Riser pipe installation method, guide pipe and hanging clamp

Abstract

To provide a construction method of a riser pipe which is excellent in construction performance, a guide pipe and a suspension clamp.SOLUTION: A construction method of a riser pipe 1 includes: an exposure process for exposing an end part 2e of submarine piping 2 to an atmosphere; a guide clamp attachment process for attaching a guide clamp 3 for guiding an end part of the riser pipe 1 to the end part 2e of the submarine pipe 2; a suspension process for suspending the riser pipe 1 in a posture that a pipe axis 1a of a vertical part 11 of the riser pipe 1 progresses along a vertical direction; a core alignment process for core-aligning the end part 2e of the submarine piping 2 and the end part of the riser pipe 1; a weld process for welding the end part of the riser pipe 1 and the end part 2e of the submarine piping 2 along an annular clearance 31 which is formed at the guide clamp 3; and a hang-down process for hanging down the welded and guided riser pipe 1 and the submarine piping 2 to a seabed.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a riser pipe installation method, a guide pipe, and a hanging clamp. [Background technology]

[0002] Conventionally, there is a piping for carrying liquids such as petroleum, which is composed of a subsea piping placed on the seabed, a piping placed in the air, and a riser pipe placed between them and rising vertically. In construction for newly installing or updating such a piping, particularly a riser pipe, it is necessary to weld the existing subsea piping and the new riser pipe in the air above sea level.

[0003] However, at sea, the relationship between the attitude of the existing submarine piping and the attitude of the newly installed riser pipe is unstable due to the action of waves and wind, making welding difficult, so there was room for improvement in the ease of installation of the riser pipe. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6726813 Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the problems in the background art described above, an object of the present invention is to provide a riser pipe installation method, a guide pipe, and a hanging clamp that are easy to install. [Means for solving the problem]

[0006] The gist of the present invention is as follows.

[0007] (1) A method for constructing a riser pipe according to one aspect of the present invention includes an exposing step of exposing an end of a subsea pipe to air, a guide clamp attaching step of attaching a guide clamp to the end of the subsea pipe to guide the end of the riser pipe, a suspending step of suspending the riser pipe in a position in which the pipe axis of a vertical portion of the riser pipe is aligned vertically, a centering step of aligning the center of the end of the subsea pipe with the center of the riser pipe, a welding step of welding the end of the riser pipe to the end of the subsea pipe along an annular gap formed in the guide clamp, and a suspending step of suspending the welded and connected riser pipe and subsea pipe to the seabed. (2) In the above (1), the guide clamp may be a tubular body whose inner cavity can be freely expanded or contracted, and the centering step may include reducing the diameter of the inner cavity. (3) In the above (1) or (2), the suspending step may include a step of suspending the intermediate clamp after performing an intermediate clamp mounting step of mounting an intermediate clamp to an intermediate portion of the riser pipe, an anchor clamp mounting step of mounting an anchor clamp to a lower end of the riser pipe, and a clamp connecting step of connecting the intermediate clamp and the anchor clamp with a cord-like body. (4) In any of the above (1) to (3), a reinforcing step of attaching a reinforcing member to the curved portion of the riser pipe may be included. (5) A guide clamp according to one embodiment of the present invention is a guide clamp used for welding piping in which a subsea piping and a riser pipe are connected, the guide clamp comprising a first guide clamp segment and a second guide clamp segment that are divided in a direction perpendicular to the axis of the piping, and a fastening member that fastens the first guide clamp segment and the second guide clamp segment together, the guide clamp having a subsea piping side mounting portion that can be freely attached to an end of the subsea piping, a riser pipe side mounting portion that has a tapered guide that guides the riser pipe and can be freely attached to the end of the riser pipe, and a connecting portion that connects the subsea piping side mounting portion and the riser pipe side mounting portion, and the guide clamp has an annular gap between the subsea piping side mounting portion and the riser pipe side mounting portion, exposing a welded portion between the subsea piping and the riser pipe. (6) A hanging clamp according to one embodiment of the present invention is a hanging clamp used for lifting a riser pipe with a hanging device, the hanging clamp having a locking portion for locking the hanging device and including an intermediate clamp that can be freely attached to an intermediate portion of the riser pipe, an anchor clamp that can be freely attached to a lower end portion of the riser pipe, and a cord-like body connecting the intermediate clamp and the anchor clamp. Effect of the Invention

[0008] According to the present invention, a riser pipe installation method, a guide pipe, and a hanging clamp that are excellent in workability can be provided. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is an explanatory diagram of the subsea piping immediately after the existing riser pipe has been removed. [Diagram 2] 11A and 11B are explanatory diagrams of an exposure process and a guide clamp attachment process. [Diagram 3] FIG. 13 is an explanatory diagram showing a state in which a riser pipe is suspended. [Figure 4] FIG. [Diagram 5] FIG. 4 is an explanatory diagram of a hanging process, a centering process, and a welding process. [Figure 6] FIG. [Figure 7] FIG. [Figure 8] FIG. [Figure 9] FIG. [Figure 10] FIG. [Figure 11] FIG. 4 is a side view of the first divided body. [Figure 12] FIG. 4 is a side view of the second divided body. [Figure 13] FIG. [Figure 14] FIG. [Figure 15] 13 is another embodiment of the hanging clamp. [Figure 16]FIG. 16 is a detailed view of part P in FIG. [Figure 17] FIG. 16 is a detailed view of part Q in FIG. [Figure 18] 16 is a detailed view of the R portion in FIG. 15. FIG. [Figure 19] FIG. 16 is a detailed view of a portion S in FIG. [Figure 20] FIG. 16 is a detailed view of a T portion in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (Embodiment) Fig. 1 is an explanatory diagram of the subsea piping 2 immediately after the existing riser pipe is removed. Fig. 2 is an explanatory diagram of the exposing process and the guide clamp attachment process. Fig. 3 is an explanatory diagram showing the state in which the riser pipe 1 is suspended. Fig. 4 is an explanatory diagram of the centering process. Fig. 5 is an explanatory diagram of the suspension process, centering process, and welding process. Fig. 6 is an explanatory diagram of the suspension process.

[0011] As shown in Fig. 1, the construction method of the riser pipe 1 according to the present embodiment can be applied to a construction work for removing an existing pipe for carrying liquid such as petroleum and replacing it with a new pipe. The construction method of the riser pipe 1 according to the present embodiment is particularly suitable for a construction work for removing the riser pipe 1 from an existing pipe composed of a subsea pipe 2 placed underwater, a land pipe 4 placed on land, and a riser pipe 1 that connects them and extends in the vertical direction with a length according to the elevation difference between them, and replacing it with a new riser pipe 1. The construction method of the riser pipe 1 is not limited to a construction work for updating the riser pipe 1, and may be applied to a construction work for newly installing the riser pipe 1. Hereinafter, the construction method for the riser pipe 1 according to this embodiment will be described in chronological order, taking as an example construction work for updating the riser pipe 1.

[0012] (riser pipe) As shown in Figs. 3 and 5, the riser pipe 1 has a vertical portion 11, a horizontal portion 12, and a curved portion 13 between the vertical portion 11 and the horizontal portion 12. The vertical portion 11 and the horizontal portion 12 each extend linearly. The riser pipe 1 may have a horizontal portion 12 connected to the vertical portion 11 via a curved portion 13, and another horizontal portion 12 connected to the horizontal portion 12 via another curved portion 13. That is, the first horizontal portion and the second horizontal portion may have different orientations. The riser pipe 1 may not have the horizontal portion 12.

[0013] As shown in Figs. 1 to 6, the construction method of the riser pipe 1 according to the present embodiment includes an exposure step (see Fig. 2) of exposing the end 2e of the subsea piping 2 to air in order to meet the quality assurance or technical requirement that welding be performed in air. The construction method of the riser pipe 1 according to the present embodiment also includes a guide clamp attachment step (see Fig. 4) of attaching a guide clamp 3 for guiding the end 1e of the riser pipe 1 to the end 2e of the subsea piping 2. The construction method of the riser pipe 1 according to the present embodiment also includes a hanging step (see Figs. 3, 5, etc.) of suspending the riser pipe 1 in a position in which the pipe axis 1a of the vertical part 11 in the riser pipe 1 is aligned vertically. Note that, here, "along the vertical" means approximately vertical, and does not have to be strictly vertical, and includes a case in which the pipe is inclined within a range of, for example, about ±10 degrees. The construction method of the riser pipe 1 according to the present embodiment also includes a centering step of centering the end 2e of the subsea piping 2 and the end 1e of the riser pipe 1. In addition, the construction method of the riser pipe 1 in this embodiment includes a welding process of welding the end 1e of the riser pipe 1 and the end 2e of the subsea piping 2 along the annular gap 31 formed in the guide clamp 3. Since the construction method of the riser pipe 1 according to the present embodiment includes such steps, even in offshore construction involving welding of objects to be welded with unstable positions and postures on unstable scaffolding, such as welding of the submarine pipe 2 exposed to the air on a floating structure F such as a barge and the riser pipe 1 suspended by a crane or the like supported by the floating structure F such as a barge, the submarine pipe 2 and the riser pipe 1 can be easily aligned and welded. Therefore, a construction method of the riser pipe 1 with excellent workability can be provided.

[0014] Specifically, as shown in Fig. 1, a floating structure F such as a barge equipped with a crane or the like is prepared on the sea where an end 2e of the subsea piping 2, which will be the joint (see welded portion W in Fig. 14) with the riser pipe 1 (not shown), is located. Note that the existing riser pipe to be updated is separated from the subsea piping 2 and the onshore piping 4 in advance.

[0015] (1) Exposure process 2, the end 2e of the subsea piping 2 is exposed to the air (exposing step). Specifically, for example, a float is provided on the subsea piping 2 to generate buoyancy, causing the end 2e of the subsea piping 2 to float up until it is exposed to the air. Alternatively, for example, the subsea piping 2 is lifted up by a crane or the like supported by a floating structure F, thereby lifting the end 2e of the subsea piping 2 up until it is exposed to the air.

[0016] (2) Guide clamp installation process Then, as shown in FIG. 2, a guide clamp 3 for guiding the end 1e of the riser pipe 1 is attached to the end 2e of the subsea pipe 2 (guide clamp attachment step). At this time, as shown in FIG. 14, the guide clamp 3 is attached to the end 2e of the subsea pipe 2 so that the welded portion W between the end 2e of the subsea pipe 2 and the end 1e of the riser pipe 1 is exposed from the annular gap 31 provided in the guide clamp 3. That is, the end 2e of the subsea pipe 2 is clamped in a state where it is accommodated in the inner cavity 3v of the subsea pipe side attachment portion 36 of the guide clamp 3, and the guide clamp 3 is attached to the end 2e in a state where the end 2e is not interposed in the inner cavity 3v of the riser pipe side attachment portion 37 including the guide 32. Details of the guide clamp 3 will be described later.

[0017] (3) Hanging process In parallel with the above-mentioned exposure process and guide clamp attachment process, as shown in Figures 3, 5, etc., the riser pipe 1 is suspended by a crane or the like in a position in which the pipe axis 1a of the vertical portion 11 of the riser pipe 1 is aligned vertically (suspending process). Then, while the riser pipe 1 is suspended, the attitude of the riser pipe 1 is changed by appropriately operating a rope or the like connected to the riser pipe 1, so that the end 1e of the riser pipe 1 facing the end 2e of the subsea piping 2 is directed toward the end 2e of the subsea piping 2. When the riser pipe 1 has a horizontal portion 12 as shown in Figures 3 to 5, the end 1e of the riser pipe 1 directed toward the end 2e of the subsea piping 2 is the end 1e of the horizontal portion 12.

[0018] As shown in Figs. 3 and 5, the suspending process includes a process of suspending the intermediate clamp 51 after performing an intermediate clamp mounting process of mounting the intermediate clamp 51 to the intermediate portion of the riser pipe 1, an anchor clamp mounting process of mounting the anchor clamp 52 to the lower end of the riser pipe 1, and a clamp connecting process of connecting the intermediate clamp 51 and the anchor clamp 52 with a cord-like body 53. The lower end of the riser pipe 1 here is a portion located at the lower end of the vertical portion 11 of the riser pipe 1, and the intermediate portion of the riser pipe 1 is a portion located at the middle of the vertical portion 11 of the riser pipe 1 (between the upper end and the lower end). The number of intermediate clamps 51 may be one, but may be two (see Fig. 3) or three or more as long as they are mounted above the anchor clamp 52 in the vertical portion 11. The cord-like body 53 is, for example, a steel or resin wire rope, a chain, a sling, or the like.

[0019] In detail, an intermediate clamp 51 and an anchor clamp 52 are attached to the riser pipe 1 and connected to each other with a rope-like body 53, and then a hoisting device H such as a hook at the end of a wire rope or the like suspended from a crane or the like is engaged with the intermediate clamp 51. The rope-like body 53 may be attached to an eye plate provided on the hoisting clamp 50 (the intermediate clamp 51 or the anchor clamp 52) via a shackle or the like.

[0020] In this state, the riser pipe 1 is suspended by the hoisting tool H. Then, as shown in FIG. 3, the vertical portion 11 of the riser pipe 1 assumes a vertical posture. In such a posture, even if the frictional force (holding force) of the intermediate clamp 51 is insufficient, part of the force acting on the intermediate clamp 51 along the pipe axis 1a is transmitted to the anchor clamp 52 via the cord-like body 53 and becomes a reaction force due to the frictional force of the anchor clamp 52. Therefore, the force acting on the intermediate clamp 51 along the pipe axis 1a can be reduced. Therefore, even if the frictional force of the intermediate clamp 51 is small, the intermediate clamp 51 can be prevented from slipping along the pipe axis 1a of the riser pipe 1.

[0021] (Reinforcement process) Here, as shown in FIG. 3, when the riser pipe 1 has not only the vertical portion 11 but also the curved portion 13 that is connected to the vertical portion 11 and continuously changes the direction of the pipe axis 1a, and the horizontal portion 12 that is connected to the curved portion 13 and has the pipe axis 1a aligned horizontally, a reinforcing member 60 is attached between the vertical portion 11 and the horizontal portion 12 so as to straddle the curved portion 13 of the riser pipe 1 as appropriate (reinforcing step). Also, when the horizontal portion 12 is curved via the curved portion 13, the reinforcing member 60 is attached between the adjacent horizontal portions 12 so as to straddle the curved portion 13. The reinforcing member 60 is, for example, a hollow steel tube. Both ends of the reinforcing member 60 are fixed to the riser pipe 1 by clamps having the same structure as the hanging clamp 50 described later. This suppresses deformation of the curved portion 13, so that the stress on the curved portion 13 due to the weight acting on the riser pipe 1 during hanging can be reduced, and damage can be prevented. In addition, the clamp that fixes the reinforcing member 60 can be used as the anchor clamp 52 of the hanging clamp 50.

[0022] (Hanging clamp) As described above, it is preferable to use the lifting clamps 50 (the intermediate clamps 51 and the anchor clamps 52) to lift the riser pipe 1 by the lifting tool H. The lifting clamps 50 can be used to lift the riser pipe 1 by the lifting tool H.

[0023] Fig. 7 is a side view of the hanging clamp 50. Fig. 8 is a rear view of the hanging clamp 50. Fig. 9 is a front view of the hanging clamp 50. Fig. 10 is a bottom view of the hanging clamp 50. Fig. 11 is a side view of the first divided body 61. Fig. 12 is a side view of the second divided body 62. 7 to 12, the hoisting clamp 50 has a locking portion 66 for locking the hoisting tool H, and includes an intermediate clamp 51 that can be attached to the intermediate portion of the riser pipe 1, an anchor clamp 52 that can be attached to the lower end of the riser pipe 1, and a cord-like body 53 that connects the intermediate clamp 51 and the anchor clamp 52. It is preferable that the cord-like body 53 is in a tensioned state without slack. The locking portion 66 is a plate-like body with a hole formed therein, and may be a so-called pad-eye plate.

[0024] The intermediate clamp 51 or the anchor clamp 52 has, for example, the structure shown in Figures 7 to 12. The intermediate clamp 51 and the anchor clamp 52 may have the same structure.

[0025] As shown in Fig. 7, the hanging clamp 50 includes a first division body 61 and a second division body 62. The first division body 61 and the second division body 62 are structured to swing toward and away from each other about an axis 60a along the pipe axis 1a. Specifically, when the first division body 61 and the second division body 62 are open in a direction perpendicular to the pipe axis 1a of the riser pipe 1, the riser pipe 1 can be accommodated between the first division body 61 and the second division body 62. When the first division body 61 and the second division body 62 are closed, the riser pipe 1 is sandwiched between the first division body 61 and the second division body 62.

[0026] The hanging clamp 50 has a first fastening body 63 and a second fastening body 64 . Then, with the riser pipe 1 sandwiched between the first division 61 and the second division 62, the riser pipe 1 can be gripped by fastening the first fastener 63 and the second fastener 64.

[0027] The hanging clamp 50 also includes an eye plate 65 .

[0028] As shown in Figures 3, 5 and 6, the eye plate 65 provided on the intermediate clamp 51 and the eye plate 65 provided on the anchor clamp 52 are connected by a rope-like body 53 via an appropriate connector such as a shackle. As a result, even if the gripping force of the intermediate clamp 51 is insufficient, part of the force acting on the intermediate clamp 51 along the pipe axis 1a is transmitted to the anchor clamp 52 via the rope-like body 53 and becomes a reaction force due to the frictional force of the anchor clamp 52. Therefore, even if the frictional force of the intermediate clamp 51 is small, the intermediate clamp 51 can be prevented from slipping along the pipe axis 1a of the riser pipe 1. Therefore, even if the frictional force per suspension point of the suspension clamp 50 is small, the suspension clamp 50 can firmly grip the riser pipe 1 without shifting.

[0029] (4) Centering process Next, the end 2e of the subsea piping 2 and the end 1e of the riser pipe 1 are aligned with each other so as to change from the state shown in FIG. 4 to the state shown in FIG. 5 (alignment step). Specifically, while the riser pipe 1 is suspended, the position and attitude of the riser pipe 1 are adjusted by manipulating a rope or the like appropriately connected to the riser pipe 1 so that the pipe axis 2a at the end 2e of the subsea piping 2 and the pipe axis 1a at the end 1e of the riser pipe 1 coincide with each other. At this time, the end 2e of the subsea pipe 2 is attached to the guide clamp 3 provided with a tapered guide 32 having a truncated cone-shaped inner cavity 3v expanding from the subsea pipe 2 side toward the riser pipe 1 side, so that the end 1e of the riser pipe 1 can be easily inserted into the inner cavity 3v of the guide 32. Then, the end 1e of the riser pipe 1 is inserted into the inner cavity 3v of the guide 32, and then the end 1e of the riser pipe 1 is pushed toward the end 2e of the subsea pipe 2. For example, an eye plate provided on the guide 32 and an eye plate provided on the clamp of the riser pipe 1 are connected with a rope or the like, and tension is applied to the rope with a lever block (registered trademark) or the like, so that the end 1e of the riser pipe 1 is pulled closer to the end 2e of the subsea pipe 2. Then, the end 1e of the riser pipe 1 reaches the inner cavity 3v of the riser pipe side mounting part 37 (see FIG. 14). In this manner, the end 1e of the riser pipe 1 is guided so that the end faces and pipe axes of the riser pipe 1 and the subsea piping 2 approach each other while the movement of the end 1e of the riser pipe 1 is restricted by the guide clamp 3. In this manner, centering can be easily performed.

[0030] Here, the guide clamp 3 is a tubular body whose inner cavity 3v (see Figs. 13 and 14) can be freely expanded or contracted by the fastening member 3S. The centering step may include reducing the diameter of the inner cavity 3v. Specifically, the centering step may include reducing the diameter of the inner cavity 3v by, for example, screwing the fastening member 3S. More specifically, the fastening member 3S is loosened to expand the inner cavity 3v, and the end 1e of the riser pipe 1 is inserted in that state, and the fastening member 3S is tightened to reduce the inner cavity 3v, thereby correcting the posture of the pipe axis 1a of the end 1e of the riser pipe 1 to match the posture of the pipe axis 2a of the end 2e of the subsea piping 2. In this case, the inner cavity 3v may be reduced using a hydraulic or pneumatic jack from the state in which the fastening member 3S is loosened to expand the inner cavity 3v, and then the fastening member 3S may be tightened. This allows fine adjustment so that the end faces of the end 1e of the riser pipe 1 and the end 2e of the subsea pipe 2 and their pipe axes 1a, 2a coincide with each other. Incidentally, instead of using the fastening member 3S, a hydraulic or pneumatic jack or the like may be used to increase or decrease the distance between the first guide clamp divided body 3A and the second guide clamp divided body 3B, thereby increasing or decreasing the inner cavity 3v.

[0031] (Guide clamp) Fig. 13 is a side view of the guide clamp 3. Fig. 14 is a view taken along the line A in Fig. 13. As described above, the guide clamp 3 is suitably used for welding the subsea piping 2 and the riser pipe 1 together. 13 and 14, the guide clamp 3 includes a first guide clamp divided body 3A and a second guide clamp divided body 3B divided in a direction perpendicular to the pipe axis 1a, 2a of the pipe to which the subsea pipe 2 and the riser pipe 1 are connected, and a fastening member 3S for fastening the first guide clamp divided body 3A and the second guide clamp divided body 3B. The first guide clamp divided body 3A and the second guide clamp divided body 3B are arranged facing each other to cover and sandwich the outer peripheries of the end 1e of the riser pipe 1 and the end 2e of the subsea pipe 2, and the fastening member 3S is fastened, thereby generating a normal force between the riser pipe 1 and the subsea pipe 2 and the guide clamp 3, thereby enabling both to be gripped.

[0032] The guide clamp 3 also has a subsea piping side mounting portion 36 which can be attached to the end portion 2e of the subsea piping 2, a riser pipe side mounting portion 37 which has a tapered guide 32 for guiding the riser pipe 1 and can be attached to the end portion 1e of the riser pipe 1, and a connecting portion 38 which connects the subsea piping side mounting portion 36 and the riser pipe side mounting portion 37. The subsea piping side mounting portion 36 is configured to grip the end 2e of the subsea piping 2 by covering and clamping the outer periphery of the end 1e of the riser pipe 1 and fastening the fastening member 3S. The riser pipe side attachment portion 37 covers and clamps the outer periphery of the end portion 1e of the riser pipe 1, and is capable of gripping the end portion 1e of the riser pipe 1 by fastening the fastening member 3S.

[0033] Here, the guide clamp 3 has an annular gap 31 between the subsea piping side mounting part 36 and the riser pipe side mounting part 37, which exposes the welded part W between the subsea piping 2 and the riser pipe 1. The annular gap 31 is provided in an annular shape. For this reason, the central part of the connecting part 38 is cut out so as to avoid the vicinity of the welded part W. Since the guide clamp 3 has such a structure, the position and posture relationship between the end 1e of the riser pipe 1 and the end 2e of the subsea piping 2 can be maintained in a state in which the pipe axis 1a of the riser pipe 1 and the pipe axis 2a of the subsea piping 2 are aligned and the end faces of both are butted against each other. In this state, the welded part W (the outer periphery of the butted end faces) can be exposed so that an operator can easily perform welding work using a welding device.

[0034] (5) Welding process Next, the end 1e of the riser pipe 1 and the end 2e of the subsea piping 2 are welded together along the annular gap 31 formed in the guide clamp 3 (welding step). In this way, the guide clamp 3 has an annular gap 31 formed therein, and the guide clamp 3 is attached to the end 2e of the subsea piping 2 with the welded portion exposed from the annular gap 31, so that the end 1e of the riser pipe 1 and the end 2e of the subsea piping 2 can be welded together along the annular gap 31 by the guide clamp 3 while adjusting the positional and pose relationship between the end 1e of the riser pipe 1 and the end 2e of the subsea piping 2. Therefore, even on unstable scaffolding in offshore construction, it is possible to weld and join the end 1e of the riser pipe 1 and the end 2e of the subsea piping 2 while stabilizing the positional and pose relationship between them, improving workability.

[0035] (5) Hanging process Finally, as shown in Fig. 6, the riser pipe 1 and the subsea piping 2, which are welded and connected, are lowered to a desired position in the sea while the riser pipe 1 is suspended by the hoisting tool H. Specifically, the riser pipe 1 and the subsea piping 2, which are welded and connected, are suspended to the seabed (suspension process). Thereafter, the riser pipe 1 and the onshore piping 4 are appropriately connected by welding or the like. The above steps complete the renewal of the riser pipe 1. In this manner, according to the above steps, a riser pipe construction method with excellent workability can be provided even when work is performed on the sea where footing is unstable. The construction method of the riser pipe 1 described above is not limited to work on the sea where footing is unstable, but may also include work on stable footing, such as a jacket-type temporary scaffolding constructed with piles supported on the seabed.

[0036] (Other embodiments) Although one embodiment has been described in detail above with reference to the drawings, the specific configuration is not limited to the above, and various design modifications and the like are possible. For example, the construction method of the riser pipe 1 is not limited to construction for updating the riser pipe 1, but may be applied to construction for newly installing the riser pipe 1.

[0037] For example, in order to move or change the position of a newly installed riser pipe 1 lying on a stockyard, before suspending the intermediate clamp 51 with the hoisting tool H to place the vertical section 11 in a vertical position, the vertical section 11 may first be suspended in the air in a horizontal position as shown in Fig. 15. Here, a case is assumed in which the riser pipe 1 does not have a horizontal section 12. Fig. 15 shows another embodiment of the hanging clamp 50. Fig. 16 is a detailed view of portion P in Fig. 15. Fig. 17 is a detailed view of portion Q in Fig. 15. Fig. 18 is a detailed view of portion R in Fig. 15. Fig. 19 is a detailed view of portion S in Fig. 15. Fig. 20 is a detailed view of portion T in Fig. 15.

[0038] As shown in Fig. 15, the riser pipe 1 with the vertical portion 11 lying horizontally is lifted by the hoist H via intermediate clamps 51 (51A) provided at the upper end of the riser pipe 1 and at the Q portion of the vertical portion 11 of the riser pipe 1, and the vertical portion 11 is raised vertically. The vertical portion 11 is supported via intermediate clamps 51 (51B, 51C) at two points, the R portion and the S portion, which are different from the points lifted by the hoist H. This allows the vertical portion 11 to be supported at multiple points, so that even if the vertical portion 11 is long, excessive load is not applied to the vertical portion 11. At this time, each of the intermediate clamps 51 (51A, 51B, 51C) is connected to an anchor clamp 52 fixed to the lower end of the riser pipe 1 via a cord-like body 53. Specifically, the intermediate clamp 51A is connected to the intermediate clamp 51C via a cord-like body 53C. The intermediate clamp 51B is connected to the intermediate clamp 51C via a cord-like body 53B, and the intermediate clamp 51C is connected to the anchor clamp 52 via a cord-like body 53A. The intermediate clamp 51C is connected to the anchor clamp 52 via the cord-like body 53A. The anchor clamp 52 is fixed to the lower end of the riser pipe 1 (the lower end when the riser pipe 1 is lifted, and the right end in FIG. 15). In this way, the intermediate clamp 51 is connected to the anchor clamp 52 via the cord-like body 53. Therefore, when the vertical section 11 of the riser pipe 1 is suspended in a vertical position by the suspension device H, even if a force acts on the intermediate clamp 51 to shift the intermediate clamp 51 from the riser pipe 1 along the pipe axis 1a, the force is resisted by the cord-like body 53 connected to the anchor clamp 52, so that the intermediate clamp 51 will not shift.

[0039] The construction method of the riser pipe 1 of this embodiment includes an exposing step of exposing the end 2e of the subsea pipe 2 to the air, a guide clamp attachment step of attaching a guide clamp 3 for guiding the end 1e of the riser pipe 1 to the end 2e of the subsea pipe 2, a hanging step of suspending the riser pipe 1 in a posture in which the pipe axis 1a of the vertical part 11 of the riser pipe 1 is aligned vertically, a centering step of aligning the end 2e of the subsea pipe 2 with the end 1e of the riser pipe 1, and a welding step of welding the end 1e of the riser pipe 1 to the end 2e of the subsea pipe 2 along the annular gap 31 formed in the guide clamp 3. As a result, even on an unstable scaffold in offshore construction, the end 1e of the riser pipe 1 can be easily guided to the end 2e of the subsea pipe 2, and the pipe axes of the two pipes can be aligned. Therefore, a construction method of the riser pipe with excellent workability can be provided.

[0040] The guide clamp 3 used for welding the subsea piping 2 and the riser pipe 1 in this embodiment includes a first guide clamp divided body 3A and a second guide clamp divided body 3B divided in a direction perpendicular to the pipe axis of the piping, and a fastening member 3S for fastening the first guide clamp divided body 3A and the second guide clamp divided body 3B. The guide clamp 3 includes a subsea piping side mounting part 36 that can be attached to the end 2e of the subsea piping 2, a riser pipe side mounting part 37 that is provided with a tapered guide 32 for guiding the riser pipe 1 and can be attached to the end 1e of the riser pipe 1, and a connecting part 38 that connects the subsea piping side mounting part 36 and the riser pipe side mounting part 37. The guide clamp 3 includes an annular gap 31 between the subsea piping side mounting part 36 and the riser pipe side mounting part 37, which exposes the welded part W between the subsea piping 2 and the riser pipe 1. As a result, even on unstable scaffolding in offshore construction, welding can be performed with the positional and attitude relationship between the end 1e of the riser pipe 1 and the end 2e of the subsea piping 2 stabilized, improving workability.

[0041] The lifting clamp 50 used to lift the riser pipe 1 with the lifting tool H of this embodiment has a locking portion 66 for locking the lifting tool H, and is equipped with an intermediate clamp 51 that can be attached to the intermediate portion of the riser pipe 1, an anchor clamp 52 that can be attached to the lower end portion of the riser pipe 1, and a cord-like body 53 that connects the intermediate clamp 51 and the anchor clamp 52. As a result, in offshore construction, the riser pipe 1 can be securely held by the lifting clamp 50 and can be suspended by the lifting tool H. This improves the ease of construction of the riser pipe 1 in offshore construction. [Explanation of symbols]

[0042] 1 Riser Pipe 1a (riser pipe) axis 1e End (of riser pipe) 2. Undersea piping 2a Pipe axis (of subsea piping) 2e End (of subsea pipe) 3 Guide clamp 3A First guide clamp division 3B Second guide clamp division 3S Fastening Materials 3v lumen 4. Onshore piping 11 Vertical section 12 Horizontal section 13 Curved section 31 Annular gap 32 Guide 36 Subsea piping side attachment part 37 Riser pipe side attachment part 38 Connecting part 50 Hanging clamp 51 Intermediate clamp 51A Intermediate clamp 51B Intermediate clamp 51C Intermediate clamp 52 Anchor clamp 53,53A,53B,53C funicular body 60 Reinforcement member 60a shaft 61 1st division body 62 Second division body 63 First Clause 64 Second Fastening Body 65 Eye Plate 66 Locking part F. Floating Structures H Hanging tool W Welding

Claims

1. A method for installing a riser pipe, comprising the steps of: an exposing step of exposing an end of the subsea piping to air; a guide clamp attachment step of attaching a guide clamp to an end of the subsea piping to guide an end of the riser pipe; a suspending step of suspending the riser pipe by a plurality of suspenders in a position in which a pipe axis of a vertical portion of the riser pipe is aligned vertically; a centering step of centering an end of the subsea piping and an end of the riser pipe; a welding step of welding an end of the riser pipe and an end of the subsea piping along an annular gap formed in the guide clamp; and a hoisting step of hoisting the riser pipe and the subsea piping, which are welded and connected, to the seabed, The method for constructing a riser pipe is characterized in that the suspending step includes an intermediate clamp mounting step of mounting an intermediate clamp to an intermediate portion of the riser pipe, an anchor clamp mounting step of mounting an anchor clamp to a lower end portion of the riser pipe, a clamp connecting step of connecting the intermediate clamp and the anchor clamp with a cord-like body, and a suspending tool engaging step of engaging the suspending tool to the intermediate clamp, and then a suspending tool engaging step of suspending the intermediate clamp.

2. A method for installing a riser pipe, comprising the steps of: an exposing step of exposing an end of the subsea piping to air; a guide clamp attachment step of attaching a guide clamp to an end of the subsea piping to guide an end of the riser pipe; a suspending step of suspending the riser pipe in a position in which a pipe axis of a vertical portion of the riser pipe is aligned vertically; a centering step of centering an end of the subsea piping and an end of the riser pipe; a welding step of welding an end of the riser pipe and an end of the subsea piping along an annular gap formed in the guide clamp; and a hoisting step of hoisting the riser pipe and the subsea piping, which are welded and connected, to the seabed, In the guide clamp attachment step, the guide clamp is attached to the end of the subsea piping exposed to air. A method for installing a riser pipe.

3. The guide clamp is a tubular body whose inner cavity can be freely expanded and contracted, The centering step includes narrowing the inner cavity.

3. The method for installing a riser pipe according to claim 1 or 2.

4. 4. The method for constructing a riser pipe according to claim 1, further comprising a reinforcing step of attaching a reinforcing member to the curved portion of the riser pipe.

5. A guide clamp used for welding a piping in which a subsea piping and a riser pipe are connected, The guide clamp includes a first guide clamp divided body and a second guide clamp divided body that are divided in a direction perpendicular to a pipe axis of the piping, and a fastening member that fastens the first guide clamp divided body and the second guide clamp divided body, The guide clamp includes a subsea pipe side mounting portion that can be freely attached to an end portion of a subsea pipe, a riser pipe side attachment part that is provided with a tapered guide having a truncated cone-shaped inner cavity for guiding the riser pipe and is freely attachable to an end part of the riser pipe; A connecting portion that connects the subsea piping side mounting portion and the riser pipe side mounting portion, The guide clamp is characterized in that it has an annular gap between the subsea piping side mounting portion and the riser pipe side mounting portion, through which a welded portion between the subsea piping and the riser pipe is exposed.

6. A guide clamp used for welding a piping in which a subsea piping and a riser pipe are connected, The guide clamp includes a first guide clamp divided body and a second guide clamp divided body that are divided in a direction perpendicular to a pipe axis of the piping, and a fastening member that fastens the first guide clamp divided body and the second guide clamp divided body, The guide clamp includes a subsea pipe side mounting portion that can be freely attached to an end portion of a subsea pipe, a riser pipe side attachment part provided with a tapered guide for guiding the riser pipe and attachable to an end part of the riser pipe; A connecting portion that connects the subsea piping side mounting portion and the riser pipe side mounting portion, The guide clamp has an annular gap between the subsea piping side mounting portion and the riser pipe side mounting portion, through which a welded portion between the subsea piping and the riser pipe is exposed, The longitudinal directions of the subsea piping side mounting portion and the riser pipe side mounting portion are arranged so as to be substantially aligned with the axial direction of the riser pipe. A guide clamp characterized by:

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