Pipe connection mechanism, pipe connection method, and pipe connection device

Abstract

To maintain connection of a pipe against a total weight when the pipe is connected on a ship.SOLUTION: A pipe connection mechanism of a long pipe has: plural pipe 30, 34; and a connection pipe 32 covering an outer face of a portion including one end of each pipe, and fixed to the outer face of each pipe to extend from the end of each pipe. A minimum inside diameter portion of the connection pipe has inside diameter dimension smaller than an outside diameter of a pipe to be connected in a temperature range of -80°C to 50°C. The inside diameter dimension is set so that the inside diameter dimension becomes larger than outside diameter of the pipe to be connected and the pipe to be connected is fitted with the connection pipe, by heating and thermally expanding the minimum inside diameter portion of the connection pipe in a temperature range higher than 50°C and 450°C or lower. A refined martensite steel, an austenite-base stainless steel, or an austenite-ferrite base stainless steel is used for the connection pipe.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention is a method for connecting a plurality of pipes to a water surface. PIPE CONNECTION MECHANISM FOR EXTENDING LONG PIPE BETWEEN PIPE CONNECTION METHOD AND PIPE CONNECTION DEVICE - Patent application Regarding. [Background technology]

[0002] To efficiently draw up heavy oil, which is slightly lighter than seawater, from offshore oil fields with poor flow pressure. The bubble lift technology is widely used in crude oil production. By injecting a gas with a relatively negligible mass into the liquid inside the tube, The liquid column pressure in the pipe is reduced by the volume ratio, and the riser pipe The pressure generated by the external seawater and oil reservoir pressure is used to generate a pushing force, and the rising force of the bubbles is used to The specified target substances are brought to the surface. Even heavy minerals can be crushed into small pieces and mixed with seawater to form a slurry. It is believed that the above-mentioned bubble lift technology can be effectively used from deep seas, such as 6,000 m below the seabed.

[0003] The riser pipe used in the above-mentioned bubble lift technology is approximately linear, extending from the sea surface to the seabed several thousand meters. This type of piping is installed on a ship and Above, it is necessary to connect these pipes to create a riser pipe. In the conventional method of connecting pipes to create a riser pipe, A thread is formed on the outer surface of one pipe and the inner surface of the other pipe, and the thread on the outer surface and the thread on the inner surface are connected. On the other hand, there are methods for connecting the cable by screwing the cable together. The number of pipes in the riser pipe is very large, and the total weight of the riser pipe is very large. The riser pipe is subjected to buoyancy in the sea surface, which acts at the joint between the pipes near the sea surface at the top of the riser pipe. Although the resultant vertical force, i.e., the tensile load, is reduced compared to the total weight, Since the force is very large, the mechanical strength of the pipe joints must be taken into consideration, and the pipe wall thickness must be thinned and the However, the resultant vertical force on the upper part of the riser pipe must be reduced. In the above connection method, in which a large vertical thread is provided on the threaded portion of the pipe on the sea surface side, Furthermore, the riser pipe is subjected to large lateral forces due to ocean currents, etc. As a result, the threaded portion of the thinned pipe may not be able to withstand the resultant force and may be damaged. There is a match.

[0004] On the other hand, the following technique is known regarding a method for connecting tubular metal members (Patent Document 1). In this technique, a concentric small diameter pipe member and a flange portion which is a large diameter pipe member are prepared. The inside diameter of the large flange is equal to or slightly smaller than the outside diameter of the small flange. A temperature difference is created between the tube and the small-diameter tube, and the thermal expansion caused by this temperature difference is used to expand the tube. The inner diameter of the hole in the flange is made larger than the outer diameter of the small diameter pipe member, and they are connected by fitting together. In other words, this technology is a shrink fitting technology. Instead of connecting them directly, the pipes are inserted into holes in the flanges and fitted together. As a result, the pipes are indirectly connected to each other via the flange portion (see Figures 1 to 3 of Patent Document 1). ). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2009 / 077735 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the above technology for connecting pipes via flanges is difficult to achieve at sea level, even when the pipes are several thousand meters below the sea surface. When applied to a riser pipe extending to the tower, a The flanges are then fastened together with bolts, etc., so the total weight of the riser pipe is very large. In particular, by connecting multiple pipes, Long pipes extending between the In order to ensure the mechanical strength of the riser pipe, the pipe thickness is increased, and the total weight becomes very large. In contrast, by installing a buoyancy body around the riser pipe body, Although the total weight of the riser pipe can be reduced, the mass of the buoyancy body itself is also added when the buoyancy body is installed. Since the total mass of the riser pipe and the buoyancy body becomes large, the tensile load acting on the riser pipe becomes larger than that of the buoyancy body. This cannot be reduced due to the inertial force caused by the motion. It becomes difficult to suspend the riser pipe from a force body, ship, etc.

[0007] Therefore, the present invention is a method for connecting a plurality of pipes to the bottom of the water or the ground below the bottom of the water. The mechanical strength of the piping can be ensured against the tensile load of the long pipe that extends between the water surface. The present invention aims to provide a pipe connection mechanism, a pipe connection method, and a pipe connection device for connecting pipes. The target. [Means for solving the problem]

[0008] One aspect of the present invention is to connect a plurality of pipes to the bottom of the water or the ground below the bottom of the water, This is a piping connection mechanism for a long pipe that extends between the water surface and the water surface. Multiple pipes and Each pipe is provided with a pipe covering an outer surface of a portion including one end thereof and extending from the end of each pipe. and a connecting pipe having a minimum inner diameter portion fixed to the outer surface of the piping. The minimum inner diameter portion of the connecting pipe is designed to be connected in a temperature range of -80°C to 50°C. The inner diameter is smaller than the outer diameter of the pipe to be used, and the temperature range is from 50°C to 450°C. The smallest inner diameter portion of the connecting pipe is heated in the surrounding area to thermally expand the smallest inner diameter portion. The outer diameter of the pipe to be connected is larger than that of the pipe to be connected. The inner diameter is set so that it can fit onto the connecting pipe. The connecting pipe is made of tempered martensitic steel, austenitic stainless steel, or Austenitic and ferritic stainless steels are used.

[0009] Another aspect of the present invention is to connect a plurality of pipes to the bottom of the water or the underground below the bottom of the water. and a piping connection mechanism for a long pipe that extends between the water surface and the piping connection mechanism. Multiple pipes and Each pipe is provided with a pipe covering an outer surface of a portion including one end thereof and extending from the end of each pipe. and a connecting pipe having a minimum inner diameter portion fixed to the outer surface of the piping. The minimum inner diameter portion of the connecting pipe is designed to be connected in a temperature range of -80°C to 50°C. The inner diameter is smaller than the outer diameter of the pipe to be used, and the temperature range is from 50°C to 450°C. The smallest inner diameter portion of the connecting pipe is heated in the surrounding area to thermally expand the smallest inner diameter portion. The outer diameter of the pipe to be connected is larger than that of the pipe to be connected. The inner diameter is set so that it can fit onto the connecting pipe. The length of the connecting pipe farthest from the water surface in the axial direction is the same as that of the connecting pipe closest to the water surface. It is short compared to the length of the direction.

[0010] The length of the connecting pipe in the pipe axis direction is increased continuously or stepwise as it moves away from the water surface. It is preferable that the length of time is shortened.

[0011] The outer surface of the pipe to be connected is inclined toward the end that fits into the connecting pipe. It is preferable that the outer diameter of the cylindrical member has a tapered surface in which the outer diameter of the cylindrical member is continuously reduced.

[0012] The inner surface of the connecting pipe is formed from the smallest inner diameter portion toward the pipe to be connected. It is preferable that the connecting pipe has a tapered surface in which the inner diameter thereof increases continuously.

[0013] The ratio of the length of the tapered surface along the axial direction of the connecting pipe to the thickness of the pipe is preferably 1 to 20.

[0014] The outer diameter of at least a part of the tapered surface is in the temperature range of -80°C to 50°C. , which is larger than the inner diameter of the connecting pipe at the opposing position, and the remaining portion of the tapered surface The outer diameter is equal to or smaller than the inner diameter of the connecting pipe in a temperature range of -80°C to 50°C, and the connecting pipe By heating, the inner diameter of the connecting pipe at the opposing position becomes It is preferable that the outer diameter of the outer periphery of the periphery is at least partially larger than the outer diameter of the outer periphery of the periphery.

[0015] The inner diameter of at least a part of the tapered surface is in the temperature range of -80°C to 50°C. , the outer diameter of the pipe to be connected at the opposing position is smaller than the outer diameter of the pipe, and the tapered surface The inner diameter of the remaining part is in the temperature range of -80°C to 50°C. the outer diameter of the connecting pipe is equal to or larger than the outer diameter of the pipe, and by heating the connecting pipe, The inner diameter at the portion is larger than the outer diameter at the opposing position of the pipe to be connected. It is preferable that the

[0016] The carbon equivalent of the piping and the connecting pipe is preferably 0.43 mass % or more.

[0017] The tensile yield strength of the piping and the connecting pipe is 555 [N / mm] or more. preferable.

[0018] The long pipe is configured by connecting at least 10 or more of the pipes with the connecting pipes, and is arranged vertically. extending in the direction The mass of each of the pipes is 100 kg to 10,000 kg, and each of the pipes The pipe thickness is preferably 5 mm to 100 mm.

[0019] The linear expansion coefficient of the connecting pipe between 50°C and 450°C is It is preferable that the modulus is at least 20% larger than the modulus of elasticity.

[0020] In addition to heating the smallest inner diameter portion of the connecting pipe, the end of the pipe to be connected is also heated. The inner diameter dimension is reduced by cooling the part to a temperature below 0°C to shrink the outer diameter of the part. The outer diameter of the pipe to be connected is larger than the outer diameter of the pipe to be connected. The inner diameter is set so that the connecting pipe can be fitted thereto, and the heating temperature of the smallest inner diameter portion and the The temperature difference between the cooling temperatures of the part including the end of the pipe to be connected is 50°C to 400°C. It is preferable.

[0021] The cross-sectional shape of the inner surface of the connecting pipe is elliptical, and the cross-sectional shape of the outer surface of the pipe to be connected is elliptical. The cross section is also preferably elliptical.

[0022] It is preferable that the ratio of the minor axis to the major axis of the ellipse is 0.9 or more and less than 1.0. .

[0023] Another aspect of the present invention is to connect a plurality of pipes to the bottom of the water or the underground below the bottom of the water. The method for connecting a long pipe extends between the water surface and the pipe. A pipe covering the outer surface of a portion including one end thereof and extending from at least one end of the pipe. a portion of the connecting pipe having the smallest inner diameter portion fixed to the outer surface of the piping is heated so as to The minimum inner diameter portion is formed at a temperature in the range of -80°C to 50°C. The inside diameter is smaller than the outside diameter of the pipe to be heated, and the minimum inside diameter portion is heated to a temperature of 50°C or less. By heating in a temperature range of up to 450°C and causing thermal expansion, making the inner diameter dimension larger than the outer diameter of the pipe to be connected; inserting the pipe to be connected into the thermally expanded connecting pipe; After inserting the pipe to be connected, the temperature of the connecting pipe is set to a temperature of -80℃ to 50℃. and returning the image to the desired image range. The connecting pipe is made of tempered martensitic steel, austenitic stainless steel, or Austenitic and ferritic stainless steels are used.

[0024] The inner diameter of the smallest inner diameter portion is made larger than the outer diameter of the pipe to be connected. the step of heating the connecting pipe from an outer surface side, The step of restoring the temperature of the connecting pipe to a temperature range of -80°C to 50°C includes Preferably, the method includes cooling from the face side.

[0025] Before inserting the pipe to be connected into the thermally expanded connecting pipe, A step of shrinking the outer diameter of the portion including the end of the pipe to be cut by cooling it to a temperature of less than -80°C. , preferably including.

[0026] Another aspect of the present invention is to connect a plurality of pipes to the bottom of the water or the underground below the bottom of the water. The method for connecting a long pipe extends between the water surface and the pipe. A pipe covering the outer surface of a portion including one end thereof and extending from at least one end of the pipe. The pipe is connected to the outside of the pipe via a connecting pipe having a minimum inner diameter portion fixed to the outside of the pipe. a step of cooling a portion including an end of a pipe to be connected to the smallest inner diameter portion is smaller than the outer diameter of the pipe to be connected in the temperature range of -80℃ to 50℃. The pipe has an inner diameter of 100 mm and the part including the end of the pipe to be connected is kept at a temperature of less than -80°C. By cooling and shrinking the outer diameter of the pipe to be connected, the outer diameter of the pipe to be connected is reduced to the minimum inner diameter portion. a step of reducing the inner diameter dimension of the nozzle to less than the inner diameter dimension of the nozzle; inserting the shrunk pipe to be connected into the connecting pipe; A portion including the end of the pipe to be connected after the pipe to be connected is inserted and returning the temperature to the temperature range of -80°C to 50°C. The connecting pipe is made of tempered martensitic steel, austenitic stainless steel, or Austenitic and ferritic stainless steels are used.

[0027] The outer diameter of the pipe to be connected is made smaller than the inner diameter dimension of the minimum inner diameter portion. The step of inserting the connector into the pipe to be connected is The cooling medium pipe is guided along the inner surface to the end of the pipe to be connected, and the cooling medium By supplying a cooling medium from the pipe to the inner surface of the end, the end of the pipe to be connected is cooled. Preferably, the method further comprises cooling the pipe from the inner surface side thereof.

[0028] The outer diameter of the pipe to be connected is made smaller than the inner diameter dimension of the minimum inner diameter portion. The step of attaching a sealing member to the end of the pipe to be connected includes: Preferably, the cooling medium is supplied from the side.

[0029] The part of the pipe to be connected, including the end thereof, is returned to a temperature range of -80°C to 50°C. The step is inserted into the pipe to be connected and is fixed to the inner surface of the pipe to be connected. The heating medium pipe is guided along the pipe to the end of the pipe to be connected, and the heating medium pipe is By supplying a heating medium to the inner surface of the end, the end of the pipe to be connected is It is preferable that the heating method includes heating the pipe from the inner surface side.

[0030] Another aspect of the present invention is to connect a plurality of pipes to the bottom of the water or the underground below the bottom of the water. The method for connecting a long pipe extends between the water surface and the pipe. A pipe covering the outer surface of a portion including one end thereof and extending from at least one end of the pipe. a portion of the connecting pipe having the smallest inner diameter portion fixed to the outer surface of the piping is heated so as to The minimum inner diameter portion is formed at a temperature in the range of -80°C to 50°C. The inside diameter is smaller than the outside diameter of the pipe to be heated, and the minimum inside diameter portion is heated to a temperature of 50°C or less. By heating in a temperature range of up to 450°C and causing thermal expansion, making the inner diameter dimension larger than the outer diameter of the pipe to be connected; inserting the pipe to be connected into the thermally expanded connecting pipe; After inserting the pipe to be connected, the temperature of the connecting pipe should be kept between -80℃ and 50℃. and c) returning the range. The step of inserting into the connecting pipe is repeated; The length of the connecting pipe in the axial direction of the connecting pipe used in the step of inserting the connecting pipe is As the number of repetitions of the insertion step increases, the length increases continuously or in stages. do.

[0031] When the pipe to be connected is inserted into the thermally expanded connecting pipe, The outer surface of the pipe has a tapered surface where the outer diameter continuously decreases up to the end of the pipe. It is preferable to insert the connecting pipe.

[0032] The inner surface of the connecting pipe is formed from the smallest inner diameter portion toward the pipe to be connected. It is preferable that the connecting pipe has a tapered surface in which the inner diameter thereof increases continuously.

[0033] The heating temperature of the connecting pipe and the temperature after cooling of the part including the end of the pipe to be connected The temperature difference is preferably set to 50°C to 400°C.

[0034] The cross-sectional shape of the inner surface of the connecting pipe is elliptical, and the cross-sectional shape of the outer surface of the pipe to be connected is elliptical. The cross-sectional shape is also elliptical, When the pipe to be connected is inserted into the thermally expanded connecting pipe, The direction of the minor axis of the ellipse of the pipe to be inserted is aligned with the direction of the minor axis of the ellipse of the connecting pipe. It is preferable to include

[0035] The cross-sectional shape of the inner surface of the connecting pipe before the pipe to be connected is inserted into the connecting pipe. is a perfect circle, and the cross section of the outer surface of the pipe to be connected is also a perfect circle, After inserting the pipe to be connected into the connecting pipe, the connecting pipe and the connected pipe are and applying compressive stress from the outside of the pipe in a direction perpendicular to the pipe axis direction to form an ellipse. Yes, it is preferable.

[0036] Another aspect of the present invention is to connect a plurality of pipes to the bottom of the water or the underground below the bottom of the water. The pipe connecting device is a device for connecting a long pipe that extends between the water surface and the pipe. The device is A pipe that receives a connecting pipe, and covers the outer surface of a portion including the end of the connected pipe. a connecting pipe fixed to the outer surface of the connecting pipe so as to extend from the end of the connecting pipe; a connected pipe gripping portion that grips the pipe in an upright position; The connecting pipe is held in an upright position by a connecting pipe gripper. A connection pipe gripping portion; In order to bring the end of the connecting pipe closer to the connecting pipe, the connecting pipe gripping portion is a moving mechanism for moving the tube gripping portion relative to the tube gripping portion; In order to connect the connecting pipe and the connected pipe, the smallest inner diameter portion of the connecting pipe is heated. a process of thermally expanding the end of the connecting pipe and cooling the end of the connecting pipe to reduce the outer diameter of the end of the connecting pipe; and a heat treatment device for performing at least one of the following treatments:

[0037] The gripping contact area where the connection pipe gripping portion comes into contact with and grips the connection pipe is It is preferable that the pipe gripping portion has a gripping contact area larger than the gripping contact area of ​​the pipe to be connected. It's nice.

[0038] The connecting pipe gripping portion is provided on the opposing surfaces of the connecting gripping portion and the connected gripped portion. and the connected pipe gripping portion. Preferably, a slot is provided.

[0039] a pipe whose diameter expands toward the connection pipe gripping portion, the pipe being arranged to cover the outer periphery of the connection pipe; Preferably, the nozzle further comprises a shaped expanding member.

[0040] In order to connect and fix the connecting pipe to the connected pipe, a protective cover is provided to cover the outer periphery of the connecting pipe. a connecting pipe gripping portion that is gripped by the connecting pipe gripping portion and connected to the connecting pipe, The connecting pipe gripping portion is moved to the uppermost end of the connected pipe to hold the connecting pipe against the connected pipe. When connecting to the pipe, the outer periphery of the connecting pipe rotates in the circumferential direction at a speed exceeding 0 to 1 revolution per second. It is preferable to provide a rotation mechanism that applies the following rotation speed to the connecting pipe.

[0041] The connection pipe gripping portion grips the outer periphery of the connection pipe before connection so as to cover the outer periphery of the connection pipe. The connecting pipe gripping portion is configured such that the moving mechanism moves the connecting pipe gripping portion closer to the connected pipe gripping portion. When the connecting pipe is connected to the connecting tube, the outer periphery of the connecting pipe rotates in the circumferential direction. a rotation mechanism that applies a rotation speed of more than 0 and not more than 1 rotation / second to the connecting pipe so that the connecting pipe rotates , is preferred. [Effects of the Invention]

[0042] According to the above-mentioned pipe connection mechanism, pipe connection method, and pipe connection device, On the other hand, the mechanical strength of the piping can be ensured. [Brief explanation of the drawings]

[0043] [Figure 1] 1 is a schematic diagram of a resource recovery system to which a piping connection mechanism and a piping connection method for a riser pipe according to an embodiment are applied. [Figure 2] 1A and 1B are diagrams illustrating an example of a connection configuration of a pipe connection mechanism according to an embodiment. [Figure 3] 1 is a diagram illustrating in detail an example of a connecting pipe and an end of a pipe used in a pipe connection mechanism of an embodiment. FIG. [Figure 4] 10 is a diagram showing in detail another example of a connecting pipe and an end of a pipe used in the pipe connection mechanism of the embodiment. FIG. [Figure 5] 5 is a detailed view of a modification of the example of the connecting pipe and pipe end shown in FIGS. 3 and 4. FIG. [Figure 6] 3A and 3B are diagrams illustrating an example of the cross-sectional shape of a pipe and a connecting pipe used in the pipe connection mechanism of the embodiment. [Figure 7] 1A and 1B are diagrams illustrating an example of a pipe connecting method according to an embodiment. [Figure 8] 10(a) and 10(b) are diagrams illustrating an example of a pipe connecting method according to another embodiment. [Figure 9] 1A and 1B are diagrams illustrating an outline of a pipe connecting device that performs a pipe connecting method according to an embodiment. [Figure 10] 1 is a diagram illustrating an example of a pipe connection device according to an embodiment; [Figure 11] 1 is a diagram illustrating an example of a pipe connection device according to an embodiment; [Figure 12] 1 is a diagram illustrating an example of a pipe connection device according to an embodiment; [Figure 13] 1 is a diagram illustrating an example of a pipe connection device according to an embodiment; [Figure 14] 1 is a diagram illustrating an example of a pipe connection device according to an embodiment; [Figure 15] 1 is a diagram illustrating an example of a pipe connection device according to an embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0044] The following describes in detail the piping connection mechanism and the piping connection method for long pipes according to this embodiment. A long pipe is a pipe that is at least 400m long and is made up of multiple pipes connected together. The long pipe is used, for example, with the extension direction of the pipe being approximately vertical. As a result, solid or liquid substances at or below the bottom of the water are brought to the surface. In addition to the riser pipe, liquid or solid materials on the water surface are transported to the bottom or near the bottom. It can also be applied to the supply pipe. FIG. 1 shows an embodiment of a riser pipe connection mechanism and a riser pipe connection method. FIG. 1 is a schematic diagram of a resource recovery system. In the embodiment described below, an example is given in which resources on the seabed are pulled up using a drilling ship. However, the applicable locations are not limited to the ocean, but can also be applied to lakes and rivers. do.

[0045] The lift system 10 shown in FIG. 1 is a drilling vessel 12 floating on the water surface (ocean surface), and The lift system 10 is used to raise resources below the bottom. The system mainly comprises a lifting device 22, a collecting device 26, and a processing device 28.

[0046] The lift system 10 is used to lift the bottom of the water, such as the bottom of a sea, lake, or river, or the sand and sediment below the bottom of the water. A slurry containing solid or liquid substances such as minerals is passed through a riser pipe 20. A lifting device 22 is provided on the riser pipe 20 to lift it up to the surface. 0 is the riser pipe 20 due to the pressure reduction effect in the riser pipe 20 caused by the function of the lift device 22. The sediment collected by the collection device 26 is fed into the riser pipe 20 together with the surrounding water from the lower end of the riser pipe 20. The lift device 2 can be used to suck the water or gas into the tank and lift it above the water surface. 2 may be a jet pump that discharges high-pressure jet water toward the sea surface, Gas is supplied to the inside of the pump pipe 20 to form bubbles, and the floating force of the bubbles is used to push the slurry into the sea. It may be a bubble lift device that lifts the liquid to the surface, or a jet pump and bubble lift device. A combination of a jet pump and a bubble lift device may also be used. In this case, the bubble lift device is provided in the middle of the riser pipe 20 and extends from the lower end of the riser pipe 20. The lift force of a jet pump provided near the lower end of the riser pipe 20 is applied from the riser pipe 20 to the bubble lift device. Preferably, the slurry is fried by

[0047] The drillship 12 is a vessel equipped with a drill mechanism equipped with a dynamic positioning system. The riser pipe 20 of the system 10 is the riser pipe used by the drilling ship 12. The riser pipe of the drillship 12 is used to collect drilling mud during drilling. The riser pipe 20 carries a slurry containing solid or liquid materials collected from the bottom of the water. A riser pipe is a pipe used to raise the vessel above the water surface. For example, the riser pipe has an inner diameter of 50 cm and a length of 27 m. The riser pipe 20 is configured by connecting a number of pipes of this size in a connection form to be described later. A collection device 26 is connected to the side.

[0048] The collector 26 is a device for collecting material on or below the seabed. The configuration of 26 is not particularly limited, but for example, a caisson with suction capacity is placed in contact with the seabed. It pushes the water into the seabed or inside the seabed, sucking up the sediments on the seabed or inside the seabed. The inner space of the caisson has nozzles that spray high-pressure water, and the water that is drawn into this inner space The collected sediment is converted into fine particles or liquid (fluidized) by high-pressure water, and the solid or liquid material is The sucked solid or liquid material is collected and collected as a slurry. The riser pipe 20 is connected to the lower end of the device 26. A conventional suction head can also be used. An example of such a caisson or suction head is disclosed in Japanese Patent Application Laid-Open No. 2018-532918. Examples of such caissons include those described in the report.

[0049] The riser pipe 20 includes a plurality of pipes and a connecting pipe. It is composed of the following: FIG. 2 shows the connection of the plurality of pipes that make up the riser pipe 20, with reference to the connection between the pipes 30 and 34. FIG. 10 is a diagram for explaining an example of a continuation mode. The pipe 30 has a portion including one end 30a of the pipe 30, which covers the outer surface of this portion and has a a connecting pipe having a minimum inner diameter portion fixed to the outer surface of the piping 30 so as to extend from the connecting pipe 30a; 32 will be provided. The pipe 34 to be connected to this pipe 30 is inserted into the connecting pipe 32 and connected. Here, the connecting pipe 32 has a length that is more than 0% and not more than 50% of the length of the piping 30 along the pipe axis, for example. The length of the connecting pipe 32 is 1% or more and 20% or less, and the portion in the range of more than 1% and 80% or less of the length of the connecting pipe 32 is The connecting pipe 32 is fixed to the pipe 30 by welding. Alternatively, they may be joined by fitting.

[0050] In this way, the pipe 34 to be connected to the pipe 30 is connected via the connecting pipe 32. Therefore, although not shown, the end of the pipe 34 opposite to the end connected to the pipe 30 is included. A connecting pipe similar to the connecting pipe 32 is provided in the remaining portion, and is configured to be connected to other piping. The pipes 30, 34 and the connecting pipe 32 are made of metal material.

[0051] The pipe 34 is configured to be connected to the pipe 30 via the connecting pipe 32. Specifically, The minimum inner diameter portion of the connecting pipe 32 is in the temperature range of -80°C to 50°C. The inner diameter is smaller than the outer diameter of the pipe 34. This inner diameter is designed to withstand temperatures of at least 50°C. The smallest inner diameter portion of the connecting pipe 32 is heated to a temperature range higher than 450°C and lower to cause thermal expansion. As a result, the outer diameter of the connecting pipe 30 becomes larger than the outer diameter of the pipe 34 to be connected. In other words, the shrink fitting technique is used. The minimum inner diameter portion of the connecting pipe 32 has an inner diameter that is larger than the inner diameter of any other portion of the inner surface of the connecting pipe 32. In addition to the smaller portion, the entire inner surface of the connecting pipe 32 when the inner diameter of the inner surface is constant is also included. The upper limit of the heating temperature of the smallest inner diameter portion of the connecting pipe 32 is set to 450°C. The upper limit of the temperature difference between the heat temperature and the temperature of the pipe 34 to be connected is set to 400°C. If the heating temperature exceeds 450°C, the strength of the connecting pipe 32 may be reduced. arise.

[0052] The heating of the smallest inner diameter portion of the connecting pipe 32 is performed by passing electricity through the connecting pipe 32. Heating may be performed by electrical heating, high frequency induction heating, or infrared heating. Heating may be carried out using an apparatus.

[0053] The metal material of such a connecting pipe 32 is austenitic stainless steel (for example, S US304) or austenitic-ferritic stainless steel is used. The ferritic-ferritic stainless steel is a duplex stainless steel (e.g., SUS329J). 4L), a stainless steel consisting of austenite and ferrite phases. Ferritic stainless steels are austenitic stainless steels such as SUS304. It has a lower Ni content than stainless steel. These metal materials are high-strength steels with high tensile yield strength, and are used to connect multiple pipes. It extends between the water bottom or the ground below the water bottom and the water surface, and the part closer to the water surface This is suitable for long pipes that are greatly affected by tensile loads due to their own weight. The closer to the surface, the greater the downward tensile load, so the connecting pipe will not be subject to plastic deformation or breakage. High tensile yield strength is required to prevent cracks.

[0054] In this way, the connecting pipe 32 is used to connect the pipe 30 and the pipe 34, and the connecting pipe 32 By connecting the two using shrink fitting technology, the weight is reduced compared to conventional flange joints. Furthermore, since the riser pipe 20 itself is not welded, it is possible to achieve a high level of rigidity. It is possible to use materials with higher strength than the riser pipe material, and the pipe thickness can be made thinner. Therefore, the total weight of the riser pipe 20 can be reduced, and further, fatigue cracks are prevented from occurring. Since there are no easily welded parts, the mechanical properties of the connection part of the piping 34 are not affected by the tensile load of the riser pipe 20. Therefore, the required strength can be ensured.

[0055] According to one embodiment, the connecting pipe 32 that is farthest from the water surface in the pipe axial direction The length is preferably shorter than the length in the axial direction of the connecting pipe closest to the water surface. The direction refers to the longitudinal direction of the connecting pipe. Therefore, in the case of the configuration shown in Figures 3 and 4, , the longitudinal direction of the pipes 30 and 34. In particular, the length of the connecting pipe 32 in the pipe axis direction is It is preferable that the length of the spool decreases continuously or in stages as the distance increases. The tensile load applied to the connecting pipe 32 becomes smaller as the connecting pipe 32 becomes smaller. The length of the riser can be shortened to weaken the strength of the piping connection. The total weight of the pipe 20 can be reduced, so that the load on the connecting pipe 32 located at a shallow depth can be reduced. The tension load can be reduced, and the increase in the axial length of the connecting pipe 32 located at a shallow water depth can be suppressed. It can be controlled.

[0056] FIG. 3 is a detailed view of an example of the ends of the connecting pipe 32 and the pipes 30 and 34. As shown, the inner diameter of the connecting pipe 32 is constant, while the inner diameter of the pipe 34 to be connected is constant. The outer surface of the pipe 34 has an outer diameter that increases toward the end 34a that fits into the connecting pipe 32. The outer diameter of the pipe 34 is tapered continuously. The inner diameter of the pipe 34 at the part surface 34b does not change. When the tapered surface 34b is not present, the heated and expanded diameter of the connecting pipe 32 is The inner diameter of the pipe 32 is only slightly larger than the outer diameter of the pipe 34. It is difficult to smoothly and quickly insert the area including the end 34a of the tape into the connecting tube 32. When the port surface 34b is not provided, the outer diameter of the pipe to be connected and the connecting pipe 32 The ratio of the difference from the maximum inner diameter to the maximum inner diameter of the connecting pipe 32 is preferably more than 0% and less than 10%. The difference is very small, between 0.001% and 8%, making smooth and quick insertion difficult. In particular, since the connection work is carried out on the ocean, for example, on a ship, where there is a lot of shaking, 2. By providing the par surface 34b, the insertion of the piping 34 into the connecting pipe 32 can be performed smoothly and quickly. Moreover, the tapered surface 34b allows the inner wall of the connecting pipe 32 to be easily opened. The pipes 34 can be accurately positioned in a direction perpendicular to the row direction.

[0057] 4 is a detailed view of another example of the ends of the connecting pipe 32 and the pipes 30 and 34. As shown in the figure, the outer diameter of the pipe 34 is constant, while the inner surface of the connecting pipe 32 varies from the smallest inner diameter portion to the The inner diameter of the connecting pipe 32 is extended from the connecting pipe 32 toward the side of the pipe 34 to be connected to the connecting pipe 32 to the open end of the connecting pipe 32. It has a tapered surface 32a that expands continuously. When the piping 34 is inserted into the connecting pipe 32 using a shrink fitting technique, the tapered surface 32a If there is no heat, the inner diameter of the connecting pipe 32 expanded by heating will be much larger than the outer diameter of the pipe 34. Since the area including the end 34a of the pipe 34 is only slightly larger, the area including the end 34a of the pipe 34 can be smoothly and quickly connected to the connecting pipe 32. It is difficult to insert the wires quickly. This is especially true when joining is done on the ocean, where there is a lot of rocking, for example, on a ship. It becomes even more difficult to insert the piping 34 smoothly and quickly. By providing a tapered surface 32a on the inner surface from the region including the pipe 34, it is possible to insert the pipe 34 into the connecting pipe 32. Moreover, the tapered surface 32a allows the connecting pipe 3 Since the inner diameter becomes smaller as it advances in the depth direction of 2, The pipe 34 can be accurately positioned in the direction.

[0058] In the example shown in FIG. 4, the inner surface of the connecting pipe 32 on the pipe 30 side also has a tapered surface 32a. However, the connecting pipe 32 is fixed to the piping 30 in advance by welding or shrink fitting on land. Therefore, the tapered surface 32a does not necessarily have to be provided on the pipe 30 side.

[0059] FIG. 5 shows in detail a modification of the example of the connecting pipe 32 and the ends of the piping 30, 34 shown in FIGS. 3 and 4. This is a diagram. As shown in FIG. 5, the pipe 34 is provided with a tapered surface 34b, similar to the example shown in FIG. Furthermore, the inner surface of the connecting pipe 32 is provided with a smallest inner diameter portion of the connecting pipe 32 and a smallest inner diameter portion of the piping 34. A tapered surface 32a is provided so that the inner diameter of the connecting pipe 32 increases continuously toward the side. This allows the area including the end 34a of the pipe 34 to be inserted into the connecting pipe 32 smoothly and quickly. It is possible. The tapered surface 32a and the tapered surface 34b are mutually insulated in the temperature range of -80°C to 50°C. The inclination of the tapered surface 32a and the tapered surface 34b with respect to the tube axis direction X is set so that the tapered surface 32a and the tapered surface 34b come into contact with each other. Preferably, the angle is set. Furthermore, the tapered surface 32a and the tapered surface 34b allow the fluid to flow in the depth direction of the connecting pipe 32. Therefore, in the connecting pipe 34, the inner diameter of the pipe 3 is 4 can be accurately positioned, and the pipe 34 can also be accurately positioned in the depth direction. Positioning can be performed.

[0060] At this time, the tapered surfaces 32a and 34b are aligned so that they are in contact with each other. The inclination angles of the tapered surface 32a and the tapered surface 34b with respect to the tube axis direction X are the same, and the tapered surface 3 It is also preferable that the lengths of the tapered surface 2a and the tapered surface 34b in the tube axis direction are the same. The inner diameter of the tapered surface 32a is set to a value that is in the range of temperatures from -80°C to 50°C. The inner diameter is smaller than the outer diameter of the corresponding portion of the tapered surface 34b of the tube 34, This inner diameter dimension must be maintained at least within the temperature range of 50°C to 450°C. By heating and thermally expanding the outer diameter of the connecting pipe 32, the outer diameter of the connecting pipe 32 becomes larger than the above-mentioned outer diameter. The tapered surface 34b of the pipe 34 is designed to fit into the tapered surface 34b. It is preferable that the above-mentioned conditions are set. As a result, the tapered surfaces 32a and 34b are fitted together by shrink fitting, so that the connecting pipe 3 The connection between the pipe 30 and the pipe 34 via the pipe 2 can be made stronger.

[0061] In the example shown in FIG. 5, a tapered surface 32a is also provided on the inner surface of the connecting pipe 32 on the side of the piping 30. However, the inner surface of the connecting pipe 32 on the pipe 30 side is not necessarily provided with a tapered surface 32a. It's not necessary.

[0062] According to one embodiment, the tapered surface 34b shown in FIG. 3 and the tapered surface 32a shown in FIG. The ratio of the length l [mm] of the connecting pipe 32 along the pipe axis to the pipe thickness t [mm] of the piping 34 1 to 20, the pipe 34 can be inserted into the connecting pipe 32 smoothly and in a short time. The thickness t [mm] of the pipe 34 is preferably set to a value that is smaller than the thickness t [mm] of the pipe 34. b is the thickness of the portion where no coating is provided.

[0063] According to one embodiment, the linear expansion coefficient (linear expansion coefficient between 50°C and 450°C) of the material of the connecting pipe 32 is The linear expansion coefficient (linear expansion coefficient between -80℃ and 50℃) of the material of the pipe 34 to be connected is The riser must be at least 5% higher than the expansion coefficient of the heat exchanger by properly using the shrink fitting technique described above. The resultant vertical force acting on the riser pipe 20 is the tensile load (total weight of the riser pipe 20 - riser pipe The material of the connecting pipe 32 is preferable for realizing a connection between pipes that can withstand the buoyancy of the connecting pipe 32. The linear expansion coefficient (linear expansion coefficient between 50°C and 450°C) of the pipe 34 to be connected is It is more preferable that the linear expansion coefficient is 20% or more higher than that of the Preferably, it is particularly preferably 30% or more higher. When connecting, a high carbon equivalent tends to reduce the toughness of the base material and the circumferential weld. Therefore, it is necessary to suppress the carbon equivalent in order to improve the strength. Since no welded joints are used for the pipes 30 and 34, the carbon equivalent of the pipes 30 and 34 can be reduced. Therefore, high strength can be easily achieved. In order to increase the strength of the connecting pipe 32, the carbon equivalent is preferably 0.43 mass % or more. It's nice. The carbon equivalent Ceq (mass%) is Ceq = C + Mn / 6 + Si / 24 + Ni / 40 +Cr / 5+Mo / 4+V / 14 (C, Mn, Si, Ni, Cr, Mo, V are respectively , the mass percent of carbon, manganese, nickel, chromium, molybdenum, and vanadium contained ) can be expressed as The pipes 30, 34 of the riser pipe 20 and the connecting pipe 32 are provided with a pull-out pipe to ensure mechanical strength. Tensile yield strength is 555 [N / mm 2 At this time, it is preferable that the piping 30 ,34, for example, the linear expansion coefficient is 12 × 10 -6 [ / ℃] For example, when using SCM440H QT material, the connecting pipe 32 has a linear expansion coefficient of, for example, 16×10 -6[ / ℃] austenitic stainless steel (e.g., SUS304) It is recommended to use

[0064] The riser pipe 20 (long pipe) is connected to at least 10 or more pipes 30, 34, for example. The pipes 30 and 34 are connected by a pipe 32 and extend vertically. The mass of each of the pipes 30 and 34 is 10 The load capacity is 0kg to 10,000kg, and the thickness of each pipe is 5mm to 100mm. More than 10 large mass pipes are connected, and the pipes are relatively thin and located near the water surface. Even if the piping is subjected to a large tensile load resulting from the mass of the piping, the material has a high tensile yield strength. The pipes 30 and 34 are not easily plastically deformed. Since the mass is smaller than that of a connection mechanism including a connecting member, the tensile load can be suppressed. The length of each of the pipes 30 and 34 is, for example, 3000 mm to 30,000 mm. .

[0065] According to one embodiment, in addition to heating the smallest inner diameter portion of the connecting pipe 32, The portion including the end 34a of the tube 34 is cooled to a temperature below -80°C to shrink the outer diameter of the portion. By doing so, the inner diameter of the smallest inner diameter portion is made larger than the outer diameter of the pipe 34. The inside diameter of the smallest inside diameter portion of the connecting pipe 32 is set to The heating temperature of the smallest inner diameter part of the connecting pipe 32 and the cooling temperature of the part including the end of the pipe 34 are set. It is preferable that the temperature difference is set to 50°C to 400°C. A relatively large gap can be provided between the inner surface of the portion and the outer surface of the portion including the end of the pipe 34. Therefore, the piping 34 can be inserted into the connecting pipe 32 smoothly and quickly.

[0066] The portion of the pipe 34 including the end 34a can be cooled by immersing it in liquid nitrogen, or The pipe 34 is cooled by spraying a cooling medium such as liquid nitrogen onto the end 34a of the pipe 34. Alternatively, cooling may be performed using a Peltier element, or by magnetic cooling (magnetic refrigeration). It may be cooled.

[0067] In addition, the surface of the joint portion of the outer surface including the end of the piping 34 that joins with the inner surface of the connecting pipe 32, and The surface of the inner surface of the connecting pipe 32 that joins with the joint of the pipe 34 improves friction. For this reason, it is preferable that the surface be roughened.

[0068] According to one embodiment, the outer diameter of at least a portion of the tapered surface 34b shown in FIG. 3 is: In the temperature range of -80°C to 50°C, the inner diameter of the connecting pipe 32 is larger than that of the opposite position, and the temperature The outer diameter of the remaining part of the surface is 32 mm. When the connecting pipe 32 is heated, the inner diameter of the connecting pipe 32 is equal to or smaller than the inner diameter of the connecting pipe 32. The inner diameter at this point is larger than the outer diameter at least in the portion of the tapered surface 34b. It is preferable that: According to one embodiment, the inner surface of at least a part of the tapered surface 32a shown in FIG. The diameter is determined by the temperature range of -80°C to 50°C and the diameter of the pipe 34 to be connected. The inner diameter of the remaining portion of the tapered surface 32a is smaller than the outer diameter. ° C., and the temperature is greater than the outer diameter of the pipe 34 to be connected. The inner diameter of at least the part of the tapered surface 32a is It is preferable that the outer diameter of at least one of the tapered surfaces 34b and 32a is larger than the outer diameter of the tapered surface 34b. By applying shrink fitting technology to the fitting area, the fitting area can be widened, reducing friction. This allows the piping connections to be maintained sufficiently even with respect to the total weight of the riser pipe 20.

[0069] FIG. 6 is a diagram illustrating an example of the cross-sectional shape of the piping and the connecting pipe according to an embodiment. As shown in the figure, according to one embodiment, the cross-sectional shape of the inner surface of the connecting pipe 32 is elliptical. The outer pipe cross section of the pipe 34 to be connected is also elliptical. 4 around the central axis of the pipe 34, the occurrence of rotational deviation can be suppressed. Similarly, the cross section of the outer surface of the piping 30 is preferably elliptical. In addition, if the cross-sectional shape of the outer surface of the pipe 34 is a perfect circle, when a rotational movement occurs in the pipe 34, Rotational misalignment occurs between the pipe 34 and the connecting pipe 32, and the frictional force in the pipe axis direction X decreases, causing the riser pipe The resultant vertical force of the riser pipe 20 is the tensile load (total weight of the riser pipe 20 - buoyancy of the riser pipe 20) ) may make it difficult for the connecting pipe 32 to be easily removed from the piping 34. The ratio of the minor axis to the major axis of the ellipse is 0.9 or more and less than 1.0 to suppress rotational deviation. When the ratio of the minor axis to the major axis is less than 0.9, the distribution The radius of curvature of the outer surface of the pipe 34 varies greatly, so high pressure The compressive pressure that the piping experiences in the environment also varies depending on the location, which results in the maximum compressive stress and In some parts, this compressive stress may exceed the mechanical strength of the pipe 34, causing damage to the pipe 34. It becomes easier. The elliptical cross section is obtained by, for example, replacing the pipe 34 having a circular cross section with a pipe having a circular cross section. When the pipe 34 is fitted into the connecting pipe 32, the pipe 34 and the connecting pipe 32 are in a state where the pipe 34 and the connecting pipe 32 are fitted into the connecting pipe 32. It may be obtained by applying compressive stress from the side to cause plastic deformation, or by The cross section of the connecting pipe 32 may already be oval.

[0070] The connection mechanism for such a long pipe such as the riser pipe 20 is based on the following long pipe connection method. It can be obtained. (1) Covering the outer surface of the portion including one end 30a of the pipe 30, and a welding part having a minimum inner diameter portion fixed to the outer surface of the pipe 30 so as to extend from the end 30a of the pipe 30; A part of the connecting tube 32 is heated. The part with the smallest inner diameter to be heated is heated at a temperature of -80°C to 50°C. The inner diameter of the pipe 34 is smaller than the outer diameter of the pipe 34 to be connected. The diameter part is heated to a temperature range of 50°C to 450°C to cause thermal expansion. Therefore, the inner diameter of the smallest inner diameter portion is made larger than the outer diameter of the pipe 34 to be connected. (2) Next, the pipe 34 to be connected is inserted into the thermally expanded connecting pipe 32. (3) The temperature of the connecting pipe 32 into which the piping 34 is inserted is returned to the temperature range of -80°C to 50°C. The method for restoring the temperature of the connecting pipe 30 to the temperature range of -80℃ to 50℃ is air cooling, water cooling, air cooling and water cooling. In the case of water cooling, for example, the pipes 30 and 34 are connected to the The connecting portion of the pipe 32 is restrained using a fixing jig, and in this restrained state, it is immersed in seawater or After cooling by spraying water or a cooling medium, the fixture is removed. The connecting pipe 32 is made of tempered martensitic steel, austenitic stainless steel, or Austenitic and ferritic stainless steels are used.

[0071] In the above (1), the inner diameter is made larger than the outer diameter of the pipe 34 to be connected. At this time, the connecting pipe 32 is heated from the outer surface side, and the temperature of the connecting pipe 32 is set to -8 When returning the temperature to the range of 0°C to 50°C, it is preferable to cool the connecting pipe 32 from the outer surface side.

[0072] In addition, the connection mechanism for long pipes such as the riser pipe 20 is different from the above-mentioned piping connection method in the following length: This can be achieved by using a long pipe piping connection method. (4) Covering the outer surface of the portion including one end 30a of the pipe 30, and a welding part having a minimum inner diameter portion fixed to the outer surface of the pipe 30 so as to extend from the end 30a of the pipe 30; The portion including the end of the pipe 34 to be connected to the pipe 30 via the connecting pipe 32 is cooled. The minimum inner diameter of the pipe 34 to be connected is within the temperature range of -80°C to 50°C. The part including the end of the pipe 34 to be connected is heated to a temperature of -8 By cooling the pipe 34 to a temperature below 0°C, the outer diameter of the pipe 34 to be connected is reduced to the minimum inner diameter of the pipe 34. Make it smaller than the inner diameter. (5) Next, the contracted pipe 34 to be connected is inserted into the connecting pipe 32. (6) A part including the end of the pipe 34 to be connected after the pipe 34 to be connected is inserted Return the temperature to the -80°C to 50°C temperature range. The connecting pipe 32 is made of tempered martensitic steel, austenitic stainless steel, or Austenitic and ferritic stainless steels are used.

[0073] 7(a) and (b) are diagrams showing an example of a pipe connecting method according to an embodiment. 3 is a cross section of the pipe 34 and the cooling medium pipe 35 cut along a plane perpendicular to the longitudinal direction of the pipe 34. 7(b) shows a cross section of the pipe 34 along a plane parallel to the longitudinal direction of the pipe 34 and including the center of the pipe 34. 1 shows cross sections of the pipe 34 and the cooling medium pipe 35. The outer diameter of the pipe 34 to be connected is made smaller than the inner diameter of the smallest inner diameter portion of the connecting pipe 32. When connecting the pipe 34, as shown in Figs. 7(a) and (b), the pipe 34 is inserted into the pipe 34 to be connected. The pipe 34 is inserted along the inner surface of the pipe 34 to be connected, and the pipe 35 is inserted along the inner surface of the pipe 34 to be connected. The cooling medium C is supplied to the inner surface of the end of the pipe 34 from the cooling medium pipe 35. It is preferable to cool the end of the pipe 34 to be connected from the inside surface side of the pipe 34. The cooling medium pipe 35 is positioned at the center of the pipe 34. A plurality of arms 35a extending in the direction of the arrow and a plurality of rotors 35 provided at the tip of each arm 35a. The arms 35a and the rotors 35b are arranged at a plurality of positions in the longitudinal direction of the cooling medium pipe 35. The rotors 35b are provided at three locations (three locations in the example shown in FIG. 7(b)). Therefore, the cooling medium pipe 35 has a length long enough to contact the inner surface of the pipe 34. The cooling medium C is cooled to a temperature of less than -80°C. Therefore, for example, liquid nitrogen is preferably used.

[0074] In the example shown in FIGS. 7(a) and 7(b), the outer diameter of the pipe 34 to be connected is set to the outer diameter of the connecting pipe 34. When the inner diameter of the pipe 34 is smaller than the minimum inner diameter of the pipe 32, the cooling medium is applied to the inner surface of the end of the pipe 34. The cooling medium is supplied to the end of the pipe 34 from the outer surface side of the pipe 34. It is also preferable to cool the material from the outside by supplying the material with water.

[0075] 8(a) and 8(b) are diagrams showing an example of a pipe connecting method according to another embodiment. a) is a diagram of the pipe 34 and the heating medium pipe 36 cut along a plane perpendicular to the longitudinal direction of the pipe 34. 8(b) shows a cross section of the pipe 34, and FIG. 8(b) shows a cross section of the pipe 34 on a plane including the center of the pipe 34 and parallel to the longitudinal direction of the pipe 34. A cross section of the cut pipe 34 and the heating medium pipe 36 is shown. When the cooled portion including the end of the pipe 34 is returned to the temperature range of -80°C to 50°C, the pipe 34 The heating medium pipe 36 is inserted into the inside of the pipe 34 along the inner surface of the pipe 34 and guided to the end of the pipe 34. By supplying the heating medium H from the heat medium pipe 36 to the inner surface of the end, the end of the pipe 34 is It is preferable to heat from the inside surface side. The heating medium pipe 36 is positioned at the center of the pipe 34. A plurality of arms 36a extending in the direction of the arrow and a plurality of rotors 36 provided at the tip of each arm 36a. The arms 36a and the rotors 36b are arranged at a plurality of positions in the longitudinal direction of the heating medium pipe 36. The rotors 36b are provided at three locations (three locations in the example shown in FIG. 8(b)). Therefore, the heating medium pipe 36 has a length long enough to contact the inner surface of the pipe 34. The heating medium H is guided to the end of the pipe 34 while passing through the approximate center. Since heating is required, for example, water or seawater is preferably used.

[0076] The above method is a method for connecting pipes, but the separation and recovery of pipes is done when connecting pipes. The heated portion may be cooled to expand, and the cooled portion may be heated to contract.

[0077] According to one embodiment, the piping 34 is repeatedly inserted into the connecting pipe 32 to form a long pipe. When manufacturing the pipe 34, the length in the axial direction of the connecting pipe 32 into which the pipe 34 is inserted is As the number of repetitions increases, the length is increased continuously or in stages. When preparing a long pipe (for example, riser pipe 20) to extend between As the connecting pipe 32 is inserted and connected, it is sunk below the water surface. On the other hand, the last connected connecting pipe 32 is located near the water surface. The connecting pipe 32 located near the water surface is subjected to a large tension caused by the total weight of the long pipe. Since the connecting pipe 32 is subjected to a load, in order to increase the strength of the connection of the connecting pipe 32, the length in the pipe axial direction is On the other hand, the connecting pipe 32 located near the bottom of the water is almost the total weight of the long pipe. Since only a small tensile load is applied from a part of the pipe, the length of the connecting pipe 32 in the pipe axial direction is shortened. Even if the strength of the connection is weakened, the connection is not affected. By shortening the length of the pipe, the total weight of the long pipe can be reduced, so it can be positioned near the water surface. Therefore, the tensile load applied to the connecting pipe 32 can be reduced. As the number of times the connecting pipe 32 is repeatedly inserted increases, the length of the connecting pipe 32 in the axial direction increases. Therefore, it is preferable to lengthen the length continuously or stepwise.

[0078] At this time, as shown in FIG. 5, the inner surface of the connecting pipe 32 is formed from the smallest inner diameter portion. The connecting pipe 32 has a tapered surface 32a in which the inner diameter of the connecting pipe 32 continuously increases toward the pipe 34. It is preferable that

[0079] The following method can also be used to connect long pipes. (1) Covering the outer surface of the portion including one end 30a of the pipe 30, and a welding part having a minimum inner diameter portion fixed to the outer surface of the pipe 30 so as to extend from the end 30a of the pipe 30; A part of the connecting tube 32 is heated. The part with the smallest inner diameter to be heated is heated at a temperature of -80°C to 50°C. The inner diameter of the pipe 34 is smaller than the outer diameter of the pipe 34 to be connected. The diameter part is heated to a temperature range of 50°C to 450°C to cause thermal expansion. Therefore, the inner diameter of the smallest inner diameter portion is made larger than the outer diameter of the pipe 34 to be connected. (2) Next, the pipe 34 to be connected is inserted into the thermally expanded connecting pipe 32. (3) The temperature of the connecting pipe 32 into which the piping 34 is inserted is returned to the temperature range of -80°C to 50°C. The method for returning the temperature of the connecting pipe 32 to the temperature range of -80°C to 50°C is air cooling, water cooling, air cooling and water cooling. In the case of water cooling, for example, the pipes 30 and 34 are connected to the The connecting portion of the pipe 32 is restrained using a fixing jig, and in this state, it is immersed in seawater or cooled. After cooling by spraying a cooling medium, the fixture is removed. The inner surface of the connecting pipe 32 is formed from the smallest inner diameter portion toward the pipe 34 to be connected. The inner diameter of the tube 32 has a tapered surface 32a that continuously expands to the open end of the connecting tube 32.

[0080] Furthermore, in the above-mentioned pipe connecting method, the pipe 34 to be connected is a connecting pipe that has been thermally expanded. Before inserting the pipe 34 into the pipe 32, the outer diameter of the pipe 34 including the end is cooled to a temperature of less than -80°C. At this time, it is preferable to heat the connecting pipe 32 and the pipe 34 to be connected. It is preferable that the temperature difference between the cooled portion including the end portion is 50°C to 400°C.

[0081] As shown in FIG. 8, the cross-sectional shape of the inner surface of the connecting pipe 32 is elliptical. The cross section of the outer surface of the pipe is also an ellipse. When inserting the pipe 34 into the expanded connecting pipe 32, the direction of the minor axis of the ellipse of the pipe 34 is adjusted to the same as the direction of the minor axis of the ellipse of the connecting pipe 32. It is preferable to insert the pipe 34 in the direction of the minor axis of the circle. 32 around the tube axis direction X can be suppressed.

[0082] In addition, before inserting the pipe 34 to be connected into the connecting pipe 32, the inner surface of the connecting pipe 32 is cut off. The surface shape is a perfect circle, and the outer pipe cross section of the pipe 34 to be connected is also a perfect circle. After inserting the pipe 34 to be connected to the connecting pipe 30, the connecting pipe 34 and the pipe 34 are connected to the connecting pipe 30 in the pipe axis direction X. The pipe 34 may be elliptical by applying compressive stress from the outside in the direction of the connection. Rotational deviation around the tube axis relative to the tube 32 can be suppressed.

[0083] 9(a) and 9(b) are diagrams for explaining an outline of a pipe connecting device for carrying out a pipe connecting method according to one embodiment. This is a diagram. In the example shown in FIGS. 9(a) and 9(b), the connecting pipe 32 is heated using a heat treatment device 52. The portion including the end of the pipe 34 is cooled using a heat treatment device 54, and further, the heat treatment device 56 is used to This is an example of cooling the connecting pipe 32 after the pipe 30 and the pipe 34 are connected. The pipe 34 is called the connecting pipe 34, and the pipe 30 to which the pipe 34 is connected is called the connected pipe 30. cormorant. The heat treatment device 56 is, for example, a device for spraying a heating medium or a device for irradiating heat rays such as infrared rays. is.

[0084] The pipe connection device 40 is grounded, for example, on the ocean where there is a lot of movement, for example, on a ship. The connecting device 40 includes a connecting pipe gripping portion 46, a connecting pipe gripping portion 50, a moving mechanism 42, and a heat The moving mechanism 42 is controlled by a control device (not shown). The connected pipe gripping portion 46 is configured to move along the support 42a under control of the support. The pipe 30 is connected to the pillar 42a via an arm 44. The pipe 30 is attached to the outer surface of the pipe 30 by the connecting pipe gripping portion 46. The connection pipe gripping portion 50 is configured so that it can be freely controlled to grip or not grip the support 42a. The connecting pipe gripping portion 50 is connected to the outer surface of the pipe 34 via the arm 48. The connected pipe gripping portion 46 and the connecting pipe gripping portion 50 are configured so that gripping and non-gripping can be freely controlled. For example, a hydraulic gripping mechanism or an air gripping mechanism is used.

[0085] The connected pipe gripping portion 46 is configured to grip the connected pipe 30 in an upright position. do. The connecting pipe gripping portion 50 is provided above the connected pipe gripping portion 46 and holds the connecting pipe 34 in an upright position. The connecting pipe gripping portion 50 is configured to grip, for example, one of the connecting pipes 34. While one end is suspended in mid-air by a crane or the like, the vicinity of the other end (lower end) is grasped. The moving mechanism 42 moves the connection pipe gripping part 5 so that the end of the connection pipe 34 approaches the connection pipe 32. 0 is configured to move relative to the connected pipe gripping portion 46. The heat treatment devices 52, 54, and 56 are connected to the connecting pipe 34 and the connected pipe 30. The smallest inner diameter portion of the pipe 32 is heated to expand it, and the end of the connecting pipe 34 is cooled to expand it. and reducing the outer diameter of the end of the connecting pipe 34.

[0086] The heat treatment device 52 heats the smallest inner diameter portion of the connecting pipe 32 at a temperature higher than 50° C., for example, 450° C. The heat treatment device 54 is configured to heat the end of the connecting pipe 34 to a temperature of, for example, 100° C. or less. The heat treatment device 56 is configured to cool the connecting pipe 32 to a temperature below -80°C. The temperature of the inner diameter portion is returned to a temperature of, for example, -80°C to 50°C.

[0087] As shown in FIG. 9(a), the connecting pipe 32 is heated by a heat treatment device 52, and the end of the connecting pipe 34 is 9(b), from the state where the part including 42, the connecting pipe gripping portion 50 descends to the connected pipe gripping portion 46, The portion including the end of the pipe 34 is inserted into the connecting pipe 32. After this, the heat treatment device 56 By cooling the connecting pipe 32, the inner diameter of the connecting pipe 32 shrinks, and the connecting pipe 32 tightens the connecting pipe 34. As a result, the connected pipe 30 and the connecting pipe 34 are connected via the connecting pipe 32. It is possible. In this manner, the connecting pipe 30 and the connected pipe 34 are installed upright. Since the pipe 34 can be connected, the piping can be easily connected even on the ocean where there is a lot of movement, for example, on a ship. While the above-mentioned process is being carried out, the process of extending the riser pipe toward the seabed can be easily carried out.

[0088] At this time, the gripping contact area where the connection pipe gripping portion 50 comes into contact with and grips the connection pipe 34 is The connecting pipe gripping portion 46 has a larger gripping contact area than the gripping contact area of ​​the connecting pipe 30 that comes into contact with and grips the connecting pipe 30. It is preferable that: FIG. 10 is a diagram showing an example of a pipe connecting device 40 according to an embodiment. The connecting pipe gripping portion 50a contacts and grips the connecting pipe 34. The gripping portion 46 is larger than the gripping portion that contacts and grips the connected pipe 30. The gripping contact area of ​​the pipe gripping portion 50a is larger than the gripping contact area of ​​the connected pipe gripping portion 46. The arm 48a connecting the connection pipe gripping portion 50a and the moving mechanism 42 has a connection pipe (not shown). An orientation adjustment mechanism is provided to adjust the orientation of the pipe gripping portion 50a relative to the pipe axis direction of the connected pipe 30. By adjusting the orientation of the connection pipe gripping portion 50a using the orientation adjustment mechanism, The pipe axis direction of the connecting pipe 34 can be made to coincide with the pipe axis direction of the connected pipe 30. This allows the connection pipe 34 to be smoothly inserted into the connection pipe 32. However, even if the orientation of the connection pipe gripping portion 50 shown in FIG. 9(a) is appropriate, The gripping portion 50 does not properly grip the connection pipe 34, and the axial direction of the connection pipe 34 is When the connecting pipe 34 is held in a state where it is slightly inclined with respect to the axial direction of the pipe 30, For this reason, the gripping contact area of ​​the connecting pipe gripping portion 50a is set to be equal to that of the connected pipe gripping portion 46. By making it larger than the gripping contact area, it is possible to prevent the connection pipe 34 from being gripped at an angle. Therefore, the orientation of the connection pipe gripping portion 50a, which has a large gripping contact area, can be appropriately adjusted. This allows the axial direction of the connected pipe 34 to coincide with the axial direction of the connected pipe 30. do.

[0089] 11 is a diagram showing an example of a pipe connecting device according to an embodiment. The device 40 includes a tubular diameter expanding member 60. The tubular diameter expanding member 60 extends toward the connection pipe gripping portion 50. The tubular expanded portion 60 is arranged to cover the outer periphery of the connecting pipe 32. By providing the connecting pipe 34, when the connecting pipe 32 approaches the connecting pipe 32, the tubular expanding member 60 The connecting pipe 34 can be smoothly guided to the connecting pipe 32. Since the pipe 34 is held in an upright position, the opening of the connecting pipe 34 is aligned with the opening of the connecting pipe 32. Therefore, when the connection pipe gripping portion 50 is lowered, the tubular It can reach the opening of the connecting pipe 32 by being guided by the diameter expanding member 60 .

[0090] FIG. 12 is a diagram showing an example of a pipe connection device 40 according to an embodiment. In the example shown in FIG. The connecting pipe grippers 50b and 50c are connected to the moving mechanism 42 via the arms 48b and 48c. The total area of ​​the gripping portion where the connecting pipe 34 is gripped by the connecting pipe gripping portion 46 is The area of ​​the gripping portion that comes into contact with and grips the connected pipe 30 is larger than that of the gripping portion. By adjusting the orientation of the connection pipe gripping parts 50b and 50c using the adjustment mechanism, the connection pipe 3 4 can be aligned with the axial direction of the connected pipe 30. The connecting pipe 34 can be smoothly inserted into the connecting pipe 32.

[0091] 13 is a diagram showing an example of a pipe connecting device according to an embodiment. The connecting pipe gripping portion 50 and the connected pipe gripping portion 46 are provided on opposing surfaces thereof. and the connected pipe gripping portion 46. The connecting pipe gripping portion 50 and the connected pipe gripping portion 46 are provided with a mating hole 62. The misalignment means that the openings of the gripping parts are not facing in the same direction. The measurement unit 62 is a laser that irradiates the laser light L. The laser beam L is received by the irradiation device 62a and a photodiode 62b. Information on the position of the laser light L received by the electrode 62b on the opposing surface of the connected pipe gripping portion 46 A processing device (not shown) receives the output signal and outputs an output signal indicating the laser light L This determines whether the irradiation position is at the target position. It is possible to determine whether or not there is any positional deviation. In FIG. 13, the measurement units 62 are provided at two locations, but they may be provided at three or more locations. Thus, it is possible to accurately check whether or not there is any deviation in the direction or the position.

[0092] If there is any deviation in the direction or position, the above-mentioned direction adjustment mechanism can be used to adjust the direction of the connecting pipe. The orientation of the gripping portion 50 is adjusted, or a position adjusting mechanism (not shown) provided on the arm 48 is used. The connecting pipe gripping portion 50 is driven to adjust the position of the connecting pipe gripping portion 50. As a result, the connecting pipe 34 is moved in the axial direction. the pipe axial direction of the connecting pipe 34 and the pipe axial direction of the connecting pipe 30. It can be positioned in the correct position relative to the 0 opening. Instead of the photodiode 62b, it is possible to determine whether the irradiation position of the laser light L is at the target position. A target marker can be used to visually judge the position of the laser beam L. If the marker position is misaligned, the orientation adjustment function can be manually adjusted as described above. The mechanism or position adjustment mechanism can be adjusted.

[0093] The inner diameter surface of the connecting pipe 32 and the outer diameter surface of the top end of the connected pipe 30 are machined to a certain tolerance. However, the inner diameter of the connecting pipe 32 and the outer diameter of the connected pipe 30 are within the tolerance. Fluctuations in the diameter are inevitable. Also, due to the rolling and pitching of the ship, The geometric center of the lower end surface of the connecting pipe 32 to be connected and the geometric center of the uppermost end surface of the pipe 30 to be connected are A slight misalignment of the geometric center is inevitable. The geometric center of the lower end surface of the connecting pipe 34 and the geometric center of the uppermost end surface of the connecting pipe 32 are slightly different from each other. Misalignment is unavoidable.

[0094] Even in a situation where such misalignment is unavoidable, the connecting pipe 32 and the connected pipe 30 can be easily Alternatively, as a preferred form for smoothly connecting the connection pipe 34 and the connection pipe 30, 14 or 15. In these configurations, the connecting pipe 32 is connected to When connecting to the piping 30 or when connecting the connecting piping 34 to the connecting pipe 32, Rotation along the circumferential direction is given to the connecting pipe 32 or the connecting pipe 34. The continuation can be done smoothly.

[0095] FIG. 14 is a diagram showing an example of a pipe connection device according to an embodiment. As shown in FIG. The tube gripping portion 70 grips the outer periphery of the connecting tube 32 before connection so as to cover it, and rotates at a rate of more than 0 and 1 revolutions per second. While applying the following rotation speed to the connecting pipe 32, the connecting pipe is gripped by the connecting pipe gripping portion 46. It is preferable to provide the pipe connecting device 40 with a mechanism for moving the pipe connecting device 40 to the uppermost end of the connected pipe 30. That is, the pipe connecting device 40 connects and fixes the connecting pipe 32 to the connected pipe 30. In order to do so, a connecting pipe gripping portion is provided which grips the outer periphery of the connecting pipe 32 so as to cover it and connect it to the connected pipe 30. The connecting pipe gripping portion 70 moves to the top end of the connected pipe 30 and grips the connecting pipe 32. When connecting to the connected pipe 30, the outer periphery of the connecting pipe 32 is rotated in the circumferential direction. It is preferable to provide a rotation mechanism that applies a rotation speed of more than 1 rotation / second to the connecting pipe 32. The rotation mechanism may be, for example, a rotation mechanism in which the portion of the connecting pipe gripping portion 70 that comes into contact with and grips the connecting pipe 32 is rotated. The roller surface of the roller is rotated by a driving mechanism (not shown).

[0096] 15 is a diagram showing an example of a pipe connection device according to an embodiment. The connection pipe gripping portion 71 is provided on the moving mechanism 42 shown in FIG. The outer periphery of the pipe 34 is gripped so as to cover it, and the moving mechanism 42 shown in FIG. When the connecting pipe 34 is moved to the uppermost end of the connecting pipe 32 and connected to the connecting pipe 32, the connecting pipe 34 rotates by more than 0 turns and 1 turn. It is preferable to provide a rotation mechanism that applies a rotation speed of 1 / sec or less to the connection pipe 34. That is, the connection pipe gripping portion 71 grips the outer periphery of the connection pipe 34 before connection so as to cover it, and further, The connecting pipe gripping portion 71 is moved by the moving mechanism 42 shown in FIG. When the connecting pipe 34 is connected to the connecting pipe 32 by bringing it close to the holding portion 46, the outer periphery of the connecting pipe 34 A rotation speed of more than 0 and not more than 1 rotation / second is applied to the connecting pipe 34 so that the connecting pipe 34 rotates in the circumferential direction. It is preferable that a rotation mechanism is provided. This rotation mechanism is, for example, The portion that comes into contact with and grips the connecting pipe 34 is the roller surface of the rotating roller. It is driven to rotate by a drive mechanism not shown.

[0097] As described above, the pipe connecting device 40 is configured to install the connecting pipe 30 and the connected pipe 34 upright. Therefore, the connecting pipe 30 and the connected pipe 34 can be connected in this state. For example, the process of extending the riser pipe toward the seabed can be easily performed while connecting the pipes on board the ship. It can be done easily.

[0098] The pipe connection mechanism, the pipe connection method, and the pipe connection device of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. Of course, various improvements and modifications may be made. [Explanation of symbols]

[0099] 10. Lift System 12 Drilling Ship 20 Riser Pipe 22 Lifting device 26 Collection device 28 Processing equipment 30,34 Piping 30a,34a edge 30b, 32a, 34b Tapered surface 32 Connecting pipe 35 Coolant piping 35a, 36a Arms 35b, 36b Rotating body 36 Heating medium piping 40 Piping connection device 42 Moving mechanism 42a post 44, 48, 48a, 48b, 48c Arms 46 Connected pipe grip part 50 Connected pipe grip part 50a Connection pipe gripping part 52 Heat treatment equipment (heating above 50°C and below 450°C) 54 Heat treatment equipment (cooled to below -80℃) 56 Heat treatment equipment (returning heating temperatures from 50°C to 450°C to -80°C to 50°C) 60 Tubular expansion member 62 Measurement Unit 62a Laser irradiation device 62b Photodiode 70 Connecting pipe grip 71 Connection pipe grip

Claims

1. A piping connection mechanism for a long pipe, A plurality of pipes, A first pipe; a second pipe connected to the first pipe; a plurality of pipes having a connecting pipe having a minimum inner diameter portion, the connecting pipe covering an outer surface of a portion of the first pipe that is connected to the second pipe and that extends from the end of the first pipe toward the second pipe, and that is fixed to an outer surface of a connecting portion between the first pipe and the second pipe; the minimum inner diameter portion of the connecting pipe has an inner diameter dimension smaller than the outer diameter of the second pipe in a temperature range of −80° C. to 50° C., and the inner diameter dimension is set so that by heating the minimum inner diameter portion of the connecting pipe in a temperature range of more than 50° C. and not more than 450° C. to cause thermal expansion, the inner diameter dimension becomes larger than the outer diameter of the second pipe, allowing the second pipe to be fitted into the connecting pipe; A pipe connection mechanism, characterized in that the carbon equivalent of the first pipe and the second pipe is 0.43 mass % or more.

2. 2. The pipe connection mechanism according to claim 1, wherein the connecting pipe is made of a tempered martensitic steel, an austenitic stainless steel, or an austenitic-ferritic stainless steel.

3. 3. The pipe connection mechanism according to claim 1, wherein the outer surface of the second pipe has a tapered surface whose outer diameter continuously decreases toward the end that fits into the connecting pipe.

4. The piping connection mechanism according to any one of claims 1 to 3, wherein the inner surface of the connecting pipe has a tapered surface in which the inner diameter of the connecting pipe continuously increases from the minimum inner diameter portion toward the second piping side.

5. 5. The pipe connection mechanism according to claim 3, wherein the ratio of the length of the tapered surface along the pipe axis direction of the connecting pipe to the pipe thickness of the first pipe and the second pipe is 1 to 20.

6. 4. The piping connection mechanism according to claim 3, wherein the outer diameter of at least a portion of the tapered surface is larger than the inner diameter of the connecting pipe at the opposing position in a temperature range of -80°C to 50°C, and the outer diameter of the remaining portion of the tapered surface is equal to or smaller than the inner diameter of the connecting pipe at a temperature range of -80°C to 50°C, and when the connecting pipe is heated, the inner diameter of the connecting pipe at the opposing position becomes larger than the outer diameter of at least the portion of the tapered surface.

7. 5. The pipe connection mechanism according to claim 4, wherein the inner diameter of at least a portion of the tapered surface is smaller than the outer diameter of the second pipe at the opposing position in a temperature range of −80°C to 50°C, and the inner diameter of the remaining portion of the tapered surface is equal to or larger than the outer diameter of the second pipe at a temperature range of −80°C to 50°C, and wherein heating of the connecting pipe causes the inner diameter of at least a portion of the tapered surface to become larger than the outer diameter of the second pipe at the opposing position.

8. The tensile yield strength of the first pipe and the second pipe is 555 [N / mm ２ 8. The pipe connection mechanism according to claim 1, wherein the number of the connecting members is equal to or greater than 1.

9. the long pipe is configured to connect at least 10 or more of the first pipes and the second pipes by the connecting pipes; The piping connection mechanism according to any one of claims 1 to 8, wherein the mass of each of the first piping and the second piping is 100 kg to 10,000 kg, and the pipe thickness of each of the first piping and the second piping is 5 mm to 100 mm.

10. The pipe connection mechanism according to any one of claims 1 to 9, wherein the linear expansion coefficient of the connecting pipe between 50°C and 450°C is 20% or more greater than the linear expansion coefficient of the pipe between -80°C and 50°C.

11. The pipe connection mechanism according to any one of claims 1 to 10, wherein in addition to heating the smallest inner diameter portion of the connecting pipe, a portion including the end of the second pipe is cooled to a temperature of less than 0°C to shrink the outer diameter of that portion, so that the inner diameter dimension is set to be larger than the outer diameter of the second pipe and the second pipe can be fitted into the connecting pipe, and the temperature difference between the heating temperature of the smallest inner diameter portion and the cooling temperature of the portion including the end of the second pipe is set to be 50°C to 400°C.

12. 12. The pipe connection mechanism according to claim 1, wherein the pipe cross section of the inner surface of the connecting pipe is elliptical, and the pipe cross section of the outer surface of the second pipe is also elliptical.

13. The pipe connection mechanism according to claim 12, wherein the ratio of the minor axis to the major axis of the ellipse is equal to or greater than 0.9 and less than 1.

0.

14. A method for connecting long pipes, comprising: a step of heating a portion of a connecting pipe having a minimum inner diameter portion, the connecting pipe having a minimum inner diameter portion fixed to the outer surface of the first pipe in advance so as to cover an outer surface of a portion including one end of the first pipe and extend from at least one end of the first pipe, the minimum inner diameter portion having an inner diameter dimension smaller than the outer diameter of a second pipe connected to the first pipe in a temperature range of −80° C. to 50° C., and a step of heating the minimum inner diameter portion in a temperature range of more than 50° C. to 450° C. to thermally expand the minimum inner diameter portion, thereby making the inner diameter dimension of the minimum inner diameter portion larger than the outer diameter of the second pipe; inserting the second pipe into the thermally expanded connecting pipe; and returning the temperature of the connecting pipe to a temperature range of −80° C. to 50° C. after inserting the second pipe. The step of inserting into the connecting pipe is repeated; A pipe connecting method, characterized in that the carbon equivalent of the first pipe and the second pipe is 0.43 mass% or more.

15. 15. The pipe connecting method according to claim 14, wherein the connecting pipe is made of tempered martensitic steel, austenitic stainless steel, or austenitic-ferritic stainless steel.

16. the step of making the inner diameter dimension of the minimum inner diameter portion larger than the outer diameter of the second pipe includes heating the connecting pipe from an outer surface side; 16. The pipe connecting method according to claim 14, wherein the step of returning the temperature of the connecting pipe to the temperature range of -80°C to 50°C includes cooling the connecting pipe from an outer surface side.

17. The pipe connecting method according to any one of claims 14 to 16, comprising the step of: before inserting the second pipe into the thermally expanded connecting pipe, cooling the outer diameter of a portion including the end of the second pipe to a temperature of less than -80°C to shrink it.

18. 18. The pipe connecting method according to claim 17, wherein the step of making the outer diameter of the second pipe smaller than the inner diameter dimension of the minimum inner diameter portion includes: inserting a cooling medium pipe into the second pipe, guiding the cooling medium pipe along an inner surface of the second pipe to the end of the second pipe, and supplying cooling medium from the cooling medium pipe to the inner surface of the end, thereby cooling the end of the second pipe from the inner surface side of the pipe.

19. 18. The pipe connecting method according to claim 17, wherein the step of making the outer diameter of the second pipe smaller than the inner diameter dimension of the minimum inner diameter portion includes supplying a cooling medium to the end of the second pipe from an outer surface side of the second pipe.

20. The piping connection method according to any one of claims 17 to 19, wherein the step of returning the portion including the end of the second piping to a temperature range of -80°C to 50°C includes heating the end of the second piping from the inner surface side of the second piping by inserting a heating medium piping into the second piping and guiding it along the inner surface of the second piping to the end of the second piping, and supplying the heating medium from the heating medium piping to the inner surface of the end.

21. 21. The pipe connecting method according to claim 14, wherein when inserting the second pipe into the thermally expanded connecting pipe, one end of the second pipe having a tapered surface on its outer surface, the outer diameter of which continuously decreases up to the end of the second pipe, is inserted into the connecting pipe.

22. The pipe connecting method according to any one of claims 14 to 20, wherein the inner surface of the connecting pipe has a tapered surface in which the inner diameter of the connecting pipe continuously increases from the minimum inner diameter portion toward the second pipe side.

23. The pipe connecting method according to any one of claims 14 to 22, wherein the temperature difference between the heating temperature of the connecting pipe and the temperature after cooling of the portion including the end of the second pipe is 50°C to 400°C.

24. the cross-sectional shape of the inner surface of the connecting pipe is elliptical, and the cross-sectional shape of the outer surface of the second pipe is also elliptical; The pipe connecting method according to any one of claims 14 to 23, wherein when inserting the second pipe into the thermally expanded connecting pipe, the second pipe is inserted so that the orientation of the minor axis of the ellipse of the second pipe is aligned with the orientation of the minor axis of the ellipse of the connecting pipe.

25. a cross-sectional shape of an inner surface of the connecting pipe before inserting the second pipe into the connecting pipe is a perfect circle, and a cross-sectional shape of an outer surface of the second pipe is also a perfect circle; The pipe connecting method according to any one of claims 14 to 24, further comprising the step of: after inserting the second pipe into the connecting pipe, applying compressive stress from the outside of the connecting pipe and the connected second pipe in a direction perpendicular to the pipe axis direction to form an ellipse.

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