Submarine cable protection conduit

Abstract

This invention provides a submarine cable protection tube that is lightweight in structure, yet the bolt holes provided in the split section are resistant to deformation even when subjected to the effects of seawater currents and floating debris. [Solution] The submarine cable protection tube of the present invention comprises a cylindrical cover body 1 having a cable insertion hole 1a inside in which a submarine cable is placed. This cover body 1 is composed of a pair of halves 2, 2, each provided with a groove 2a. The pair of halves 2, 2 are assembled so that the open sides of the grooves 2a face each other, thereby forming the cable insertion hole 1a with the pair of grooves 2a, 2a.

Description

Technical Field

[0001] The present invention relates to a protective pipe used when laying submarine cables, and particularly to a resin-made submarine cable protective pipe composed of a pair of half bodies.

Background Art

[0002] Normally, submarine cables are buried in the seabed. However, when the buried machine cannot be used due to the influence of bedrock or the like, or in a location where the water depth exceeds a predetermined value, the submarine cable cannot be buried in the seabed. The cable in the unburied part of the seabed may be damaged by being caught by an anchor of a fishing boat or the like, or by suffering from tidal current corrosion (electrolytic corrosion). Therefore, conventionally, a cast iron half protective pipe has been attached to the unburied part of the cable on the seabed. However, since the cast iron protective pipe is heavy, it is not easy to transport or handle, and it has been a great burden even for a diver who performs the work of attaching it to the cable in the sea.

[0003] As a solution to such problems, for example, Patent Document 1 discloses an invention related to a protective pipe for submarine cables under the name of "protective pipe for submarine cables" made of glass fiber reinforced plastic. The invention disclosed in Patent Document 1 has a structure in which a pair of half bodies divided in the axial direction sandwich the submarine cable, and a nut is tightened against a bolt inserted into a bolt hole provided in the half body to be fixed to the submarine cable.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the invention disclosed in Patent Document 1, there was a possibility that the bolt holes provided in the split body could deform when affected by seawater currents or when debris collided with it, eventually causing the bolts to come out of the bolt holes. Patent Document 1 also describes a structure in which a pair of male and female hooks are attached to a pair of split bodies instead of bolts, and the pair of split bodies are connected by these hooks. However, with such a structure equipped with hooks, it may not be possible to obtain sufficient force to fix the pair of split bodies.

[0006] This invention addresses the aforementioned conventional circumstances and aims to provide a submarine cable protection tube that is lightweight in structure, yet in which the bolt holes provided in the split body are less likely to deform even when affected by seawater currents or floating debris. [Means for solving the problem]

[0007] To achieve the above objective, the first invention is a submarine cable protection tube assembled into a cylindrical shape having a cable insertion hole inside in which a submarine cable is placed, comprising: a resin cover body consisting of a pair of halves each provided with a groove, the two halves being assembled so that the open sides of the grooves face each other to form a cable insertion hole, and a plurality of bolt insertion holes formed at both circumferential edges of each halve that penetrate in the assembly direction; a pair of metal plates, one for each halve, with at least a portion of them embedded and bolt holes formed at positions corresponding to the bolt insertion holes; a bolt whose shaft is connected to both bolt insertion holes and both bolt holes so that its head is positioned outside the halves when the two halves are assembled; and a nut which is screwed onto the tip of the shaft of the bolt and connects the two halves and the two metal plates by sandwiching them with the head of the bolt.

[0008] The second invention is characterized in that, in the first invention, the metal plate has a portion that is exposed from the half-cut body, and the bolt holes are provided in the exposed portion.

[0009] The third invention is characterized in that, in the first or second invention, the metal plate comprises a U-shaped central portion and a pair of mounting portions extending symmetrically from each edge of the central portion in opposite directions, with each mounting portion having a bolt hole.

[0010] The fourth invention is characterized in that, in the third invention, each half-body has a pair of recesses provided symmetrically on its outer surface, with a groove in between, and the mounting portion is exposed at the bottom surface of the recess. [Effects of the Invention]

[0011] In the first invention, the strength of the cover body is increased by a metal plate partially embedded in the split body. Therefore, even if a part of the protective pipe deforms due to the influence of seawater currents, the cover body at the location where the metal plate is embedded is less likely to deform, and even if floating debris collides with the protective pipe, that part of the cover body is less likely to be damaged. Furthermore, according to the first invention, since the bolts inserted through bolt holes provided in the metal plate are held by the metal plate, even if the bolt insertion holes provided in the split body deform due to the action of seawater currents, there is no risk of the bolts falling out of the split body. In addition, in the first invention, since the head of the bolt is positioned outside the split body and the tip of the bolt shaft protrudes from the split body, the work of screwing a nut onto the bolt and tightening it, and the work of loosening the nut and removing it from the bolt, can be easily performed. Moreover, the part of the split body in which the metal plate is embedded is not susceptible to wear due to friction with seabed sand or damage due to collision with boulders. Furthermore, unlike the case where the metal plate is attached from the outside of the cover body, the first invention does not require the metal plate to be fixed to the cover body, resulting in improved workability.

[0012] In the second invention, when a pair of halved bodies are combined into a cylindrical shape, the bolt insertion holes are sandwiched between a pair of metal plates. Therefore, even if the cover body deforms, the deformation of the bolt insertion holes is prevented by the pair of metal plates, thus further enhancing the effect of the first invention, which prevents bolts from falling out due to deformation of the bolt insertion holes.

[0013] In the third invention, since the submarine cable placed inside the cable insertion hole is surrounded by a pair of metal plates, even if the cover body is deformed by an external force, the submarine cable in the portion surrounded by the pair of metal plates is less affected by the deformation of the cover body. In other words, according to the third invention, even if the cover body deforms in a portion where no metal plates are embedded, the effect of the deformation of the cover body on the submarine cable in the portion where metal plates are embedded is mitigated by the metal plates.

[0014] In the fourth invention, when a pair of halves are connected using a bolt and nut, the bolt head is positioned in a space formed by the recess so as to extend inward from the outer surface of the halves. Therefore, even if floating debris collides with the cover body, there is no risk of the debris colliding with the bolt head. Accordingly, according to the fourth invention, it is possible to prevent damage to the parts of the metal plate or halves provided with bolt holes or bolt insertion holes from being caused by impacts resulting from floating debris colliding with the bolt head. [Brief explanation of the drawing]

[0015] [Figure 1] (a) is a front view showing an example of the external appearance of a submarine cable protection tube according to an embodiment of the present invention, and (b) is a cross-sectional view taken along the line AA in Figure (a). [Figure 2] (a) is an enlarged view of section B enclosed by the dashed line in Figure 1(a), and (b) is a view of section B in direction D as seen by arrow D in Figure 1(a). [Figure 3] (a) is a perspective view of the metal plate shown in Figure 1(a), and (b) is a cross-sectional view taken along the line CC in Figure 1(a). [Modes for carrying out the invention]

[0016] The structure, operation, and effects of the submarine cable protection tube of the present invention will be specifically explained with reference to Figures 1 to 3. Note that the metal plate is not shown in Figure 1(b). [Examples]

[0017] As shown in Figures 1(a) and 1(b), the submarine cable protection tube according to an embodiment of the present invention comprises a cylindrical cover body 1 consisting of a pair of half-split bodies 2, 2 made of polyurethane, a metal plate 3 partially embedded in the cover body 1, and bolts 4 and nuts 5 (see Figure 2(b)) connecting the pair of half-split bodies 2, 2. The split body 2 has a shape in which a cylindrical body slightly larger than the submarine cable is divided into two by a plane passing through the cylindrical axis, and the cross-section of the inner wall is semicircular, and it has a pair of grooves 2a that extend long in the axial direction. In other words, the submarine cable protection tube of the present invention comprises a cylindrical cover body 1 having a cable insertion hole 1a inside in which the submarine cable is placed, and this cover body 1 is made up of a pair of split bodies 2, 2, each provided with grooves 2a. When the pair of split bodies 2, 2 are combined so that the open sides of the grooves 2a face each other, the pair of grooves 2a, 2a form the cable insertion hole 1a.

[0018] As shown in Figures 2(a) and 2(b), the outer surface 2b of the split body 2 is provided with recesses 2c that are symmetrical across the groove 2a, each recess being formed by a bottom surface 7a parallel to the split surface 2d, an elevation surface 7b connected to the bottom surface 7a, and a pair of side surfaces 7c connecting the bottom surface 7a and the elevation surface 7b. When the bottom surface 7a and the elevation surface 7b are viewed from the direction of their normal vectors, their surfaces form a trapezoid with an upper base on the side closer to the groove 2a and a lower base that is longer than this upper base, but the upper base is shared by the bottom surface 7a and the elevation surface 7b. In addition, a plurality of bolt insertion holes 2e (see Fig. 3(b)) are formed in both circumferential edge portions of the half body 2 so as to penetrate in the combination direction (the direction perpendicular to the half plane 2d). Further, a pair of metal plates 3, 3, each of which is embedded in one of the pair of half bodies 2, 2 and at least a partial region thereof, has bolt holes 3c (see Fig. 3(b)) formed at positions corresponding to the bolt insertion holes 2e. When the shaft portion 4a of the bolt 4 is inserted into the bolt hole 3c of the metal plate 3 and the bolt insertion hole 2e of the half body 2 and the nut 5 is screwed onto the tip of the shaft portion 4a, washers 6 are respectively installed between the nut 5 and the half body 2. Instead of the nut 5 and the washer 6, a nut integrated with the washer can also be used. In this case, the assembly work under the sea becomes easier.

[0019] As shown in Fig. 3(a), the metal plate 3 is composed of a strip-shaped plate member, and includes a U-shaped central portion 3a and a pair of mounting portions 3b, 3b that symmetrically extend from each edge of the central portion 3a in opposite directions around the central portion 3a. Bolt holes 3c through which the shaft portion 4a of the bolt 4 is inserted are respectively formed in the mounting portions 3b parallel to the half plane 2d. As shown in Fig. 3(b), a pair of bolt insertion holes 2e, 2e that reach the half plane 2d (see Fig. 2(b)) from the recess 2c are provided in the half body 2 so as to communicate with the pair of bolt holes 3c, 3c of the metal plate 3 respectively. Further, the mounting portions 3b of the metal plate 3 are exposed on the bottom surface 7a of the recess 2c, and the bolt holes 3c are provided at the exposed portions. When the pair of half bodies 2, 2 are combined so that the bolt insertion holes 2e communicate with each other, the cable insertion hole 1a is sandwiched between the pair of metal plates 3, 3. Therefore, after the shaft portion 4a of the bolt 4 is communicated from the side of one half body 2 to the bolt holes 3c and bolt insertion holes 2e of the metal plate 3 in one half body 2 and the bolt holes 3c and bolt insertion holes 2e of the metal plate 3 in the other half body 2, the nut 5 screwed to the tip of the shaft portion 4a protruding from the bolt hole 3c of the metal plate 3 in the other half body 2 is tightened. As a result, the pair of half bodies 2, 2 are connected in such a manner that they are sandwiched between the nut 5 and the head portion 4b of the bolt 4 together with the pair of metal plates 3, 3 with the submarine cable disposed inside the cable insertion hole 1a.

[0020] In the submarine cable protection pipe having such a structure, since the strength of the cover body 1 is increased by the metal plate 3 partially embedded in the half body 2, even if a part of the protection pipe is deformed under the influence of the seawater flow, the cover body 1 at the location where the metal plate 3 is embedded is difficult to deform. Further, even when a drifting object collides with the protection pipe itself, the relevant portion of the cover body 1 is difficult to be damaged. Furthermore, according to the above submarine cable protection pipe, since the bolt 4 inserted through the bolt hole 3c provided in the metal plate 3 is held by the metal plate 3, even when the bolt insertion hole 2e provided in the half body 2 is deformed under the action of the seawater flow, there is no risk that the bolt 4 will drop off from the half body 2. In addition, in the above submarine cable protection pipe, since the head portion 4b of the bolt 4 is disposed outside the half body 2 and the tip of the shaft portion 4a of the bolt 4 protrudes from the half body 2, the operation of screwing and tightening the nut 5 to the bolt 4 and the operation of loosening the nut 5 and removing it from the bolt 4 can be easily performed. Also, for the portion where the metal plate 3 is embedded in the half body 2, there is no worry that the metal plate 3 will be worn due to friction with the seabed sand or the like or damaged due to collision with a boulder.

[0021] In the submarine cable protection pipe of the present invention, when the pair of half bodies 2, 2 are combined in a cylindrical shape, since the bolt insertion holes 2e are sandwiched between the pair of metal plates 3, 3, even when other portions of the cover body 1 are deformed, the deformation of the bolt insertion holes 2e is blocked by the pair of metal plates 3, 3 at the portion sandwiched between the pair of metal plates 3, 3. Therefore, the effect of preventing the bolt 4 from dropping off due to the deformation of the bolt insertion holes 2e is further exerted. Furthermore, in the submarine cable protection tube of the present invention, the submarine cable placed inside the cable insertion hole 1a of the cover body 1 is surrounded by a pair of metal plates 3, 3. Therefore, even if the cover body 1 is deformed by an external force, the portion of the submarine cable surrounded by the pair of metal plates 3, 3 is less affected by the deformation of the cover body 1. In other words, with the submarine cable protection tube of the present invention, even if the cover body 1 is deformed in a portion where the metal plates 3 are not embedded, the portion where the metal plates 3 are embedded will have the effect of mitigating the impact of the deformation of the cover body 1 on the submarine cable.

[0022] In the submarine cable protection tube of the present invention, when a pair of split bodies 2, 2 are connected using bolts 4 and nuts 5, the head 4b of the bolt 4 is positioned in a space formed by the recess 2c so as to extend inward from the outer surface 2b of the split body 2. Therefore, even if floating debris collides with the cover body 1, there is no risk of the debris colliding with the head 4b of the bolt 4. Accordingly, the submarine cable protection tube of the present invention prevents damage to the parts of the metal plate 3 and split body 2 provided with bolt holes 3c and bolt insertion holes 2e due to impacts such as those caused by floating debris colliding with the head 4b of the bolt 4.

[0023] The submarine cable protection tube of the present invention is not limited to the structure shown in the examples. For example, a polyurethane synthetic resin can be used for the cover body. [Industrial applicability]

[0024] The submarine cable protection tube of the present invention is used attached to the outer surface of a submarine cable to protect it from abrasion and impact caused by boulders that occur in rocky areas and landing areas. [Explanation of symbols]

[0025] 1…Cover body 1a…Cable insertion hole 2…Half body 2a…Recessed groove 2b…Outer surface 2c…Recess 2d…Half surface 2e…Bolt insertion hole 3…Metal plate 3a…Center part 3b…Mounting part 3c…Bolt hole 4…Bolt 4a…Shaft part 4b…Head 5…Nut 6…Washer 7a…Bottom surface 7b…Vertical surface 7c…Side

Claims

[Claim 1] A submarine cable protection tube assembled into a cylindrical shape, having a cable insertion hole inside through which a submarine cable is placed, A resin cover body consisting of a pair of halves, each having a groove, wherein the cable insertion hole is formed when the two halves are assembled so that the open sides of the grooves face each other, and a plurality of bolt insertion holes are formed at both circumferential edges of each halve, penetrating in the assembly direction. Each of the aforementioned halved bodies is provided with a pair of metal plates, one of which is embedded in at least a portion of the body, and each plate has a bolt hole formed at a position corresponding to the bolt insertion hole. A bolt whose shaft is connected to both bolt insertion holes and both bolt holes such that, in the state in which the two halves are combined, the head is positioned outside the halves, The system includes a nut that is screwed onto the tip of the shaft portion of the bolt, and which connects the two halves and the two metal plates by sandwiching them between the head of the bolt, The metal plate comprises a U-shaped central portion and a pair of mounting portions extending symmetrically from each edge of the central portion in opposite directions, with respect to the central portion. The central portion is entirely embedded in the aforementioned split body. On the outer surface of the aforementioned split body, a pair of recesses are provided symmetrically on either side of the groove. The mounting portion is exposed at the bottom surface of the recess, The submarine cable protection tube is characterized in that the bolt holes are provided in the exposed portion.

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