Super-long thermal insulation steel jacket pipe and machining process thereof

Abstract

A super-long thermal insulation steel jacket pipe and a machining process for making such a pipe are provided. The pipe is designed to exhibit good thermal insulation performance and corrosion resistance. An annular cavity of the pipe is in a vacuum state, and the pipe is internally provided with a support frame and filled with a phase change material. When the pipe is used for underground energy exploitation, temperature in a working steel pipe in the pipe can be effectively kept unaffected when external temperature decreases. The steel jacket pipe has long service life, and can greatly reduce costs of exploitation of petroleum and/or of an underground heat source, such as by reducing a heat loss in exploitation.

Claims

1. A machining process for producing a super-long thermal insulation steel jacket pipe, comprising: (1) cleaning a surface of a steel plate used to define a working steel pipe; performing crimping and laser welding; performing heat treatment after the working steel pipe is obtained through welding; and performing sizing and non-destructive testing on the working steel pipe; (2) making a support frame defined by one of the following: a spiral annular support frame sleeved on an outer peripheral side of the working steel pipe, and C-shaped support frames that wind the outer peripheral side of the working steel pipe at intervals, wherein the spiral annular support frame is not in contact with the working steel pipe; (3) cleaning a surface of a steel plate used to define an outer steel pipe; performing crimping while wrapping the working steel pipe whose outer surface is provided with the support frame, wherein the support frame tightly supports an inner wall of the outer steel pipe; then performing laser seal welding to form a jacket pipe; performing heat treatment on the jacket pipe; and performing sizing and non-destructive testing on the fabricated outer steel pipe, wherein a thickness of an annular cavity between the outer steel pipe and the working steel pipe is 2 mm to 7 mm; (4) placing a phase-change energy storage material in the annular cavity of the jacket pipe; then placing several rubber rings at a tightened end of the outer steel pipe for sealing, and performing vacuumizing treatment on the annular cavity to make the annular cavity become a vacuum cavity; and finally performing solder sealing on the tightened end of the outer steel pipe; and (5) performing heat treatment at 50 C. to 280 C. for 30 min to 60 min on a steel jacket pipe fabricated in step (4), cooling, and coating anti-corrosion liquid outside the steel jacket pipe, that is, obtaining the insulation steel jacket pipe.

2. The machining process of claim 1, wherein a heat treatment process in step (1) and (2) comprises: heating, at 700 C. to 1070 C. for 10 min to 40 min, the outer steel pipe and the working steel pipe formed through welding, and then cooling in a reducing atmosphere, tempering at 550 C. to 720 C. to eliminate internal stress of the outer steel pipe and the working steel pipe, and thereby adjusting toughness and hardness of the outer steel pipe and the working steel pipe.

3. The machining process of claim 1, wherein during laser welding of the steel plates for forming the outer steel pipe and the working steel pipe in step (1) and (3), a surplus height of a welding seam is less than or equal to 0.25 mm.

4. The machining process of claim 1, wherein in step (5), before heat treatment of the steel jacket pipe fabricated in step (4), the steel jacket pipe is first rolled into an S shape.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Various additional features and advantages of the invention will become more apparent to those of ordinary skill in the art upon review of the following detailed description of one or more illustrative embodiments taken in conjunction with the accompanying drawings. The accompanying drawings, which are incorporated in and constitutes a part of this specification, illustrate one or more embodiments of the invention and, together with the general description given above and the detailed description given below, explain the one or more embodiments of the invention.

(2) FIG. 1 is a schematic structural diagram of a side profile of a super-long thermal insulation steel jacket pipe according to one embodiment of the invention.

(3) FIG. 2 is a schematic structural diagram of a side profile of a super-long thermal insulation steel jacket pipe according to another embodiment of the invention.

DETAILED DESCRIPTION

(4) The following clearly and completely describes the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. To make objectives, features, and advantages of the present invention clearer, the following describes embodiments of the present invention in more detail with reference to accompanying drawings and specific implementations.

(5) A super-long thermal insulation steel jacket pipe in accordance with one embodiment of the present invention is shown in FIG. 1, and includes a working steel pipe 1 and an outer steel pipe 2, where the outer steel pipe 2 is sleeved outside the working steel pipe 1, an annular cavity 3 formed by a gap is reserved between the working steel pipe 1 and the outer steel pipe 2; a support frame is disposed between the working steel pipe 1 and the outer steel pipe 2; the annular cavity 3 is a vacuum cavity, two ends of the outer steel pipe 2 are tightened, a tightened part of the outer steel pipe 2 is sealed with an outer wall of the working steel pipe 1 through several seal rings 4, and the annular cavity 3 is further filled with a phase-change material; the support frame is a spiral annular support frame 5, the spiral annular support frame 5 is sleeved on an outer peripheral side of the working steel pipe 1, and is not in contact with the working steel pipe 1.

(6) In some embodiments, a super-long thermal insulation steel jacket pipe in the present invention is shown in FIG. 2, and includes a working steel pipe 1 and an outer steel pipe 2, where the outer steel pipe 2 is sleeved outside the working steel pipe 1, an annular cavity 3 formed by a gap is reserved between the working steel pipe 1 and the outer steel pipe 2; a support frame is disposed between the working steel pipe 1 and the outer steel pipe 2; two ends of the outer steel pipe 2 are tightened, a tightened part of the outer steel pipe 2 is sealed with an outer wall of the working steel pipe 1 through several seal rings 4, and the annular cavity 3 is further filled with a phase-change material; and the support frame is a C-shaped support frame 6, and several C-shaped support frames 6 wind an outer peripheral side of the working steel pipe 1 at intervals.

(7) In some embodiments, a thickness of the annular cavity of the super-long thermal insulation steel jacket pipe in the present invention is 2 mm to 7 mm.

(8) In some embodiments, the spiral annular support frame or the C-shaped support frame of the super-long thermal insulation steel jacket pipe in the present invention is made of an elastic material, and is preferably made of rubber.

(9) In some embodiments, the phase-change material of the super-long thermal insulation steel jacket pipe in the present invention is an organic phase-change material and is preferably paraffin.

(10) The working steel pipe and the outer steel pipe of the steel jacket pipe in the present invention are made of any one or a combination of stainless steel, carbon steel, or titanium alloy.

(11) With reference to specific examples, the following describes a process for fabricating the insulation steel jacket pipe in the present invention by using different combinations of steel materials.

Embodiment 1

(12) Stainless steel is selected as a steel material of a working steel pipe, and main components of stainless steel include the following by weight percentage: C 0.019%, Si 0.49%, Mn 1.25%, P 0.022%, S 0.00005%, Ni 5.16%, Cr 22.46%, N 0.163%, Cu 0.003%, Mo 3.07%, and Fe and inevitable impurities as balance. Titanium alloy TA18 is selected as a steel material of an outer steel pipe, and main components of TA18 alloy include the following by weight percentage: Al 3.5%, V 1.5%-3.0%, Fe 0.25%, C 0.05%, N 0.05%, H 0.015%, O 0.12%, and Ti and inevitable impurities as balance. A 1000-meter insulation steel jacket pipe fabricated by using the foregoing selected steel materials (the two steel materials both have a length of 1000 meters) is shown in FIG. 1, and a specific fabrication process thereof includes the following steps.

(13) (1) Clean a surface of a steel plate used by the working steel pipe, where cleaning is specifically performed in an ultrasonic cleaning tank for multiple times by using a surfactant (preferably, sodium dodecyl benzene sulfonate is used) and clear water; air-dry the cleaned steel plate, then crimp the steel plate, and perform laser welding to form a pipe, where an inner diameter of the pipe is 31 mm, a surplus height of a welding seam needs to be strictly controlled during laser welding and cannot exceed 0.25 mm (a height is preferably 0.20 mm); and it should be noted that welding is one-time continuous welding; perform heat treatment on the welded steel pipe, where a preferable heat treatment process includes first heating at 700 C. for 20 min; then cool in a reducing atmosphere, temper at 550 C. to eliminate internal stress of the steel pipe, and adjust toughness and hardness of the steel pipe; and perform sizing and non-destructive testing on the heat-treated working steel pipe.

(14) (2) Make a spiral annular support frame sleeved on an outer peripheral side of a qualified working steel pipe, where the spiral annular support frame is not in contact with the working steel pipe, and the support frame is made of elastic rubber.

(15) (3) Clean a surface of a steel plate used by the outer steel pipe; perform crimping while wrapping the working steel pipe whose outer surface is sleeved with the support frame to make the support frame tightly support an inner wall of the outer steel pipe; then perform laser seal welding to form a jacket pipe, where a thickness of an annular cavity between the outer steel pipe and the working steel pipe is 7 mm; perform heat treatment as described in step (1) on the jacket pipe obtained through welding, to improve mechanical performance of the outer steel pipe; and perform sizing and non-destructive testing on the fabricated the outer steel pipe.

(16) (4) Place a phase-change energy storage material in the annular cavity of the jacket pipe; then place several rubber rings at a tightened end of the outer steel pipe for sealing, and perform vacuumizing treatment on the annular cavity to make the annular cavity become a vacuum cavity; and finally perform solder sealing on the end of the outer steel pipe.

(17) (5) Roll, into an S shape, the steel jacket pipe fabricated in step (4), and then perform heat treatment on the steel jacket pipe to eliminate stress that may be generated due to thermal expansion during actual underground work, where the heat treatment process includes heating the steel jacket pipe at 50 C. for 60 min; air-cool to room temperature; and coat anti-corrosion liquid, where the anti-corrosion liquid is composed of the following components by weight parts: silicone oil 55, zinc powder 25, citric acid 2, epoxy resin 6, aluminum oxide 3, diatomite 3, and polyacrylamide 8. The foregoing components of the anti-corrosion liquid are mixed evenly according to the proportion and then coated on an outer wall of the outer steel pipe, and an anti-corrosion layer with a thickness of 0.1 mm can be formed through layer-by-layer coating. In this case, the 1000-meter insulation steel jacket pipe in the present invention is fabricated.

Embodiment 2

(18) Titanium alloy TA18 is selected as a material for fabricating a working steel pipe, and main components of TA18 alloy include the following by weight percentage: Al 2.0%, V 1.5%, Fe 0.25%, C 0.05%, N 0.05%, H 0.015%, O 0.12%, and Ti and inevitable impurities as balance. Carbon steel is selected as a material for fabricating an outer steel pipe, and main components of carbon steel include the following by weight percentage: C 0.11%, Si 0.22%, Mn 1.44%, P 0.008%, S 0.001%, Cr 0.58%, Ni 0.14%, Cu 0.24%, Mo 0.15%, and Fe and inevitable impurities as balance. A 3000-meter insulation steel jacket pipe fabricated by using the foregoing selected steel materials (the two steel materials both have a length of 3000 meters) is shown in FIG. 2, and a specific fabrication process of the pipe includes the following steps.

(19) (1) Clean a surface of a steel plate used by the working steel pipe, where cleaning is specifically performed in an ultrasonic cleaning tank for multiple times by using a surfactant (preferably, sodium dodecyl benzene sulfonate is used) and clear water; air-dry the cleaned steel plate, then crimp the steel plate, and perform laser welding to form a pipe, where an inner diameter of the pipe is 44.5 mm, a surplus height of a welding seam needs to be strictly controlled during laser welding and cannot exceed 0.25 mm (a height is preferably 0.20 mm); and it should be noted that welding is one-time continuous welding; perform heat treatment on the welded steel pipe, where a preferable heat treatment process includes first heating at 800 C. for 25 min; then cool in a reducing atmosphere, temper at 600 C. to eliminate internal stress of the steel pipe, and adjust toughness and hardness of the steel pipe; and perform sizing and non-destructive testing on the heat-treated working steel pipe.

(20) (2) Make several C-shaped support frames wind an outer surface of a qualified working steel pipe at intervals, where the C-shaped support frame is made of elastic rubber.

(21) (3) Clean a surface of a steel plate used by the outer steel pipe; perform crimping while wrapping the working steel pipe whose outer surface is winded with the support frame; then perform laser seal welding to form a jacket pipe, where a thickness of an annular cavity between the outer steel pipe and the working steel pipe is 5 mm; perform heat treatment as described in step (1) on the jacket pipe obtained through welding, to improve mechanical performance of the outer steel pipe; and perform sizing and non-destructive testing on the fabricated the outer steel pipe.

(22) (4) Place a phase-change energy storage material in the annular cavity of the jacket pipe; then place several rubber rings at a tightened end of the outer steel pipe for sealing, and perform vacuumizing treatment on the annular cavity to make the annular cavity become a vacuum cavity; and finally perform solder sealing on the end of the outer steel pipe.

(23) (5) Roll, into an S shape, the steel jacket pipe fabricated in step (4), and then perform heat treatment on the steel jacket pipe to eliminate stress that may be generated due to thermal expansion during actual underground work, where the heat treatment process includes heating the steel jacket pipe at 150 C. for 30 min; air-cool to room temperature; and coat the anti-corrosion liquid in Embodiment 1. In this case, the 3000-meter insulation steel jacket pipe in the present invention is fabricated.

Embodiment 3

(24) Carbon steel is selected as a material for fabricating a working steel pipe, and main components of carbon steel include the following by weight percentage: C 0.11%, Si 0.24%, Mn 1.5%, P 0.012%, S 0.001%, Cr 0.58%, Ni 0.14%, Cu 0.24%, Mo 0.16%, and Fe and inevitable impurities as balance. Stainless steel is selected as a material for fabricating an outer steel pipe, and main components of stainless steel include the following by weight percentage: C 0.020%, Si 0.50%, Mn 1.26%, P 0.022%, S 0.00005%, Ni 5.17%, Cr 22.52%, N 0.163%, Cu 0.006%, Mo 3.07%-3.09%, and Fe and inevitable impurities as balance. A 5000-meter insulation steel jacket pipe is fabricated by using the foregoing selected steel materials (the two steel materials both have a length of 5000 meters), and a fabrication process of the pipe includes the following steps.

(25) (1) Clean a surface of a steel plate used by the working steel pipe, where cleaning is specifically performed in an ultrasonic cleaning tank for multiple times by using a surfactant (preferably, sodium dodecyl benzene sulfonate is used) and clear water; air-dry the cleaned steel plate, then crimp the steel plate, and perform laser welding to form a pipe, where an inner diameter of the pipe is 31.8 mm, a surplus height of a welding seam needs to be strictly controlled during laser welding and cannot exceed 0.25 mm (a height is preferably 0.20 mm); and it should be noted that welding is one-time continuous welding; perform heat treatment on the welded steel pipe, where a preferable heat treatment process includes first heating at 900 C. for 30 min; then cool in a reducing atmosphere (preferably, hydrogen gas is used), temper at 650 C. to eliminate internal stress of the steel pipe, and adjust toughness and hardness of the steel pipe; and perform sizing and non-destructive testing on the heat-treated working steel pipe.

(26) (2) Make a spiral annular support frame sleeved on an outer peripheral side of a qualified working steel pipe, where the spiral annular support frame is not in contact with the working steel pipe, and the support frame is made of elastic rubber.

(27) (3) Clean a surface of a steel plate used by the outer steel pipe; perform crimping while wrapping the working steel pipe whose outer surface is sleeved with the support frame, where the support frame tightly supports an inner wall of the outer steel pipe; then perform laser seal welding to form a jacket pipe, where a thickness of an annular cavity between the outer steel pipe and the working steel pipe is 2 mm; perform heat treatment as described in step (1) on the jacket pipe obtained through welding, to improve mechanical performance of the outer steel pipe; and perform sizing and non-destructive testing on the fabricated the outer steel pipe.

(28) (4) Place a phase-change energy storage material in the annular cavity of the jacket pipe; then place several rubber rings at a tightened end of the outer steel pipe for sealing, and perform vacuumizing treatment on the annular cavity to make the annular cavity become a vacuum cavity; and finally perform solder sealing on the end of the outer steel pipe.

(29) (5) Roll, into an S shape, the steel jacket pipe fabricated in step (4), and then perform heat treatment on the steel jacket pipe to eliminate stress that may be generated due to thermal expansion during actual underground work, where the heat treatment process includes heating the steel jacket pipe at 200 C. for 30 min; air-cool to room temperature; and coat the anti-corrosion liquid in Embodiment 1. In this case, the 5000-meter insulation steel jacket pipe in the present invention is fabricated.

Embodiment 4

(30) Titanium alloy TA18 is selected as a material for fabricating a working steel pipe and an outer steel pipe, and main components of TA18 alloy include the following by weight percentage: Al 3.5%, V 3.0%, Fe 0.25%, C 0.05%, N 0.05%, H 0.015%, O 0.12%, and Ti and inevitable impurities as balance. An 8000-meter insulation steel jacket pipe is fabricated by using the foregoing selected steel materials (the two steel materials both have a length of 5000 meters). The pipe is fabricated according to the process in Embodiment 1, and only the heat treatment process of the steel jacket pipe in step (5) is changed, and the heat treatment process in step (5) specifically includes: heating the steel jacket pipe at 280 C. for 60 min, air-cooling to room temperature, and coating the anti-corrosion liquid in Embodiment 1. In this case, the 8000-meter insulation steel jacket pipe in the present invention is fabricated.

(31) The insulation steel jacket pipes each fabricated in Embodiment 1 to Embodiment 4 of the present invention are used to perform a test operation to simulate heat source exploitation in an underground working environment. Temperature of extracted water is set to 250 C., 200 C., 150 C., and 100 C., respectively. The 1000-meter steel jacket pipe fabricated in Embodiment 1 is used to extract a 100 C. water source, an environment outside the pipe is simulated to be an environment at temperature of 1000 meters underground to the land surface (it is specified that the pipe is placed into the 1000 meters underground to extract the 100 C. water source), step heating is performed on the pipe until temperature of a top end of the pipe is room temperature. Similarly, the 3000-meter steel jacket pipe fabricated in Embodiment 2 is used to extract a 150 C. water source; the 5000-meter steel jacket pipe fabricated in Embodiment 3 is used to extract a 200 C. water source; and the 8000-meter steel jacket pipe fabricated in Embodiment 4 is used to extract a 250 C. water source. It can be found by detecting temperature of a water source extracted from a pipe outlet, that temperature of the water source extracted by the 1000-meter steel jacket pipe fabricated in Embodiment 1 is 98 C., temperature of the water source extracted by the 3000-meter steel jacket pipe fabricated in Embodiment 2 is 142 C., temperature of the water source extracted by the 5000-meter steel jacket pipe fabricated in Embodiment 3 is 190 C., temperature of the water source extracted by the 8000-meter steel jacket pipe fabricated in Embodiment 4 is 242 C. It can be learned from the foregoing that the super-long thermal insulation steel jacket pipes have very good thermal insulation performance, and it can be found through detection of a tested steel jacket pipe that no obvious mechanical deformation occurs on a working steel pipe or an outer steel pipe in the pipe.

(32) The embodiments described above are only descriptions of preferred embodiments of the present invention, and do not intended to limit the scope of the present invention. Various variations and modifications can be made to the technical solution of the present invention by those of ordinary skills in the art, without departing from the design and spirit of the present invention. The variations and modifications should all fall within the claimed scope defined by the claims of the present invention.