Fish bank and method of manufacturing the same

Abstract

To provide a fish bank that can be manufactured at a low cost, and a method of manufacturing such a fish bank.SOLUTION: A fish bank 1 comprises a skeleton structure 150 and an oil-well pipe P fixed to the skeleton structure 150.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a fish reef and a method for manufacturing the fish reef.

Background Art

[0002] Conventionally, a fish reef that is installed on the bottom of the water such as the seabed and forms an environment suitable for aquatic organisms to inhabit is known. For example, Patent Document 1 discloses a fish reef including four columnar bodies that contact the bottom of the water, a beam-like body stretched between the four columnar bodies, and a top surface portion, and having an internal space surrounded by these members. A plurality of woods are accommodated in this internal space, and the gaps between the woods form an environment suitable for the inhabitation of aquatic organisms.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, it is preferable to use a material excellent in durability (for example, corrosion resistance and rust prevention) in water (for example, in the sea or a lake) for the members for constructing the fish reef. For this reason, the members used for the fish reef are more expensive than the members used for general structures, which has contributed to an increase in the cost of constructing the fish reef.

[0005] The present invention has been made to solve the above problems, and an object thereof is to provide a fish reef that can be manufactured at low cost and a method for manufacturing the fish reef.

Means for Solving the Problems

[0006] The fish reef according to the first invention includes a skeletal structure and an oil well pipe fixed to the skeletal structure.

[0007] According to this configuration, by using an oil well pipe excellent in corrosion resistance and rust prevention in water as a component of the fish reef, the fish reef can be constructed at low cost. As this oil well pipe, for example, those generated as waste materials when disassembling an oil well (submarine oil well) constructed for extracting oil or the like from a submarine oil field can be used. By reusing the oil well pipes generated as such waste materials, the fish reef can be constructed at low cost. Note that the oil well pipe may be an unused one. Even when using an unused oil well pipe, the cost can be reduced compared to the case of using dedicated parts (dedicated parts having no other uses) designed specifically for fish reefs.

[0008] In the second invention, in the first invention, a pair of connection and support bodies are further provided, which are interposed between two locations spaced apart in the length direction on the outer peripheral surface of the oil well pipe and the skeleton structure, and connect and support the oil well pipe to the skeleton structure. Each of the pair of connection and support bodies has a support plate fixed to the outer peripheral surface of the oil well pipe via a first weld bead portion. It is preferable that each support plate has a first end surface that is an end surface connecting both side surfaces in the thickness direction and abuts against the outer peripheral surface of the oil well pipe and extends along the length direction thereof.

[0009] According to this configuration, by minimizing the length of the welding portion (i.e., the portion where the first welding bead portion is formed) when fixing the oil well pipe to the skeletal structure, the amount of heat transferred to the oil well pipe during welding can be minimized, thereby preventing low-temperature cracking from occurring in the oil well pipe after welding. Here, low-temperature cracking is, for example, cracking that occurs within 48 hours due to the cooling of the oil well pipe after welding. Generally, oil well pipes are known as materials not suitable for welding because this low-temperature cracking is likely to occur. According to this configuration, by bringing the first end face of the support plate, which is a plate-like body, into contact with the outer peripheral surface of the oil well pipe along its length direction, for example, compared to the case where a block-shaped member fitted to the outer peripheral surface of the oil well pipe is used as the connecting support, the length (total length) of the welding portion between the connecting support and the oil well pipe can be shortened, and the amount of heat transferred to the oil well pipe during welding can be reduced. Therefore, the temperature gradient associated with the cooling of the oil well pipe after welding can be moderated, and the occurrence of the low-temperature cracking can be prevented. Note that the cooling mentioned here is not limited to natural cooling and may be forced cooling.

[0010] In a third invention, in the second invention, it is preferable that the first welding bead portion is formed along the entire peripheral edge of the contact portion between the first end face of each support plate and the outer peripheral surface of the oil well pipe.

[0011] According to this configuration, the entire peripheral edge of the contact portion between the first end face of each support plate and the outer peripheral surface of the oil well pipe can be surrounded by the first bead portion, so that it is possible to prevent seawater from entering this contact portion and damaging the welding portion.

[0012] In a fourth invention, in the third invention, each of the connecting supports further has a seat plate fixed to the support plate via a second welding bead portion and fixed to the skeletal structure via a third welding bead portion. The support plate has a second end face facing the first end face. The seat plate preferably has a back side surface that constitutes one side surface in the thickness direction and abuts against the outer surface of the skeletal structure, and a front side surface that constitutes the other side surface in the thickness direction of the seat plate and abuts against the second end face of the support plate.

[0013] According to this configuration, the support plates of the respective connection supports are not directly welded to the skeletal structure, but are welded to the seat plate welded to the skeletal structure. Therefore, even if there are irregularities or the like on the outer surface of the skeletal structure, the support plates of the respective connection supports can be firmly fixed to the skeletal structure via the seat plate.

[0014] In the fifth invention, in the fourth invention, it is preferable that the second weld bead portion is formed along the entire peripheral edge of the contact portion between the second end surface of the support plate and the front side surface of the seat plate, and the third weld bead portion is formed along the entire peripheral edge of the contact portion between the back side surface of the seat plate and the skeletal structure.

[0015] According to this configuration, it is possible to prevent seawater from entering the contact portion between the support plate and the seat plate and the contact portion between the seat plate and the skeletal structure and damaging the welded portion.

[0016] In the sixth invention, in the fourth or fifth invention, it is preferable that the support plates of the pair of connection supports have extension portions that extend outside the both ends in the length direction of the oil well pipe, and are supported by the seat plate via the extension portions.

[0017] According to this configuration, since the extension portions that extend outside the both ends of the oil well pipe in the support plates of the pair of connection supports are supported by the seat plate, the welding location (the location where the second weld bead portion is formed) when welding the support plate to the seat plate can be positioned outside rather than directly below the both ends of the oil well pipe. Therefore, it is not necessary to insert welding equipment (for example, the welding rod of a welding torch) into the narrow space directly below the both ends of the oil well pipe when welding the support plate to the seat plate. Therefore, the workability when welding the support plate to the seat plate can be improved.

[0018] In the seventh invention, in the sixth invention, a plurality of the oil well pipes are provided, and the skeleton structure has a pair of frame members that extend in a predetermined direction and are spaced apart from each other in a direction orthogonal to the predetermined direction. The plurality of oil well pipes are each connected to the pair of frame members via the pair of connection supports, and it is preferable that the plurality of oil well pipes are arranged adjacent to each other in the predetermined direction to form an oil well pipe group wall that covers between the pair of frame members.

[0019] According to this configuration, by forming an oil well pipe group wall with a plurality of oil well pipes, the outer surface of this oil well pipe group wall can be used as a habitat or spawning ground for fish. And when forming such an oil well pipe group wall, it is necessary to sequentially weld a plurality of oil well pipes to the skeleton structure. At that time, there is a possibility that the welding work may be hindered by adjacent oil well pipes. Therefore, in a configuration provided with such an oil well pipe group wall, the configuration of the sixth invention (the configuration of welding the extending portion extending outside both ends of the oil well pipe on the support plate to the seat plate) is particularly useful for improving the workability of the welding work.

[0020] In the eighth invention, it is preferable that each of the plurality of oil well pipes is arranged so as to fit between the central positions of one of the pair of frame members and the central position of the other frame member in the orthogonal direction.

[0021] According to this configuration, by minimizing the overlapping portions of both ends of the oil well pipe with the pair of frame members, it is possible to prevent an operator from being forced to perform welding work in a narrow space between both ends of the oil well pipe and the pair of frame members.

[0022] The ninth invention is a method for manufacturing a fish reef, comprising a preparation step of preparing an oil well pipe in advance and constructing a pair of connection support bodies each composed of a seat plate and a support plate erected on the front surface of the seat plate in advance; and a sub-assembly construction step of constructing an oil well pipe sub-assembly composed of the oil well pipe and the pair of connection support bodies by abutting, along the length direction of the oil well pipe, the first end surfaces of the respective support plates of the pair of connection support bodies, which connect both side surfaces in the thickness direction, to two locations spaced apart in the length direction on the outer peripheral surface of the oil well pipe, and fixing each support plate to the outer peripheral surface by welding; and a sub-assembly welding step of fixing, by welding, the seat plates of the respective connection support bodies of the oil well pipe sub-assembly constructed in the sub-assembly construction step to the skeleton structure of the fish reef.

[0023] According to this method, in the sub-assembly construction step, the first end surfaces of the respective support plates of the pair of connection support plates are abutted against the outer peripheral surface of the oil well pipe along the length direction of the oil well pipe to perform the welding operation between the oil well pipe and the support plates. By doing so, the welding length can be minimized as much as possible to prevent the occurrence of cold cracking after welding of the oil well pipe. Therefore, even if an oil well pipe is used as a component of the fish reef, cold cracking will not occur due to the welding. Thus, a fish reef can be inexpensively constructed using an oil well pipe having excellent corrosion resistance and rust prevention properties. Further, by separating the sub-assembly construction step, which requires careful work because it includes the welding operation of the oil well pipe, from other steps (preparation step and sub-assembly welding step) that do not include the welding operation of the oil well pipe, the work processes can be differentiated, and the sub-assembly construction step including the welding operation of the oil well pipe can be carefully performed by the operator. Therefore, it is possible to surely prevent the occurrence of cold cracking after welding of the oil well pipe.

[0024] In the tenth invention, in the ninth invention, on the outer peripheral surfaces of both ends of the oil well pipe prepared in the preparation step, there are screw portions for connecting adjacent oil well pipes when the oil well pipe is used as a fluid flow path pipe. Before the sub-assembly construction step, there is further a cutting step of cutting both ends of the oil well pipe so as to remove the screw portions at both ends of the oil well pipe prepared in the preparation step. In the sub-assembly construction step, it is preferable to weld each support plate of the pair of connection supports to the outer peripheral surface of the oil well pipe after the cutting step.

[0025] According to this method, after cutting and removing the screw portions originally formed at both ends of the oil well pipe, each support plate of the pair of connection supports is welded to the outer peripheral surface of the oil well pipe. Therefore, it is possible to prevent welding defects from occurring between the oil well pipe and the support plate due to the unevenness of the screw portions of the oil well pipe.

[0026] In the eleventh invention, in the tenth invention, the skeleton structure has a pair of frame members that extend in a predetermined direction and are spaced apart from each other in a direction orthogonal to the predetermined direction. In the cutting step, the oil well pipe is cut so that the length of the oil well pipe becomes a predetermined length shorter than the distance between the central position in the orthogonal direction of one of the pair of frame members and the central position in the orthogonal direction of the other frame member. In the sub-assembly construction step, when welding each support plate of the pair of connection supports to each of the cut oil well pipes, the welding is performed so that each support plate has an extension portion that extends outside the length direction of the oil well pipe from both end positions in the length direction of the oil well pipe. When constructing the connection support in the preparation step, it is preferable to construct the connection support by welding at least a portion of the support plate corresponding to the extension portion to the seat plate.

[0027] According to this method, the welding operation of a pair of seat plates constituting the oil well pipe sub-assembly can be performed outside rather than directly below both ends of the oil well pipe. Therefore, the same operational effects as those of the sixth invention can be obtained. In this method, at least the portion corresponding to the extending portion on the support plate may be welded to the seat plate, and portions other than the extending portion may also be welded to the seat plate.

[0028] In the twelfth invention, in any one of the ninth to eleventh inventions, it is preferable to further include a preheating step of preheating the portions corresponding to the two locations on the outer peripheral surface of the oil well pipe to a predetermined target temperature by a heater before the sub-assembly construction step.

[0029] According to this method, before the sub-assembly construction step (that is, before welding the oil well pipe sub-assembly to the outer peripheral surfaces of both ends of the oil well pipe), by preheating the two locations on the outer peripheral surface of the oil well pipe (that is, the planned welding locations of the oil well pipe sub-assembly) to a predetermined target temperature in advance, it is possible to prevent the occurrence of the low-temperature cracking after welding the support plates to the outer peripheral surfaces of both ends of the oil well pipe in the sub-assembly construction step.

[0030] In the thirteenth invention, in any one of the ninth to eleventh inventions, in the sub-assembly construction step, it is preferable to perform the welding along the entire peripheral edge of each contact portion between the first end surface of each support plate of the pair of connection supports and the outer peripheral surface of the oil well pipe.

[0031] According to this method, the same operational effects as those of the third invention can be obtained.

[0032] In the fourteenth invention, in any one of the ninth to eleventh inventions, in the preparation step, when constructing each connection support, it is preferable to bring the second end surface of the support plate prepared in advance, which faces the first end surface, into contact with the front surface of the seat plate prepared in advance and perform welding along the entire peripheral edge of this contact portion.

[0033] According to this method, the same operational effects as those of the fifth invention can be obtained.

[0034] In the 15th invention, in the 11th invention, in the preparation step, a plurality of the oil well pipes are prepared, and in the sub-assembly construction step, the pair of connection supports are fixed to each of the plurality of the oil well pipes by welding to construct a plurality of the oil well pipe sub-assemblies. In the sub-assembly welding step, while arranging the plurality of the oil well pipe sub-assemblies at predetermined intervals along the predetermined direction in a state of straddling between a pair of frame members, each seat plate is fixed to the outer surface of the pair of frame members by welding to form an oil well pipe group wall composed of a plurality of the oil well pipes arranged in the predetermined direction, which is preferable.

[0035] According to this method, a plurality of oil well pipes can be fixed to a pair of frame members by welding to construct an oil well pipe group wall.

Effect of the Invention

[0036] According to the present invention, an artificial reef that can be manufactured at low cost and a method for manufacturing the artificial reef are provided.

Brief Description of the Drawings

[0037]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6A

Figure 6B

Figure 7

Figure 8

Figure 9A

Figure 9B

Figure 9C

Figure 9D

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0038] Hereinafter, with reference to the drawings, the fish reef 1 according to an embodiment of the present invention will be described.

[0039] [Overall Configuration of the Fish Reef] FIG. 1 is a perspective view showing a schematic configuration of the fish reef 1 according to an embodiment of the present invention. The fish reef 1 is installed on the seabed to form an environment suitable for the inhabitation of marine organisms. In particular, the fish reef 1 according to the present embodiment forms an environment suitable for the inhabitation of squids. However, the fish reef 1 may form an environment suitable for the inhabitation of marine organisms other than squids, and the fish reef 1 may be installed on the bottom of a pond, lake, river, etc.

[0040] As shown in Fig. 1, the fish reef 1 includes a metal fish reef frame 10. The fish reef frame 10 is a structure having a rectangular parallelepiped outer shape. In the following description, when the fish reef frame 10 is viewed from the upper side in the vertical direction, the directions along two sides perpendicular to each other are defined as the front-back direction and the left-right direction of the fish reef 1 respectively. In Fig. 1, "front side", "rear side", "left side", "right side", "upper side" and "lower side" are shown for convenience by the direction axes. It should be noted that this direction is defined for convenience in explaining the structure of the fish reef 1 according to the embodiment of the present invention, and does not limit the configuration and usage mode of the fish reef 1 and the like.

[0041] The fish reef frame 10 has a support column part 20, a frame upper end part 30, a frame middle part 40, and a frame lower end part 50.

[0042] [Configuration of the support column part 20] The support column part 20 has four support columns 21 (only three are shown in Fig. 1) arranged at the four corners of the fish reef frame 10 and extending in the vertical direction. In this example, the four support columns 21 are constituted by angle members having an L-shaped cross section that bend at right angles along the four corners of the fish reef frame 10 in plan view. The four support columns 21 are arranged in plan view (viewed from the upper side) such that the virtual lines connecting the centers of the respective support columns 21 form a square shape. That is, in this example, the interval between the support columns 21 in the front-back direction is equal to the interval between the support columns 21 in the left-right direction.

[0043] [Configuration of the frame upper end part 30] The frame upper end part 30 is fixed to the upper ends of the four support columns 21 by welding. Specifically, the frame upper end part 30 has a front cross beam 31, a rear cross beam 32, a left cross beam 33, a right cross beam 34, an upper oil well pipe group wall 35, and a side oil well pipe part 36.

[0044] The front cross beam 31 and the rear cross beam 32 are cross beams that horizontally extend in the left - right direction and are arranged parallel to each other with a space therebetween in the front - rear direction. The front cross beam 31 connects the upper ends of the two left - right struts 21 arranged at the front end of the fish reef 1. The rear cross beam 32 connects the upper ends of the two left - right struts 21 arranged at the rear end of the fish reef 1. In this example, the front cross beam 31 and the rear cross beam 32 are each composed of an L - shaped angle member consisting of a horizontal plate portion extending in the left - right direction and a vertical plate portion hanging down from the outer edge of the horizontal plate portion.

[0045] The left cross beam 33 and the right cross beam 34 are cross beams that horizontally extend in the front - rear direction and are arranged parallel to each other with a space therebetween in the left - right direction. The left cross beam 33 connects the upper ends of the two front - rear struts 21 arranged at the left end of the fish reef 1. The right cross beam 34 connects the upper ends of the two front - rear struts 21 arranged at the right end of the fish reef 1. In this example, the left cross beam 33 and the right cross beam 34 are each composed of an L - shaped angle member consisting of a horizontal plate portion extending in the front - rear direction and a vertical plate portion hanging down from the outer edge of the horizontal plate portion.

[0046] The upper - end oil - well pipe group wall 35 is a wall portion formed by a plurality of oil - well pipes P and is arranged spanning across the left cross beam 33 and the right cross beam 34. The plurality of oil - well pipes P constituting the upper - end oil - well pipe group wall 35 are arranged such that the length direction of each oil - well pipe P coincides with the left - right direction. And the plurality of oil - well pipes P are arranged in close contact (an example of adjacency) with no gap between them in the front - rear direction. Both ends of each oil - well pipe P are respectively connected to and supported on the upper surfaces of the left cross beam 33 and the right cross beam 34 via the connection support 11. The details of the support structure of each oil - well pipe P by this connection support 11 will be described later.

[0047] The side oil well pipe portion 36 has four oil well pipes P respectively arranged to face the outer surfaces of the four cross beams 31 to 34 on the front, rear, left, and right sides at the upper end portion 30 of the frame. Each of these four oil well pipes P extends horizontally along the respective cross beams 31 to 34 facing the oil well pipes P, and is connected to the respective cross beams 31 to 34 via a connecting support 11. The support structure of each oil well pipe P by this connecting support 11 is the same as the support structure of each oil well pipe P constituting the upper oil well pipe group wall 35, and the details thereof will be described later.

[0048] [Configuration of the middle portion 40 of the frame] Next, the middle portion 40 of the frame will be described. Since the configuration of the middle portion 40 of the frame is the same as that of the upper end portion 30 of the frame except for the different height positions, the description will be appropriately omitted.

[0049] That is, the middle portion 40 of the frame is fixed by welding to the middle portion in the vertical direction (the middle portion between the upper end portion and the lower end portion) of the four columns 21. The middle portion 40 of the frame has a front cross beam 41, a rear cross beam 42, a left cross beam 43, a right cross beam 44, a middle oil well pipe group wall 45, and a side oil well pipe portion 46. Since the cross beams 41 to 44 have the same shape and connection configuration to the respective columns 21 as the cross beams 31 to 34 of the upper end portion 30 of the frame described above, except for the different height positions, the detailed description thereof will be omitted.

[0050] The middle oil well pipe group wall 45 has the same configuration as the upper oil well pipe group wall 35 described above, but is different from the upper oil well pipe group wall 35 in that it is arranged across the left cross beam 33 and the right cross beam 34. That is, the plurality of oil well pipes P constituting the middle oil well pipe group wall 45 are arranged such that the length direction thereof coincides with the front-rear direction. And the plurality of oil well pipes P are arranged in close contact with each other (an example of adjacency) without a gap in the left-right direction. Both ends of each oil well pipe P are respectively connected and supported to the upper surfaces of the front cross beam 41 and the rear cross beam 42 via a connecting support 11. The support structure of each oil well pipe P by this connecting support 11 is the same as the support structure of each oil well pipe P constituting the upper oil well pipe group wall 35, and the details thereof will be described later.

[0051] The side oil well pipe portion 46 has the same configuration as the side oil well pipe portion 36 at the upper end of the frame described above, but is different from the side oil well pipe portion 36 in that the connection target position is the outer surface of the support column 21. That is, the side oil well pipe portion 46 has four oil well pipes P arranged opposite to the outer surfaces of the four cross beams 41 to 44 in the front, rear, left, and right directions in the middle portion 40 of the frame. Each of these four oil well pipes P extends horizontally along the respective cross beams 41 to 44 facing each oil well pipe P, and is connected to a pair of support columns 21 located at both ends of each of the cross beams 41 to 44 via a connection support 11. The support structure of each oil well pipe P by this connection support 11 is the same as the support structure of each oil well pipe P constituting the upper oil well pipe group wall 35, and the details thereof will be described later.

[0052] [Configuration of the lower end portion 50 of the frame] Next, the lower end portion 50 of the frame will be described. Since the configuration of the lower end portion 50 of the frame is the same as that of the upper end portion 30 of the frame except for the different height positions, the description will be omitted as appropriate.

[0053] That is, the lower end portion 50 of the frame is fixed to the lower ends of the four support columns 21 by welding. The lower end portion 50 of the frame has a front cross beam 51, a rear cross beam 52, a left cross beam 53, a right cross beam 54, a lower oil well pipe group wall 55, and a side oil well pipe portion 56. Each of the cross beams 51 to 54 has the same shape and connection configuration to the respective support columns 21 as the cross beams 31 to 34 at the upper end of the frame, except for the different height positions, so the detailed description thereof will be omitted.

[0054] The lower oil well pipe group wall 55 has the same configuration as the upper oil well pipe group wall 35 described above. That is, the plurality of oil well pipes P constituting the lower oil well pipe group wall 55 are arranged in a state where the length directions thereof coincide with the left - right direction and are in close contact with each other without gaps in the front - rear direction (an example of adjacency). Both ends of each oil well pipe P are respectively connected to and supported on the upper surfaces of the left cross beam 53 and the right cross beam 54 via a connection support 11. The support structure of each oil well pipe P by this connection support 11 is the same as the support structure of each oil well pipe P constituting the upper oil well pipe group wall 35, and the details thereof will be described later.

[0055] The side oil well pipe part 56 has the same configuration as the side oil well pipe part 36 at the upper end part 30 of the frame described above, but is different from the side oil well pipe part 36 in that the connection target position thereof is the outer surface of the support column 21. That is, the side oil well pipe part 56 has four oil well pipes P arranged to face the outer surfaces of the four cross beams 51 to 54 on the front, rear, left, and right at the lower end part 50 of the frame. Each of these four oil well pipes P extends horizontally along the respective cross beams 51 to 54 facing the oil well pipes P, and is connected to a pair of support columns 21 located at both ends of each of the cross beams 51 to 54 via a connection support body 11. The support structure of each oil well pipe P by this connection support body 11 is the same as the support structure of each oil well pipe P constituting the upper end oil well pipe group wall 35, and the details thereof will be described later.

[0056] [Details of Oil Well Pipe P] Each oil well pipe P is made by processing a used oil well pipe to a predetermined length. In this example, the oil well pipes P used for each oil well pipe group wall 35, 45, 55 and each side oil well pipe part 36, 46, 56 are all set to the same length, but this is not restrictive, and they may be of different lengths. Further, as the used oil well pipe, for example, those generated as waste materials when disassembling an oil well (subsea oil well) constructed for extracting oil or the like from a subsea oil field may be used. However, the oil well pipe P is not limited to a used oil well pipe, and may be, for example, a newly manufactured oil well pipe (unused oil well pipe) at a factory or the like for manufacturing the artificial reef 1 according to the present embodiment.

[0057] Table 1 shows the material composition of the oil well pipes used in the fish reef 1. In this table, the results of measuring the material compositions of 10 oil well pipe samples 1 to 10 randomly extracted from the inventory of the oil well pipes are shown. The numbers in the table indicate the percentages (%) of the masses of the compositional elements multiplied by 100. However, for the compositional elements marked with "※", the percentages (%) of the masses are shown multiplied by 1000. According to this table, the material compositions of the oil well pipe samples 1 to 10 are C: 0.23 - 0.24%, Si: 0.31 - 0.33%, Mu: 1.38 - 1.44%, P: 0.015 - 0.018%, S: 0.002 - 0.007%, Cu: 0.01 - 0.02%, Cr: 0.05 - 0.08%, Ni: 0.02 - 0.03%, Mo: 0.01%, Ti: 0 - 0.001%, AL: 0.030 - 0.038%.

[0058]

Table 1

[0059] [Support structure of the oil well pipes constituting each oil well pipe group wall] Next, with reference to FIGS. 3 to 5, the support structure of each oil well pipe P using the connection support 11 will be described. Hereinafter, the support structure of one oil well pipe P included in the upper oil well pipe group wall 35 will be described as a representative.

[0060] FIG. 3 is a view corresponding to the cross-section taken along line III-III of FIG. 1 showing the upper oil well pipe group wall 35, FIG. 4 is an extraction view seen from the IV direction of FIG. 3 showing one oil well pipe P included in the upper oil well pipe group wall 35 and its support structure extracted, and FIG. 5 is a view seen in the direction of the arrow V of FIG. 4.

[0061] As shown in FIGS. 3 and 5, the oil well pipe P is arranged straddling the left and right cross beams 33, 34 corresponding to a pair of frame members. The oil well pipe P is connected to the upper surfaces of the respective cross beams 33, 34 via a pair of connection supports 11 fixed to both ends thereof.

[0062] As shown in FIGS. 3 to 5, each connecting support 11 has a support plate 111 and a seat plate 112 that are connected to each other by welding. Note that the support plate 111 and the seat plate 112 may be integrally formed by casting or the like.

[0063] The seat plate 112 is composed of a rectangular plate material and has a front surface 112a and a back surface 112b that face each other in the thickness direction. The seat plate 112 is arranged such that its back surface 112b abuts on the upper surfaces of the left and right cross beams 33, 34.

[0064] As shown in FIG. 5, the seat plate 112 is arranged so as to be within the width range of the left and right cross beams 33, 34. Here, the width of the left and right cross beams 33, 34 means the width in the orthogonal direction (the direction in which the left and right cross beams 33, 34 face each other, which is the left - right direction in this example) orthogonal to their extending direction.

[0065] Here, the distance L between the central position in the width direction of the left cross beam 33 and the central position in the width direction of the right cross beam 34 is longer than the length of the oil well pipe P. The central position in the width direction of the left cross beam 33 coincides with the central position in the width direction of the seat plate 112 arranged on its upper surface. Similarly, the central position in the width direction of the right cross beam 34 coincides with the central position in the width direction of the seat plate 112 arranged on its upper surface.

[0066] As shown in FIGS. 3 and 4, the support plate 111 is composed of a rectangular plate extending in the length direction (the same direction as the axial direction) of the oil well pipe P. The support plate 111 is fixed in a state of standing perpendicular to the front surface 112a of the seat plate 112. And the support plate 111 supports the oil well pipe P at a predetermined height with respect to the front surface 112a of the seat plate 112. The support plate 111 is arranged at the center in the width direction (the left - right direction in FIG. 6B) of the seat plate 112. Thus, the support plate 111 and the seat plate 112 are connected in an inverted T - shape when viewed from the length direction (axial direction) of the oil well pipe P (see FIG. 4).

[0067] The support plate 111 has a first side surface 111a, a second side surface 111b, a first end surface 111c, and a second end surface 111d.

[0068] The first side surface 111a and the second side surface 111b are side surfaces facing each other in the thickness direction of the support plate 111.

[0069] The first end surface 111c connects the upper ends of the first side surface 111a and the second side surface 111b. The first end surface 111c extends along the length direction of the oil well pipe P in a state of being in contact with the outer peripheral surface of the oil well pipe P. The second end surface 111d is an end surface facing the first end surface 111c, and connects the lower ends of the first side surface 111a and the second side surface 111b. The second end surface 111d extends in the length direction of the oil well pipe P parallel to the first end surface 111c and abuts against the front side surface 112a of the seat plate 112.

[0070] As shown in FIG. 3, the support plate 111 has an extension portion 111e that extends outside the length direction of the oil well pipe P beyond both end positions in the length direction of the oil well pipe P, and is fixed to the seat plate 112 via the extension portion 111e. The support plate 111 is arranged so as to protrude inward of the left and right cross beams 33, 34 while being supported by each seat plate 112.

[0071] [Explanation of the Welded Portion of the Oil Well Pipe and the Connection Support] Next, with reference to FIGS. 6A and 6B, the welded portion of the oil well pipe P and the connection support 11 will be described.

[0072] FIG. 6A is an explanatory diagram for explaining the welded portion in the VIA portion of FIG. 3, and FIG. 6B is a view in the direction of arrow VIB of FIG. 6A.

[0073] FIGS. 6A and 6B show a first weld bead portion B1, a second weld bead portion B2, and a third weld bead portion B3 formed by welding. Each weld bead portion B1 - B3 is a portion where the metal as the base material is melted and solidified by welding, and is a portion that connects two members in contact with each other with each weld bead portion B1 - B3 as a boundary.

[0074] Specifically, the first weld bead portion B1 connects the oil well pipe P and the support plate 111. The first weld bead portion B1 is formed along the entire peripheral edge of the contact portion between the oil well pipe P and the support plate 111 (that is, so as to surround the periphery of the contact portion over the entire circumference). The length of the first weld bead portion B1 along the axial direction (length direction) of the oil well pipe P is preferably 50 mm or more, and in this example, it is taken as 100 mm as an example. In this example, as an example, the support plate 111 is a plate material with dimensions of 50 mm × 180 mm (height × length), and its thickness is 12 mm.

[0075] The second weld bead portion B2 is formed along the entire peripheral edge of the contact portion between the support plate 111 and the seat plate 112 (that is, so as to surround the periphery of the contact portion over the entire circumference).

[0076] The third weld bead portion B3 is formed along the entire peripheral edge of the contact portion between the seat plate 112 and the cross beam 33 or 34 to which the seat plate 112 is fixed (in FIGS. 6A and 6B, only the cross beam 33 is shown). (That is, so as to surround the periphery of the contact portion over the entire circumference).

[0077] [Method for manufacturing a fish reef] Next, the method for manufacturing the fish reef 1 will be described. FIG. 7 is a flowchart showing a general flow of the method for manufacturing the fish reef 1.

[0078] The method for manufacturing the fish reef 1 is roughly divided into a skeleton structure construction step S1, an oil well pipe group wall construction step S2, and a side oil well pipe portion construction step S3.

[0079] In the skeleton structure construction step S1, the skeleton structure 150 of the fish reef 1 is constructed by welding. The skeleton structure 150 is the framework portion forming the skeleton of the fish reef 1. In this example, it consists of four columns 21, four cross beams 31 - 34 included in the frame upper end portion 30, four cross beams 41 - 44 included in the frame middle portion 40, and four cross beams 51 - 54 included in the frame lower end portion 50.

[0080] The oil well pipe group wall construction process S2 is a process of constructing (adding) the upper oil well pipe group wall 35, the intermediate oil well pipe group wall 45, and the lower oil well pipe group wall 55 with respect to the skeletal structure 150. In this process S2, in order to construct each oil well pipe group wall 35, 45, 55, a plurality of oil well pipes P are arranged in close contact with each other in a predetermined direction (in this example, the left - right direction or the front - back direction), and are fixed to the skeletal structure 150 by welding through the connecting support 11. Details of this oil well pipe group wall construction process S2 will be described later.

[0081] The side oil well pipe part construction process S3 is a process of constructing (adding) the side oil well pipe parts 36, 46, 56 with respect to the skeletal structure 150. In this side oil well pipe part construction process S3, the four oil well pipes P that make up each side oil well pipe part 36, 46, 56 are welded to the skeletal structure 150 one by one through the connecting support 11. Since this welding procedure is the same as the welding procedure in the oil well pipe group wall construction process S2, detailed description is omitted.

[0082] Figure 8 is a flowchart showing the details of the oil well pipe group wall construction process S2. Figure 9A shows the pre - heating process S22 which is a part of the oil well pipe group construction process, Figure 9B shows the sub - assembly construction process S23, Figure 9C shows the connection planned locations of the oil well pipe sub - assembly 60 to be described later, and Figure 9D is an explanatory diagram showing the sub - assembly welding process S24. Hereinafter, the construction method of the upper oil well pipe group wall 35 which is an example of the oil well pipe group wall will be mainly described, but the intermediate oil well pipe group wall 45 and the lower oil well pipe group wall 55 can also be constructed by the same procedure.

[0083] As shown in Figure 8, the oil well pipe group wall construction process S2 includes a preparation process S20, a cutting process S21, a pre - heating process S22, a sub - assembly construction process S23, and a sub - assembly welding process S24.

[0084] In the preparation step S20, a plurality of used oil well pipes are prepared in advance, and a pair of connection supports 11 are constructed in advance. Screw portions (not shown) are formed on the outer peripheral surfaces of both ends of the oil well pipes prepared in advance. These screw portions are used to connect adjacent oil well pipes in the flow path length direction when the oil well pipes are used as flow path pipes for fluids (such as petroleum and natural gas) for their original intended use.

[0085] When constructing the connection support 11 in the preparation step S20, the second end face 111d of the previously prepared support plate 111 and the front side face 112a of the previously prepared seat plate 112 are brought into contact with each other, and welding is performed along the entire peripheral edge of this contact portion. At this time, at least the portion corresponding to the extension portion 111e in the support plate 111 is welded to the seat plate 112. Then, as described above, the support plate 111 and the seat plate 112 are connected in an inverted T shape to construct the connection support 11.

[0086] In the cutting step S21, both ends of the oil well pipe prepared in the preparation step S20 are cut so as to remove the screw portions at both ends of the oil well pipe, thereby forming the oil well pipe P used for manufacturing the artificial reef 1. Also, in this cutting step S21, the oil well pipe is cut so that the length of the oil well pipe P becomes a predetermined length shorter than the distance between the central positions in the width direction of a pair of frame members to which both ends of the oil well pipe P are connected (distance L in the example of FIG. 3). Here, a pair of frame members are composed of left and right cross beams 33, 34 for each oil well pipe P of the upper end oil well pipe group wall 35, front and rear cross beams 41, 42 for each oil well pipe P of the middle oil well pipe group wall 45, and left and right cross beams 53, 54 for each oil well pipe P of the lower end oil well pipe group wall 55 (see FIG. 1).

[0087] In the preheating step S22, as shown in FIG. 9A, the cut oil well pipe P is supported at both ends from below by a pair of holding jigs 100, and the outer peripheral surfaces of both ends of the oil well pipe P (that is, the welding planned portions of the support plates 111 of the connecting support 11) are heated by a burner 101 (an example of a heating device). The holding jig 100 includes an arch-shaped holding portion 100a that engages with the outer peripheral surface of the oil well pipe P, a support column portion 100b that extends downward from the central portion of the holding portion 100a, and a leg portion 100c connected to the lower end portion of the support column portion 100b. In this preheating step S22, while monitoring the temperature of the outer peripheral surfaces of both ends of the oil well pipe P using, for example, a non-contact digital temperature sensor, the heating operation by the burner 101 is performed so that the temperature of the outer peripheral surfaces of both ends of the oil well pipe P reaches the target temperature (for example, 100°).

[0088] In the sub-assembly construction step S23, as shown in FIG. 9B, using a welding torch 102, each support plate 111 of a pair of connecting supports 11 is welded to both ends of the oil well pipe P to construct an oil well pipe sub-assembly 60 composed of the pair of connecting supports 11 and the oil well pipe P. At the time of this welding, the first end surface 111c of each support plate 111 is directed downward and abutted against the outer peripheral surfaces of both ends of the oil well pipe P from above. Then, the position of the support plate 111 is adjusted so as to form an extending portion 111e in which a part of the support plate 111 extends outward in the length direction (axial direction) from both end positions of the oil well pipe P. After this position adjustment is completed, the support plate 111 is temporarily fixed by a fixing jig (not shown). Then, in this temporarily fixed state, by moving the tip of the welding rod of the welding torch 102 along the entire peripheral edge of the contact portion of the support plate 111 with the oil well pipe P, the above-described first weld bead portion B1 (see FIG. 6A) is formed, and the welding of the support plate 111 to the oil well pipe P is completed.

[0089] In the sub-assembly welding step S24, as shown in FIG. 9D, a plurality of oil well pipe sub-assemblies 60 constructed in the sub-assembly construction step S23 are welded to the connection planned location R of a pair of frame members (the left cross beam 33 and the right cross beam 34 in the example of FIG. 9C) shown in FIG. 9. Specifically, while arranging the plurality of oil well pipe sub-assemblies 60 at predetermined intervals along a predetermined direction (the front-rear direction in the example of FIG. 9) in a state of straddling between a pair of frame members, the respective seat plates 112 are fixed to the outer surface (the upper surface in the example of FIG. 9) of the pair of frame members by welding.

[0090] Thus, by completing the sub-assembly welding step S24, the construction (addition) of the upper oil well pipe group wall 35 to the skeleton structure 150 is completed. Since the intermediate oil well pipe group wall 45 and the lower oil well pipe group wall 55 can also be constructed by the same procedure, detailed description thereof is omitted. Also, since the welding procedure of each oil well pipe P in the side oil well pipe part construction step S3 described above is the same, description thereof is omitted.

[0091] The thus-completed artificial reef 1 is installed on the seabed or lake bottom to form a habitat and spawning ground for fish and the like. When using the artificial reef 1, the artificial reef 1 is thrown into the sea with the frame lower end portion 50 of the artificial reef 1 facing the water bottom. Thereby, the frame lower end portion 50 of the artificial reef 1 is seated so as to be slightly buried in the sediment on the seabed, and the artificial reef 1 is installed on the seabed in the state shown in FIG. 1. And in the installed state of the artificial reef 1, for example, the outer surfaces of the upper oil well pipe group wall 35, the intermediate oil well pipe group wall 45, and the lower oil well pipe group wall 55 and the internal spaces of the respective oil well pipes P are provided as habitats for fish. As an example, the lower surfaces of the upper oil well pipe group wall 35 and the intermediate oil well pipe group wall 45 in the artificial reef 1 form an environment more suitable for marine organisms such as squid that have the habit of laying eggs on the back (lower surface) of an object.

[0092] [Function and Effect] As described above, in the present embodiment, the artificial reef 1 includes the skeleton structure 150 and a plurality of oil well pipes P fixed to the skeleton structure 150.

[0093] According to this configuration, by using the oil well pipe P, which is excellent in corrosion resistance and rust prevention in water, as a component of the fish reef 1, the fish reef 1 can be constructed at low cost.

[0094] In addition, in the present embodiment, both end portions (an example of two locations spaced apart in the length direction) of the outer peripheral surface of each oil well pipe P are connected to and supported by the skeletal structure 150 via a pair of connection supports 11. Each of the pair of connection supports 11 has a support plate 111 fixed to each oil well pipe P via a first weld bead portion B1, and each of the support plates 111 has a first end surface 111c that connects both side surfaces in the thickness direction and abuts against the outer peripheral surface of the oil well pipe P and extends along the length direction thereof.

[0095] According to this configuration, by minimizing the length of the welding location (the first weld bead portion B1) when fixing the oil well pipe P to the skeletal structure 150 and reducing the amount of heat transmitted to the oil well pipe P during welding, it is possible to prevent the occurrence of cold cracking in the oil well pipe P after welding. That is, generally, the oil well pipe P is known as a material that is prone to cold cracking after welding and is not suitable for welding. However, according to this configuration, by bringing the first end surface 111c, which is the end surface of the support plate 111 that is a plate-like body, into contact with the outer peripheral surface of the oil well pipe P along the length direction thereof, for example, compared to the case where a block-shaped member fitted to the outer peripheral surface of the oil well pipe P is used as the connection support, the length of the welding location between the connection support 11 and the oil well pipe P can be shortened, and the amount of heat transmitted to the oil well pipe P during welding can be reduced. Therefore, the temperature gradient associated with the cooling of the oil well pipe P after welding can be alleviated, and cold cracking can be prevented. Note that this cooling is not limited to natural cooling and may be forced cooling.

[0096] In the present embodiment, the first weld bead portion B1 is formed along the entire peripheral edge of the contact portion between the first end surface 111c of each support plate 111 and the outer peripheral surface of the oil well pipe P.

[0097] According to this configuration, since the entire peripheral edge of the contact portion between the first end face 111c of each support plate 111 and the outer peripheral surface of the oil well pipe P is surrounded by the first weld bead portion B1, it is possible to prevent seawater from entering this contact portion and damaging the welded portion.

[0098] In the present embodiment, each connecting support 11 further has a seat plate 112 that is connected to the support plate 111 via a second weld bead portion B2 and fixed to the skeletal structure 150 via a third weld bead portion B3. The support plate 111 has a second end face 111d facing the first end face 111c. The seat plate 112 has a back side face 112b that constitutes one side face in the thickness direction thereof and abuts against the outer surface of the skeletal structure 150, and a front side face 112a that constitutes the other side face in the thickness direction of the seat plate 112 and abuts against the second end face 111d of the support plate 111.

[0099] According to this configuration, instead of directly welding the support plate 111 of each connecting support 11 to the skeletal structure 150, welding is performed on the seat plate 112 welded to the skeletal structure 150. Thus, even if there are irregularities or the like on the outer surface of the skeletal structure 150, the support plate 111 of each connecting support 11 can be firmly fixed to the skeletal structure 150 via the seat plate 112.

[0100] Also, in the present embodiment, the second weld bead portion B2 is formed along the entire peripheral edge of the contact portion between the second end face 111d of the support plate 111 and the front side face 112a of the seat plate 112, and the third weld bead portion B3 is formed along the entire peripheral edge of the contact portion between the back side face 112b of the seat plate 112 and the skeletal structure 150.

[0101] According to this configuration, it is possible to prevent seawater from entering the contact portion between the support plate 111 and the seat plate 112 and the contact portion between the seat plate 112 and the skeletal structure 150 and damaging the welded portion.

[0102] In addition, in the present embodiment, each support plate 111 of the pair of connection supports 11 connected to both ends of each oil well pipe P has an extension portion 111e that extends outward in the length direction of each oil well pipe P beyond both ends in the length direction of each oil well pipe P. Each support plate 111 is arranged such that a portion of the second end face 111d corresponding to the extension portion 111e abuts against the front side surface 112a of the seat plate 112.

[0103] According to this configuration, when welding the support plates 111 at both ends of the oil well pipe subassembly 60 to the seat plate 112, the welding location (the location where the second weld bead portion B2 is formed) can be positioned outside rather than directly below both ends of the oil well pipe P. Therefore, when welding the support plate 111 to the seat plate 112, it is not necessary to insert the welding rod of the welding torch 102 into the narrow space directly below both ends of the oil well pipe P. Thus, the workability when welding the support plate 111 to the seat plate 112 can be improved.

[0104] Also, in the present embodiment, the skeleton structure 150 has an upper end oil well pipe group wall 35, an intermediate oil well pipe group wall 45, and a lower end oil well pipe group wall 55. Each oil well pipe group wall 35, 45, 55 has a plurality of oil well pipes P arranged adjacent to each other. Both ends of each oil well pipe P in its respective length direction are connected to a pair of frame members via a pair of connection supports 11.

[0105] According to this configuration, by forming each oil well pipe group wall 35, 45, 55 with a plurality of oil well pipes P, the outer surface of each oil well pipe group wall 35, 45, 55 can be utilized as a habitat or spawning ground for fish. And when forming such oil well pipe group walls 35, 45, 55, it is necessary to sequentially weld a plurality of oil well pipes P to the skeleton structure 150. At this time, by welding the extension portion 111e of the support plate 111 to the seat plate 112, the welding torch 102 can be used without interfering with adjacent oil well pipes P, and the workability of the welding operation can be improved.

[0106] In this embodiment, each oil well pipe P that constitutes each of the oil well pipe group walls 35, 45, and 55 is arranged so as to fit between the central position in the width direction of one of the pair of frame members and the central position in the width direction of the other frame member. As an example, in the upper oil well pipe group wall 35 shown in FIG. 3, the oil well pipe P is arranged so as to fit between the central position in the width direction of the left cross beam 33 and the central position in the width direction of the right cross beam 34 (see FIG. 3).

[0107] According to this configuration, by minimizing the overlapping portions of both ends of the oil well pipe P with the pair of frame members, it is possible to prevent an operator from being forced to perform welding work in the narrow space between both ends of the oil well pipe P and the pair of frame members.

[0108] Further, the method for manufacturing the artificial reef 1 includes a preparation step S20 of preparing the oil well pipe P in advance and constructing a pair of connection supports 11 in advance, a sub-assembly construction step S23, and a sub-assembly welding step S24. The sub-assembly construction step S23 is a step of constructing an oil well pipe sub-assembly 60 composed of the oil well pipe P and a pair of connection supports 11 by bringing the first end surface 111c (the end surface connecting both side surfaces in the thickness direction) of each support plate 111 of the pair of connection supports 11 constructed in the preparation step S20 into contact with the outer peripheral surfaces of both ends in the length direction of the oil well pipe P along the length direction of the oil well pipe P and fixing each support plate 111 to the outer peripheral surface by welding. The sub-assembly welding step S24 is a step of fixing the seat plate 112 of each connection support 11 of the oil well pipe sub-assembly 60 constructed in the sub-assembly construction step S23 to the skeleton structure 150 of the artificial reef 1 by welding.

[0109] According to this method, in the sub-assembly construction step S23, the first end surface 111c of the support plate 111 is brought into contact with the outer peripheral surface of the oil well pipe P along the length direction of the oil well pipe P, and the welding operation between the oil well pipe P and the support plate 111 is performed. By doing so, the welding length is minimized as much as possible to reduce the amount of heat transferred to the oil well pipe P during welding. As a result, the temperature gradient associated with the cooling of the oil well pipe P after welding is alleviated, and the occurrence of cold cracking can be prevented. Therefore, even if the oil well pipe P is used as a component of the artificial reef 1, cold cracking does not occur after welding. Thus, the artificial reef 1 can be inexpensively constructed using the oil well pipe P with excellent corrosion resistance and rust prevention properties. Further, since the sub-assembly construction step S23, which requires careful work because it includes the welding operation of the oil well pipe P, is separated from other steps (the preparation step S20 and the sub-assembly welding step S24) that do not include the welding operation of the oil well pipe P, the work steps can be differentiated, and the sub-assembly construction step S23 including the welding operation of the oil well pipe P can be made to be carefully performed by the operator (by appropriately performing temperature control, etc.). Therefore, cold cracking after welding of the oil well pipe P can be surely prevented.

[0110] In the present embodiment, screw portions (not shown) for connecting adjacent oil well pipes are formed on the outer peripheral surfaces of both ends of the oil well pipe P prepared in the preparation step S20 when the oil well pipe P is used as a flow path pipe for fluids (such as petroleum and natural gas). The method for manufacturing the artificial reef 1 of the present embodiment further includes a cutting step S21 of cutting both ends of the oil well pipe P so as to remove the screw portions at both ends of the oil well pipe P prepared in the preparation step S20 before the sub-assembly construction step S23.

[0111] According to this method, after cutting and removing the screw portions originally formed at both ends of the oil well pipe P, a pair of support plates 111 are welded to the outer peripheral surfaces of both ends of the oil well pipe P. Therefore, it is possible to prevent welding defects from occurring between the oil well pipe P and the pair of support plates 111 due to the unevenness of the screw portions of the oil well pipe P.

[0112] In this embodiment, in the cutting step S21, the oil well pipe P is cut so that its length becomes a predetermined length shorter than the distance L (see FIG. 3) between the central position in the width direction (an example of the orthogonal direction) of one frame member and the central position in the width direction (an example of the orthogonal direction) of the other frame member. In the sub-assembly construction step S23, when welding a pair of support plates 111 to each of the cut oil well pipes P, welding is performed such that each support plate 111 of the pair of connection supports 11 has an extension portion 111e extending outward from both end positions in the length direction of the oil well pipe P. When constructing the connection support 11 in the preparation step S20, the connection support 11 is constructed by welding at least the portion of the support plate 111 corresponding to the extension portion 111e to the seat plate 112.

[0113] According to this method, the welding operation of the pair of seat plates 112 constituting the oil well pipe sub-assembly 60 can be performed outside both ends of the oil well pipe P. Therefore, a sufficient space for using the welding torch 102 can be secured, and the work accuracy can be improved.

[0114] Further, the method for manufacturing the artificial reef 1 further includes a preheating step S22 of preheating the outer peripheral surfaces of both ends in the length direction of the oil well pipe P to a predetermined target temperature by a burner 101 (an example of a heater) before the sub-assembly construction step S23.

[0115] According to this method, before the sub-assembly construction step S23 (that is, before welding the support plates 111 to the outer peripheral surfaces of both ends of the oil well pipe P), by preheating the outer peripheral surfaces of both ends in the length direction of the oil well pipe P to a predetermined target temperature, it is possible to prevent the occurrence of the low-temperature cracking after welding the support plates 111 to the outer peripheral surfaces of both ends of the oil well pipe P in the sub-assembly construction step S23.

[0116] In this embodiment, in the sub-assembly welding step S24, while arranging a plurality of oil well pipe sub-assemblies 60 at predetermined intervals (equidistant in the example of FIG. 9D) along the predetermined direction (the front-rear direction in the example of FIG. 9D) in a state of straddling between a pair of frame members, each seat plate 112 is fixed to the outer surface of the pair of frame members by welding, thereby forming oil well pipe group walls 35, 45, 55 arranged in the predetermined direction.

[0117] According to this method, a plurality of oil well pipes P can be welded to a pair of frame members without causing the low-temperature cracking in the oil well pipes P, thereby constructing the oil well pipe group walls 35, 45, 55.

[0118] (Other embodiments) As described above, the fish reef 1 and its manufacturing method according to the embodiment of the present invention have been described. However, the present invention is not limited thereto, and for example, the following modified embodiments can be adopted.

[0119] (1) FIG. 10 shows a fish reef 1A according to a modified embodiment 1, and FIG. 11 shows a fish reef 1B according to a modified embodiment 2. In each modified embodiment, the same components as those in the above embodiment are denoted by the same reference numerals, and the detailed description thereof is omitted.

[0120] As shown in FIG. 10, the fish reef 1A according to the modified embodiment 1 is different from the above embodiment in that it includes four oil well pipe group walls 210 that cover the front, rear, left, and right side surfaces of the skeletal structure 150 instead of the above-described oil well pipe group walls 35, 45, 55. Further, the fish reef 1A includes an upper oil well pipe portion 220 fixed to the upper surface of the skeletal structure 150 instead of the side oil well pipe portion 46. Each oil well pipe P constituting the oil well pipe group walls 210 and the upper oil well pipe portion 220 is connected to the skeletal structure 150 via a connection support 11 connected to both ends thereof, similarly to the above embodiment. According to the fish reef 1A according to this modified example embodiment 1, by constructing the fish reef 1A using the oil well pipes P, the same operational effects as those in the above embodiment can be obtained. Note that this fish reef 1A is a so-called potted type fish reef, and for example, it can form an environment suitable for the growth of seaweeds such as eelgrass.

[0121] As shown in Fig. 11, the artificial reef 1B according to the second modified embodiment is different from the first modified embodiment in that a plurality of oil well pipes P constituting each oil well pipe group wall 210 are arranged adjacent to each other with a gap therebetween. According to the artificial reef 1B according to the second modified embodiment, similarly to the above embodiment, by using the oil well pipes P to form the artificial reef 1B, the same operational effects as those of the above embodiment can be obtained. Note that this artificial reef 1B is a so-called cage-type artificial reef, capable of accommodating a plurality of conglomerates therein and forming a suitable environment for the habitation of crustaceans such as lobsters.

[0122] (2) In the above embodiment and each modified embodiment, the skeletal structure 150 of the artificial reef frame 10 has a three-dimensional rectangular parallelepiped shape, but it is not limited thereto, and for example, it may be a two-dimensional planar structure. As an example, the skeletal structure 150 may be formed in a two-dimensional rectangular frame shape.

[0123] (3) In the method for manufacturing the artificial reef 1 in the above embodiment and each modified embodiment, in the sub-assembly construction step S23, after constructing a plurality of oil well pipe sub-assemblies 60, in the sub-assembly welding step S24, the plurality of oil well pipe sub-assemblies 60 are sequentially welded and fixed to a pair of frame members. However, it is not limited thereto, and one oil well pipe sub-assembly 60 may be constructed in the sub-assembly construction step S23, and then the above-described process of welding and fixing the constructed one oil well pipe sub-assembly 60 to a pair of frame members may be repeatedly executed in the sub-assembly welding step S24.

[0124] (4) In the above embodiment and each modified embodiment, as an example of two locations (connection locations of the connection support 11) spaced apart in the longitudinal direction on the outer peripheral surface of the oil well pipe P, both ends of the outer peripheral surface of the oil well pipe P are described. However, it is not limited thereto, and the two locations may be located inside both ends of the oil well pipe P.

[0125] (5) In the above-described embodiment and each modified embodiment, the oil well pipe P is fixed to the skeletal structure 150 by welding, but it is not limited thereto. For example, fastening members such as bolts may be used for fixing.

Explanation of Reference Numerals

[0126] B1: First welding bead portion B2: Second welding bead portion B3: Third welding bead portion P: Oil well pipe S2: Process S21: Cutting process S22: Preheating process S23: Sub-assembly construction process S24: Sub-assembly welding process 1: Artificial reef 1A: Artificial reef 1B: Artificial reef 11: Connecting support 12: Seat plate 21: Support column 30: Upper end of frame 33: Left cross beam (frame member) 34: Right cross beam (frame member) 35: Upper end oil well pipe group wall 41: Front cross beam (frame member) 42: Rear cross beam (frame member 45: Intermediate oil well pipe group wall 53: Left cross beam (frame member) 54: Right cross beam (frame member) 55: Lower end oil well pipe group wall 60: Oil well pipe sub-assembly 101: Burner (heating device) 111: Support plate 111c: First end face 111d: Second end face 111e: Extended portion 112: Seat plate 112a: Front side 112b: Rear side 150: Skeletal structure

Claims

1. A fish reef comprising a skeletal structure and an oil well pipe fixed to the skeletal structure.

2. The fish reef according to claim 1, wherein a pair of connecting and supporting members are interposed between two locations spaced apart in the longitudinal direction on the outer peripheral surface of the oil well pipe and the skeletal structure, and the oil well pipe is connected to and supported by the skeletal structure through the pair of connecting and supporting members, each of the pair of connecting and supporting members has a support plate fixed to the outer peripheral surface of the oil well pipe via a first welding bead portion, each support plate has a first end face which is an end face connecting both side faces in the thickness direction thereof and which abuts against the outer peripheral surface of the oil well pipe and extends along the longitudinal direction thereof.

3. The fish reef according to claim 2, wherein the first welding bead portion is formed along the entire peripheral edge of the contact portion between the first end face of each support plate and the outer peripheral surface of the oil well pipe.

4. The fish reef according to claim 3, wherein each of the connecting and supporting members further has a seat plate fixed to the support plate via a second welding bead portion and fixed to the skeletal structure via a third welding bead portion, the support plate has a second end face facing the first end face, the seat plate has a back side face which constitutes one side face in the thickness direction thereof and abuts against the outer surface of the skeletal structure, and a front side face which constitutes the other side face in the thickness direction of the seat plate and abuts against the second end face of the support plate.

5. The fish reef according to claim 4, wherein the second welding bead portion is formed along the entire peripheral edge of the contact portion between the second end face of the support plate and the front side face of the seat plate, the third welding bead portion is formed along the entire peripheral edge of the contact portion between the back side face of the seat plate and the skeletal structure.

6. The fish reef according to claim 4 or 5, wherein the support plates of the pair of connecting and supporting members have extending portions extending outward of the longitudinal direction of the oil well pipe beyond both end portions in the longitudinal direction thereof, and are supported by the seat plates through the extending portions.

7. The fish reef according to claim 6, wherein a plurality of the oil well pipes are provided, the skeletal structure has a pair of frame members extending in a predetermined direction and spaced apart from each other in a direction orthogonal to the predetermined direction, the plurality of oil well pipes are respectively connected to the pair of frame members through the pair of connecting and supporting members, and form an oil well pipe group wall covering between the pair of frame members by being arranged adjacent to each other in the predetermined direction.

8. The fish reef according to claim 7, wherein Each of the plurality of oil well pipes is arranged so as to fit between the central position of one of the pair of frame members and the central position of the other frame member in the orthogonal direction, the artificial reef.

9. A method for manufacturing an artificial reef, comprising: A preparation step of preparing oil well pipes in advance and constructing a pair of connection supports each composed of a seat plate and a support plate erected on the front surface of the seat plate in advance; A sub-assembly construction step of constructing a sub-assembly of an oil well pipe and the pair of connection supports by abutting, along the length direction of the oil well pipe, a first end surface that connects both side surfaces in the thickness direction of each support plate of the pair of connection supports to two positions spaced apart in the length direction on the outer peripheral surface of the oil well pipe, and fixing each support plate to the outer peripheral surface by welding; A sub-assembly welding step of fixing, by welding, the seat plate of each connection support of the oil well pipe sub-assembly constructed in the sub-assembly construction step to the skeleton structure of the artificial reef.

10. In the method for manufacturing an artificial reef according to Claim 9, On the outer peripheral surfaces of both ends of the oil well pipe prepared in the preparation step, screw portions are formed for connecting adjacent oil well pipes when the oil well pipe is used as a flow path pipe for a fluid. Before the sub-assembly construction step, a cutting step of cutting both ends of the oil well pipe prepared in the preparation step so as to remove the screw portions at both ends of the oil well pipe is further provided. In the sub-assembly construction step, the support plates of the pair of connection supports are welded to the outer peripheral surface of the oil well pipe after the cutting step.

11. The method for manufacturing an artificial reef according to Claim 10, The skeleton structure has a pair of frame members extending in a predetermined direction and spaced apart from each other in an orthogonal direction orthogonal to the predetermined direction. In the cutting step, the oil well pipe is cut so that the length of the oil well pipe becomes a predetermined length shorter than the distance between the central position in the orthogonal direction of one of the pair of frame members and the central position in the orthogonal direction of the other frame member. In the sub-assembly construction step, when welding the support plates of the pair of connection supports to each of the cut oil well pipes, the welding is performed so that each support plate has an extension portion extending outward in the length direction of the oil well pipe from both end positions in the length direction of the oil well pipe. In the construction of the connection support in the preparation step, a method for manufacturing a fish reef is provided, wherein the connection support is constructed by welding at least a portion of the support plate corresponding to the extending portion to the seat plate.

12. In the method for manufacturing a fish reef according to any one of Claims 9 to 11, the method for manufacturing a fish reef further includes a preheating step of preheating, by a heater, portions corresponding to the two locations on the outer peripheral surface of the oil well pipe to a predetermined target temperature before the sub-assembly construction step.

13. In the method for manufacturing a fish reef according to any one of Claims 9 to 11, in the sub-assembly construction step, the welding is performed along the entire peripheral edge of each contact portion between the first end face of each support plate of the pair of connection supports and the outer peripheral surface of the oil well pipe.

14. In the method for manufacturing a fish reef according to any one of Claims 9 to 11, in the preparation step, when constructing each connection support, the second end face of the support plate prepared in advance facing the first end face and the front side surface of the seat plate prepared in advance are brought into contact with each other, and welding is performed along the entire peripheral edge of this contact portion.

15. In the method for manufacturing a fish reef according to Claim 11, in the preparation step, a plurality of the oil well pipes are prepared, in the sub-assembly construction step, a plurality of oil well pipe sub-assemblies are constructed by fixing the pair of connection supports to each of the plurality of oil well pipes by welding, in the sub-assembly welding step, while arranging the plurality of oil well pipe sub-assemblies at predetermined intervals along the predetermined direction in a state of straddling between a pair of frame members, each seat plate is fixed to the outer surfaces of the pair of frame members by welding to form an oil well pipe group wall composed of a plurality of oil well pipes arranged in the predetermined direction.

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