Steel pipes and methods for manufacturing steel pipes

Abstract

The present invention provides a steel pipe capable of enhancing corrosion resistance, and a method for manufacturing the steel pipe. [Solution] The steel pipe 10 comprises a steel pipe body 11 made of carbon steel into which a columnar member 100 is inserted, an injection port 12 provided on the peripheral wall of the steel pipe body 11 for injecting a filler into the gap between the columnar member 100 and the steel pipe body 11, and a first lining 13 made of stainless steel provided on the outer surface of the steel pipe body 11. The first lining 13 is provided at a position above the lower end of the steel pipe body 11, and the injection port 12 is provided at a position below the lower end of the first lining 13.

Description

Technical Field

[0001] The present disclosure relates to steel pipes and a method for manufacturing steel pipes.

Background Art

[0002] Conventionally, there is known a technique of inserting the legs (jacket legs) of an ocean structure into piles driven into the seabed and injecting grout into the gaps between them to solidify and join the piles and the jacket legs (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Jacket legs are made of steel pipes made of carbon steel, and anticorrosion treatments such as cathodic protection and anticorrosion painting are applied to the outer peripheral surface of the steel pipes. For this type of steel pipe, further anticorrosion performance may be required. For example, in steel pipes used for ocean structures, maintenance - free (almost no repairs during the use period) and long - term (for example, about 100 years) anticorrosion performance may be required.

[0005] An object of the present disclosure is to provide a steel pipe capable of enhancing anticorrosion performance and a method for manufacturing the steel pipe.

Means for Solving the Problems

[0006] A steel pipe according to one aspect of the present disclosure comprises a steel pipe body made of carbon steel into which a columnar member is inserted; an injection port provided on the peripheral wall of the steel pipe body for injecting a filler into the gap between the columnar member and the steel pipe body; and a first lining made of stainless steel provided on the outer circumferential surface of the steel pipe body, wherein the first lining is provided at a position above the lower end of the steel pipe body, and the injection port is provided at a position below the lower end of the first lining. [Effects of the Invention]

[0007] According to one aspect of this disclosure, a steel pipe capable of improving corrosion resistance and a method for manufacturing a steel pipe are provided. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a side view showing the steel pipe of this embodiment and the columnar member (a pile driven into the seabed) to which the steel pipe is joined. [Figure 2] Figure 2 is a plan view showing the inlet provided on the peripheral wall of the steel pipe body, the first lining provided on the outer surface of the steel pipe body, and the second lining provided on the outer surface of the first lining. [Figure 3] Figure 3 is a cross-sectional view showing the peripheral wall, inlet, first lining, and second lining of the steel pipe body. [Figure 4] Figure 4 is a schematic perspective view showing the steel pipe body. [Figure 5] Figure 5 is a plan view illustrating the first lining step of the steel pipe manufacturing method of this embodiment, showing the state in which the first lining is wrapped around the outer surface of the steel pipe body. [Figure 6] Figure 6 is a plan view illustrating the first lining step and the injection port step of the steel pipe manufacturing method of this embodiment. Specifically, it shows the state in which the first lining is tack-welded to the outer surface of the steel pipe body by the first lining step, and the state in which an injection port is provided in the circumferential wall of the steel pipe body by the injection port step. [Figure 7]Figure 7 is a plan view illustrating the second lining step of the steel pipe manufacturing method of this embodiment, showing the state in which the second lining is provided on the outer surface of the first lining. [Modes for carrying out the invention]

[0009] A steel pipe 10 and a method for manufacturing the steel pipe 10 according to one embodiment of the present invention will be described with reference to the drawings. As shown in Figures 1(a) and 1(b), the steel pipe 10 of this embodiment is used, for example, as a leg (jacket leg) 1 of an offshore structure. In this embodiment, the offshore structure is assumed to be, for example, a jacket foundation. The steel pipe 10 is connected to a columnar member 100 such as a pile driven into the seabed and fixed to the columnar member 100.

[0010] The steel pipe 10 is cylindrical in shape and extends vertically. The steel pipe 10 is positioned both above and below the sea surface (below the sea surface S). Specifically in this embodiment, the steel pipe 10 is positioned above the sea surface and extends at least to a predetermined depth D from the sea surface S. The depth D is, for example, about 1 m from the sea surface S and is defined as the area of ​​the spray and tidal zone where particularly high corrosion protection performance is required.

[0011] The steel pipe 10 comprises a steel pipe body 11 into which a columnar member 100 is inserted, an injection port 12 provided on the peripheral wall of the steel pipe body 11 for injecting a filler (not shown) into the gap between the columnar member 100 and the steel pipe body 11, and a first lining 13 provided on the outer circumferential surface of the steel pipe body 11. The first lining 13 is also positioned on the outer circumferential surface of the steel pipe body 11 in the area from the sea surface S to the water depth D.

[0012] Here, we will explain each of the steel pipes 10 shown in Figures 1(a) and 1(b). In Figure 1(a), the steel pipe 10 has a columnar member 100, such as a pile, driven into the seabed at a depth sufficiently greater than the water depth D. Therefore, the lower end of the steel pipe body 11 into which the columnar member 100 is inserted is also located at a depth greater than the water depth D. In other words, in the case of Figure 1(a), the point where the columnar member 100 and the steel pipe body 11 overlap due to insertion (i.e., the point where the filler is injected) is located below the water depth D. For this reason, the injection port 12 for injecting the filler is located below the first lining 13, that is, outside the outer circumference of the first lining 13.

[0013] In Figure 1(a), the portion of the steel pipe 10 located below the water depth D (the lower end of the steel pipe 10) and the portion of the columnar member 100 exposed in the sea are subjected to corrosion protection treatment such as cathodic protection.

[0014] On the other hand, in the case of the steel pipe 10 shown in Figure 1(b), the columnar members 100, such as piles, are driven into the seabed at a shallow depth close to the water depth D. Therefore, the lower end of the steel pipe body 11 into which the columnar members 100 are inserted is located within the range of the water depth D. In other words, in the case of Figure 1(b), the point where the columnar members 100 and the steel pipe body 11 overlap due to insertion is located within the range of the water depth D. For this reason, the injection port 12 for injecting the filler is located within the outer circumference of the first lining 13.

[0015] In Figure 1(b), the portion of the steel pipe 10 that is submerged in the sea (within the range of water depth D) is entirely covered by the first lining 13. In addition, the portion of the columnar member 100 that is exposed in the sea is treated with corrosion protection such as cathodic protection.

[0016] In this embodiment, the steel pipe main body 11 is the leg (jacket leg) 1 of the jacket foundation. Here, FIG. 4 is a perspective view schematically showing the steel pipe main body 11 included in the steel pipe 10 as a single unit. As shown in FIG. 4, the steel pipe main body 11 has a cylindrical shape, and in this embodiment, it has a circular cylindrical shape. The steel pipe main body 11 is made of carbon steel. The steel pipe main body 11 has mounting holes 11a penetrating the peripheral wall of the steel pipe main body 11. The mounting holes 11a are, for example, circular holes. One or more mounting holes 11a are provided in the peripheral wall of the steel pipe main body 11.

[0017] As shown in FIGS. 1 to 3, the injection port 12 has a cylindrical shape, and in this embodiment, it has a circular cylindrical shape. The injection port 12 is, for example, made of carbon steel. One or more injection ports 12 are provided in the peripheral wall of the steel pipe main body 11. The number of injection ports 12 is the same as the number of mounting holes 11a. The central axis (not shown) of the injection port 12 extends in a direction intersecting (for example, orthogonal) to the peripheral wall of the steel pipe main body 11. In this embodiment, the direction in which the central axis of the injection port 12 extends is referred to as the central axis direction. Also, among the central axis directions, the direction from the outside to the inside of the peripheral wall of the steel pipe main body 11 is referred to as the steel pipe inner side, and the direction from the inside to the outside of the peripheral wall of the steel pipe main body 11 is referred to as the steel pipe outer side.

[0018] As shown in FIG. 3, the injection port 12 is fixed to the mounting hole 11a of the steel pipe main body 11 by welding. Specifically, between the outer peripheral surface of the injection port 12 and the outer peripheral surface of the steel pipe main body 11, and between the end surface facing the steel pipe inner side in the central axis direction of the injection port 12 and the inner peripheral surface of the mounting hole 11a, welding beads 15 built up by welding are respectively formed. Also, the injection port 12 protrudes from the peripheral wall of the steel pipe main body 11 toward the steel pipe outer side in the central axis direction (that is, the radially outer side of the steel pipe main body 11).

[0019] As shown in FIGS. 1(a) and (b), the injection port 12 is disposed at a position overlapping the columnar member 100 in the peripheral wall of the steel pipe main body 11 when viewed from the radial direction of the steel pipe main body 11. That is, the injection port 12 is provided in a range where the columnar member 100 and the steel pipe main body 11 overlap in the radial direction when the columnar member 100 is inserted into the steel pipe main body 11.

[0020] Although not specifically shown in the diagram, the filler is injected from outside the steel pipe 10 through the injection port 12 into the gap between at least the outer surface of the columnar member 100 and the inner surface of the steel pipe body 11. The gap may also be referred to as the annular space, etc. In this embodiment, grout is used as the filler. However, this disclosure is not limited to this, and other than grout, for example, mortar, cement milk, cement paste, etc. may be used as the filler. The steel pipe 10 is joined to the columnar member 100 when the filler injected into the gap solidifies.

[0021] As shown in Figures 1 to 3, the first lining 13 is wrapped around the outer surface of the steel pipe body 11 in the circumferential direction. The first lining 13 is fixed to the steel pipe body 11 by welding using an indirect current-driven seam welding method (indirect seam welding method).

[0022] The first lining 13 is a plate-shaped member made of stainless steel. More specifically, the first lining 13 is made of, for example, SUS312L, which has excellent corrosion resistance to seawater, and its plate thickness is, for example, about 0.4 mm. However, the plate thickness of the first lining 13 is not limited to 0.4 mm. The first lining 13 is in the form of a thin sheet and can be appropriately deformed to match the curved shape of the outer surface of the steel pipe body 11 when it is attached to the outer surface of the steel pipe body 11.

[0023] In the steel pipe 10 shown in Figure 1(b), an opening 13a is formed in the portion of the first lining 13 corresponding to the inlet 12, as shown in Figures 2 and 3. The opening 13a penetrates the first lining 13 in the direction of its plate thickness. In this embodiment, the opening 13a is, for example, a rectangular hole. The opening dimensions of the opening 13a are larger than the outer diameter of the inlet 12. The inlet 12 is located inside the opening 13a. Note that the shape of the opening 13a is not limited to a rectangle. The shape of the opening 13a may be, for example, circular.

[0024] As shown in Figure 2, a bead-shaped weld mark 16 is positioned around the opening 13a of the first lining 13, formed by welding the first lining 13 to the steel pipe body 11. The weld mark 16 is formed by tack welding the first lining 13 to the steel pipe body 11 using the indirect seam welding method. The weld mark 16 extends continuously around the opening 13a, surrounding the opening 13a from the outside.

[0025] Specifically, the weld mark 16 forms a double frame that surrounds the opening 13a from the outside. In this embodiment, the weld mark 16 forms a double rectangular frame. The weld mark 16 has an inner frame weld mark 16a located outside the opening 13a and extending along the inner periphery of the opening 13a, and an outer frame weld mark 16b located outside the inner frame weld mark 16a and extending along the inner frame weld mark 16a. In this embodiment, the inner frame weld mark 16a and the outer frame weld mark 16b each form a rectangular frame.

[0026] As shown in Figures 2 and 3, the steel pipe 10 further comprises a second lining 14 provided on the outer surface (surface) of the first lining 13. The second lining 14 is a plate-shaped member made of stainless steel, and in this embodiment, it is a rectangular plate. The second lining 14 is made of, for example, SUS312L, and its plate thickness is, for example, about 1.0 mm. That is, the thickness (plate thickness dimension) of the second lining 14 is greater than the thickness of the first lining 13. In this embodiment, the thickness of the second lining 14 is set to more than twice the thickness of the first lining 13. Note that the plate thickness dimension of the second lining 14 is not limited to 1.0 mm.

[0027] The second lining 14 is positioned on the outer circumferential surface of the first lining 13 so as to cover the opening 13a of the first lining 13. The shape of the outer circumferential surface of the second lining 14 is larger than the opening 13a. In this embodiment, the shape of the outer circumferential surface of the second lining 14 is larger than the inner frame weld marks 16a. Furthermore, the shape of the outer circumferential surface of the second lining 14 is substantially the same as the outer frame weld marks 16b. The second lining 14 covers the outer circumferential surface of the steel pipe body 11 exposed from the opening 13a. The second lining 14 also covers the inner frame weld marks 16a. Although not specifically shown, a portion of the inner frame weld marks 16a may be located outside the second lining 14 and not covered by the second lining 14.

[0028] The second lining 14 has an insertion hole 14a that penetrates the second lining 14 in the thickness direction. The injection port 12 is inserted through the insertion hole 14a. The inner circumferential shape of the insertion hole 14a corresponds to the outer circumferential shape of the injection port 12. In this embodiment, the insertion hole 14a is circular.

[0029] As shown in Figure 3, the second lining 14 is welded to the injection port 12 and the first lining 13. Specifically, a weld bead 17 is formed between the inner circumference of the insertion hole 14a of the second lining 14 and the outer circumference of the injection port 12. The weld bead 17 has a circular shape that extends circumferentially along the outer circumference of the injection port 12 (see Figure 7). In addition, a weld bead 18 is formed between the outer circumference of the second lining 14 and the outer circumference of the first lining 13. The weld bead 18 has a rectangular shape that extends along the outer frame weld mark 16b (see Figure 7).

[0030] Next, the manufacturing method of the steel pipe 10 described above will be explained with reference to Figures 3 to 7. The manufacturing method for the steel pipe 10 in this embodiment includes an injection port step in which an injection port 12 is provided on the peripheral wall of the steel pipe body 11 for injecting a filler into the gap between the columnar member 100 and the steel pipe body 11, and a first lining step in which a first stainless steel lining 13 is provided on the outer peripheral surface of the steel pipe body 11. In this embodiment, the injection port step is performed after the first lining step.

[0031] As shown in Figures 3 to 5, in the first lining step, the first lining 13 is positioned to cover the outer surface of the steel pipe body 11. Specifically, one or more first linings 13 are wrapped around the outer surface of the steel pipe body 11 in the circumferential direction. Then, with the ends of adjacent first linings 13 overlapping in the circumferential direction, welding is performed using the indirect seam welding method. This fixes adjacent first linings 13 to each other, and to the first linings 13 and the steel pipe body 11. In addition, in the first lining step, the mounting holes 11a of the steel pipe body 11 are positioned within the openings 13a of the first lining 13. Although not specifically illustrated, in the first lining step, the steel pipe body 11 is placed on a base called a turning roller, and while the steel pipe body 11 is rotated around its axis (circumferential direction) by this base, the first lining 13 is stretched (wrapped) around the outer surface of the steel pipe body 11.

[0032] As shown in Figure 6, in the first lining step, the opening 13a is welded around by indirect seam welding, and the first lining 13 and the steel pipe body 11 are tack welded. Specifically, two roller-shaped electrodes (not shown) are brought into contact with the surface side of the first lining 13, which is placed on the outer surface of the steel pipe body 11, and these electrodes are rolled in parallel to weld the overlapping first lining 13 and the steel pipe body 11. At this time, a current passage is obtained through the steel pipe body 11 on the back side of the first lining 13, so the first lining 13 can be directly welded to the steel pipe body 11. The contact portion (current-carrying portion) between the first lining 13 and the steel pipe body 11 is melted by electrical resistance heat, and the first lining 13 and the steel pipe body 11 are tack welded and fixed to each other.

[0033] Furthermore, as described above, by tack welding with the two electrodes running parallel to each other, two parallel welding lines (double-frame-shaped welding marks 16) are formed around the opening 13a of the first lining 13. In this embodiment, during the first lining step, air passages 19 and 20 for leak testing, described later, are formed in a portion of the double-frame-shaped welded joint 16. Specifically, in the inner frame welded joint 16a, an air passage 19, which is an unwelded portion, is provided on a portion of the frame, and in the outer frame welded joint 16b, an air passage 20, which is an unwelded portion, is provided on a portion of the frame. The air passages 19 and 20 are positioned close to each other and facing each other.

[0034] As shown in Figures 3 and 6, in the injection port step, the end of the injection port 12 is inserted into the mounting hole 11a that opens in the peripheral wall of the steel pipe body 11, and the injection port 12 and the mounting hole 11a are welded from the inside and outside of the injection port 12. This fixes the injection port 12 to the peripheral wall of the steel pipe body 11.

[0035] Furthermore, the manufacturing method of the steel pipe 10 in this embodiment further includes a second lining step of providing a second stainless steel lining 14 on the outer circumferential surface (surface) of the first lining 13.

[0036] As shown in Figures 3 and 7, in the second lining step, with the second lining 14 positioned to cover the opening 13a of the first lining 13, the outer periphery of the second lining 14 and the outer periphery of the first lining 13 are welded (for example, by TIG welding) along the outer frame weld mark 16b of the double-frame-shaped weld marks 16 (inner frame weld mark 16a and outer frame weld mark 16b). Specifically, the outer periphery of the second lining 14 is welded to the outer periphery of the first lining 13 over its entire circumference (in a rectangular shape in this embodiment). This forms a weld bead 18 connecting the outer periphery of the second lining 14 and the outer periphery of the first lining 13.

[0037] In this embodiment, the outer periphery of the second lining 14 is TIG welded along the outer frame weld mark 16b of the indirect seam welding. As a result, the steel pipe body 11, the first lining 13, and the second lining 14 are stably welded in a tightly packed laminated state, suppressing the occurrence of wrinkles and other issues caused by welding.

[0038] Furthermore, in the second lining step, the insertion hole 14a of the second lining 14 and the outer surface of the injection port 12 are welded (for example, by TIG welding). Specifically, the insertion hole 14a of the second lining 14 is welded to the outer surface of the injection port 12 along its entire circumference (in a circular shape in this embodiment). This forms a weld bead 17 connecting the insertion hole 14a of the second lining 14 and the outer surface of the injection port 12. In this way, the second lining 14 is fixed to the inlet 12 and the first lining 13. The opening 13a is also sealed by the second lining step.

[0039] Furthermore, the manufacturing method of the steel pipe 10 in this embodiment further includes a leak test step in which air is sent between the outer surface of the steel pipe body 11 and the first lining 13 to check for air leakage.

[0040] In the leak test step, although not specifically shown in the diagram, a leak test hole is made that penetrates a portion of the peripheral wall of the steel pipe body 11, and air is introduced through this leak test hole between the outer surface of the steel pipe body 11 and the inner surface (back surface) of the first lining 13. The leak test step allows for confirmation of air leaks at each joint (each welded area) of the outer surface of the steel pipe body 11, the first lining 13, and the second lining 14, thereby ensuring the integrity of each joint.

[0041] After confirming that there are no air leaks in the leak test step, perform the following polishing step. In other words, the manufacturing method of the steel pipe 10 in this embodiment further includes a polishing step as a post-leak test step in which the weld marks 16 (outer frame weld marks 16b) and weld beads 17, 18 exposed on the surface of the steel pipe 10 are electropolished.

[0042] In the steel pipe 10 of this embodiment described above, a columnar member 100, such as a pile driven into the seabed, is inserted into the carbon steel pipe body 11, and a filler such as grout is injected from the injection port 12 on the peripheral wall of the steel pipe body 11. The filler fills the gap between the columnar member 100 and the steel pipe body 11 and solidifies, thereby joining the columnar member 100 and the steel pipe body 11.

[0043] Furthermore, a first stainless steel lining 13 is provided on the outer surface of the steel pipe body 11. In other words, the steel pipe body 11 is covered with stainless steel by the first lining 13. Therefore, according to the steel pipe 10 of this embodiment, when used in the jacket legs (legs of jacket foundations) 1 of offshore structures, for example, high corrosion protection performance can be obtained for up to 100 years with virtually no maintenance.

[0044] Furthermore, in Figure 1(b), the inlet 12 is located within the outer circumference of the first lining 13.

[0045] As described above, the first stainless steel lining 13 is preferably provided on the outer surface of the steel pipe body 11, for example, in the range of water depth D from the sea surface S to about 1 m (particularly in the spray and tidal zone where high corrosion protection performance is required). Here, as shown in Figure 1(a), if the columnar member 100, such as a pile, is driven into the seabed at a depth sufficiently greater than the water depth D, the point where the columnar member 100 and the steel pipe body 11 overlap by insertion (i.e., the point where the filler is injected) will also be located at a depth greater than the water depth D. For this reason, the injection port 12 for injecting the filler is also located at a depth greater than the water depth D, and therefore the injection port 12 will not be located within the outer circumference of the first lining 13.

[0046] On the other hand, as shown in Figure 1(b), when a columnar member 100 such as a pile is driven into the seabed at a shallow depth, the overlapping points between the columnar member 100 and the steel pipe body 11 due to insertion may be located within the range of water depth D. In this case, as in the above configuration, by arranging the injection port 12 within the range of the outer circumference of the first lining 13, the steel pipe 10 of this disclosure can be flexibly applied to columnar members 100 driven into the seabed at a shallow depth, and the above-mentioned excellent effects can be stably achieved.

[0047] Furthermore, the steel pipe 10 of this embodiment includes a second stainless steel lining 14 provided on the outer surface of the first lining 13. According to the above configuration, when providing the first lining 13 on the outer surface of the steel pipe body 11, even if, for example, an opening 13a or a notch (not shown) is required in the first lining 13, this opening 13a or notch can be covered with stainless steel by the second lining 14. In other words, by providing the second lining 14 on the outer surface of the first lining 13, it becomes possible to maintain high corrosion protection performance well.

[0048] In this embodiment, the second lining 14 is welded to the injection port 12 and the first lining 13. With the above configuration, the space between the second lining 14 and the inlet 12, and the space between the second lining 14 and the first lining 13 can be sealed by welding. This prevents seawater from entering the outer surface of the steel pipe body 11 through the space between the second lining 14 and the inlet 12, and the space between the second lining 14 and the first lining 13.

[0049] In this embodiment, the thickness of the second lining 14 is greater than the thickness of the first lining 13. With the above configuration, since the second lining 14 is thick, the second lining 14 can be easily attached to the steel pipe 10 by welding or the like. In particular, workability is improved when closing (patching) openings 13a or notches in the first lining 13 with the second lining 14.

[0050] In this embodiment, an opening 13a is formed in the portion of the first lining 13 corresponding to the inlet 12, and the inlet 12 is located within the opening 13a. In the above configuration, the inlet 12 is located within the opening 13a of the first lining 13. Therefore, the inlet 12 can be easily provided in the portion of the peripheral wall of the steel pipe body 11 that is covered with stainless steel by the first lining 13.

[0051] In this embodiment, the second lining 14 covers the outer surface of the steel pipe body 11 that is exposed through the opening 13a. In the above configuration, the opening 13a provided in the first lining 13 for arranging the inlet 12 can be covered with stainless steel by the second lining 14. The second lining 14 can prevent corrosion of the outer surface of the steel pipe body 11 exposed through the opening 13a of the first lining 13.

[0052] In this embodiment, the outer shape of the second lining 14 is larger than the opening 13a. In the above configuration, the second lining 14 can stably cover the entire opening 13a of the first lining 13. The second lining 14 can reliably prevent corrosion of the outer surface of the steel pipe body 11 that is exposed through the opening 13a of the first lining 13.

[0053] In this embodiment, the steel pipe body 11 is the leg 1 of the jacket foundation. The above configuration effectively enhances the corrosion protection performance of the jacket foundation leg 1, i.e., the jacket leg 1 of the offshore structure.

[0054] Furthermore, this embodiment is a method for manufacturing a steel pipe 10, which comprises a steel pipe body 11 made of carbon steel into which a columnar member 100 is inserted, and includes an injection port step in which an injection port 12 is provided on the peripheral wall of the steel pipe body 11 for injecting a filler into the gap between the columnar member 100 and the steel pipe body 11, and a first lining step in which a first lining 13 made of stainless steel is provided on the outer peripheral surface of the steel pipe body 11.

[0055] In this embodiment, an injection port 12 is provided in the peripheral wall of the steel pipe body 11 by an injection port step. Therefore, when a columnar member 100 such as a pile driven into the seabed is inserted into the carbon steel pipe body 11, a filler such as grout is injected from the injection port 12 in the peripheral wall of the steel pipe body 11, filling the gap between the columnar member 100 and the steel pipe body 11, and solidifying, the columnar member 100 and the steel pipe body 11 are joined together.

[0056] Furthermore, a first lining step is provided, and the steel pipe body 11 is covered with stainless steel by the first lining 13. Therefore, according to the manufacturing method of the steel pipe 10 of this embodiment, when the manufactured steel pipe 10 is used as a jacket leg (leg of jacket foundation) 1 of an offshore structure, for example, high corrosion protection performance that can last for about 100 years without maintenance can be obtained.

[0057] Furthermore, the manufacturing method of the steel pipe 10 in this embodiment includes a second lining step in which a second lining 14 made of stainless steel is provided on the outer circumferential surface of the first lining 13. In the above configuration, a second lining step is provided. When providing the first lining 13 on the outer surface of the steel pipe body 11, even if, for example, an opening 13a or notch is required in the first lining 13, this opening 13a or notch can be covered with stainless steel by the second lining 14. In other words, by providing the second lining 14 on the outer surface of the first lining 13, it becomes possible to maintain high corrosion protection performance well.

[0058] In this embodiment, the manufacturing method for the steel pipe 10 is described in which the first lining step, the inlet step, the second lining step, the leak test step, and the polishing step are performed in this order, but the method is not limited to this. For example, the order of the first lining step and the inlet step may be reversed. That is, the first lining step may be performed after the inlet step. In this case, in the first lining step, the inlet 12 is placed in the opening 13a of the first lining 13.

[0059] However, as in the embodiment described above, if the injection port step is performed after the first lining step, the first lining 13 can be wrapped around the outer surface of the steel pipe body 11 without the injection port 12 protruding from the peripheral wall of the steel pipe body 11. The first lining 13 can be efficiently stretched over the outer surface of the steel pipe body 11 while rotating the steel pipe body 11 around its axis using a base called a turning roller. In this case, a work platform for wrapping the first lining 13 around the steel pipe body 11 is not required, improving the workability of the steel pipe 10 manufacturing process.

[0060] Furthermore, when the first lining step is performed after the injection port step, it is also possible to wrap the first lining 13 around the steel pipe body 11 using the base mentioned above. However, in this case, it is necessary to note that the injection port 12 may come into contact with the ground or other surfaces.

[0061] The present invention is not limited to the embodiments described above, and modifications to the configuration, etc., are possible without departing from the spirit of the invention, as described below, for example.

[0062] In the embodiments described above, an example was given in which the thickness (plate thickness dimension) of the second lining 14 is greater than the thickness of the first lining 13, but the invention is not limited to this. The thickness of the second lining 14 may be the same as the thickness of the first lining 13.

[0063] Furthermore, this disclosure is also applicable to steel pipes used in applications other than the legs of jacket foundations. Specifically, for example, this disclosure can be applied to double-tube piles used in berthing piles (boat landings). In detail, a berthing pile is integrally joined in a double-tube shape by covering a columnar member such as a pile driven into the seabed with a top-cylindrical steel pipe body from above, filling the gap between them with a filler through an injection port, and allowing it to solidify. In this case, the upper end of the berthing pile is positioned above the sea surface.

[0064] The present invention may be combined in any way that does not depart from the spirit of the invention, as described in the above embodiments and modifications, and the configurations may be added, omitted, substituted, or otherwise modified. Furthermore, the present invention is not limited by the above embodiments, but is limited only by the claims.

[0065] (Note) The steel pipe and the method for manufacturing the steel pipe according to the above embodiment can be understood, for example, as follows.

[0066] <Aspect 1 of this disclosure> A steel pipe comprising: a steel pipe body made of carbon steel into which a columnar member is inserted; an injection port provided on the peripheral wall of the steel pipe body for injecting a filler into the gap between the columnar member and the steel pipe body; and a first lining made of stainless steel provided on the outer surface of the steel pipe body.

[0067] In the aforementioned embodiment of the present disclosure, a columnar member such as a pile driven into the seabed is inserted inside a carbon steel pipe body, and a filler such as grout is injected from an injection port in the peripheral wall of the steel pipe body. The filler fills the gap between the columnar member and the steel pipe body and solidifies, thereby joining the columnar member and the steel pipe body.

[0068] Furthermore, a first stainless steel lining is provided on the outer surface of the steel pipe body. In other words, the steel pipe body is coated with stainless steel by the first lining. Therefore, with the steel pipe of the above embodiment, when used in the jacket legs (legs of jacket foundations) of offshore structures, for example, high corrosion resistance can be obtained for up to 100 years with virtually no maintenance.

[0069] <Aspect 2 of this disclosure> The steel pipe according to embodiment 1, wherein the inlet is located within the outer circumference of the first lining.

[0070] The first stainless steel lining is preferably installed on the outer surface of the steel pipe body, for example, in the water depth range from the sea surface to about 1 meter (particularly in the spray and tidal zone where high corrosion resistance is required). In this case, if the columnar members such as piles are driven into the seabed at a depth sufficiently greater than the water depth, the points where the columnar members and the steel pipe body overlap by insertion (i.e., the points where the filler is injected) will also be located at a depth greater than the water depth. Therefore, the injection port for the filler will also be located at a depth greater than the water depth, and thus the injection port will not be located within the outer circumference of the first lining.

[0071] On the other hand, when columnar members such as piles are driven into the seabed at a shallow depth, the overlapping points between the columnar members and the steel pipe body due to insertion may be located within the aforementioned water depth range. In this case, as in the above configuration, by arranging the injection port within the outer circumference of the first lining, the steel pipe of this disclosure can be flexibly applied even to columnar members driven into the seabed at a shallow depth, and the above-mentioned excellent effects can be stably achieved.

[0072] <Aspect 3 of this disclosure> The steel pipe according to embodiment 1 or 2, further comprising a second stainless steel lining provided on the outer circumferential surface of the first lining.

[0073] According to the above configuration, when providing the first lining on the outer surface of the steel pipe body, even if openings or notches are required in the first lining, these openings or notches can be covered with stainless steel by the second lining. In other words, by providing the second lining on the outer surface of the first lining, it becomes possible to maintain high corrosion protection performance well.

[0074] <Aspect 4 of this disclosure> The steel pipe according to embodiment 3, wherein the second lining is welded to the inlet and the first lining.

[0075] With the above configuration, the gap between the second lining and the inlet, and the gap between the second lining and the first lining can be sealed by welding. This prevents seawater from entering the outer surface of the steel pipe body through the gap between the second lining and the inlet, and the gap between the second lining and the first lining.

[0076] <Aspect 5 of this disclosure> The steel pipe according to embodiment 3 or 4, wherein the thickness of the second lining is greater than the thickness of the first lining.

[0077] With the above configuration, the second lining is thicker, making it easy to attach to the steel pipe by welding or other means. In particular, workability is improved when closing (patching) openings or notches in the first lining with the second lining.

[0078] <Aspect 6 of this disclosure> A steel pipe according to any one of embodiments 3 to 5, wherein an opening is formed in the portion of the first lining corresponding to the inlet, and the inlet is located within the opening.

[0079] In the above configuration, the inlet is located within the opening of the first lining. Therefore, the inlet can be easily provided in the portion of the peripheral wall of the steel pipe body that is covered with stainless steel by the first lining.

[0080] <Aspect 7 of this disclosure> The steel pipe according to embodiment 6, wherein the second lining covers the outer circumferential surface of the steel pipe body exposed from the opening.

[0081] In the above configuration, the opening provided in the first lining for arranging the inlet can be covered with stainless steel by the second lining. The second lining can prevent corrosion of the outer surface of the steel pipe body exposed through the opening in the first lining.

[0082] <Aspect 8 of this disclosure> The steel pipe according to embodiment 7, wherein the shape of the outer circumference of the second lining is larger than the opening.

[0083] In the above configuration, the second lining can stably cover the entire opening of the first lining. The second lining can reliably protect the outer surface of the steel pipe body exposed through the opening of the first lining from corrosion.

[0084] <Aspect 9 of this disclosure> The steel pipe body is a leg of a jacket foundation, as described in any one of embodiments 1 to 8.

[0085] The above configuration effectively enhances the corrosion protection performance of the jacket foundation legs, i.e., the jacket legs of offshore structures.

[0086] <Aspect 10 of this disclosure> A method for manufacturing a steel pipe, comprising a steel pipe body made of carbon steel into which a columnar member is inserted, the method comprising: an injection port step provided on the peripheral wall of the steel pipe body for injecting an injection port for injecting a filler into the gap between the columnar member and the steel pipe body; and a first lining step provided on the outer peripheral surface of the steel pipe body for providing a first lining made of stainless steel.

[0087] In the above-described embodiment of the present disclosure, an injection port is provided in the peripheral wall of the steel pipe body by an injection port step. Therefore, when a columnar member such as a pile driven into the seabed is inserted into the carbon steel pipe body, a filler such as grout is injected from the injection port in the peripheral wall of the steel pipe body, and the filler fills the gap between the columnar member and the steel pipe body and solidifies, thereby joining the columnar member and the steel pipe body.

[0088] Furthermore, a first lining step is provided, and the steel pipe body is coated with stainless steel by the first lining. Therefore, according to the steel pipe manufacturing method of the above embodiment, when the manufactured steel pipe is used as a jacket leg (leg of a jacket foundation) of an offshore structure, for example, high corrosion protection performance that can last for about 100 years without maintenance can be obtained.

[0089] <Aspect 11 of this disclosure> A method for manufacturing a steel pipe according to embodiment 10, comprising a second lining step of providing a second lining made of stainless steel on the outer circumferential surface of the first lining.

[0090] The above configuration includes a second lining step. When applying the first lining to the outer surface of the steel pipe body, even if openings or notches are required in the first lining, these openings or notches can be covered with stainless steel by the second lining. In other words, by applying the second lining to the outer surface of the first lining, it becomes possible to maintain high corrosion protection performance well. [Explanation of Symbols]

[0091] 1…Jacket legs (basic jacket legs) 10...Steel pipe 11...Steel pipe body 12…Inlet 13…First lining 13a...Aperture 14…Second lining 100... Columnar member

Claims

1. A steel pipe body made of carbon steel into which a columnar member is inserted, An inlet is provided on the peripheral wall of the steel pipe body for injecting a filler into the gap between the columnar member and the steel pipe body, The steel pipe body is provided with a first lining made of stainless steel on its outer surface, The first lining is provided at a position above the lower end of the steel pipe body, and the inlet is provided at a position below the lower end of the first lining. Steel pipe.

2. A steel pipe body made of carbon steel into which a columnar member is inserted, An inlet is provided on the peripheral wall of the steel pipe body for injecting a filler into the gap between the columnar member and the steel pipe body, The steel pipe body is provided with a first lining made of stainless steel on its outer surface, The first lining and the inlet are provided at positions that overlap each other in the axial direction of the steel pipe body. Steel pipe.

3. A steel pipe body made of carbon steel into which a columnar member is inserted, An inlet is provided on the peripheral wall of the steel pipe body for injecting a filler into the gap between the columnar member and the steel pipe body, The steel pipe body is provided with a first lining made of stainless steel on its outer surface, The inlet is located within the area enclosed by the outer circumference of the first lining, when viewed along a direction perpendicular to the axial direction of the steel pipe body. Steel pipe.

4. A steel pipe body made of carbon steel into which a columnar member is inserted, An inlet is provided on the peripheral wall of the steel pipe body for injecting a filler into the gap between the columnar member and the steel pipe body, The steel pipe body is provided with a first lining made of stainless steel on its outer surface, The first lining is provided within a water depth range of approximately 1 meter from the sea surface, and the inlet is provided outside the water depth range of approximately 1 meter from the sea surface. Steel pipe.

5. A steel pipe body made of carbon steel into which a columnar member is inserted, An inlet is provided on the peripheral wall of the steel pipe body for injecting a filler into the gap between the columnar member and the steel pipe body, The steel pipe body is provided with a first lining made of stainless steel on its outer surface, The first lining is provided within a water depth range of approximately 1 meter from the low tide line, and the inlet is provided outside the water depth range of approximately 1 meter from the low tide line. Steel pipe.

6. A steel pipe body made of carbon steel into which a columnar member is inserted, An inlet is provided on the peripheral wall of the steel pipe body for injecting a filler into the gap between the columnar member and the steel pipe body, The steel pipe body is provided with a first lining made of stainless steel on its outer surface, The first lining and the inlet are provided within a water depth range of approximately 1 m from the sea surface. Steel pipe.

7. A steel pipe body made of carbon steel into which a columnar member is inserted, An inlet is provided on the peripheral wall of the steel pipe body for injecting a filler into the gap between the columnar member and the steel pipe body, The steel pipe body is provided with a first lining made of stainless steel on its outer surface, The first lining and the inlet are provided within a water depth range of approximately 1 m from the low tide line. Steel pipe.

8. A steel pipe body made of carbon steel into which a columnar member is inserted, An inlet is provided on the peripheral wall of the steel pipe body for injecting a filler into the gap between the columnar member and the steel pipe body, The steel pipe body is provided with a first lining made of stainless steel on its outer surface, The steel pipe body is a leg provided in multiple locations on the jacket foundation. The first lining is provided on all of the multiple legs. Steel pipe.

9. A method for manufacturing a steel pipe, comprising a steel pipe body made of carbon steel into which a columnar member is inserted, An injection port step is provided on the peripheral wall of the steel pipe body for injecting a filler into the gap between the columnar member and the steel pipe body. The steel pipe body is provided with a first lining step, which involves providing a first lining made of stainless steel on its outer surface. The first lining and the inlet are provided within a water depth range of approximately 1 m from the sea surface. A method for manufacturing steel pipes.

10. A method for manufacturing a steel pipe, comprising a steel pipe body made of carbon steel into which a columnar member is inserted, An injection port step is provided on the peripheral wall of the steel pipe body for injecting a filler into the gap between the columnar member and the steel pipe body. The steel pipe body is provided with a first lining step, which involves providing a first lining made of stainless steel on its outer surface. The first lining and the inlet are provided within a water depth range of approximately 1 m from the low tide line. A method for manufacturing steel pipes.

11. A method for manufacturing a steel pipe, comprising a steel pipe body made of carbon steel into which a columnar member is inserted, An injection port step is provided on the peripheral wall of the steel pipe body for injecting a filler into the gap between the columnar member and the steel pipe body. The steel pipe body is provided with a first lining step, which involves providing a first lining made of stainless steel on its outer surface. The first lining and the inlet are provided at positions that overlap each other in the axial direction of the steel pipe body. A method for manufacturing steel pipes.

12. A method for manufacturing a steel pipe, comprising a steel pipe body made of carbon steel into which a columnar member is inserted, An injection port step is provided on the peripheral wall of the steel pipe body for injecting a filler into the gap between the columnar member and the steel pipe body. The steel pipe body is provided with a first lining step, which involves providing a first lining made of stainless steel on its outer surface. The inlet is located within the range of the outer edge of the first lining when viewed in a direction perpendicular to the axial direction of the steel pipe body. A method for manufacturing steel pipes.

13. A method for manufacturing a steel pipe, comprising a steel pipe body made of carbon steel into which a columnar member is inserted, An injection port step is provided on the peripheral wall of the steel pipe body for injecting a filler into the gap between the columnar member and the steel pipe body. The steel pipe body is provided with a first lining step, which involves providing a first lining made of stainless steel on its outer surface. The steel pipe body is a leg provided in multiple locations on the jacket foundation. The first lining is provided on all of the multiple legs. A method for manufacturing steel pipes.

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