JPS62148022A - Production of steel pipe for outer pipe of heat insulating clad pipe - Google Patents

Abstract

PURPOSE:To simply and easily manufacture the steel pipe for the outer pipe of a heat insulating clad pipe by forming plural dimple parts on the outer peripheral face on the same periphery of the steel pipe by pressing a punch from the outer peripheral face and by performing that in the length direction of the steel pipe at intervals. CONSTITUTION:Plural dimple parts 6 which sink from the outer peripheral side by pressing a punch and project to the inner peripheral face side are formed on the same periphery at the position >= two places on the outer peripheral face on the same periphery of the steel pipe 5 for outer pipe. Said steel pipe 5 is then fed each in the prescribed length along the axial line direction. Numerous dimple parts 6 are formed at intervals in the peripheral direction and at the prescribed intervals in the length direction of the steel pipe 5 by repeating said process alternately. The heat insulating clad pipe 9 is obtd. by assembling the outer pipe 5 and inner pipe 7 thus obtd. and by forming the gap 8 for heat insulating layer including some gap G between both pipes.

Description

[Detailed Description of the Invention] Industrial Field of Application This invention manufactures a steel pipe for the outer pipe of an insulated double pipe used when injecting high temperature steam etc. underground for the tertiary recovery of crude oil in an oil well. It is about the method.

Conventional technology In general, in the recovery of petroleum resources, in the initial stage after oil well drilling, crude oil can be recovered by natural pressure within the crude oil-containing layer or by pumping it from the ground surface (-number of times); When the natural pressure of crude oil decreases, water or gas is injected to increase the pressure and the pressure is used for recovery (secondary recovery). When this becomes difficult, high-temperature steam is injected underground to raise the temperature, or chemicals are injected to increase the fluidity of the crude oil and pumped to the surface (tertiary recovery). There is.

When injecting high-temperature steam underground in the above-mentioned tertiary recovery, it is necessary to ensure that the temperature does not drop due to heat loss from the pipe walls while the high-temperature steam reaches the underground crude oil-containing layer. It is desirable to use insulated double pipes for injection of high temperature steam.

Insulated double pipes consist of an outer pipe and an inner pipe arranged concentrically with a gap between them, and a heat insulating layer such as vacuum insulation between the outer pipe and the inner pipe. The insulated double pipe shown in FIG. 7 is known as a heat-insulating double pipe used for the tertiary recovery of crude oil as described above. This insulated double pipe has a large number of ring-shaped centerizers 2 fitted on the outer circumferential surface of an inner pipe 1 made of a straight steel pipe at predetermined intervals in the length direction, and each centerizer 2 is attached to the inner pipe 1. The inner tube 1 is fixed by welding or the like, and an outer tube 3 made of a straight steel tube is disposed so as to concentrically surround the inner tube 1.

In such a heat-insulated double pipe, the centerizer 2 secures a gap 4 between the inner pipe 1 and the outer pipe 3, which should serve as a heat-insulating layer,
It also serves as a fulcrum against bending of the inner tube 1 due to thermal stress during high-temperature steam flow, and serves to prevent buckling of the inner tube 1.

Problems to be Solved by the Invention When assembling the conventional insulated double pipe as described above, it is necessary to fit the ring-shaped centerizer 2 into the inner pipe 1 and to fix it to the inner pipe 1 by welding or the like. Because it requires a large number of assembly man-hours, the assembly work cost is inevitably high.Also, since a large number of centerizers 2 are required, the number of parts is large, and there are various problems in their management. The reality was that the cost had to be high.

This invention was made against the background of the above circumstances, and it eliminates the need to separately prepare a centerizer for conventional insulated double pipes, thereby reducing the number of parts and assembly man-hours. The object of the present invention is to provide a method for manufacturing an outer tube extremely simply and easily.

Means for Solving the Problems This invention provides a steel pipe for an outer pipe used for an insulated double pipe in which an outer pipe and an inner pipe are arranged concentrically and a heat insulating layer is provided between the outer pipe and the inner pipe. During manufacturing, a punch is pressed at two or more positions on the outer peripheral surface of the steel pipe to form a plurality of dimples that are recessed from the outer peripheral surface and protrude toward the inner peripheral surface on the same circumference. The forming process and the process of feeding the steel pipe a predetermined length along the axial direction are alternately repeated, thereby forming a large number of dimples at predetermined intervals in the length direction of the steel pipe and at intervals in the circumferential direction. It is characterized by forming.

Function: In the method for manufacturing a steel pipe for the outer pipe of an insulated double pipe according to the present invention, a large number of dimples that are recessed from the outer surface side and protrude toward the inner surface side are formed at intervals in the length direction on the steel pipe as a raw material. They are also formed at intervals in the circumferential direction. For this purpose, there is a process of forming two or more dimples on the same circumference by pressing, for example, a punch with a spherical tip at two or more positions on the outer peripheral surface of the steel pipe on the same circumference, and a process of forming two or more dimples on the same circumference. ~The process of feeding by a predetermined length along the line direction is repeated alternately.

When a steel pipe in which a large number of dimples are formed in this manner is used as an outer pipe of a heat-insulating double pipe, the dimples serve as a centerizer in the prior art. In other words, since the dimple portion protrudes toward the inner surface of the outer tube, that portion maintains the gap between the inner tube and the outer tube, which should serve as a heat insulating layer, and serves as a fulcrum against bending of the inner tube due to thermal stress. Prevents buckling of the inner tube. Therefore, an insulated double pipe can be constructed simply by combining the outer pipe with the dimpled portion formed with the straight inner pipe without using a separate centerizer.

To form the dimples, all you need to do is alternately repeat the process of pressing the outer peripheral surface of the steel pipe on the same circumference with two or more punches as described above, and the process of feeding the steel pipe a predetermined length at a time. A steel pipe for an outer pipe having a large number of dimples can be easily obtained using simple equipment.

Embodiment FIGS. 1 and 2 show an example of a steel pipe 5 for an outer pipe to be manufactured by the method of the present invention, and FIGS. 3 and 4 show an insulated double pipe 9 using the steel pipe 5 for an outer pipe. show.

The steel pipe 5 for the outer pipe is made of a seamless steel pipe, etc.
In the case of the above-mentioned insulated double pipe for high-temperature steam injection in oil wells, its length is, for example, about 9.5 m or 12 m, and its outer diameter is from 88.9R+1 to 139.7.
The degree and wall thickness are approximately 5°OR'11 to 10.0. The dimple portion 6 is formed into, for example, a spherical curved surface so as to be recessed from the outer surface side of the outer steel tube 5 and protrude toward the inner surface side. They are formed at intervals S of about 1 to 3 meters in the width direction and at intervals of 90' in the circumferential direction. The protruding height H of the dimple portion 6 toward the inner surface of the steel pipe (therefore, it is substantially the same as the depth of the recess from the outer circumferential surface) is not particularly limited, but when the axes of the steel pipe 5 for the outer pipe and the inner pipe 7 are aligned. The height is set so that a slight gap G of about 1.0 to 3.0 m is created between the inner protruding end of the dimple portion 6 and the outer surface of the inner tube 7.

The steel pipe 5 for the outer pipe as described above is inserted into the inner pipe 7 made of a straight steel pipe, as shown in FIGS. The heat insulating double pipe 9 can be formed by appropriately combining them. Although the outer diameter of the inner tube 7 varies depending on the usage conditions, it is usually about 48.3 to 88.9 mm, and the wall thickness is 3.5 to 10.0 mm.
The width W of the gap 8 is approximately 5 to 15 m. If the steel pipe 5 for the outer pipe with the dimpled portion 6 formed in this way is used, the dimpled portion 6 will play the role of a centerizer, as described above, and will ensure the gap 8 that should serve as a heat insulating layer, as well as prevent the inner pipe from forming due to thermal stress. Buckling can be prevented.

FIGS. 5 and 6 show an example of equipment for manufacturing an outer steel pipe 5 having the dimple portion 6 as described above, that is, an example of equipment for carrying out the method of the present invention.

In FIG. 5, the steel pipe 5 is intermittently fed to a predetermined distance from the right to the left in the figure by feed rollers 10A, 10B, and IOC. A vertical press 11 is installed on this feed line, and on the front and rear sides of the vertical press 11, turning devices 12A and 12B are installed to turn the steel pipe 5 by 90'' around its axis. Further, an induction heating device 13 is provided at a position before the vertical press 11 in the steel pipe feeding direction, as required.

The vertical press 11 has m
Punches 14A and 14B with spherical tip surfaces are disposed above and below the pipe 5, and the upper and lower parts of the steel pipe 5 are pressed by the punches 14A and 14B when the hydraulic device 15 is operated. It is configured as follows. In addition, in FIG. 6, 16A and 16B are kites for regulating the outer peripheral surface of the steel pipe 5.

In the equipment shown in FIGS. 5 and 6, the hydraulic system 15 of the vertical press machine 11 is in a state where the steel pipe 5 is fed into at least the vertical press @ 11 and the movement of the steel pipe 5 is stopped.
When activated, the upper and lower parts of the steel pipe 5 are pressed by the punches 14A and 14B, and the steel pipe 5 is caved inward at the upper and lower parts of the steel pipe, forming a pair of upper and lower dimples 6. Next, after releasing the press 11, the turning devices 12A and 12B are activated. In this way, a pair of dimple portions 6 are formed at positions roughly shifted by 90” from the pair of dimple portions that have already been formed, and as a result, as shown in FIG. This means that four dimple portions 6 are formed at intervals. Next, the press machine 11 was released, and the feed rollers 'IOA, 10B
, 10C is activated to feed the steel pipe 5 a predetermined distance, and the same process as described above is repeated. In this way, four dimple portions 6 are successively formed at predetermined intervals on the same circumference at intervals of 90 inches.

In the above description, the dimple portion 6 may be processed cold by the press 11, but the induction heating device 13 may be operated to heat the portion where the dimple portion 6 is to be formed in advance before processing. It's okay. In this case, since the working pressure can be reduced, the hydraulic system 15 of the press 11 can be downsized, and it is possible to prevent the characteristics of the dimple portion 5 from deteriorating due to working distortion. In this case, the distance between the centers of the induction heating device 13 and the vertical press machine 11! should be determined so as to match the intermittent feeding distance of the steel pipe 5, that is, the dimple formation interval in the length direction of the steel pipe 5. In this way, the heated portions will be dimpled in sequence. Become. Further, the preheating temperature for dimple processing mentioned above is not particularly limited, but in the case of quenched and tempered steel pipes, the tempering temperature (usually 600 to 7
00°C) or lower, or approximately 500°C or higher. Further, in the case of an as-rolled (As Roll) steel pipe that has not been subjected to heat treatment, it may be heated at a temperature lower than the A1 transformation point and about 500° C. or higher.

Further, contrary to the above-mentioned case, after forming the dimple portion 6 in a cold manner, the portion where the dimple portion 6 is formed may be subjected to stress relief annealing by induction heating or the like to remove processing strain. The temperature in this case can also be set to the same level as in the case of preheating described above.

Note that in the above example, the tip surfaces of the punches 14A and 14B are spherical to form the spherical dimple portion 6;
Of course, the dimple portion is not limited to such a spherical shape, and may have a U-shaped cross section. In addition, in the illustrated example, after forming a pair of upper and lower dimples, the steel pipe is rotated 90' at the same position without feeding, and a pair of dimples are formed again, thereby forming a total of four dimples on the same circumference. The dimples are formed at 90° intervals, but in some cases, four punches are used to simultaneously form four dimples at 90° intervals on the same circumference without turning the dimples 90° as described above.
The dimples may be formed at intervals of 120 degrees, or three dimples may be formed at intervals of 120 degrees on the same circumference using three punches. In some cases, after forming a pair of upper and lower dimples using the apparatus shown in FIGS. 5 and 6,
Send the steel pipe a short distance and then turn it 90 degrees (or
After rotating the steel pipe by 0° and feeding the steel pipe a short distance), the press machine 11 may be operated again to form a pair of dimple portions. In this case, a pair of dimple portions at symmetrical positions and a pair of dimple portions at positions shifted by 90° with respect to the dimple portions are formed so as to slide in the length direction of the steel pipe.

Effects of the Invention As is clear from the above explanation, the method for manufacturing the steel pipe for the outer pipe of the insulated double pipe of the present invention maintains the gap between the inner pipe and the outer pipe, which should serve as a heat insulating layer, and A steel pipe for an outer pipe that has a large number of dimples that serve as a fulcrum to prevent buckling of the inner pipe by acting as a fulcrum against bending due to thermal stress of the pipe can be easily manufactured at low cost with simple installation. . Furthermore, if the steel pipe for the outer pipe obtained by the method of the present invention is used, the centerizer that was conventionally used when assembling the insulated double pipe becomes unnecessary, so the number of man-hours for assembling the insulated double pipe is significantly reduced compared to the conventional method, and the amount of time required for assembling the insulated double pipe is reduced. The number of parts required is also reduced. Therefore, by applying the method of the present invention, the total cost of the insulated double pipe can be significantly reduced compared to the conventional method.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional side view showing an example of a steel pipe for an outer pipe to be manufactured by the method of the present invention, Fig. 2 is a sectional view taken along the line ■-■ in Fig. 1, and Fig. 3 is a cross-sectional view of Fig. 1 and Fig. 2. FIG. 4 is a cross-sectional view taken along line IV--IV in FIG. 3, and FIG. 5 is a diagram of equipment for carrying out the method of the present invention. A schematic diagram showing an example, FIG. 6 shows an example of a vertical press machine used in the method of the present invention.
FIG. 7 is a cutaway side view taken along line Vl-Vl in the figure, and a longitudinal sectional side view showing an example of a conventional heat-insulating double pipe. 5... Steel pipe for outer pipe, 6... Dimple portion, 7.
... Inner pipe, 8 ... Gap for heat insulation layer, 11 ... Vertical press machine, 12A, 12B ... Turning device, 13
...Induction heating device, 14A, 14B...Punch.

Claims (1)

[Claims] When manufacturing steel pipes for outer pipes used for insulated double pipes in which an outer pipe and an inner pipe are arranged concentrically and a heat insulating layer is formed between the outer pipe and the inner pipe, the outer periphery of the steel pipe on the same circumference is The process involves pressing a punch at two or more positions on the surface to form a plurality of dimples on the same circumference that are concave from the outer circumferential side and protruding toward the inner circumferential side, and the process of forming the steel pipe along the axial direction. The process of alternately repeating the process of feeding the steel pipe by a predetermined length, thereby forming a large number of dimples at predetermined intervals in the length direction of the steel pipe and at intervals in the circumferential direction. Method for manufacturing steel pipes for outer pipes.