A kind of anti-corrosion and heat-insulating ground pipeline welding structure and welding method

Abstract

The present invention relates to an anti-corrosion and heat-insulating ground pipeline welding structure and a welding method, comprising a straight section of the end face of an inner liner pipe and a second steel pipe, an end anti-corrosion layer is arranged on the right side of the straight section of the end face of the inner liner pipe, and a trapezoidal groove is arranged on the right side of the end anti-corrosion layer, a connecting sleeve is arranged on the outside of the trapezoidal groove, and a first steel pipe is arranged on the upper end of the connecting sleeve, a vacuum layer is arranged on the right side of the connecting sleeve, and the second steel pipe is located at the lower end of the supporting sleeve. The beneficial effects of the present invention are as follows: the anti-corrosion and heat-insulating ground pipeline welding structure and welding method are formed into one piece by welding the straight section of the end of the inner liner of the double-layer pipe with plastic hot-melt butt welding, and the welding sleeve welds the two ends of the outer wall of the first steel pipe with electric welding to form an integrated body, thereby forming an anti-corrosion and heat-insulating ground pipeline welding structure, the inner liner pipe weld has no gaps and no leakage points, the outer welding sleeve weld is arranged on the vacuum layer of the two pipe ends, and the vacuum layer blocks the damage of the inner liner pipe by the high temperature of electric welding during welding, and the inner anti-corrosion layer is as good as new after the inner hole of the weld is welded, and there is no need for the inner anti-corrosion layer to be patched, thereby achieving an all-round anti-corrosion effect, and the vacuum layer has a heat-insulating effect, which is 22℃-25℃ higher than the static temperature of the steel pipe with the same diameter.

Description

Technical Field

[0001] The invention relates to the technical field of anti-corrosion and thermal insulation ground pipelines, and in particular to an anti-corrosion and thermal insulation ground pipeline welding structure and a welding method. Background Art

[0002] At present, crude oil transportation from oil wells to metering rooms, metering rooms to joint stations, and joint stations to refineries and docks in my country is basically carried out by pipeline transportation. Oil pipelines have the characteristics of large transportation volume, good sealing, low cost and high safety factor. There are three main ways to connect pipelines: threaded, welded and flanged. Most pipelines are connected by welding. The welding method has the advantages of convenient construction, firmness, strictness and saving steel. There are hundreds of thousands of oil wells and hundreds of thousands of kilometers of oil pipelines (pipelines, pipelines) in my country. However, corrosion wax perforation is a key factor affecting the reliability and service life of pipeline systems. my country's underground oil and gas pipelines will be corroded and perforated 1-2 years after they are put into production. According to statistics, Daqing Oilfield has built more than 100,000 kilometers of various pipelines. Daqing Oilfield Production Plant No. 6 had more than 7,000 perforations in 2018, and corrosion perforations at welds accounted for more than 70%. In 2019, the annual failure rate of Daqing Oilfield pipelines was 0.461 times / km year. It has caused huge economic losses and environmental pollution to the oilfield.

[0003] At present, high-viscosity and easy-to-condense crude oil accounts for more than 80% of the crude oil produced in my country. In particular, high-condensation point, high-wax content, high-viscosity, and three-high oil products have poor fluidity at room temperature (for example, the suspected point of Daqing Oilfield crude oil is as high as 32°C). Traditionally, the heating transportation process is mainly used, and a heating station is set up every few dozen kilometers along the pipeline. The disadvantages are high energy consumption for oil transportation, small allowable range of variation in transportation volume, and long pipeline shutdown time may cause condensation due to excessive temperature drop of crude oil, leading to serious pipeline blockage accidents. my country's long-distance oil pipelines consume hundreds of thousands of tons of fuel oil for heating every year. Therefore, the energy-saving and safe transportation of high-viscosity and easy-to-condense crude oil is one of the main technical difficulties in my country's oil storage and transportation field.

[0004] The existing welded pipeline is two-pipe butt welding. The high temperature at the weld joint destroys the anti-corrosion layer on the inner wall of the weld joint. So far, there is no good new technology for repairing the anti-corrosion layer on the inner hole of the weld joint. At present, the anti-corrosion layer in my country's oil pipelines mostly adopts epoxy powder coating anti-corrosion technology. Its disadvantage is that it uses air as a carrier, and solidifies quickly. After the film is formed, a trace amount of air or volatiles are sealed in the coating, or break through the coating to form pores. Too many pores will absorb moisture and diffuse along the interface, dissipating the bonding force between the coating and the steel substrate, and severely causing delamination. The wall thickness of the solid epoxy powder anti-corrosion coating is only a dozen microns, the surface is rough, and the friction coefficient is large. It disappears in a short time during the high-pressure liquid flow rate flushing process, and cannot achieve long-term anti-corrosion use.

[0005] Therefore, it is necessary to design an anti-corrosion and thermal insulation ground pipeline welding structure and welding method to address the above problems. Summary of the invention

[0006] The purpose of the present invention is to provide an anti-corrosion and heat-insulating ground pipeline welding structure and welding method, so as to solve the above-mentioned background technology that the welding pipeline is two-pipe butt welding, the high temperature at the weld joint destroys the anti-corrosion layer of the inner wall of the weld joint, and there is no good new technology for repairing the anti-corrosion layer of the inner hole of the weld joint. At present, the anti-corrosion layer in the oil pipeline in my country mostly adopts epoxy powder coating anti-corrosion technology, which has the disadvantage of using air as a carrier, curing quickly, and after film formation, a trace amount of air or volatiles are enclosed in the coating, or break through the coating to form pores. Too many pores will absorb moisture and diffuse along the interface, dissipating the bonding force between the coating and the steel substrate, and severely causing delamination and peeling. The wall thickness of the solid epoxy powder anti-corrosion coating is only a dozen microns, the surface is rough, and the friction coefficient is large. It disappears in a short time during the high-pressure liquid flow rate flushing process, and cannot achieve long-term anti-corrosion use.

[0007] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a corrosion-resistant and thermal-insulating ground pipeline welding structure and welding method, comprising a straight section of the end face of an inner liner pipe and a second steel pipe, an end anti-corrosion layer is arranged on the right side of the straight section of the end face of the inner liner pipe, and a trapezoidal groove is arranged on the right side of the end anti-corrosion layer, a connecting sleeve is arranged on the outside of the trapezoidal groove, and a first steel pipe is arranged on the upper end of the connecting sleeve, a vacuum layer is arranged on the right side of the connecting sleeve, and a supporting sleeve is arranged on the right side of the vacuum layer, the second steel pipe is located at the lower end of the supporting sleeve connecting sleeve, and an inner village pipe is arranged at the lower end of the second steel pipe, the outside of the first steel pipe is arranged with an outer anti-corrosion layer and a welding sleeve in sequence from left to right, a plastic weld is arranged on the inner lower end of the welding sleeve, and welding joints are arranged on the left and right ends of the welding sleeve.

[0008] Preferably, the anti-corrosion and heat-insulating ground pipeline welding method comprises the following steps: A. steel pipe selection; B. manufacturing double-layer vacuum steel pipe; C. manufacturing inner-lined plastic pipe; D. hot-melt coating of the outer wall of the double-layer vacuum steel pipe with an anti-corrosion and heat-insulating layer; E. forming of the double-layer vacuum heat-insulating steel-plastic composite oil pipe; F. installation of welding sleeve; G. welding; H. manufacturing of the anti-corrosion and heat-insulating ground pipeline welding structure; I. connection completed;

[0009] A. Selection of steel pipes: select a first steel pipe and a second steel pipe, the two pipes have the same length, the wall thickness of the first steel pipe is greater than that of the second steel pipe, the wall thickness is based on the outer diameter of the first steel pipe, the larger the pipe diameter, the thicker the wall, and the smaller the pipe diameter, the thinner the wall. The outer diameter of the second steel pipe is 6-20mm smaller than the inner diameter of the first steel pipe, which is a vacuum layer. The size of the vacuum layer is based on the inner diameter of the first steel pipe. The larger the diameter, the larger the vacuum layer, and the smaller the diameter, the smaller the vacuum layer. The first steel pipe is implemented according to the oil pipe implementation standard, and the second steel pipe is implemented according to the ground pipeline standard.

[0010] Preferably, B. manufactures a double-layer vacuum steel pipe: install the connecting sleeve and the intermediate supporting sleeve equidistantly on the outer wall of the second steel pipe, weld the connecting sleeves and the intermediate supporting sleeve at both ends to the outer wall of the second steel pipe by resistance welding, insert the second steel pipe into the inner hole of the first steel pipe, align the two ends and have the same length, and weld the first steel pipe and the second steel pipe into one by vacuum sealing welding.

[0011] Preferably, C. manufactures the inner lining plastic pipe: the selected PP-PE plastic raw material is modified and granulated by a parallel twin-screw granulator, and the material has memory characteristics and elastic-plasticity after modification; the inner village pipe is processed by a plastic extruder vacuum shaping process, the outer diameter of the inner village pipe is 1-3mm larger than the inner diameter of the second steel pipe, the inner wall of the double-layer vacuum steel pipe is sandblasted, rust-removed, and shot-blasted to meet the Sa2.5 standard, the prefabricated inner village pipe is inserted into the inner hole of the second steel pipe while being reduced by a reducing machine, the two ends of the inner village pipe are 200-250mm longer than the second steel pipe, and the length is adjustable. After being inserted into the inner village pipe, it is placed at room temperature for 72-120 hours, and the outer wall of the inner village pipe naturally rebounds and tightly presses against the inner wall of the second steel pipe to form an inner anti-corrosion layer.

[0012] Preferably, D. hot-melt coating of the anti-corrosion and thermal insulation layer on the outer wall of the double-layer vacuum steel pipe: the outer wall of the double-layer vacuum steel pipe is sandblasted and derusted to meet the Sa2.5 standard, and the double-layer vacuum steel pipe is transmitted and walked by a conveying roller for medium-frequency heating, and the steel pipe heated by the medium-frequency enters the inner hole of the right-angle head of the extruder at a uniform speed, and the outer wall is coated with an outer anti-corrosion layer, and the steel pipe coated with the outer anti-corrosion layer is moved out of the head 100-200mm, and the removed part is cooled during movement and cooled to room temperature. At this point, a double-layer vacuum steel-plastic composite oil pipe with an inner lining of plastic pipe and an outer wall hot-melt coated with an outer anti-corrosion layer is completed.

[0013] Preferably, the E. double-layer vacuum insulated steel-plastic composite oil pipe is formed: the two ends of the inner village pipe are cut to expose 25-30mm of the second steel pipe end, which can be adjusted with reference to the wall thickness of the double-layer steel pipe, and the inner village pipe exposed at both ends of the second steel pipe is heated to the melting temperature, and is molded into the trapezoidal groove at the end of the double-layer steel pipe and the outer wall of the first steel pipe by a molding machine, and the diameter is the same as the outer wall of the first steel pipe to form a right angle. At this time, a double-layer vacuum insulated steel-plastic composite oil pipe is processed and manufactured, and each double-layer vacuum insulated steel-plastic composite oil pipe is processed and manufactured by the above steps.

[0014] Preferably, the F. installation of the welding sleeve: process the welding sleeve, the length of the welding sleeve is 2 to 2.5 times the outer diameter of the first steel pipe, the inner diameter is 0.5-1mm larger than the outer diameter of the first steel pipe, so that it can be inserted into the outer wall of the first steel pipe, the wall thickness of the welding sleeve is 1.5 to 2 times the wall thickness of the first steel pipe, take a double-layer vacuum steel-plastic oil pipe, grind the outer anti-corrosion layer at both ends with an electric wire brush to the base material of the first steel pipe, the length is 1.5 times the length of the welding sleeve, insert the welding sleeve into one end, and the length of the welding sleeve is based on the weld on the vacuum layer at the end of the pipe.

[0015] Preferably, G. welding: take a double-layer steel pipe with the outer anti-corrosion layer of the end outer wall ground off, align the end of the steel pipe with the end inserted into the welding sleeve to expose the straight outer anti-corrosion layer of the end, use a plastic pipe hot-melt butt welding machine to weld the straight sections of the outer anti-corrosion layers of the two pipe ends into one, and process the outer wall of the plastic weld so that the welding sleeve can slide.

[0016] Preferably, the H. Anti-corrosion and thermal insulation ground pipeline welding structure is produced: the welding sleeve is moved to the middle position of the two pipes, and the weld is set on the vacuum layer at both ends. The two end surfaces of the welding sleeve are welded to the outer wall of the first steel pipe by electric welding. The welding standard is in accordance with the ground pipeline welding standard and is implemented in accordance with the specification. At this point, an anti-corrosion and thermal insulation ground pipeline welding structure is completed. Repeat this step until the pipeline requires the required length.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. An inner tube is provided in the inner hole of the second steel pipe. The inner sides of the flanged ends of the inner tube are hot-melt molded into the trapezoidal grooves at both ends, which solves the problem of the inner tube moving and falling off easily.

[0019] 2. The straight section at the end of the inner village pipe of the double-layer pipe is welded into one piece by plastic hot-melt butt welding. The welding sleeve welds the two ends of the outer wall of the first steel pipe into one piece by electric welding, forming an anti-corrosion and heat-insulating ground pipeline welding structure, which can make the weld of the inner village pipe seamless and leak-free. The outer weld is set on the vacuum layer of the second pipe end. During welding, the vacuum layer blocks the damage to the inner village pipe caused by the high temperature of electric welding.

[0020] 3. The ground pipeline is connected to an unlimited length with no exposed steel points on the inner and outer walls, and the inner hole of the weld does not require internal anti-corrosion patching after welding, achieving an all-round anti-corrosion effect. The second steel pipe and the inner village pipe are hot-melt welded to form an integral whole, with no gaps or leaks at the weld, achieving a complete and long-term anti-corrosion effect for the entire pipeline.

[0021] 4. The weld is located on the vacuum layer, which blocks the damage to the inner village pipe inside the second steel pipe caused by the heat conduction of electric welding. The inner village pipe does not need to be repaired.

[0022] 5. The inner anti-corrosion layer is made of an integral plastic pipe made of PP-PE modified material and lined in the inner hole of the second steel pipe. The inner wall of the plastic pipe has high finish, low friction resistance and low friction coefficient, which increases the flow rate by 15%-20% and reduces the power output by 15% compared with the steel pipe of the same diameter. Since the inner anti-corrosion layer is an integral plastic pipe for lining, the plastic pipe is made of PP material with a thermal conductivity 171.42-207.67 times lower than that of steel. The thermal conductivity coefficient of PP is 0.21-0.26, and that of steel is 36-54. The inner hole surface of the lined plastic pipe is made of vacuum processing technology, with high finish, low friction coefficient, good self-slip property and low friction coefficient, and the friction coefficient is 0.219mN / m. Because the inner lining pipe is made of PP modified material, the PP material is a saturated molecular cluster structure, which can resist the erosion of strong chemicals. The surface of the inner lining pipe is as smooth as a mirror, which increases the flow rate by 10%-15% and reduces the power output by 15% compared with the steel pipe of the same diameter, thereby improving the ground pipeline transportation capacity, reducing the transportation power and reducing the transportation cost.

[0023] 6. The vacuum layer has a heat preservation effect, which increases the static temperature of steel pipes with the same diameter by 22℃-25℃, reduces the consumption of heating fuel oil in the heating station, reduces the number of heating stations along the line, and reduces the cost of crude oil transportation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the overall structure of a steel-plastic composite ground pipeline of an anti-corrosion and heat-insulating ground pipeline welding structure of the present invention;

[0025] Figure 2 It is a schematic diagram of a double-layer vacuum steel pipe structure of an anti-corrosion and heat-insulating ground pipeline welding structure of the present invention;

[0026] Figure 3 It is a schematic diagram of the second steel pipe installation structure of an anti-corrosion and heat-insulating ground pipeline welding structure of the present invention;

[0027] Figure 4 This is a schematic diagram of the structure of a plastic layer hot-melt coated on the outside of an anti-corrosion and heat-insulating ground pipeline lined with a plastic pipe of the present invention.

[0028] In the figure: 1. Straight section of the end face of the liner pipe; 2. Anti-corrosion layer at the end; 3. Trapezoidal groove; 4. Connecting sleeve; 5. First steel pipe; 6. Vacuum layer; 7. External anti-corrosion layer; 8. Support sleeve; 9. Inner pipe; 10. Second steel pipe; 11. Welding sleeve; 12. Plastic weld; 13. Welding joint. DETAILED DESCRIPTION

[0029] like Figures 1 to 4As shown, the present invention provides a technical solution: an anti-corrosion and heat-insulating ground pipeline welding structure and welding method, comprising an inner liner pipe end face straight section 1 and a second steel pipe 10, an end anti-corrosion layer 2 is arranged on the right side of the inner liner pipe end face straight section 1, and a trapezoidal groove 3 is arranged on the right side of the end anti-corrosion layer 2, a connecting sleeve 4 is arranged on the outside of the trapezoidal groove 3, and a first steel pipe 5 is arranged on the upper end of the connecting sleeve 4, a vacuum layer 6 is arranged on the right side of the connecting sleeve 4, and a supporting sleeve 8 is arranged on the right side of the vacuum layer 6, the second steel pipe 10 is located at the lower end of the supporting sleeve 8, and an inner village pipe 9 is arranged on the lower end of the second steel pipe 10, an outer anti-corrosion layer 7 and a welding sleeve 11 are arranged on the outside of the first steel pipe 5 from left to right, a plastic weld 12 is arranged on the inner lower end of the welding sleeve 11, and welding ports 13 are arranged on the left and right ends of the welding sleeve 11;

[0030] The specific operation is as follows: the inner hole of the second steel pipe 10 is provided with an inner village pipe 9, and the inner side of the flanged ends of the inner village pipe 9 is hot-melt molded into the trapezoidal grooves 3 at both ends, which solves the problem that the inner village pipe 9 is easy to move and fall off. The straight section at the end of the double-layer inner village pipe 9 is formed into one piece by plastic hot-melt butt welding. The welding sleeve 11 welds the two ends of the outer wall of the first steel pipe 5 into one piece by electric welding, forming an anti-corrosion and heat-insulating ground pipeline welding structure, which can make the weld of the inner village pipe 9 seamless and without leakage points. The outer welding port 13 is set on the vacuum layer 6 at the second pipe end, and the vacuum is used during welding. Layer 6 blocks the damage to the inner village pipe 9 caused by the high temperature of electric welding. The ground pipeline is connected in unlimited length with no exposed steel points on the inner and outer walls, and the inner hole of the weld 13 does not require internal anti-corrosion patching after welding, achieving an all-round anti-corrosion effect. The second steel pipe 10 and the inner village pipe 9 are hot-melt welded to form a whole, and there are no gaps or leaks at the weld, achieving a complete long-term anti-corrosion effect for the entire pipeline. The weld 13 is arranged on the vacuum layer 6, and the vacuum layer 6 blocks the damage to the inner village pipe 9 inside the second steel pipe 10 caused by heat conduction from electric welding, and the inner village pipe 9 does not need patching.

[0031] The steps of the anti-corrosion and heat-insulating ground pipeline welding method are as follows: A. Selection of steel pipes: Select the first steel pipe 5 and the second steel pipe 10. The two pipes have the same length. The wall thickness of the first steel pipe 5 is greater than that of the second steel pipe 10. The wall thickness is based on the outer diameter of the first steel pipe 5. The larger the pipe diameter, the thicker the wall. The smaller the pipe diameter, the thinner the wall. The outer diameter of the second steel pipe 10 is smaller than the inner diameter of the first steel pipe 5 by 6-20mm, which is the vacuum layer 6. The size of the vacuum layer 6 is based on the inner diameter of the first steel pipe 5. The larger the diameter, the larger the vacuum layer 6. The smaller the diameter, the smaller the vacuum layer 6. The first steel pipe 5 is implemented according to the oil pipe implementation standard, and the second steel pipe 10 is implemented according to the ground pipeline standard;

[0032] B. Manufacturing double-layer vacuum steel pipe: install the connecting sleeve 4 and the middle supporting sleeve 8 equidistantly on the outer wall of the second steel pipe 10, weld the connecting sleeves 4 and the middle supporting sleeve 8 at both ends to the outer wall of the second steel pipe 10 by resistance welding, insert the second steel pipe 10 into the inner hole of the first steel pipe 5, align the two ends and make them the same length, and weld the first steel pipe 5 and the second steel pipe 10 into a body by vacuum sealing welding;

[0033] C. Manufacturing of lined plastic pipe: The selected PP-PE plastic raw material is modified and granulated by a parallel twin-screw granulator. After modification, the material has memory characteristics and elastic plasticity. The inner village pipe 9 is processed by a plastic extruder vacuum shaping process. The outer diameter of the inner village pipe 9 is 1-3mm larger than the inner diameter of the second steel pipe 10. The inner wall of the double-layer vacuum steel pipe is sandblasted, rust-removed, and shot-blasted to meet the Sa2.5 standard. The prefabricated inner village pipe 9 is inserted into the inner hole of the second steel pipe 10 while being reduced by a reducing machine. The two ends of the inner village pipe 9 are respectively 200-250mm longer than the second steel pipe 10, and the length can be adjusted. After being inserted into the inner village pipe 9, it is placed at room temperature for 72-120 hours. The outer wall of the inner village pipe 9 naturally rebounds and tightly presses against the inner wall of the second steel pipe 10 to form an inner anti-corrosion layer;

[0034] D. Hot-melt coating of the outer wall of the double-layer vacuum steel pipe with an anti-corrosion and heat-insulating layer: The outer wall of the double-layer vacuum steel pipe is sandblasted and rust-removed to meet the Sa2.5 standard. The double-layer vacuum steel pipe is transmitted and moved by a conveying roller for medium-frequency heating. The steel pipe heated by the medium-frequency enters the inner hole of the right-angle head of the extruder at a uniform speed, and the outer wall is coated with an outer anti-corrosion layer 7. When the steel pipe coated with the outer anti-corrosion layer 7 is moved out of the head by 100-200mm, the removed part is cooled during movement and cooled to room temperature. At this point, a double-layer vacuum steel-plastic composite oil pipe with an inner lining plastic pipe 9 and an outer wall hot-melt coated with an outer anti-corrosion layer 7 is processed;

[0035] E. Double-layer vacuum insulation steel-plastic composite oil pipe forming: Cut the two ends of the inner village pipe 9 to expose the end of the second steel pipe 10 by 25-30mm, which can be adjusted according to the wall thickness of the double-layer steel pipe. Heat the inner village pipe 9 exposed at both ends of the second steel pipe 10 to the melting temperature, and use a molding machine to mold it into the ladder groove 3 at the end of the double-layer steel pipe and the outer wall of the first steel pipe 5. The diameter is the same as the outer wall of the first steel pipe 5 to form a right angle. At this time, a double-layer vacuum insulation steel-plastic composite oil pipe is processed and manufactured. Each double-layer vacuum insulation steel-plastic composite oil pipe is processed and manufactured by the above steps;

[0036] F. Installation of welding sleeve: Process welding sleeve 11, the length of welding sleeve 11 is 2 to 2.5 times of the outer diameter of the first steel pipe 5, the inner diameter is 0.5-1mm larger than the outer diameter of the first steel pipe 5, and it can be inserted into the outer wall of the first steel pipe 5. The wall thickness of welding sleeve 11 is 1.5 to 2 times the wall thickness of the first steel pipe 5. Take a double-layer vacuum steel-plastic oil pipe, grind the outer anti-corrosion layer 7 at both ends to the bottom material of the first steel pipe 5 with an electric wire brush, and the length is 1.5 times the length of welding sleeve 11. Insert the welding sleeve 11 into one end, and the length of welding sleeve 11 is based on the weld 13 on the vacuum layer 6 at the end of the pipe;

[0037] G. Welding: Take a double-layer steel pipe with the outer anti-corrosion layer 7 ground off from the outer wall of the end, and put the end of the steel pipe into the welding sleeve 11 to expose the straight outer anti-corrosion layer 7 at the end. Use a plastic pipe hot-melt butt welding machine to weld the straight sections of the outer anti-corrosion layers of the two pipe ends into one, and process the outer wall of the plastic weld 13 so that the welding sleeve can slide;

[0038] H. Production of anti-corrosion and thermal insulation ground pipeline welding structure: Move the welding sleeve 11 to the middle position of the two pipes, and perform electric welding on the two end faces of the welding sleeve 11 and the outer wall of the first steel pipe 5. The welding standard shall be in accordance with the ground pipeline welding standard and specifications. At this point, an anti-corrosion and thermal insulation ground pipeline welding structure is completed. Repeat this step until the required length of the pipeline is reached;

[0039] Working principle: select the first steel pipe 5 and the second steel pipe 10, the two pipes have the same length, the wall thickness of the first steel pipe 5 is greater than that of the second steel pipe 10, the wall thickness is based on the outer diameter of the first steel pipe 5, the larger the diameter, the thicker the wall, and the smaller the diameter, the thinner the wall. The outer diameter of the second steel pipe 10 is smaller than the inner diameter of the first steel pipe 5, 6-20mm is the vacuum layer 6, the size of the vacuum layer 6 is based on the inner diameter of the first steel pipe 5, the larger the diameter, the larger the vacuum layer 6, and the smaller the diameter, the smaller the vacuum layer 6. The first steel pipe 5 is implemented according to the oil pipe implementation standard, and the second steel pipe 10 is implemented according to the ground pipeline standard. The connecting sleeve 4 and the middle support sleeve 8 are equidistantly installed on the outer wall of the second steel pipe 10, and the connecting sleeves 4 and the middle support sleeve 8 at both ends are welded to the outer wall of the second steel pipe 10 by resistance welding technology, and the second steel pipe 10 is inserted into the first steel pipe 5. The inner tube 9 is processed by vacuum shaping process of plastic extruder. The outer diameter of the inner tube 9 is 1-3mm larger than the inner diameter of the second steel tube 10. The inner wall of the double-layer vacuum steel tube is sandblasted, rust-removed and shot-blasted to reach Sa2.5 standard. The prefabricated inner tube 9 is inserted into the inner hole of the second steel tube 10 while being reduced by a reducing machine. The inner tube 9 is 200-250mm longer than the second steel tube 10 at both ends, and the length can be adjusted. After being inserted into the inner tube 9, it is placed at room temperature for 72-120 hours, and the inner tube 9 naturally rebounds and the outer wall is tightly attached. It rests against the inner wall of the second steel pipe 10 to form an inner anti-corrosion layer. The outer wall of the double-layer vacuum steel pipe is sandblasted and rust-removed to meet the Sa2.5 standard. The double-layer vacuum steel pipe is transmitted and moved by a conveying roller for medium-frequency heating. The steel pipe heated by the medium-frequency enters the inner hole of the right-angle head of the extruder at a uniform speed, and the outer wall is coated with an outer anti-corrosion layer 7. When the steel pipe coated with the outer anti-corrosion layer 7 is moved out of the head 100-200mm, the removed part is cooled during movement and cooled to room temperature. At this point, a double-layer vacuum steel-plastic composite oil pipe with an inner lining plastic pipe 9 and an outer wall hot-melt coated outer anti-corrosion layer 7 is completed. The two ends of the inner village pipe 9 are cut to expose 25-30mm of the end of the second steel pipe 10. It can be adjusted according to the wall thickness of the double-layer steel pipe. The inner village pipe 9 exposed at both ends of the second steel pipe 10 is heated. Heat to melting temperature, and use a molding machine to mold into the trapezoidal groove 3 at the end of the double-layer steel pipe and the outer wall of the first steel pipe 5. The diameter is the same as the outer wall of the first steel pipe 5 to form a right angle. At this time, a double-layer vacuum insulation steel-plastic composite oil pipe is processed and manufactured. Each double-layer vacuum insulation steel-plastic composite oil pipe is processed and manufactured by the above steps. The welding sleeve 11 is processed. The length of the welding sleeve 11 is 2 to 2.5 times the outer diameter of the first steel pipe 5. The inner diameter is 0.5-1mm larger than the outer diameter of the first steel pipe 5, so as to be able to be inserted into the outer wall of the first steel pipe 5. The wall thickness of the welding sleeve 11 is 1.5 to 2 times the wall thickness of the first steel pipe 5. Take a double-layer vacuum steel-plastic oil pipe, and polish the outer anti-corrosion layer 7 at both ends to the first steel pipe 5 base material with an electric wire brush. The length is the length of the welding sleeve 11.5 times, insert the welding sleeve 11 into one end, the length of the welding sleeve 11 is based on the weld 13 on the vacuum layer 6 at the end of the pipe, take a double-layer steel pipe with the outer anti-corrosion layer 7 polished off the outer wall of the end, and align the end of the steel pipe inserted into the welding sleeve 11 to expose the straight outer anti-corrosion layer 7 at the end. Use a plastic pipe hot-melt butt welding machine to weld the outer anti-corrosion layers 7 of the two pipe ends together, process the outer wall of the plastic weld 13, and move the welding sleeve 11 to the middle position of the two pipes based on the sliding of the welding sleeve. Electric welding is performed on the two end faces of the welding sleeve 11 and the outer wall of the first steel pipe 5. The welding standard is based on the ground pipeline welding standard and is implemented in accordance with the specification. At this point, an anti-corrosion and heat-insulating ground pipeline welding structure is completed, and this step is repeated until the required length of the pipeline is reached. .

Claims

1. A method for welding anti-corrosion and heat-insulating ground pipelines, characterized in that: The invention comprises a straight section (1) at the end face of an inner liner pipe and a second steel pipe (10), wherein an end anti-corrosion layer (2) is arranged on the right side of the straight section (1) at the end face of the inner liner pipe, and a trapezoidal groove (3) is arranged on the right side of the end anti-corrosion layer (2), a connecting sleeve (4) is arranged outside the trapezoidal groove (3), and a first steel pipe (5) is arranged at the upper end of the connecting sleeve (4), a vacuum layer (6) is arranged on the right side of the connecting sleeve (4), and a supporting sleeve (8) is arranged on the right side of the vacuum layer (6), the second steel pipe (10) is located at the lower end of the supporting sleeve (8) and the end connecting sleeve (4), and an inner pipe (9) is arranged at the lower end of the second steel pipe (10), an outer anti-corrosion layer (7) and a welding sleeve (11) are arranged on the outside of the first steel pipe (5) from left to right, a plastic weld (12) is arranged at the inner lower end of the welding sleeve (11), and welding ports (13) are arranged at the left and right ends of the welding sleeve (11); The anti-corrosion and heat-insulating ground pipeline welding method comprises the following steps: A. steel pipe selection; B. manufacturing double-layer vacuum steel pipe; C. manufacturing inner-lined plastic pipe; D. hot-melt coating of the outer wall of the double-layer vacuum steel pipe with an anti-corrosion and heat-insulating layer; E. forming of the double-layer vacuum heat-insulating steel-plastic composite oil pipe; F. installation of welding sleeve; G. welding; H. manufacturing of the anti-corrosion and heat-insulating ground pipeline welding structure; I. connection completed; A. Selection of steel pipes: Select a first steel pipe (5) and a second steel pipe (10), the two pipes have the same length, the wall thickness of the first steel pipe (5) is greater than that of the second steel pipe (10), the wall thickness is based on the outer diameter of the first steel pipe (5), the larger the pipe diameter, the thicker the wall, and the smaller the pipe diameter, the thinner the wall. The outer diameter of the second steel pipe (10) is 6-20 mm smaller than the inner diameter of the first steel pipe (5) to form a vacuum layer (6), the size of the vacuum layer (6) is based on the inner diameter of the first steel pipe (5), the larger the diameter, the larger the vacuum layer (6), and the smaller the diameter, the smaller the vacuum layer (6). The first steel pipe (5) is implemented according to the oil pipe implementation standard, and the second steel pipe (10) is implemented according to the ground pipeline standard; B. manufacturing a double-layer vacuum steel pipe: installing the connecting sleeve (4) and the intermediate supporting sleeve (8) equidistantly on the outer wall of the second steel pipe (10), welding the connecting sleeves (4) and the intermediate supporting sleeve (8) at both ends to the outer wall of the second steel pipe (10) by a resistance welding process, inserting the second steel pipe (10) into the inner hole of the first steel pipe (5), aligning the two ends and making them the same length, and welding the first steel pipe (5) and the second steel pipe (10) into a body by a vacuum sealing welding process; C. manufacturing the inner lining plastic pipe: the selected PP-PE plastic raw material is modified and granulated by a parallel twin-screw granulator, and the modified material has memory characteristics and elastic plasticity. The inner village pipe (9) is processed by a plastic extruder vacuum shaping process. The outer diameter of the inner village pipe (9) is 1-3 mm larger than the inner diameter of the second steel pipe (10). The inner wall of the double-layer vacuum steel pipe is sandblasted, rust-removed, and shot-blasted to reach the Sa2.5 grade standard. The prefabricated inner village pipe (9) is inserted into the inner hole of the second steel pipe (10) while being reduced by a reducing machine. The inner village pipe (9) is extended 200-250 mm from the second steel pipe (10) at both ends, and the length can be adjusted. After being inserted into the inner village pipe (9), it is placed at room temperature for 72-120 hours. The outer wall of the inner village pipe (9) naturally rebounds and tightly presses against the inner wall of the second steel pipe (10), forming an inner anti-corrosion layer; D. hot-melt coating of the outer wall of the double-layer vacuum steel pipe with an anti-corrosion and heat-insulating layer: the outer wall of the double-layer vacuum steel pipe is sandblasted and rust-removed to reach the Sa2.5 standard, and the double-layer vacuum steel pipe is transmitted and moved by a conveying roller for medium-frequency heating. The steel pipe heated by the medium-frequency enters the inner hole of the right-angle head of the extruder at a uniform speed, and the outer wall is coated with an outer anti-corrosion layer (7). When the steel pipe coated with the outer anti-corrosion layer (7) is moved out of the head by 100-200 mm, the removed part is cooled during movement and cooled to room temperature. At this point, a double-layer vacuum steel-plastic composite oil pipe with an inner plastic pipe (9) and an outer wall hot-melt coated with an outer anti-corrosion layer (7) is processed; E. Double-layer vacuum insulation steel-plastic composite oil pipe forming: the two ends of the inner village pipe (9) are cut to expose the end of the second steel pipe (10) by 25-30 mm, which can be adjusted according to the wall thickness of the double-layer steel pipe, the inner village pipe (9) exposed at both ends of the second steel pipe (10) is heated to the melting temperature, and is molded into the inner part of the ladder groove (3) at the end of the double-layer steel pipe and the outer wall of the first steel pipe (5) by a molding machine, and the diameter is the same as the outer wall of the first steel pipe (5) to form a right angle. At this time, a double-layer vacuum insulation steel-plastic composite oil pipe is processed and manufactured. Each double-layer vacuum insulation steel-plastic composite oil pipe is processed and manufactured by the above steps; F. Installation of the welding sleeve: Process the welding sleeve (11), the length of the welding sleeve (11) is 2 to 2.5 times the outer diameter of the first steel pipe (5), the inner diameter is 0.5-1 mm larger than the outer diameter of the first steel pipe (5), and the welding sleeve (11) can be inserted into the outer wall of the first steel pipe (5). The wall thickness of the welding sleeve (11) is 1.5 to 2 times the wall thickness of the first steel pipe (5). Take a double-layer vacuum steel-plastic oil pipe, grind the outer anti-corrosion layer (7) at both ends to the bottom material of the first steel pipe (5) with an electric wire brush, and the length is 1.5 times the length of the welding sleeve (11). Insert the welding sleeve (11) into one end, and the length of the welding sleeve (11) is based on the weld (13) on the vacuum layer (6) at the end of the pipe; G. Welding: Take a double-layer steel pipe with the outer anti-corrosion layer (7) polished off on the outer wall of the end, align the end of the steel pipe with the end inserted into the welding sleeve (11) to expose the straight outer anti-corrosion layer (7) at the end, use a plastic pipe hot-melt butt welding machine to weld the outer anti-corrosion layers (7) of the two pipe ends together, and process the outer wall of the plastic weld (13) so that the welding sleeve can slide; H. Production of the anti-corrosion and thermal insulation ground pipeline welding structure: Move the welding sleeve (11) to the middle position of the two pipes, and perform electric welding on the two end surfaces of the welding sleeve (11) and the outer wall of the first steel pipe (5). The welding standard is in accordance with the ground pipeline welding standard and is implemented in accordance with the specification. At this point, an anti-corrosion and thermal insulation ground pipeline welding structure is completed.

2. The anti-corrosion and thermal insulation ground pipeline welding method according to claim 1 is characterized in that: For the outer wall (11) of the welding sleeve and the weld joints (13) at both ends, grind off the anti-corrosion layer of the steel pipe at the ends according to the external anti-corrosion patching specification, and perform anti-corrosion treatment on the weld joints and the outer wall of the welding sleeve. At this point, the two double-layer insulated steel pipes are connected. Repeat this step until the required length of the pipeline is reached.

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