Steel pipe and steel pipe manufacturing method

Abstract

Provided are a steel pipe capable of improving 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 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.

Description

[Technical Field]

[0001] The present disclosure relates to steel pipes and methods for manufacturing steel pipes. [Background technology]

[0002] Conventionally, a technique has been known in which the legs (jacket legs) of an offshore structure are inserted into piles driven into the seabed, and grout is injected into the gaps between them and allowed to solidify, thereby joining the piles and jacket legs (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2024-8791 Summary of the Invention [Problem to be solved by the invention]

[0004] The jacket legs are made of carbon steel pipes, and the outer surfaces of the steel pipes are treated with anti-corrosion treatments such as cathodic protection and anti-corrosion coating. Even greater corrosion protection performance is sometimes required for this type of steel pipe. For example, steel pipes used in marine structures may be required to have maintenance-free (negligible need for repairs during use) and long-term corrosion protection (for example, about 100 years).

[0005] An object of the present disclosure is to provide a steel pipe that can improve corrosion resistance, and a method for manufacturing a steel pipe. [Means for solving the problem]

[0006] A steel pipe according to one embodiment 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 surface of the steel pipe body. [Effects of the Invention]

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

[0008] [Figure 1] FIG. 1 is a side view showing a steel pipe of this embodiment and a columnar member (a pile driven into the seabed) to which the steel pipe is joined. [Figure 2] FIG. 2 is a plan view showing an injection port provided on the peripheral wall of a steel pipe body, a first lining provided on the outer peripheral surface of the steel pipe body, and a second lining provided on the outer peripheral surface of the first lining. [Figure 3] FIG. 3 is a cross-sectional view showing the peripheral wall of the steel pipe body, the injection port, the first lining, and the second lining. [Figure 4] FIG. 4 is a perspective view schematically showing a steel pipe body. [Figure 5] FIG. 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 has been wrapped around the outer peripheral surface of the steel pipe body. [Figure 6] Figure 6 is a plan view illustrating the first lining step and injection port step of the steel pipe manufacturing method of this embodiment, and more specifically, shows the state in which the first lining is tack-welded to the outer peripheral surface of the steel pipe body by the first lining step, and also shows the state in which an injection port is provided on the peripheral wall of the steel pipe body by the injection port step. [Figure 7] FIG. 7 is a plan view illustrating the second lining step in the method for producing a steel pipe of this embodiment, showing the state in which the second lining has been provided on the outer peripheral surface of the first lining. DETAILED DESCRIPTION OF THE INVENTION

[0009] A steel pipe 10 according to one embodiment of the present invention and a method for manufacturing the steel pipe 10 will be described with reference to the drawings. As shown in Figures 1(a) and 1(b), a 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 and fixed to a columnar member 100 such as a pile driven into the seabed.

[0010] The steel pipe 10 has a cylindrical shape that extends in the vertical direction. The steel pipe 10 is disposed both above the sea and under the sea (below the sea surface S). Specifically, in this embodiment, the steel pipe 10 is disposed above the sea and from the sea surface S to at least a predetermined water depth D. The water depth D is, for example, about 1 m below the sea surface S, and is set to the range of the splash and tidal zones 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 peripheral surface of the steel pipe body 11. The first lining 13 is arranged on the outer peripheral surface of the steel pipe body 11 above sea level and in the range from sea level S to water depth D.

[0012] Here, the steel pipes 10 shown in FIGS. 1(a) and 1(b) will be described. In the steel pipe 10 shown in Figure 1(a), a columnar member 100 such as a pile is driven into the seabed at a depth sufficiently deeper 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 position deeper than the water depth D. That is, in the case of Figure 1(a), the point where the columnar member 100 and the steel pipe body 11 overlap upon insertion (i.e., the point where the filler is injected) is located below the water depth D. Therefore, the injection port 12 for injecting the filler is located below the first lining 13, that is, outside the outer periphery of the first lining 13.

[0013] In addition, 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 to the sea are subjected to corrosion protection treatment such as cathodic protection.

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

[0015] In Fig. 1(b), the portion of the steel pipe 10 that is immersed in the sea (within the range of water depth D) is entirely covered with a first lining 13. In addition, the portion of the columnar member 100 that is exposed in the sea is subjected to anti-corrosion treatment such as cathodic protection.

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

[0017] As shown in Figures 1 to 3, the injection port 12 has a tubular shape, and in this embodiment, it has a cylindrical shape. The injection port 12 is made of, for example, carbon steel. One or more injection ports 12 are provided on the peripheral wall of the steel pipe 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 (e.g., perpendicular to) the peripheral wall of the steel pipe 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. Furthermore, within the central axis direction, the direction from the outside to the inside of the peripheral wall of the steel pipe 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 body 11 is referred to as the steel pipe outer side.

[0018] As shown in Fig. 3, the injection port 12 is fixed by welding to the mounting hole 11a of the steel pipe body 11. Specifically, weld beads 15 are formed by welding between the outer circumferential surface of the injection port 12 and the outer circumferential surface of the steel pipe body 11, and between the end face of the injection port 12 facing the inside of the steel pipe in the central axis direction and the inner circumferential surface of the mounting hole 11a. The injection port 12 also protrudes from the peripheral wall of the steel pipe body 11 toward the outside of the steel pipe in the central axis direction (i.e., radially outward from the steel pipe body 11).

[0019] 1(a) and 1(b), the injection port 12 is arranged at a position on the peripheral wall of the steel pipe body 11 where it overlaps with the columnar member 100 when the steel pipe body 11 is viewed from the radial direction. In other words, the injection port 12 is provided in a range where the columnar member 100 and the steel pipe body 11 overlap in the radial direction when the columnar member 100 is inserted into the steel pipe body 11.

[0020] Although not specifically shown, the filler is injected from the outside of the steel pipe 10 through the injection port 12 into at least the gap between the outer circumferential surface of the columnar member 100 and the inner circumferential surface of the steel pipe body 11. Note that the gap may also be referred to as an annular space, etc. In this embodiment, grout is used as the filler. However, the present disclosure is not limited to this, and in addition to grout, other fillers such as mortar, cement milk, cement paste, etc. may also be used. The steel pipe 10 is joined to the columnar member 100 by solidifying (hardening) the filler injected into the gap.

[0021] 1 to 3, the first lining 13 is wrapped around the entire circumferential surface of the steel pipe body 11. The first lining 13 is fixed to the steel pipe body 11 by welding using an indirect current seam welding method (indirect seam welding method) or the like.

[0022] The first lining 13 is a plate-like 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 has a plate thickness of, 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 when attached to the outer peripheral surface of the steel pipe body 11, it can be deformed appropriately to fit the curved shape of the outer peripheral surface of the steel pipe body 11.

[0023] In the steel pipe 10 shown in FIG. 1(b), an opening 13a is formed in the first lining 13 in a portion corresponding to the injection port 12, as shown in FIGS. 2 and 3. The opening 13a penetrates the first lining 13 in its thickness direction. In this embodiment, the opening 13a has, for example, a rectangular hole shape. The opening dimension of the opening 13a is larger than the outer diameter dimension of the injection port 12. The injection port 12 is located within the opening 13a. Note that the shape of the opening 13a is not limited to a rectangular shape. The shape of the opening 13a may be, for example, a circular shape.

[0024] As shown in Fig. 2, a bead-shaped weld mark 16 is disposed 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 an indirect seam welding method. The weld mark 16 extends continuously around the opening 13a so as to surround the opening 13a from the outside.

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

[0026] As shown in Figures 2 and 3, the steel pipe 10 further includes a second lining 14 provided on the outer peripheral surface (surface) of the first lining 13. The second lining 14 is a plate-shaped member made of stainless steel, and in this embodiment, 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) of the second lining 14 is thicker than the thickness of the first lining 13. In this embodiment, the thickness of the second lining 14 is at least twice the thickness of the first lining 13. However, the plate thickness of the second lining 14 is not limited to 1.0 mm.

[0027] The second lining 14 is arranged on the outer peripheral surface of the first lining 13 so as to cover the opening 13a of the first lining 13. The shape of the outer periphery of the second lining 14 is larger than the opening 13a. In this embodiment, the shape of the outer periphery of the second lining 14 is larger than the inner frame weld mark 16a. The shape of the outer periphery of the second lining 14 is also substantially the same as the shape of the outer frame weld mark 16b. The second lining 14 covers the outer peripheral surface of the steel pipe body 11 exposed from the opening 13a. The second lining 14 also covers the inner frame weld mark 16a. Although not specifically shown, a portion of the inner frame weld mark 16a may be located outside the second lining 14 without being covered by the second lining 14.

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

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

[0030] Next, a method for manufacturing the above-mentioned steel pipe 10 will be described with reference to FIGS. The manufacturing method of the steel pipe 10 of this embodiment comprises an injection port step of providing an injection port 12 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 of providing a first lining 13 made of stainless steel on the outer peripheral surface of the steel pipe body 11. In this embodiment, the injection port step is carried out after the first lining step is carried out.

[0031] As shown in Figures 3 to 5, in the first lining step, a first lining 13 is placed so as to cover the outer peripheral surface of the steel pipe body 11. Specifically, one or more first linings 13 are wrapped around the outer peripheral surface of the steel pipe body 11 over the entire circumferential direction. Then, with the ends of adjacent first linings 13 overlapping each other in the circumferential direction, they are welded by indirect seam welding. This fixes adjacent first linings 13 to each other and the first linings 13 to the steel pipe body 11. Also, in the first lining step, the mounting hole 11a of the steel pipe body 11 is placed within the opening 13a of the first lining 13. Although not specifically shown, in the first lining step, the steel pipe body 11 is placed on a base called a turning roller, and the steel pipe body 11 is rotated around its axis (circumferential direction) by this base while 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 periphery of the opening 13a is welded using an indirect seam welding method, and the first lining 13 and the steel pipe body 11 are tack-welded together. Specifically, two roller-shaped electrodes (not shown) are brought into contact with the surface side of the first lining 13 arranged on the outer circumferential surface of the steel pipe body 11, and these electrodes are rolled in parallel to weld the overlapping first lining 13 and steel pipe body 11 together. At this time, a current path 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, by tack welding while the two electrodes are arranged side by side as described above, two parallel welding lines (double frame-shaped welding marks 16) are formed around the opening 13a of the first lining 13. In this embodiment, in the first lining step, air passages 19, 20 for a leak test, which will be described later, are formed in parts of the double-frame-shaped weld mark 16. Specifically, in the inner frame weld mark 16a, passage 19, which is a non-welded portion, is provided in part of the frame, and in the outer frame weld mark 16b, passage 20, which is a non-welded portion, is provided in part of the frame. Passages 19 and 20 are positioned close to and opposite each other.

[0034] 3 and 6, in the injection port step, the end of the injection port 12 is inserted into an attachment hole 11a that opens into the peripheral wall of the steel pipe body 11, and the injection port 12 and the attachment hole 11a are welded from the inside and outside of the injection port 12. In this way, the injection port 12 is fixed to the peripheral wall of the steel pipe body 11.

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

[0036] 3 and 7 , in the second lining step, with the second lining 14 positioned so as to cover the opening 13a of the first lining 13, the outer periphery of the second lining 14 and the outer periphery surface of the first lining 13 are welded (by TIG welding, for example) along the outer periphery weld mark 16b of the double-frame-shaped weld mark 16 (the inner periphery weld mark 16a and the outer periphery weld mark 16b). Specifically, the outer periphery of the second lining 14 is welded to the outer periphery surface of the first lining 13 along its entire circumference (in a rectangular shape in this embodiment). This forms a weld bead 18 that connects the outer periphery of the second lining 14 and the outer periphery surface 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 weld, so that the steel pipe body 11, the first lining 13 and the second lining 14 are stably welded in a tightly adhered laminated state, and the occurrence of wrinkles due to welding is suppressed.

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

[0039] The manufacturing method of the steel pipe 10 of this embodiment further includes a leak test step in which air is fed between the outer peripheral 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, a leak test hole is provided that penetrates a portion of the peripheral wall of the steel pipe body 11, and air is sent through this leak test hole to between the outer peripheral surface of the steel pipe body 11 and the inner peripheral surface (back surface) of the first lining 13. The leak test step makes it possible to check for air leaks at each joint (each welded portion) between the outer peripheral surface of the steel pipe body 11, the first lining 13, and the second lining 14, and ensures the soundness of each joint.

[0041] After it is confirmed that there is no air leakage in the leak test step, the polishing step described below is carried out. That is, the manufacturing method of the steel pipe 10 of this embodiment further includes a polishing step, after the leak test step, of electrolytically polishing the weld mark 16 (outer frame weld mark 16b) and weld beads 17, 18 exposed on the surface of the steel pipe 10.

[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 a steel pipe body 11 made of carbon steel, and a filler such as grout is injected from an 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] A first lining 13 made of stainless steel is provided on the outer peripheral surface of the steel pipe body 11. That is, the steel pipe body 11 is stainless-coated with the first lining 13. Therefore, according to the steel pipe 10 of this embodiment, when used in a jacket leg (jacket foundation leg) 1 of an offshore structure, high corrosion resistance can be obtained for up to about 100 years without maintenance, for example.

[0044] In addition, in FIG. 1( b ), the injection port 12 is located within the outer periphery of the first lining 13 .

[0045] As described above, the first lining 13 made of stainless steel is suitably provided on the outer surface of the steel pipe body 11, for example, in a range of water depth D from sea level S to about 1 m (the range of splash and tidal zones where particularly high corrosion protection performance is required). Here, as shown in Figure 1(a), when a columnar member 100 such as a pile is driven into the seabed at a depth sufficiently deeper than the water depth D, the point where the columnar member 100 and the steel pipe body 11 overlap upon insertion (i.e., the point where the filler is injected) will also be located at a position deeper than the water depth D. Therefore, the injection port 12 for injecting the filler will also be located at a position deeper than the water depth D, and therefore the injection port 12 will not be located within the outer periphery 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 a shallow seabed, the point where the columnar member 100 and the steel pipe body 11 overlap due to insertion may be located within the range of water depth D. In this case, by locating the injection port 12 within the range of the outer periphery of the first lining 13 as in the above configuration, the steel pipe 10 of the present disclosure can be flexibly applied to columnar members 100 driven into a shallow seabed, and the above-mentioned excellent effects can be stably achieved.

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

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

[0049] In this embodiment, the second lining 14 is thicker than the first lining 13 . According to the above configuration, the second lining 14 is thick, so that 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) the openings 13a, notches, etc. provided in the first lining 13 with the second lining 14.

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

[0051] In this embodiment, the second lining 14 covers the outer peripheral surface of the steel pipe body 11 exposed from the opening 13a. In the above configuration, the opening 13a provided in the first lining 13 for locating the injection port 12 can be covered with stainless steel by the second lining 14. The second lining 14 can protect the outer surface of the steel pipe body 11 exposed from the opening 13a of the first lining 13 from corrosion.

[0052] In this embodiment, the outer periphery 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 protect the outer surface of the steel pipe body 11 exposed from the opening 13a of the first lining 13 from corrosion.

[0053] In this embodiment, the steel pipe body 11 is the leg 1 of the jacket foundation. With the above configuration, the corrosion prevention performance of the leg 1 of the jacket foundation, that is, the jacket leg 1 of the offshore structure, can be effectively improved.

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

[0055] In this embodiment, the injection port step provides an injection port 12 on the peripheral wall of the steel pipe body 11. Therefore, with a columnar member 100 such as a pile driven into the seabed inserted into the carbon steel steel pipe body 11, a filler such as grout is injected from the injection port 12 on the peripheral wall of the steel pipe body 11, and 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.

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

[0057] The method for manufacturing the steel pipe 10 of this embodiment also includes a second lining step in which a second lining 14 made of stainless steel is provided on the outer peripheral surface of the first lining 13 . The above configuration includes a second lining step. When providing the first lining 13 on the outer peripheral surface of the steel pipe body 11, even if openings 13a or notches are required in the first lining 13, these openings 13a or notches can be covered with stainless steel by the second lining 14. In other words, by providing the second lining 14 on the outer peripheral surface of the first lining 13, it is possible to maintain high corrosion resistance.

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

[0059] However, when the injection port step is performed after the first lining step, as in the present embodiment described above, the first lining 13 can be wrapped around the outer peripheral surface of the steel pipe body 11 in a state where the injection port 12 does not protrude from the peripheral wall of the steel pipe body 11. The first lining 13 can be efficiently spread over the outer peripheral surface of the steel pipe body 11 while the steel pipe body 11 is rotated around its axis by a base called a turning roller. In this case, no work scaffolding is required for wrapping the first lining 13 around the steel pipe body 11, improving the workability of manufacturing the steel pipe 10.

[0060] When the first lining step is performed after the injection port step, it is also possible to use the above-mentioned base to wrap the first lining 13 around the steel pipe body 11. In this case, however, it is necessary to note that the injection port 12 may come into contact with the ground or the like.

[0061] The present invention is not limited to the above-described embodiment, and modifications to the configuration are possible within the scope of the invention, as described below.

[0062] In the above embodiment, an example was given in which the thickness (plate thickness dimension) of the second lining 14 was made thicker than the thickness of the first lining 13, but this is not limitative. The thickness of the second lining 14 may be the same as the thickness of the first lining 13.

[0063] The present disclosure can also be applied to steel pipes used for purposes other than the legs of a jacket foundation. Specifically, the present disclosure can be applied to, for example, double-tube piles used for boat landings. In detail, a quay pile is formed by covering a columnar member such as a pile driven into the seabed with a topped tubular steel pipe body from above, filling the gap between the two with a filler through an injection port, and allowing it to solidify, thereby joining the two together into a double-tube structure. In this case, the upper end of the quay pile is positioned above the sea surface.

[0064] The present invention may be combined with the various configurations described in the above-described embodiments and modifications, and may also include additions, omissions, substitutions, and other modifications of the configurations, without departing from the spirit of the present invention. Furthermore, the present invention is not limited to the above-described embodiments, but is limited only by the claims.

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

[0066] <First Aspect of the Present 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 peripheral surface of the steel pipe body.

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

[0068] A first lining made of stainless steel is provided on the outer peripheral surface of the steel pipe body. That is, the steel pipe body is covered with stainless steel by the first lining. Therefore, when the steel pipe of this aspect is used for the jacket legs (legs of jacket foundations) of marine structures, it can achieve high corrosion resistance for up to 100 years without maintenance.

[0069] <Aspect 2 of the present disclosure> 2. The steel pipe according to claim 1, wherein the injection port is located within an outer periphery of the first lining.

[0070] The first lining made of stainless steel is preferably provided on the outer surface of the steel pipe body within a water depth range of, for example, about 1 m from the sea surface (in the splash and tidal zones where particularly high corrosion protection is required). Here, if a columnar member such as a pile is driven into the seabed at a depth sufficiently greater than the water depth, the point where the columnar member and the steel pipe body overlap after insertion (i.e., the point where the filler is injected) will also be located at a depth greater than the water depth. Therefore, the injection port for injecting the filler will also be located at a depth greater than the water depth, and therefore the injection port will not be located within the outer periphery of the first lining.

[0071] On the other hand, when a columnar member such as a pile is driven into the shallow seabed, the point where the columnar member and the steel pipe body overlap due to insertion may be located within the range of the water depth. In this case, by locating the injection port within the outer periphery of the first lining as in the above configuration, the steel pipe of the present disclosure can be flexibly applied to columnar members driven into the shallow seabed, and the above-mentioned excellent effects can be stably achieved.

[0072] <Third Aspect of the Present Disclosure> 3. The steel pipe according to claim 1, further comprising a second lining made of stainless steel provided on an outer peripheral surface of the first lining.

[0073] According to the above configuration, even if, for example, an opening or a notch is required in the first lining when the first lining is provided on the outer circumferential surface of the steel pipe body, the opening or the notch can be covered with stainless steel by the second lining. In other words, by providing the second lining on the outer circumferential surface of the first lining, it is possible to maintain high corrosion prevention performance.

[0074] <Fourth Aspect of the Present Disclosure> Aspect 4. The steel pipe of aspect 3, wherein the second lining is welded to the inlet and the first lining.

[0075] According to the above configuration, the gap between the second lining and the injection port, and the gap between the second lining and the first lining can be sealed by welding, which prevents seawater from penetrating into the outer circumferential surface of the steel pipe body from the gap between the second lining and the injection port and the gap between the second lining and the first lining.

[0076] <Fifth Aspect of the Present Disclosure> A steel pipe according to aspect 3 or 4, wherein the second lining has a thickness greater than the thickness of the first lining.

[0077] According to the above configuration, since the second lining is thick, the second lining can be easily attached to the steel pipe by welding, etc. In particular, workability is improved when closing (patching) an opening, a notch, etc. provided in the first lining with the second lining.

[0078] Sixth Aspect of the Disclosure A steel pipe according to any one of aspects 3 to 5, wherein an opening is formed in a portion of the first lining corresponding to the injection port, and the injection port is located within the opening.

[0079] In the above configuration, the injection port is disposed within the opening of the first lining, which makes it possible to easily provide the injection port in the portion of the peripheral wall of the steel pipe body that is stainless steel coated by the first lining.

[0080] Seventh Aspect of the Disclosure Aspect 7. The steel pipe according to aspect 6, wherein the second lining covers an outer peripheral surface of the steel pipe body exposed from the opening.

[0081] In the above configuration, the opening provided in the first lining for locating the injection port can be covered with stainless steel by the second lining, and the second lining can protect the outer surface of the steel pipe body exposed through the opening in the first lining from corrosion.

[0082] Eighth Aspect of the Disclosure Aspect 8. The steel pipe according to aspect 7, wherein the outer periphery 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, and 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] <Ninth Aspect of the Disclosure> Aspect 9. The steel pipe of any one of aspects 1 to 8, wherein the steel pipe body is a leg of a jacket foundation.

[0085] With the above configuration, the corrosion prevention performance of the legs of the jacket foundation, i.e., the jacket legs of the offshore structure, can be effectively improved.

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

[0087] In the above aspect of the present disclosure, an injection port is provided in the peripheral wall of the steel pipe body by the injection port step, and therefore, with a columnar member such as a pile driven into the seabed inserted into the carbon steel steel pipe body, a filler such as grout is injected through the injection port in the peripheral wall of the steel pipe body, filling the gap between the columnar member and the steel pipe body and solidifying, thereby joining the columnar member and the steel pipe body.

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

[0089] <Eleventh Aspect of the Present Disclosure> A method for producing a steel pipe according to aspect 10, further comprising a second lining step of providing a second lining made of stainless steel on an outer peripheral surface of the first lining.

[0090] The above configuration includes a second lining step. When providing the first lining on the outer circumferential surface of the steel pipe body, even if an opening or notch is required in the first lining, the opening or notch can be covered with stainless steel by the second lining. In other words, by providing the second lining on the outer circumferential surface of the first lining, it is possible to maintain high corrosion resistance. [Explanation of symbols]

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

Claims

1. a carbon steel pipe body into which the columnar member is inserted; an injection port provided on the peripheral wall of the steel pipe body for injecting a filler into a gap between the columnar member and the steel pipe body; a first lining made of stainless steel provided on the outer peripheral surface of the steel pipe body; a second lining made of stainless steel provided on the outer peripheral surface of the first lining, the second lining is welded to the inlet and the first lining; Steel pipe.

2. a carbon steel pipe body into which the columnar member is inserted; an injection port provided on the peripheral wall of the steel pipe body for injecting a filler into a gap between the columnar member and the steel pipe body; a first lining made of stainless steel provided on the outer peripheral surface of the steel pipe body; a second lining made of stainless steel provided on the outer peripheral surface of the first lining, The thickness of the second lining is greater than the thickness of the first lining. Steel pipe.

3. a carbon steel pipe body into which the columnar member is inserted; an injection port provided on the peripheral wall of the steel pipe body for injecting a filler into a gap between the columnar member and the steel pipe body; a first lining made of stainless steel provided on the outer peripheral surface of the steel pipe body; a second lining made of stainless steel provided on the outer peripheral surface of the first lining, an opening is formed in a portion of the first lining corresponding to the injection port; the inlet is located within the opening; The second lining covers the outer peripheral surface of the steel pipe body exposed from the opening. Steel pipe.

4. The outer periphery of the second lining is larger than the opening. The steel pipe according to claim 3.

5. a bead-shaped weld mark is formed by welding the first lining and the steel pipe body; An air passage for a leak test is formed in a part of the welding mark. A steel pipe according to any one of claims 1 to 4.

6. A method for manufacturing a steel pipe having a steel pipe body made of carbon steel into which a columnar member is inserted, An injection port step of providing an injection port on the peripheral wall of the steel pipe body for injecting a filler into a gap between the columnar member and the steel pipe body; a first lining step of providing a first lining made of stainless steel on the outer peripheral surface of the steel pipe body, The first lining is provided within the splash zone and tidal zone, and the injection port is provided outside the splash zone and tidal zone. Steel pipe manufacturing method.

7. A method for manufacturing a steel pipe having a steel pipe body made of carbon steel into which a columnar member is inserted, An injection port step of providing an injection port on the peripheral wall of the steel pipe body for injecting a filler into a gap between the columnar member and the steel pipe body; a first lining step of providing a first lining made of stainless steel on the outer peripheral surface of the steel pipe body, the first lining and the injection port are provided within a splash zone and a tidal zone; In the first lining step, an air passage for a leak test is formed in a part of a bead-shaped weld mark formed by welding the first lining and the steel pipe body, The method further includes a leak test step of supplying air between the outer peripheral surface of the steel pipe body and the first lining to check for air leakage. Steel pipe manufacturing method.

8. A method for manufacturing a steel pipe having a steel pipe body made of carbon steel into which a columnar member is inserted, An injection port step of providing an injection port on the peripheral wall of the steel pipe body for injecting a filler into a gap between the columnar member and the steel pipe body; a first lining step of providing a first lining made of stainless steel on the outer peripheral surface of the steel pipe body, The steel pipe body is a leg of a jacket foundation, In the first lining step, an air passage for a leak test is formed in a part of a bead-shaped weld mark formed by welding the first lining and the steel pipe body, The method further includes a leak test step of supplying air between the outer peripheral surface of the steel pipe body and the first lining to check for air leakage. Steel pipe manufacturing method.

9. a second lining step for providing a second lining made of stainless steel on an outer peripheral surface of the first lining; The method for manufacturing a steel pipe according to any one of claims 6 to 8.

10. In the first lining step, an air passage for a leak test is formed in a part of a bead-shaped weld mark formed by welding the first lining and the steel pipe body, The method further includes a leak test step of supplying air between the outer peripheral surface of the steel pipe body and the first lining to check for air leakage. The method for manufacturing a steel pipe according to claim 6.

Images