 2a and 2b around the tube axis 13 common to the tubes 2a and 2b. The outer peripheral surface side region 30 (upper side in FIG. 5) is scraped over the entire circumference. Thereby, the groove part 25 is formed in the outer peripheral surface side area | region 30 of the butt | matching part 5 over the perimeter.
[0024]
Next, in step s3, as shown in FIGS. 2 and 6, welding is performed while moving the laser output head 7 around the tube axis 13 common to the tubes 2a and 2b along the outer periphery of the tubes 2a and 2b. In a state where the atmosphere is under atmospheric pressure, the laser beam 21 is irradiated toward the groove portion 25 formed in the butt portion 5. As a result, the groove portion 25 is partially melt welded over the entire circumference. Thus, since the groove part 25 of the butt | matching part 5 is partially welded by the 1st welding process which welds in the state where welding atmosphere is under atmospheric pressure, in the outer peripheral surface side area | region 30 of the butt | matching part 5, Over the circumference, the surging that rises to the outer peripheral surface side, that is, the back bead 26 is reliably formed. In addition, since the welding operation of the outer peripheral surface side region 30 in the first welding process also serves to temporarily attach the tubes 2a and 2b, the tubes 2a and 2b are accurately positioned. Therefore, the welding operation of the inner peripheral surface side region 31 of the butt portion 5 in the second welding process of the next process becomes easy. Furthermore, the gap tolerance of the butting portion 5 is improved.
[0025]
Next, in step s4, the inside of the abutting portion 5 is evacuated and depressurized, and as shown in FIGS. 2 and 7, the electron beam output head 6 as the second welding means is connected to the tubes 2a and 2b. The electron beam 20 is radiated toward the inner peripheral surface 17 of the butt portion 5 in a state where the welding atmosphere is under reduced pressure while moving along the inner periphery of the tubes 2a and 2b around the shaft 13. Thereby, the inner peripheral surface side region 31 of the butted portion 5 is welded over the entire circumference. In this way, in the second welding process in which the welding atmosphere is in a reduced pressure state, that is, in a vacuum atmosphere, the inner peripheral surface side region 31 of the butt portion 5 is welded by electron beam welding. The side region 31 is welded at high speed. Further, since the backside bead 26 is formed over the entire circumference in the outer peripheral surface side region 30 of the abutting portion 5, the inner side 23 and the outer side 24 of the abutting portion 5 are hermetically blocked by the backside bead 26. . Therefore, in the second welding process, only the inner side 23 of the butt portion 5 may be evacuated and depressurized, and the outer side 24 need not be evacuated and depressurized.
[0026]
Next, in step s5, as shown in FIG. 8, the electron beam output head 6 is moved along the inner peripheral surface 17 about the tube axis 13 while the inner side 23 of the abutting portion 5 is maintained in a reduced pressure state. The electron beam 29 having a lower energy than that in the second welding step, that is, the focus is blurred toward the projecting portion 28 projecting to the inner side 23 of the tube of the bead 27 in the inner peripheral surface side region 31 of the butting portion 5. An electron beam 29 is irradiated. As a result, the protruding portion 28 of the bead 27 is partially melted and smoothed. That is, the inner peripheral surface side of the butting portion 5 is subjected to decorative welding. Therefore, in this smoothly processed bead 27, the flow resistance with respect to the fluid flowing through the inner side 23 of the pipes 2a and 2b is reduced as much as possible, and the pressure loss of the fluid is also reduced. Furthermore, there is no obstacle to nondestructive inspection such as ultrasonic inspection.
[0027]
Then, it progresses to step s6 and joining of the two pipe | tubes 2a and 2b is completed. As shown in FIG. 9, the thickness T2 of the backside bead 26 on the outer peripheral surface side of the butt portion 5 is preferably 50% or less of the thickness T1 of the tube 2, and the bead 27 on the inner peripheral surface side. The thickness T3 of the tube 2 is preferably 50% or more of the thickness T1 of the tube 2. That is, the butted portion 5 is welded to a depth of 50% or less of the tube 2 thickness T1 by the first welding method, and then a depth of 50% or more of the thickness T1 of the tube 2 is welded by the second welding method. It is preferable. Thus, the pipes 2a and 2b can be efficiently joined by welding more than half of the pipe thickness by the second welding method using an electron beam.
[0028]
The above-described method for joining pipes of the present invention is preferably implemented in, for example, pipeline laying work, and further includes a large-diameter pipe for transporting a fluid such as a large-capacity gas and a thick plate for withstanding high-pressure transport. This is particularly preferred when connecting the tubes.
[0029]
In the pipe joining method of the present embodiment, the laser welding method is adopted as the first welding method, but an arc welding method or a gas welding method can be adopted instead of the laser welding method.
[0030]
【The invention's effect】
According to the first aspect of the present invention, the butted portions of the two pipes whose end faces are butted against each other are welded by the first welding means that performs welding in a state where the welding atmosphere is under atmospheric pressure. A back bead can be reliably formed in the outer peripheral surface side region of the portion. Next, the second welding means for irradiating and welding an electron beam under reduced pressure irradiates and welds the electron beam from the inside of the tube toward the inner peripheral surface of the butt portion. The surface side region can be welded at high speed. Moreover, since the back bead is formed in the outer peripheral surface side region of the butt portion, the inner side and the outer side of the butt portion are blocked, and only the inner side of the butt portion is decompressed during the welding operation by the second welding means. Well, there is no need to depressurize the outside.
[0031]
According to the second aspect of the present invention, the bead on the inner peripheral surface side formed by the second welding means is irradiated with the low energy electron beam, whereby the bead is partially melted and smoothed. Therefore, this smooth bead reduces the resistance of the fluid flow in the pipe as much as possible, and also reduces the fluid pressure loss. Furthermore, there is no obstacle to nondestructive inspection such as ultrasonic inspection.
[Brief description of the drawings]
FIG. 1 is a diagram showing a welding apparatus 1 that realizes a pipe joining method according to an embodiment of the present invention.
FIG. 2 is a view for explaining a method of joining pipes according to the present invention.
FIG. 3 is a flowchart of the pipe joining method of the present invention.
FIG. 4 is a diagram showing step s1.
FIG. 5 is a diagram showing step s2.
FIG. 6 is a diagram showing step s3.
FIG. 7 is a diagram showing step s4.
FIG. 8 is a diagram showing step s5.
FIG. 9 is a diagram showing step s6.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Welding apparatus 2a, 2b Tube 4 Clamp means 5 Butt part 6 Electron beam output head 7 Laser output head 18 1st welding means 19 2nd welding means 20 Laser beam 21 Electron beam 26 Back wave bead

Claims (2)

In the joining method of the pipe | tube which joins the butt | matching part of two pipes by which an end surface is faced | matched mutually,
By the first welding means for welding under atmospheric pressure, the outer peripheral surface side region of the butt portion is welded over the entire circumference,
Next, the second welding means for irradiating and welding an electron beam under reduced pressure irradiates the electron beam from the inner side of the tube toward the inner peripheral surface of the butt portion, and thereby the inner peripheral surface side region of the butt portion is formed. A method for joining pipes, characterized by welding the entire circumference. After the inner peripheral surface side region of the butt portion is welded by the second welding means, the electron beam is directed toward the bead formed on the inner peripheral surface side with lower energy than when welding the inner peripheral surface region. The tube joining method according to claim 1, wherein:

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