Positioning jig for butt welding of pipe, and construction method of pipe

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 installing long, large-diameter steel pipes, such as chimneys, vertically above ground, and in particular to a positioning jig for butt welding. [Background technology]

[0002] Conventionally, when long, large-diameter steel pipes such as chimneys are installed vertically above ground, the steel pipes are generally joined together as follows. Fig. 4(a) shows flange welding. A pair of flanges 8 are welded to the joining side of each steel pipe 6, and the flanges 8 are welded together after circumferential alignment, for example, by aligning the through holes of each flange with a bolt. Welds 7 are required between each steel pipe 6 and each flange 8, and between the flanges 8 and each flange 8. Fig. 4(b) is called band wrapping or socket welding. A socket 9 is inserted into the outer periphery of one steel pipe 6, or a band 9 is wrapped 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 periphery of the socket (band) 6 and the other steel pipe 6 are welded. In this case, the welds 7 must extend over the entire circumference of both ends of the socket (band) 6.

[0003] Patent Document 1 also discloses a pipe joint for connecting pipes suspended in the vertical direction. This pipe joint includes a pair of plate-like flanges extending parallel to the pipe axis and fixed to the outside of a flange fixing band at two locations facing each other in the radial direction of the pipe. Each of the flanges has one or more connection holes for inserting fastening members. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-77502 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the conventional technology has the following problems. When installing long, large-diameter steel pipes vertically above ground, or when installing a duct vertically above ground, it may be necessary to stack multiple steel pipes vertically on site due to restrictions on the allowable lifting load of the heavy machinery used and installation space restrictions. In this case, the steel pipes from the second tier onwards must be precisely butted together, temporarily fixed, and seal welded circumferentially.

[0006] In this case, when flanges and sockets are used as in the conventional method, it is necessary to suspend the upper steel pipe and then align the hole positions of the flanges and the axial center positions of the socket and steel pipe. This work requires touching the suspended load, which is very dangerous and has low construction efficiency. Also, even with the technology of Patent Document 1, it is difficult to connect one side to the other while it is suspended.

[0007] The present invention has been made in consideration of the above circumstances, and has an object to provide a jig and a construction method that facilitates the alignment of steel pipes. [Means for solving the problem]

[0008] The positioning jig for butt welding of pipes of the present invention, which advantageously solves the above-mentioned problems, is characterized by comprising a pair of thin plates fixed along the outer periphery near the joint ends of two pipes that are hung in a vertical direction and joined by butt welding, one plate fixed to one of the thin plates and having a wedge-shaped tip protruding toward the other pipe, a crest fixed to the other thin plate with part of its crest notched so that the tip of the first plate can be inserted, and with the crest facing in a direction away from the first plate, and another plate fixed to the other thin plate so that the first plate can be temporarily held in place.

[0009] In addition, a more preferable solution for the pipe butt welding positioning jig of the present invention is that multiple sets of the one plate material, the angle-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 at rotationally symmetrical positions on the pipe.

[0010] The pipe construction method of the present invention, which advantageously solves the above-mentioned problems, is a pipe construction method in which a pipe is hung in the vertical direction and joined by butt welding using any of the above-mentioned pipe butt welding positioning jigs, and is characterized by including the steps of preparing the pair of thin plate materials, temporarily assembling the one plate material, the angle-shaped material, and the other plate material and arranging them in predetermined positions of the pair of thin plate materials, fixing the temporarily assembled members to the pair of thin plate materials, releasing the temporary assembly to form a pair of positioning jigs, and wrapping and fixing each positioning jig around each pipe.

[0011] In addition, a more preferable solution for the pipe installation method of the present invention may further include the steps of hanging a pipe to which a positioning jig is fixed, inserting a tip of one plate material into a notch at the top of the corresponding mountain-shaped material, aligning the axes of the pipes while butting them together, and temporarily fixing the one plate material to the other plate material with bolts, and circumferentially welding the butt portions of the pipes. Effect of the Invention

[0012] The positioning jig for butt welding of pipes and the method of construction of pipes according to the present invention facilitates alignment in the axial and circumferential directions, and enables safe lifting work of guide ropes, etc. In addition, the positioning jig does not require advanced processing of its members and can be prepared at low cost. It can flexibly respond to length changes during on-site construction. [Brief description of the drawings]

[0013] [Figure 1] 1A and 1B are schematic diagrams showing a positioning jig for butt welding of pipes according to one embodiment of the present invention, in which (a) is a side view and (b) is a front view. [Diagram 2]FIG. 2 is a schematic top view showing a state in which the pipe butt welding positioning jig according to the embodiment is fixed to the pipe. [Diagram 3] 1A and 1B are schematic diagrams showing a pipe construction method using a pipe butt welding positioning jig according to the above embodiment, in which (a) and (b) are front and side views showing the state before butt welding of the pipes, and (c) and (d) are front and side views showing the state when the pipes are joined. [Figure 4] 1A and 1B are schematic explanatory diagrams showing conventional pipe joining, in which (a) shows flange welding and (b) shows socket welding (band wrapping). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The following is a detailed description of the embodiments of the present invention. The following embodiments are merely examples of components and methods for embodying the technical idea of ​​the present invention, and are not intended to 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) FIG. 1 shows an example of a positioning jig 1 for butt welding of pipes according to this embodiment. FIG. 1(a) shows a side view, and FIG. 1(b) shows a front view. FIG. 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 materials 2 for fixing along the outer periphery of the steel pipe 6. Each thin plate material 2 is hung in the vertical direction and fixed to each of the two pipes to be joined by butt welding. The thin plate material 2 may have flexibility so as to be bent along the steel pipe 6, and examples of the thin plate material 2 include steel plates such as cold-rolled steel plate SPCC and hot-rolled steel plate SPHC. The thickness of the thin plate material 2 is about 0.5 to 3 mm, the width of the thin plate material 2 is about 20 to 100 mm, and it is preferable that the thin plate material 2 has strength to be flexibly bent. In addition, it is preferable that the length of the thin plate material 2 is about the outer periphery of the steel pipe 6. When the thin plate material 2 is placed along the outer periphery of the steel pipe 6, the axis coordinates of the thin plate material 2 can be easily aligned at any outer periphery position (any central angle) by aligning the start end and end end. The thin plate material 2 is preferably fixed to the steel pipe 6 by welding.

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

[0017] In the positioning jig 1 of this embodiment, an angle member 4 and a fixing plate member 5 for temporarily fixing a wedge-shaped plate member 3 are fixed to the other thin plate member 2, for example, a thin plate member 2B fixed to a lower steel pipe 6. In the case of FIG. 1, the angle member 4 is fixed to the thin plate member 2B, that is, the thin plate member 2A, with the crest facing the side away from the upper steel pipe and the open side facing the wedge-shaped plate member 3. The crest of the angle member 4 is notched so that the tip of the wedge-shaped plate member 3 can be inserted. The fixing plate member 5 is arranged so as to follow the inserted wedge-shaped plate member 3. When the positioning jig 1 is assembled, the through holes provided in the wedge-shaped plate member 3 and the fixing plate member 5 match, making it possible to fix them with bolts. The angle member 4 can be, for example, an equal-legged angle steel. The dimensions of the angle material 4 are about 20-50 mm×20-50 mm×t1-5 mm. The fixing plate material 5 is, for example, a general structural rolled steel SS material. The thickness of the fixing plate material 5 is about 1-5 mm.

[0018] It is preferable that the length of the notch at the top of the angle member 4 is approximately the width of the wedge-shaped plate material 3 at the insertion position in the assembled state, from the position where the angle member 4 contacts the steel pipe 6. It is also preferable that, when the positioning member 1 is in the assembled state, the entire wedge portion at the tip of the wedge-shaped plate material 3 passes through the notch portion of the angle member 4. This makes it easy to position the upper and lower steel pipes 6.

[0019] In the positioning jig 1 of this embodiment, it is preferable to install multiple sets of a wedge-shaped plate material 3, an angle-shaped material 4, and a fixing plate material 5 on the outer periphery of a steel pipe 6. As shown in FIG. 2, it is preferable to fix each set at a position that is not rotationally symmetrical in the circumferential direction. In this way, the axial positions of the upper and lower steel pipes 6 can be aligned, and the phases of the rotation angles of the upper and lower steel pipes 6 in the circumferential direction can be aligned and fixed. In the above explanation, the wedge-shaped plate material 3 is arranged on the upper side, but it may also be arranged on the lower side, and when multiple plates are arranged, they may be arranged alternately.

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

[0021] This embodiment first includes a step of preparing the pair of thin plate materials 2A, 2B. In this step, the thin plate materials 2A and 2B are placed on a flat surface such as a surface plate. As shown in FIG. 1, the cylindrical surfaces of the outer periphery of the upper and lower steel pipes 6 joined together are laid out on a flat surface.

[0022] Next, the wedge-shaped plate material 3, the angle-shaped material 4 and the fixing plate material 5 are temporarily assembled as one set, and are arranged at the position to be fixed on the thin plate material 2. At this time, the multiple sets are arranged in positions that are not rotationally symmetrical when fixed to the steel pipe 6.

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

[0024] Next, the positioning jigs 1A and 1B are wrapped around the outer periphery of the upper and lower steel pipes 6 and fixed in place.

[0025] Figure 3 shows a schematic diagram of the pipe installation procedure. To join steel pipes 6 together, first fix the lower steel pipe 6 to which the positioning jig 1B is fixed, and then hang the upper steel pipe 6 to which the positioning jig 1A is fixed (Figures 3(a) and (b)). At this time, it is not necessary to perfectly align the axes of the upper and lower steel pipes, and there is no problem as long as the tip of the wedge-shaped plate material 3 is within the range of the equal-sided opening of the angle-shaped material 4. For example, in Figure 3(a), even if the upper steel pipe is misaligned to the left and right, as the tip of the wedge-shaped plate material 3 descends, it slides along the side of the angle-shaped material 4 and can be inserted into the notch at the top of the mountain. Also, in Figure 3(b), even if the upper steel pipe is misaligned to the left and right, as the tip of the wedge-shaped plate material 3 is inserted into the notch of the angle-shaped material 4, the axes of the upper and lower steel pipes 6 will align. If multiple sets of wedge-shaped plate material 3, angle-shaped material 4 and fixing plate material 5 are fixed, the axial centers of the upper and lower steel pipes 6 can be more easily aligned.

[0026] Finally, the butt joints of the steel pipes 6 are seal welded in the circumferential direction. The positioning jig 1 may be fixed to the upper and lower steel pipes 6 in advance, or may be fixed to the upper and lower steel pipes 6 after the lengths of the steel pipes are adjusted on-site. [Explanation of symbols]

[0027] 1 (Butt welding) positioning jig 1A (Upper) Positioning Jig 1B (Lower) Positioning Jig 2, 2A, 2B Thin plate material 3 (wedge-shaped) board 4. Angle timber 5 (For fixing) Plate material 6 Steel pipe 7 Welding 8 Flanges 9 Socket (Band)

Claims

1. A pair of thin plate materials are fixed along the outer periphery of each of the two pipes near the joint ends that are joined by butt welding while being hung in the vertical direction; A plate member having a wedge-shaped tip protruding toward the other tube and fixed to one of the thin plate members; a mountain-shaped member having a portion of a crest cut out so that the tip of the first plate material can be inserted therein, the crest facing in a direction away from the first plate material and fixed to the other thin plate material; a second plate material fixed to the other thin plate material so as to be capable of being temporarily fixed in place; and

2. 2. The positioning jig for butt welding of pipes as described in claim 1, wherein a plurality of sets of the first plate material, the angle-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 positions on the pipe.

3. A pipe construction method in which a pipe is suspended in a vertical direction and joined by butt welding using the positioning jig for butt welding of a pipe according to claim 1 or 2, preparing the pair of thin plate materials; a step of provisionally assembling the one plate material, the angle-shaped material, and the other plate material, and arranging the pair of thin plate materials at predetermined positions; a step of fixing the temporarily assembled members to the pair of thin plate materials, and then releasing the temporarily assembled members to form a pair of positioning jigs; and wrapping and fixing each positioning jig around each pipe.

4. Further, a step of suspending the pipe to which the first positioning jig is fixed, inserting a tip of the first plate material into a notch at the crest of the corresponding angle-shaped member, butting the pipes together while aligning their axes, and temporarily fixing the first plate material and the other plate material with bolts; 4. The method of claim 3, further comprising the step of circumferentially welding the pipe butts.

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