Positioning jig for butt welding of pipes and method for installing pipes

Abstract

To provide a jig facilitating positioning of steel pipes, and to provide a construction method.SOLUTION: A jig includes: a pair of thin plate materials fixed along an outer periphery of the vicinity of a joint end part of two pipes suspended in the vertical direction and joined by butt welding; one plate material having a wedge-shaped tip projecting to the other pipe, and fixed to the one thin plate material; a mountain-shaped material having a part of a mountain peak cut out so as to insert the tip of the one plate material, and fixed to the other thin plate material while directing the mountain peak to a direction of separating from the one plate material; and another plate material fixed to the other thin plate material so as to temporarily fix the one plate material. A construction method of a pipe includes suspending pipes in the vertical direction and joining them with butt welding by using the jig.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for constructing a long and large-diameter steel pipe such as a chimney in a vertical direction with respect to the ground, and particularly to a positioning jig for butt welding.

Background Art

[0002] Conventionally, when constructing a long and large-diameter steel pipe such as a chimney in a vertical direction with respect to the ground, the joining of steel pipes has generally been performed as follows. FIG. 4(a) shows flange welding. A pair of flanges 8 are welded to the joining sides of each steel pipe 6, and after performing circumferential alignment, for example, by aligning the through holes of the respective flanges with bolts, the space between the flanges 8 is welded. The welded portion 7 is required between each steel pipe 6 and each flange 8, and between the flanges 8 and the flanges 8. FIG. 4(b) shows what is called band winding or socket welding. A socket 9 is inserted into the outer circumference of one steel pipe 6, or a band 9 is wound around it and one end is circumferentially welded to the steel pipe 6, and the other steel pipe 6 is inserted into the other end of the socket (band) 9, and the outer circumference of the socket (band) 6 and the other steel pipe 6 are welded. In this case, the welded portion 7 needs to extend over the entire circumference at both ends of the socket (band) 6.

[0003] Also, Patent Document 1 discloses a pipe joint for connecting pipes suspended in the vertical direction. This pipe joint includes a pair of plate-shaped flanges fixed outside a flange fixing band at two locations extending parallel to the pipe axis and facing each other in the radial direction of the pipe. One or more connection holes for inserting fastening members are provided in each of the flanges.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, conventional technology had the following problems: When installing long, large-diameter steel pipes vertically to the ground, or when installing ducts vertically to the ground, it may be necessary to stack multiple steel pipes vertically on-site due to limitations on the lifting capacity of the heavy machinery used and constraints on the installation space. In this case, the steel pipes from the second layer onwards must be precisely butted together, temporarily fixed, and then sealed with circumferential welding.

[0006] In the conventional method, when using flanges and sockets, it was necessary to suspend the upper steel pipe and then align the hole positions of the flanges and the axial positions of the socket and steel pipe. This work involved touching the suspended load, which was extremely dangerous and inefficient. Furthermore, even in the technology described in Patent Document 1, it was difficult to connect one end to the other while it was suspended.

[0007] This invention has been made in view of the above circumstances, and aims to provide a jig and construction method that facilitates the alignment of steel pipes. [Means for solving the problem]

[0008] The positioning jig for butt welding of pipes according to the present invention, which advantageously solves the above problems, is characterized by comprising: a pair of thin plate materials fixed along the outer circumference near the respective joining ends of two pipes that are suspended vertically and joined by butt welding; one plate material having a wedge-shaped tip protruding toward the other pipe and fixed to one of the thin plate materials; a mountain-shaped material having a part of the peak cut out so that the tip of the first plate material can be inserted, with the peak facing away from the first plate material and fixed to the other thin plate material; and another plate material fixed to the other thin plate material so that the first plate material can be temporarily fixed.

[0009] Furthermore, a more preferable solution for the positioning jig for butt welding of pipes according to the present invention may be that multiple sets of the combination of one plate material, the V-shaped material, and the other plate material are fixed to the pair of thin plate materials, and the fixing positions of each of the sets are not rotationally symmetrical to the pipe.

[0010] A pipe construction method according to the present invention, which advantageously solves the above problems, is a pipe construction method that uses a positioning jig for butt welding of pipes according to any of the above, to suspend the pipes in the vertical direction and join them by butt welding, and is characterized by including the steps of: preparing the pair of thin plate materials; temporarily assembling the one plate material, the V-shaped material, and the other plate material and arranging them in predetermined positions on the pair of thin plate materials; fixing the temporarily assembled members to the pair of thin plate materials, then releasing the temporary assembly to form a pair of positioning jigs; and wrapping and fixing each positioning jig around each pipe.

[0011] Furthermore, a more preferable solution for the pipe installation method according to the present invention may include the steps of: suspending a pipe to which a positioning jig is fixed; inserting the tip of the first plate into the notch at the peak of the corresponding peak of the V-shaped material; butting the pipes together while aligning their axes; and temporarily fixing the first plate and the other plate with bolts; and welding the butt joint of the pipes in the circumferential direction. [Effects of the Invention]

[0012] The positioning jig for butt welding of pipes and the pipe installation method according to the present invention facilitate axial and circumferential positioning, enabling safe lifting operations using guide ropes, etc. Furthermore, the positioning jig does not require advanced processing of its components and can be prepared inexpensively. It can also flexibly accommodate length changes during on-site construction. [Brief explanation of the drawing]

[0013] [Figure 1] A schematic diagram showing a positioning jig for butt welding of pipes according to one embodiment of the present invention, where (a) is a side view and (b) is a front view. [Figure 2]This is a schematic top view showing the positioning jig for butt welding of pipes according to the above embodiment fixed to the pipe. [Figure 3] This is a schematic diagram illustrating a pipe construction method using a positioning jig for butt welding of pipes according to the above embodiment, where (a) and (b) are a front view and a side view showing the state of the pipes before butt joining, and (c) and (d) are a front view and a side view showing the state of the pipes when they are joined. [Figure 4] This is a schematic diagram illustrating conventional pipe joining methods, where (a) represents flange welding and (b) represents socket welding (band welding). [Modes for carrying out the invention]

[0014] The embodiments of the present invention will be described in detail below. The following embodiments are illustrative of components and methods for realizing the technical idea of ​​the present invention, and do not limit the configuration to those described below. In other words, the technical idea of ​​the present invention can be modified in various ways within the technical scope described in the claims.

[0015] (Positioning jig) Figure 1 shows an example of a positioning jig 1 for butt welding of pipes according to this embodiment. Figure 1(a) is a side view, and Figure 1(b) is a front view. Figure 2 shows a top view of the positioning jig 1 fixed to a steel pipe 6. The positioning jig 1 has a pair of thin plate members 2 for fixing along the outer circumference of the steel pipe 6. Each thin plate member 2 is suspended vertically and fixed to each of the two pipes that are joined by butt welding. The thin plate members 2 only need to have flexibility so that they can be bent along the steel pipe 6, and examples include steel plates such as cold-rolled steel sheet SPCC and hot-rolled steel sheet SPHC. The thickness of the thin plate member 2 is about 0.5 to 3 mm, the width of the thin plate member 2 is about 20 to 100 mm, and it is preferable that the thin plate member 2 has strength that allows it to be bent flexibly. Also, it is preferable that the length of the thin plate member 2 is about the same as the outer circumference of the steel pipe 6. When the thin sheet material 2 is placed along the outer circumference of the steel pipe 6, the axial coordinates of the thin sheet material 2 can be easily aligned at any outer circumference position (any central angle) by matching the start and end points. It is preferable to fix the thin sheet material 2 to the steel pipe 6 by welding.

[0016] In this embodiment, the positioning jig 1 has a wedge-shaped plate 3 fixed to one of the thin plate materials 2, for example, a thin plate material 2A fixed to the upper steel pipe 6, with its tip protruding toward the lower steel pipe 6. The wedge-shaped plate 3 preferably has a right edge on the side along the steel pipe 6, and the width of the plate decreases towards the tip of the opposite side. The wedge-shaped plate 3 can be fixed to the thin plate material 2A by welding at the weld joint 7. The wedge-shaped plate 3 is exemplified by general structural rolled steel material SS. The thickness of the wedge-shaped plate 3 is about 3 to 10 mm.

[0017] The positioning jig 1 of this embodiment fixes a fixing plate 5 for temporarily fixing the angle bar 4 and the wedge-shaped plate 3 to the other thin plate material 2, for example, the thin plate material 2B fixed to the lower steel pipe 6. In the case of FIG. 1, the angle bar 4 is fixed to the thin plate material 2B with the peak of the angle facing away from the thin plate material 2A, that is, the upper steel pipe, and the opening side facing the wedge-shaped plate 3. Further, the peak of the angle bar 4 is cut out so that the tip of the wedge-shaped plate 3 can be inserted. The fixing plate 5 is arranged along the inserted wedge-shaped plate 3. In the assembled state of the positioning jig 1, the through holes provided in the wedge-shaped plate 3 and the fixing plate 5 coincide, and they can be fixed with bolts. The angle bar 4 can be, for example, an equilateral angle steel. The dimensions of the angle bar 4 are about 20 to 50 mm × 20 to 50 mm × t1 to 5 mm. The fixing plate 5 is exemplified by, for example, a general structural rolled steel material SS material. The plate thickness of the fixing plate 5 is about 1 to 5 mm.

[0018] The notch length at the peak of the angle bar 4 is preferably about the plate width of the wedge-shaped plate 3 at the insertion position in the assembled state, starting from the position where the angle bar 4 contacts the steel pipe 6. Also, in the assembled state of the positioning member 1, it is preferable that all the wedge portions at the tips of the wedge-shaped plates 3 pass through the notch portions of the angle bar 4. By doing so, the positioning of the upper and lower steel pipes 6 can be easily performed.

[0019] In this embodiment, it is preferable to install a plurality of sets of the wedge-shaped plate 3, the angle bar 4, and the fixing plate 5 on the outer periphery of the steel pipe 6 as a set. As shown in FIG. 2, it is preferable to fix each set at a position that is not rotationally symmetric in the circumferential direction. By doing so, in addition to aligning the axial center positions of the upper and lower steel pipes 6, the phase of the rotational angle in the circumferential direction of the upper and lower steel pipes 6 can be aligned and fixed. In the above description, the wedge-shaped plate 3 is arranged on the upper side, but it may also be on the lower side, and when a plurality are arranged, they may be arranged alternately.

[0020] (Construction method) The pipe construction method according to this embodiment uses the above-mentioned positioning jig for butt welding and includes the following steps, and is a method of suspending the pipes in the vertical direction and joining them by butt welding.

[0021] This embodiment first includes the step of preparing the pair of thin plate materials 2A and 2B. In this step, the thin plate materials 2A and 2B are arranged on a flat surface such as a surface plate. As shown in FIG. 1, the cylindrical surface on the outer periphery of the state where the upper and lower steel pipes 6 are joined is in a state of being developed on a plane.

[0022] Next, the wedge-shaped plate material 3, the gusset 4, and the fixing plate material 5 are temporarily assembled as a set and arranged at the positions to be fixed on the above-mentioned thin plate material 2. At this time, when a plurality of sets are fixed to the steel pipe 6, they are in positions that are not rotationally symmetric.

[0023] Next, the temporary assembly is released, for example, separated into the upper positioning jig 1A and the lower positioning jig 1B.

[0024] Next, each of the positioning jigs 1A and 1B is wound around and fixed to the outer periphery of the upper and lower steel pipes 6 respectively.

[0025] FIG. 3 schematically shows the construction procedure of the pipes. For the joining of the steel pipes 6, first, after fixing the lower steel pipe 6 to which the positioning jig 1B is fixed, the upper steel pipe 6 to which the positioning jig 1A is fixed is lifted (FIGS. 3(a) and (b)). At this time, it is not necessary to completely align the axes of the upper and lower steel pipes. As long as the tip of the wedge-shaped plate material 3 enters the range of the opening of the equilateral side of the gusset 4, there is no problem. For example, in FIG. 3(a), even if the upper steel pipe is displaced left and right, as the tip of the wedge-shaped plate material 3 descends, it can slide along the side of the gusset 4 and be inserted into the notch at the top of the mountain. Also, in FIG. 3(b), even if the upper steel pipe is displaced left and right, as the tip of the wedge-shaped plate material 3 is inserted into the notch portion of the gusset 4, the axes of the upper and lower steel pipes 6 will be aligned. If a plurality of sets of the wedge-shaped plate material 3, the gusset 4, and the fixing plate material 5 are fixed, it is possible to more easily align the axes of the upper and lower steel pipes 6.

[0026] Finally, the butting portion of the steel pipes 6 is sealed and welded in the circumferential direction. Note that the positioning jig 1 may be fixed to each of the upper and lower steel pipes 6 in advance, or may be fixed to each of the upper and lower steel pipes 6 after adjusting the length of the steel pipe on-site.

Explanation of Reference Numerals

[0027] 1. Positioning jig (for butt welding) 1A (Upper) Positioning jig 1B (Lower) positioning jig 2, 2A, 2B Thin plate material 3 (wedge-shaped) board 4. Triangular timber 5 (For fixing) Plate material 6 Steel pipe 7. Welded parts 8 flanges 9 Socket (band)

Claims

1. A pair of thin plates are fixed along the outer circumference near the joint ends of two pipes that are suspended vertically and joined by butt welding, The tip protruding toward the other pipe has a wedge shape, and one plate is fixed to one of the thin plate materials, A mountain-shaped member is fixed to the other thin plate material with the tip of the first plate material inserted into a portion of the mountain's peak, and the mountain's peak is positioned away from the first plate material. A positioning jig for butt welding pipes, comprising: one plate material fixed to another thin plate material so as to be able to temporarily fasten the aforementioned plate material; and another plate material.

2. A positioning jig for butt welding of a pipe according to claim 1, wherein multiple sets of the set of the one plate material, the V-shaped material, and the other plate material are fixed to the pair of thin plate materials, and the fixing position of each set is not in a rotationally symmetrical position on the pipe.

3. A method for installing pipes, comprising using a positioning jig for butt welding of pipes as described in claim 1 or 2, to suspend the pipes vertically and join them by butt welding, The steps include preparing the pair of thin sheet materials, The steps include temporarily assembling the first plate material, the V-shaped material, and the other plate material, and placing them in predetermined positions on the pair of thin plate materials, The steps include: fixing the temporarily assembled members to the pair of thin plate materials, then releasing the temporary assembly to form a pair of positioning jigs; A method for installing pipes, comprising the step of wrapping and securing each positioning jig around each pipe.

4. Furthermore, the procedure involves suspending a pipe to which a positioning jig is fixed, inserting the tip of the first plate into the notch at the peak of the corresponding peak of the V-shaped material, aligning the axes of the two pipes and butting them together, and temporarily fixing the first plate and the other plate with bolts. A method for constructing a pipe according to claim 3, comprising the step of welding the butt joint of the pipes in the circumferential direction.

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