Submarine cable lead sheath and lead sheath repairing method

Abstract

The invention discloses a submarine cable lead sheath and a lead sheath repairing method, the lead sheath is a cylindrical lead sheath formed by splicing at least two lead plates with arc-shaped longitudinal sections, the two sides of each lead plate are respectively provided with a plurality of clamping jaws extending outwards, the front side of the extending end part of each clamping jaw is provided with a bulge, the rear side of the extending end part of each clamping jaw is provided with a groove, and when the two adjacent lead plates are spliced, the bulges are clamped in the grooves. And the clamping jaw bulge of one lead plate is inserted into the groove of the clamping jaw of the other lead plate. The lead sleeve adopts a splicing structure, and the lead sleeve is directly spliced outside the submarine cable to be repaired, so that the inner diameter of the lead sleeve is close to the outer diameter of the buffer waterproof layer, and the workload of drawing, detaching and repairing an original protective layer is reduced; the clamping jaws of the lead sleeve can be automatically fixed after being spliced and are provided with welding rods, so that the fixing procedure is reduced.

Description

Technical Field

[0001] The invention relates to a submarine cable lead sheath and also to a method for repairing the submarine cable lead sheath, belonging to the technical field of submarine cables. Background Art

[0002] Due to the limitations of submarine cable production equipment and the load-bearing capacity of submarine cable laying vessels, it is difficult to avoid making factory joints during the manufacturing and laying of submarine cables. After the submarine cable is put into operation, it is damaged by anchor damage, cable body failure, etc., and emergency repair joints are also required for emergency repairs. The lead sheath is one of the protective layers of the submarine cable. It is used for radial waterproofing. During the operation of the DC cable, it prevents the contact protrusions at the interface between the semiconductor shielding layer and the insulation layer, thereby extending the insulation life of the entire cable. Whether it is a factory joint or an emergency repair joint, the lead sheath layer needs to be repaired.

[0003] The invention patent application with publication number CN 104299728 A discloses a method for restoring the lead sheath of a submarine cable factory joint. Before the conductor is connected, a lead tube with a diameter larger than the diameter of the lead tube of the submarine cable body is inserted in advance outside the submarine cable. After the conductor, the inner semi-conductive shielding layer, the insulating layer, and the outer shielding layer are restored and repaired, the lead sheath inserted in advance is moved to the repair position, and one end of the lead sheath is welded to the lead sheath of the submarine cable body by hydrogen-oxygen welding. After welding one end, the lead tube is pulled out with a drawing die with successively decreasing inner diameters until the outer diameter of the lead tube is the same as the outer diameter of the lead sheath, and finally the other end of the lead tube is welded to the lead sheath. The following problems exist in this scheme: in order to reduce the diameter of the pre-inserted lead pipe, it is necessary to strip a large amount of polypropylene rope, steel wire armor, PE rod, optical fiber and other structures on the surface of one of the two butted cables, and temporarily place the lead pipe to be used in the next step in the stripping area. After the lead pipe is restored, all the external protective layers are restored. The stripping and restoration increase the loss. Even if the external protective layer of the submarine cable is stripped, the inner diameter of the lead sleeve is still large, and the pulling workload is large. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to provide a submarine cable lead sheath that helps to reduce stripping loss and maintenance workload. Another purpose of the present invention is to provide a method for repairing a submarine cable lead sheath that ensures the quality of submarine cable repair.

[0005] Technical solution: The submarine cable lead sheath of the present invention is a cylindrical lead sheath formed by splicing at least two lead plates with arc-shaped longitudinal sections, and a plurality of protruding claws are respectively provided on both sides of the lead plates. A protrusion is provided on the front side of the protruding end of the claw, and a groove is provided on the rear side. When two adjacent lead plates are spliced, the protrusion of the claw of one lead plate is inserted into the groove of the claw of the other lead plate.

[0006] Preferably, in order to guide the flow of welding liquid, at least part of the contact plane between two adjacent lead plates is beveled to form a beveled surface inclined toward the outer wall of the lead plate. When the two lead plates are spliced, the two beveled surfaces are spliced ​​to form an inverted triangular groove.

[0007] Preferably, the lead has ductility. In order to take into account both the fixing strength after the two lead plates are spliced ​​and the welding rod requirements, the maximum thickness H2 of the claw and the thickness H1 of the lead plate are such that H2-H1=0-1.5mm.

[0008] Preferably, in order to align the end faces of the two lead plates, the rear side of the claw located at the end of the lead plate is coplanar with the plane of the end of the lead plate to form an L-shaped claw.

[0009] Preferably, in order to directly utilize the claw as a welding rod, the claw and the lead plate are made of the same material.

[0010] A method for repairing a submarine cable lead sheath according to the present invention comprises the following steps:

[0011] A submarine cable is taken, wherein the submarine cable is formed by butting two submarine cables, and the outer water-blocking layer of the joint has been repaired and the original lead sheaths on both sides of the joint have been trimmed; outside the water-blocking layer, lead plates with arc-shaped longitudinal sections are spliced ​​between the original lead sheaths to form a cylindrical spliced ​​lead sheath, and a cooling device is installed in the gap between the water-blocking layer and the spliced ​​lead sheath; the axial splicing seam of the spliced ​​lead sheath and the lap seam between one end of the spliced ​​lead sheath and the original lead sheath are heated to connect one end of the spliced ​​lead sheath to the original lead sheath of a cable, and the surface temperature of the spliced ​​lead sheath and / or the original lead sheath is maintained at 350-500° C. during the heating process; the spliced ​​lead sheath is pulled out using a mold to make the outer diameter of the spliced ​​lead sheath consistent with the outer diameter of the main lead sheath of the cable; and the splicing seam of the other end of the spliced ​​lead sheath and another cable is heated using the same heating method to complete the lead sheath repair.

[0012] Preferably, in order to avoid the local heating temperature being too high, which may cause the spliced ​​lead sleeve and / or the internal protective layer of the original lead sleeve to be damaged, a flamethrower is used to heat the spliced ​​seams and overlapped seams.

[0013] Preferably, in order to save frequent temperature measurements during the heating process, the inner flame temperature of the flame of the flame spray gun is controlled to be 600-750°C, the distance between the flame spray gun nozzle and the welding position is 8-12mm, and when heating, the flame is turned off after heating for 1-9 minutes and then waited for 1-9 minutes.

[0014] Preferably, when heating, turn off the heat after heating for 4 to 9 minutes and wait for 2 to 9 minutes.

[0015] Preferably, the surface temperature of the spliced ​​lead sleeve and / or the original lead sleeve is maintained at 370-490°C.

[0016] Preferably, the temperature of the flamethrower is maintained at 700-750° C., and the fuel of the flamethrower is butane.

[0017] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: 1. Reduce stripping loss and workload: The cylindrical one-piece repair lead sleeve is replaced with a spliced ​​lead sleeve. When the lead sleeve is repaired, there is no need to pre-strip the protective layer, which reduces the loss. The difference between the inner diameter of the spliced ​​lead sleeve and the inner diameter of the original lead sleeve of the submarine cable can be reduced to 2mm. The claws of the lead plate can make the spliced ​​lead sleeve self-fixed after splicing, and the claws act as welding rods, which greatly reduces the workload; 2. Ensure the quality of submarine cable repair: The welding temperature is reduced to about 400°C, reducing the risk of high-temperature damage to the submarine cable; 3. Shorten the repair time: intermittent heating, the heating peak temperature is reduced, and the heating and cooling time are shortened, and the time is reduced from 5h to 2h. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic structural diagram of a submarine cable lead sheath according to a first embodiment of the present invention;

[0019] Figure 2 It is a schematic diagram of the side structure of the submarine cable lead sheath according to the first embodiment of the present invention;

[0020] Figure 3 This is a schematic diagram of the process of splicing the lead sheath of a submarine cable according to the first embodiment of the present invention;

[0021] Figure 4 It is a schematic structural diagram of the cooperation between the submarine cable lead sheath and the submarine cable according to the second embodiment of the present invention. DETAILED DESCRIPTION

[0022] The first technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0023] Example 1: Figure 1 As shown, it is a schematic diagram of the structure of the lead sleeve 1 of the present invention. The lead sleeve 1 is formed by splicing two lead plates 11 with arc-shaped cross sections to form a cylindrical shape. A plurality of outwardly extending claws 111 are respectively provided on both sides of the outer arc surface of the lead plate 11. The front side of the extended end of the claw 111 is provided with a protrusion, and the rear side is provided with a groove. When splicing, the two adjacent lead plates 11 face oppositely, and the protrusion of the claw 111 of one lead plate is inserted into the groove of the claw 111 of the other lead plate. The groove prevents the protruding lead plate 11 from moving in the width direction, so that the two lead plates 11 can be fixed.

[0024] The clamping claws 111 are provided in multiple intermittent ways. On the one hand, it is convenient for the clamping claws of the two lead plates to be inserted and spliced. On the other hand, the thickness of the clamping claws 111 can be increased, thereby increasing the connection strength of the two lead plates and eliminating the wire rope fixing procedure. The clamping claws are preset, and the splicing error is small after the two lead plates are spliced. The clamping claws 112 at the end of the lead plate 11 are L-shaped, with only the front side protruding, and the rear side is coplanar with the end plane of the lead plate 11. When the lead plates are spliced, the clamping claws 111 form a splicing structure with the ends flush, so that the end faces of the two lead plates are aligned.

[0025] like Figure 2 The contact surface of two adjacent lead plates is a plane, and there is a connection seam between the outer arc surface of the lead plate and the plane. The lead plate is removed by beveling at the connection seam, or chamfered to form a beveled surface 113, and the beveled surface 113 is inclined toward the outer arc surface of the lead plate 11. When two lead plates 11 are spliced, the two beveled surfaces 113 are spliced ​​to form an inverted triangular groove, which is used for drainage to promote the molten welding liquid to enter the splicing seam between the two lead plates.

[0026] Taking the thickness H1 of the lead sleeve 1 as a reference, the sum of the maximum thickness H2 of the clamping claw 111 and the thickness H1 of the lead plate is H1-H2=0-1.5mm, preferably H1-H2=0-1mm. Increasing the thickness of the clamping claw 111 is beneficial to increasing the connection strength of the adjacent lead plates 11, but it should not be too thick, because too thick increases the difficulty of welding and easily damages the internal protective layer of the lead sleeve 1.

[0027] Taking the outer diameter D1 of the water-blocking layer as a reference, it is best that the inner diameter D2 of the spliced ​​lead sleeve 1 is 2 to 10 mm larger than the outer diameter D1 of the water-blocking layer. If the inner diameter of the lead sleeve 1 is too small, it is not conducive to the placement of the water cooling device, and if it is too large, it increases the difficulty of later demolding.

[0028] like Figure 3 , which is the splicing process of the lead sleeve of the present invention: the lead plate 11b is in opposite directions to the lead plate 11a. Before the two lead plates 11a and 11b are spliced ​​together, the lead plate 11b is close to the lead plate 11a and is staggered a little from the lead plate 11a in the length direction of the two. The claw 111 of the lead plate 11b is located between the two claws 111 of the lead plate 11a. The lead plate 11b is pushed to make the lead plates 11a and 11b contact, and the claws 111 of the two lead plates are spliced; finally, the lead plate 11b is moved to make the ends of the lead plates 11a and 11b flush, and the protrusion of the claw 111 of the lead plate 11b is inserted into the groove of the claw 111 of the lead plate 11a to complete the splicing.

[0029] The material of the clamping jaw 11 is preferably the same as that of the lead plate 11, both of which are lead or lead alloy. The lead alloy used to make the lead sleeve is an existing technology and will not be described in detail. Therefore, the clamping jaw 111 forms a splicing structure that can serve as a welding rod for welding the splicing seams of the lead plates in addition to fixing the two lead plates. The inverted triangular groove is used to guide the melted liquid welding rod. The clamping jaw 111 melts and flows into the splicing seams of the two lead plates 11 along the triangular groove, so that the two lead plates 11 are welded and fixed.

[0030] In the prior art, lead sleeve welding adopts oxyhydrogen welding or acetylene welding, and the welding temperature can reach 2800-3200°C. The high temperature during welding can easily damage the original lead sleeve or repair the protective layer such as the water barrier layer introduced into the lead sleeve. How to solve this problem? The second technical scheme of the present invention is further explained in combination with Examples 2 to 4 below.

[0031] Example 2: Use the lead sheath in Example 1 to repair the lead sheath of the submarine cable. In this example, the cable used is 500kV1800mm 2 Submarine cable, the repair method is:

[0032] (1) Figure 4 As shown, the joint conductor, semi-conductive layer, insulating layer, longitudinal water-blocking layer 2 of the two butted submarine cables have been repaired, and the original lead sheath 3 on both sides of the joint has been trimmed. Figure 3 In the process shown, a lead plate 11 is spliced ​​outside the repaired water-blocking layer 2 of the submarine cable core to form a spliced ​​lead sleeve 1, and the inner diameter of the spliced ​​lead sleeve 1 is 3 mm larger than the outer diameter of the water-blocking layer 2; the length of the spliced ​​lead sleeve 1 is slightly larger than the length of the area to be repaired, and a water cooling device (the water cooling device is a prior art) is installed in the gap between the water-blocking layer 2 and the spliced ​​lead sleeve 1 to prevent the spliced ​​lead sleeve 1 or the water-blocking layer 2 inside the original lead sleeve 3 from being damaged by excessive temperature during subsequent welding. The PE sheath 4, PE rod 5, PP rope 6, steel wire armor 7, and the outermost PP rope 8 outside the original lead sleeve 3 do not need to be removed;

[0033] (2) Using a butane torch, heat the claw 111 of the spliced ​​lead sleeve 1, the axial splicing seam of the spliced ​​lead sleeve 1, and the lap seam between one end of the spliced ​​lead sleeve and the original lead sleeve 3 of a cable, and control the overlap width (not shown) of one end of the spliced ​​lead sleeve 1 and the original lead sleeve 3 to be not less than 0.5 mm and not more than 5 mm. The inner flame temperature of the flame of the butane torch is about 700-750°C. During heating, keep the distance between the torch nozzle and the claw, and the distance between the torch nozzle and the splicing seam about 10 mm. Use intermittent heating: after local heating for 5 minutes, cool and wait for 3 minutes, so that the maximum surface temperature of the spliced ​​lead sleeve and the original lead sleeve can be maintained at 430±10°C and 380±10°C, respectively, without the need to monitor the surface temperature of the lead sleeve in real time;

[0034] (3) Use a mold to pull and weld the spliced ​​lead sleeve 1 to reduce its diameter, repeat the intermittent heating in step (2), connect the other end of the spliced ​​lead sleeve 1 and the splicing seam between the original lead sleeve 3 of another cable, and after welding, check the appearance of the lead seal to ensure that there are no obvious pores or burrs.

[0035] The method of this embodiment is used to repair a 500kV submarine cable lead sheath, which takes 2 hours. The repaired part of the lead sheath is firmly connected, and there are no obvious pores, voids and burrs on the lead sealing part. After dissection, the surface of the submarine cable core is intact without obvious overheating. After a 180kV 1h withstand voltage test, the test results show that there is no breakdown, which does not affect the main insulation performance of the submarine cable core and does not affect subsequent use.

[0036] Example 3: Use the lead sheath in Example 1 to repair the lead sheath of the submarine cable. In this example, the cable used is 220kV800mm 2Submarine cable, step (1) and step (3) are the same as in Example 2, except that step (2) is:

[0037] A butane flamethrower is used to heat the splicing structure formed by the claws 111 on the surface of the lead sleeve 1, the axial splicing seam of the spliced ​​lead sleeve 1, the lap seam of one end of the spliced ​​lead sleeve and the original lead sleeve 3 of a cable, and the overlapping width of the one end of the spliced ​​lead sleeve 1 and the original lead sleeve 3 is controlled to be about 0.5mm. During heating, the distance between the flamethrower nozzle and the claws is maintained at about 10mm. The heating method is intermittent heating: after local heating for 8 minutes, cooling and waiting for 8 minutes, the maximum surface temperature of the spliced ​​lead sleeve and the original lead sleeve can be maintained at 480±10℃ and 410±10℃ during the heating process.

[0038] The method of this embodiment is used to repair a 220kV submarine cable lead sheath, which takes 2 hours. The repaired part of the lead sheath is firmly connected, and there are no obvious pores, voids and burrs on the lead sealing part. After dissection, the surface of the submarine cable core is intact without obvious overheating. After the voltage test, the test results show that there is no breakdown, which does not affect the main insulation performance of the submarine cable core and does not affect subsequent use.

[0039] Effect: This method was used to repair a 220kV submarine cable lead sheath, which took 2.5 hours. The repaired lead sheath was firmly connected, and there were no obvious pores, holes or burrs in the lead sealing area. After dissection, the surface of the submarine cable core was intact and there was no obvious overheating. After the withstand voltage test, the cable was not punctured, and the main insulation performance of the submarine cable core was not affected, and the subsequent use was not affected.

[0040] Example 4: Using the lead sheath in Example 1 to repair the lead sheath of a submarine cable, this example is the same as the cable used in Example 3, steps (1) and (3), except that step (2) is:

[0041] The heating time of the flamethrower in this method is 10 minutes. It takes 1.5 hours to repair a 220kV submarine cable lead sheath using this method. The repaired part of the lead sheath is firmly connected, and there are no obvious pores, voids and burrs on the lead seal. Compared with the solution in Example 2, this solution takes less time. However, after dissection of the cable repaired by the method of this embodiment, there was overheating on the surface of the submarine cable core. After the withstand voltage test, the cable was broken down, and the main insulation performance of the submarine cable core was destroyed, and it could not be used subsequently.

Claims

1. A submarine cable lead sheath, characterized in that: A cylindrical lead sleeve (1) is formed by splicing at least two lead plates (11) with arc-shaped longitudinal sections. A plurality of outwardly extending claws (111) are provided on both sides of the outer arc surface of the lead plate (11). The front side of the extended end of the claw (111) is provided with a protrusion, and the rear side is provided with a groove. When two adjacent lead plates (11) are spliced, the protrusion of the claw of one lead plate is inserted into the groove of the claw of the other lead plate.

2. The submarine cable lead sheath according to claim 1, characterized in that: At least part of the contact plane between two adjacent lead plates (11) is chamfered to form a chamfered surface (113) inclined toward the outer wall of the lead plates. When the two adjacent lead plates are spliced, the two chamfered surfaces (113) are spliced ​​to form an inverted triangle groove.

3. The submarine cable lead sheath according to claim 1, characterized in that: The maximum thickness H2 of the clamping claw (111) and the thickness H1 of the lead plate (11) are such that H2-H1=0-1.5 mm.

4. The submarine cable lead sheath according to claim 1, characterized in that: The rear side of the clamping claw (111) located at the end of the lead plate (11) is coplanar with the plane of the end of the lead plate, forming an L-shaped clamping claw (112).

5. The submarine cable lead sheath according to claim 1, characterized in that: The clamping claw (111) and the lead plate (11) are made of the same material.

6. A method for repairing a submarine cable lead sheath, characterized in that: The following steps are involved: A submarine cable is obtained, wherein the submarine cable is formed by butting two submarine cables, and the outer water-blocking layer of the joint has been repaired and the original lead sheaths on both sides of the joint have been trimmed; a lead plate with an arc-shaped longitudinal section is spliced ​​outside the water-blocking layer and between the original lead sheaths to form a cylindrical spliced ​​lead sheath, and a cooling device is installed in the gap between the water-blocking layer and the spliced ​​lead sheath; the axial splicing seam of the spliced ​​lead sheath and the lap seam between one end of the spliced ​​lead sheath and the original lead sheath are heated to connect one end of the spliced ​​lead sheath to the original lead sheath of a cable, and the surface temperature of the spliced ​​lead sheath and / or the original lead sheath is maintained at 350-500° C. during the heating process; the spliced ​​lead sheath is pulled out using a mold to make the outer diameter of the spliced ​​lead sheath consistent with the outer diameter of the main lead sheath of the cable, and the splicing seam between the other end of the spliced ​​lead sheath and another cable is heated using the same heating method to complete the lead sheath repair.

7. The repair method according to claim 6, characterized in that: Use a flamethrower to heat the joints and lap joints, control the inner flame temperature of the flame of the flamethrower to 600-750°C, maintain the distance between the nozzle of the flamethrower and the clamping claw to be 8-12mm, and when heating, turn off the flame after heating for 1-9 minutes and wait for 1-9 minutes.

8. The repair method according to claim 7, characterized in that: During the heating process, turn off the heat after heating for 4 to 9 minutes and wait for 2 to 9 minutes.

9. The repair method according to claim 6 or 7, characterized in that: During the heating process, the surface temperature of the spliced ​​lead sleeve and / or the original lead sleeve is maintained at 370-490°C.

10. The repair method according to claim 6 or 7, characterized in that: The fuel of the flamethrower is butane.

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