WO2012048535A1

WO2012048535A1 - Connection structure for insulated oil pipe

Info

Publication number: WO2012048535A1
Application number: PCT/CN2011/001728
Authority: WO
Inventors: 周家华
Original assignee: 江苏常宝钢管股份有限公司
Priority date: 2010-10-15
Filing date: 2011-10-17
Publication date: 2012-04-19

Abstract

A connection structure for an insulated oil pipe. The connection structure comprises a coupling collar (1), an outer tubing (2), and an inner tubing (3). A sealed tubing insulation cavity (4) is formed between the inner tubing (3) and the outer tubing (2). A tube-end inner tubing (5) is disposed between the factory-end of the inner tubing (31) and the user-end of inner tubing (32). The two ends of the tube-end inner tubing (5) are sealingly fixed to the factory-end of the inner tubing (31) and the user-end of the inner tubing (32), respectively. A sealed tube-end insulation cavity (6) is formed between the tube-end inner tubing (5), the factory-end of the inner tubing (31), the factory end of the outer tubing (21), the coupling collar (1), the user-end of the inner tubing (32), and the user-end of the outer tubing (22). This structure improves insulating conditions at this location and limits loss of thermal energy from injected steam at the point of connection of the insulated oil pipe and the coupling collar. The structure also ensures that this point is sealed-off and eliminates CL^- and CO₂ corrosion of the coupling collar resulting from high temperatures.

Description

Connection structure of insulated oil pipe

The present invention relates to a joint structure of a fuel pipe, and more particularly to a joint structure of a heat insulating oil pipe for heavy oil thermal recovery. Background technique

Crude oil with high viscosity and large specific gravity is called heavy oil. The viscosity of heavy oils changes significantly with temperature. Tests have shown that for heavy oils, if the temperature is increased by 8 to 9 ° C, the viscosity can be reduced by half. Therefore, for the mining and transportation of heavy oil, heat is often used to reduce its viscosity. Injecting steam into the underground thick oil layer is the main technical measure for the heavy oil exploitation in the petroleum industry. It is called "the steam stimulation method for heavy oil thermal recovery" or "Steam drive method".

In order to reduce the heat loss and reduce the heat recovery cost when injecting steam into the underground (20 (TC~350'C), the pipe string composed of the insulated oil pipe (SY/T5324-94) is usually used. As shown in FIG. 1 , the insulated tubing outer tube 2 , the inner tube 3 and the coupling 1 are formed. The length of the inner tube 3 is slightly shorter than the length of the outer tube 2 , and the ends of the tube 3 are expanded after being expanded. Sealedly welded on the inner wall of the outer tube 2, and the inner tube 3 and the outer tube 2 are coaxial, and the outer tube 2 is provided with taper tube threads at both ends; at the factory, the outer thread of the outer tube of the outer tube of the insulated tubing The coupling 1 is screwed, and one end of the insulated tubing outer tube 2 is usually referred to as the factory end, and the other end is called the user end. In actual use, the insulated tubing outer tube 2 is connected. The connection of the hoop 1 is as shown in FIG. 1. The outer tube factory end 21 of one insulating oil pipe is screwed into the screw hole of the left end of the coupling 1, and the outer pipe end 22 of the other heat insulating oil pipe is screwed to the coupling. 1 in the right end of the threaded hole, so end to end, forming the column of the insulated tubing. Because in each insulated tubing The tube body insulation chamber 4 is formed between the tube body 3 and the outer tube 2, and the inside thereof is vacuumed and provided with multiple heat insulation structures, so that when steam is introduced into the heat insulating oil pipe The amount of heat loss from the section of the heat insulating tube 4 of the insulated tubing is small, but the insulating tubing is not covered by the tube insulating chamber 4, because at the outer tube factory end 21, the outer tube user The joint between the end 22 and the coupling 1 is not provided with any thermal insulation structure, and the inner diameter of the outer tube 2 and the inner tube 3 of the joint of the coupling 1 are greatly different, when the steam passes through the joint of the coupling 1 The steam will be turbulent, so the joint of the coupling 1 is the key part of the heat loss of the insulated tubing.

In the prior art, the connection method of the insulated oil pipe is a threaded connection, and a leakage problem occurs at the threaded joint during the introduction of the high temperature steam; at the same time, the high temperature at the joint of the coupling 1 aggravates the coupling connection. Corrosion under cr, 0 ₂ conditions.

In the tubing connection structure of API SPEC 5CT, although it is provided to improve the connection between the tubing body and the coupling The solution to the problem of sealing, as shown in Figure 2, is to add a PTFE seal to the threaded joint of the tubing, but the high temperature resistance of pure polytetrafluoroethylene is only 250 °C, when the temperature exceeds 25 (TC) The problem of seal failure still occurs. Therefore, this structural solution cannot solve the leakage problem encountered in the existing insulated tubing connection structure.

The object of the present invention is to provide a joint structure of a heat insulating oil pipe, which can reduce the heat loss at the joint of the heat insulating oil pipe joint, ensure the sealing performance here, and eliminate the joints generated by the high temperature. Cr, C0 ₂ corrosion defects.

The technical solution for achieving the object of the present invention is a joint structure of a heat insulating oil pipe, comprising a coupling, an outer pipe and a pipe body; the outer pipe comprises an outer pipe factory end screwed to the left end of the coupling, and is screwed to the right end of the coupling. The inner tube of the outer tube comprises: a factory end of the inner tube of the tube welded in the end tube of the outer tube factory, and a user end of the tube body sealedly welded in the end tube of the outer tube; the tube between the tube and the outer tube forms a closed The pipe body is insulated; a pipe end inner pipe is arranged between the pipe factory end of the pipe body and the pipe end of the pipe body, and the two ends of the pipe end inner pipe are respectively sealed with the pipe end factory end and the pipe body pipe user end. Integral, a closed tube end insulation chamber is formed between the tube end inner tube and the tube body tube factory end, the outer tube factory end, the coupling, the tube body tube user end, and the outer tube user end.

The present invention provides three solutions depending on the manner in which the inner tube of the tube end is connected to the tube inside the tube.

The first solution is that both ends of the inner tube of the tube end are welded with the tube inside the tube. In this connection mode, the inner tube of the tube end is of a split type, including a factory end tube end tube at the left end and a right end end tube. a user end pipe end inner pipe; a left end of the factory end pipe end inner pipe and a pipe inner pipe factory end, the user end pipe end inner pipe right end and a pipe inner pipe user end are sealed and welded; the factory end pipe end The inner tube and the inner tube end of the user end are sealed by the end face sealing structure.

The end face sealing structure between the inner end pipe end pipe of the pipe end inner pipe and the inner end pipe inner end pipe of the pipe end is an axial end face interference butt seal structure or an axial end face interference butt seal and a radial interference fit seal The combined structure.

The radial interference fit sealing structure between the factory end pipe end inner pipe and the customer end pipe end inner pipe is a cylindrical surface radial interference fit sealing structure or a conical surface radial interference fit sealing structure.

The axial distance between the end surface of the inner tube end of the factory end tube and the end surface of the outer tube factory end is Lg, and the axial distance between the end surface of the inner end tube of the user end tube and the end surface of the outer end of the outer tube is Ly, and the end of the factory end tube The axial distance Lg between the end face of the pipe end and the end face of the outer pipe factory end and the axial distance Ly of the end face of the inner end pipe end of the customer end pipe and the end face of the outer end end of the outer pipe are greater than or equal to the pitch P of the connecting thread, that is, Lg+Ly P.

A heat insulating sleeve is disposed in the closed tube end insulation chamber.

The heat insulation sleeve is made of ceramic fiber, and the outer circumference of the heat insulation sleeve and the inner hole wall are covered with aluminum foil.

Between the outer tube factory end and the coupling connecting thread end face and/or at the outer tube user end and the coupling connecting the thread end face Torque shoulders are provided between them.

The angle α between the shoulder surface of the torque shoulder and the positive direction of the connecting thread axis is 55° to 90°. The second solution is that any end of the inner tube of the tube ends is connected with the tube inside the tube, and the other end is connected by a sealed butt joint structure. In this connection mode, the inner tube of the tube end is integral, and the left end is the end tube of the tube end. At the factory end, the right end is a pipe end inner pipe user end; the pipe end inner pipe factory end is sealed and welded with the pipe body pipe factory end, and the pipe end inner pipe user end and the pipe body pipe user end are connected by a sealing docking structure; or The factory end of the pipe end inner pipe is connected with the pipe body factory end through a sealed butt joint structure, and the pipe end inner pipe user end is sealed and welded with the pipe body pipe user end.

The sealing docking structure between the user end of the tube end inner tube and the user end of the tube body tube is such that the user end of the tube body is provided with a docking end with an axial length L of 2 to 50 mm, and the end end of the tube end inner tube is The sleeve is in the butt joint of the user end of the tube body, and the axial end faces of the tube end are respectively subjected to the interference butt sealing and the radial interference fit sealing; the sealing docking structure between the factory end of the tube end inner tube and the factory end of the tube body is The factory end of the tube body is provided with a butt joint with an axial length L of 2^50 mm, and the factory end of the inner tube of the tube end is set in the butt joint of the factory end of the tube body, and the axial end faces of the tube are respectively crossed and sealed, and the diameter is Sealed to an interference fit.

The radial interference fit sealing structure between the user end of the pipe end inner pipe and the pipe inner pipe user end or the pipe end inner pipe factory end and the pipe inner pipe factory end is a cylindrical radial interference fit sealing structure or a conical surface Radial interference fit with the seal structure.

The axial length L of the docking port disposed at the user end of the tube body or the factory end of the tube body tube is 5 to 10 mm.

A heat insulating sleeve is disposed in the closed tube end insulation chamber.

A torque shoulder is provided between the outer tube factory end and the coupling connection thread end face and/or between the outer tube user end and the coupling connection thread end face.

The angle α between the shoulder surface of the torque shoulder and the positive direction of the connecting thread axis is 55° to 90°. The third solution is that both ends of the inner tube of the tube end are connected with the tube inside the tube through a sealed butt joint structure. In this connection mode, the tube end tube can be separated or integrated.

When the inner tube of the tube end is of a split type, it comprises a factory end tube inner tube at the left end and a user end tube end tube at the right end; the left end of the factory end tube end tube and the tube body factory end and the user end The right end of the inner tube of the tube end and the user end of the inner tube of the tube are connected by a sealed butt joint structure; the inner end tube of the factory end tube end and the inner tube end of the user end tube are cross-linked and sealed by an end face sealing structure. The end face sealing structure between the inner end pipe end of the pipe end inner pipe and the inner end pipe end end of the pipe end is an axial end face interference butt seal structure or an axial end face interference butt seal and a radial interference fit Sealed combination structure. The radial interference fit sealing structure between the factory end pipe end inner pipe and the customer end pipe end inner pipe is a cylindrical surface radial interference fit sealing structure or a conical surface radial interference fit sealing structure.

The sealing docking mechanism is provided with a docking end at the factory end of the tube body and the user end of the tube body tube, and the left end of the inner end tube of the factory end tube end of the tube end inner tube and the right end end of the inner end tube end of the user end tube are respectively set In the docking end of the tube body end of the tube body and the tube end of the tube body.

There are three options between the axial length of the connection port and the length of the inner tube end tube of the factory end and the length of the inner tube end tube of the user end. The axial length of the first type of the butt joint is L, and the end of the factory end is The length of the inner tube 1^ and the length L _{2 of the} inner tube end of the user end tube are greater than the axial length L of the butt joint, and the left end of the inner tube end of the factory end tube is fitted in the tube end of the tube body in an interference fit manner. In the docking port, the right end of the inner tube end of the user end tube is fit in the docking port of the user end of the tube body in an interference fit manner. The second axial length of the butt joint is L, and the length L ₂ of the inner tube end of the user end is 3/10~7/10 of the axial length L of the docking end, and the inner end of the user end tube In the interference fit, it is set in the docking end of the user end of the tube body, and the two ends of the inner tube end of the factory end tube are respectively arranged in the interference fit between the tube factory end and the tube body user end. In the mouth. The third axial length of the butt joint is L, the length of the inner tube end of the factory end! ^ is 3/10~7/10 of the axial length L of the butt joint, and the inner tube end pipe of the factory end is fit in the butt joint of the factory end of the pipe body in an interference fit manner, and the end pipe of the user end pipe end The two ends are respectively fitted in the docking end of the tube factory end and the tube body user end in an interference fit manner.

When the inner tube of the tube end is integral, the tube end inner tube is located at the left end of the tube end inner tube factory end and the tube body tube factory end, the right end tube end inner tube user end and the tube body tube user end are sealed and docked structure connection. The sealing docking mechanism has a docking end at the factory end of the tube body and the user end of the tube body tube, and the tube end inner tube factory end end and the tube end inner tube user end of the tube end inner tube are respectively set in the tube body tube The docking end of the factory end and the tube body of the tube body. The pipe end inner pipe factory end is in interference fit with the butt end of the pipe inner pipe factory end; the pipe end inner pipe user end is provided with a guiding section and a sealing section from right to left, and the guiding section is set in a transitional manner. In the butt joint of the user end of the tube body, the sealing section is fitted in the docking end of the user end of the tube body in an interference fit manner. The axial length of the butt joint is L, the axial length of the guiding section of the inner end of the inner end of the pipe end is L ₃ , and the axial length of the sealing section of the inner end of the inner end of the pipe end is L _{4 ;} L ₃ For the butt joint length L 1/10~9/10, L ₄ is the mating tooth length L when the tube end inner tube is integral, and may include a gasket; the washer is installed in the tube in an interference fit manner The length of the gasket is 1/10~9/10 of the length L of the butt joint. The pipe end inner pipe factory end is in interference fit with the butt end of the pipe inner tube factory end; the pipe end inner pipe user end is in interference fit with the butt end of the pipe inner tube user end; the axial direction of the butt joint port The length L is 2 to 50 mm.

In a third variant, a thermal insulation jacket can also be provided in the closed tube end insulation chamber. The heat insulation cover Made of porcelain fiber, the outer circumference of the heat insulation sleeve and the inner hole wall are covered with aluminum foil. A torque shoulder is provided between the outer tube factory end and the coupling connection thread end face and/or between the outer tube user end and the coupling connection thread end face. The angle α between the shoulder surface of the torque shoulder and the positive direction of the connecting thread axis is 55° to 90°.

By adopting the above technical solution, the present invention has the following positive effects: (1) To further reduce the heat loss of the insulated oil pipe string, the focus is to reduce the heat loss of the heat insulating oil pipe at the coupling joint, and the present invention is connected in the coupling. A pipe end inner pipe is added, and the pipe end inner pipe is composed of a pipe end inner pipe factory end and a pipe end inner pipe user end, and the left end of the pipe end inner pipe factory end is sealed with the pipe inner pipe factory end, and the pipe end inner pipe user is integrated. The right end of the end is sealed with the user end of the tube body, and a sealed connection structure is formed between the factory end of the tube end inner tube and the end end of the tube end inner tube, so that the inner tube of the coupling and the tube end, the inner tube of the tube body, and the outer tube A closed pipe end insulation chamber is formed between the factory end, the pipe body user end and the outer pipe user end, which improves the heat insulation condition here; when hot steam flows through the coupling joint, the hot steam can only be combined with The factory end of the pipe end inner pipe is in contact with the pipe end inner pipe user end, and does not contact the outer pipe factory end, the coupling and the outer pipe user end, thereby greatly reducing the heat loss caused by the conduction of steam at the coupling joint. Therefore, the joint structure of the insulated oil pipe of the invention can effectively reduce the heat loss of the injected steam at the joint of the heat insulating tubing, and ensure the sealing performance here, and can also eliminate the joint of the joint caused by the high temperature by the cr, C0 ₂ corrosion defects.

(2) The invention adds an insulating sleeve in the heat insulating cavity of the pipe end, and is covered with aluminum foil on the outer circle and the inner wall of the heat insulating sleeve, which can better reduce the heat generated by convection and radiation. loss.

(3) The present invention provides a plurality of connection modes of the inner tube of the tube end and the tube inside the tube, and a structure of a plurality of tube end inner tubes, which can ensure stable and reliable sealing performance, thereby expanding the selection range and making the invention Can be more flexibly applied to actual production.

(4) During the screwing process at the factory end of the insulated tubing, after the end face of the outer pipe at the factory end of the outer pipe contacts the end face of the coupling end of the coupling, the torque of the upper buckle will rise sharply. When the inflection point of the screwing curve appears, It indicates that the end face of the outer pipe at the factory end of the outer pipe has been in contact with the limit end face of the inner thread of the coupling, and the connection between the factory end of the outer pipe and the coupling has been accurately placed. Again, the outer tube user end is connected to the coupling. Therefore, the present invention provides a torque shoulder to ensure that the coupling is screwed to the factory end of the outer tube and the user end of the outer tube to achieve a predetermined position and torque value, so that the operator can accurately and conveniently determine the outer tube factory end and the outer tube user end. Whether the coupling is buckled in place to ensure a reliable seal between the factory end of the pipe end inner pipe and the pipe end inner pipe user end. At the same time, due to the torque of the insulating oil pipe thread, the sealing end face of the inner end of the pipe end inner pipe and the pipe end inner pipe end end of the pipe end inner pipe will have an interference effect, which can ensure that it is under the high pressure steam condition. Sealing performance; a heat-insulating sleeve is arranged in the closed pipe end insulating cavity formed between the inner end of the pipe end and the outer pipe factory end, the pipe inner pipe factory end, the coupling end, the outer pipe user end, and the pipe inner pipe user end , can reduce the conduction, convection and radiation of heat here; therefore, while greatly reducing the heat loss at the joint of the coupling, the temperature of the coupling can be greatly reduced, which helps to solve the heat insulation caused thereby. Tubing joint thread leakage and coupling corrosion problems. DRAWINGS

In order to make the content of the present invention easier to understand, the present invention will be further described in detail below with reference to the accompanying drawings,

Figure 1 is a schematic view showing the structure of a prior art (SY/T5324-94) insulated oil pipe connection.

Fig. 2 is a schematic view showing the structure of a prior art (API SPEC 5CT) in which a sealing ring is added to a taper pipe thread connection. Fig. 3 is a schematic view showing the structure of the present invention, in which both ends of the inner tube of the tube end are welded.

Fig. 4 is a schematic view showing another structure of the present invention, and a heat insulating sleeve is added on the basis of Fig. 3.

Fig. 5 is a partial enlarged view of Fig. 4.

Fig. 6 is a schematic view showing another structure of the present invention, in which the user end of the inner end of the tube end is welded to the user end of the tube inside the tube. Fig. 7 is a schematic view showing another structure of the present invention, in which the factory end of the pipe end inner pipe is welded to the factory end of the pipe body. Fig. 8 is a schematic view showing another structure of the present invention. The figure shows a first structural schematic view of the split type when both ends of the inner tube of the tube end are assembled.

Fig. 9 is a schematic view showing another structure of the present invention. The figure shows a second structural schematic view of the split type when both ends of the inner tube of the tube end are assembled.

Fig. 10 is a schematic view showing another structure of the present invention. The figure shows a third structural schematic view of the split type when both ends of the inner tube of the tube end are assembled.

Fig. 11 is a schematic view showing another structure of the present invention. The figure shows a first structural schematic view of the integral type when both ends of the inner tube of the tube end are assembled.

Figure 12 is a schematic view showing another structure of the present invention. The figure shows a second structural schematic view of the integral type when both ends of the inner tube of the pipe end are assembled;

Figure 13 is an enlarged view of A of Figure 12 .

Figure 14 is a schematic view showing another structure of the present invention. The figure shows a third structural schematic view of the integral type when both ends of the inner tube of the pipe end are assembled;

Fig. 15 is a view showing one of the sealing connection structures between the factory end of the pipe end inner pipe and the pipe end inner pipe user end when the pipe end inner pipe is a split type according to the present invention.

Fig. 16 is a second structural view of the sealing connection between the factory end of the inner end of the tube end and the end of the inner tube of the tube end when the inner tube of the tube end is in the split type.

Fig. 17 is the third sealing structure of the inner end of the inner end of the inner end of the tube end and the inner end of the inner end of the tube end when the inner tube of the tube end is in the split type.

18 is a schematic structural view of a heat insulating sleeve according to the present invention;

Figure 19 is a schematic structural view of a torque shoulder of the present invention;

Figure 20 is a graph showing the torque of the threaded buckle of the insulated oil pipe connection of the present invention. The reference numerals in the drawings are: 1 - coupling; 2 - outer tube; 21 - outer tube factory end; 22 - outer tube user end; 3-tube inner tube; 31 - tube body tube factory end; 32 - tube body tube User end; 4-tube body insulation chamber; 5-tube end inner tube; 51 - factory end tube end inner tube; 52-user end tube end inner tube; 53- tube end inner tube factory end; 54- tube end Pipe user end; 54-1 sealing section; 54-2 guiding section; 6-pipe end insulation cavity; 7-washer; 8-insulation sleeve; 9-aluminum foil; 10-torque shoulder. detailed description

The left and right sides of the present invention are referred to in the left and right directions in the drawings of the specification.

(Embodiment 1)

Referring to FIG. 3, a connection structure of the insulated oil pipe of the present embodiment includes a coupling 1, an outer tube 2, a tube inner tube 3, a tube body insulating chamber 4, and a tube end inner tube 5. The outer tube 2 includes an outer tube factory end 21 threadedly coupled to the left end of the coupling 1 and an outer tube user end 22 threadedly coupled to the right end of the coupling 1; the inner tube 3 includes a tube body tube weldedly sealed in the outer tube factory end 21 tube The factory end 31 is sealed in the tube of the outer tube user end 22 and has a tubular inner tube user end 32; a closed tube body insulating chamber 4 is formed between the outer tube 2 and the tube body tube 3; the tube factory end 31 and the tube are inside the tube body A tube end inner tube 5 is disposed between the inner tube user end 32; the tube end inner tube 5 includes a factory end tube end inner tube 51 at the left end and a user end tube end inner tube 52 at the right end; the factory end tube end inner tube 51 The left end is sealed with the inner tube end 31 of the tube body, the right end of the inner end tube 52 of the user end tube, and the user end 32 of the inner tube end of the tube; the inner end tube end 51 of the factory end tube and the inner end tube 52 of the end end of the tube are sealed by the end surface. The structural interference butt seal forms a closed tube between the tube end inner tube 5 and the inner tube factory end 3 1 , the outer tube factory end 21 , the coupling 1 , the inner tube end 32 , and the outer tube end 22 . End insulation chamber 6. The outer tube factory end 21 and the outer tube user end 22 have an outer diameter of 114.30 mm, an inner diameter of 100.54 mm, and a wall thickness of 6.88 mm _; the outer diameter of the tube end inner tube factory end 51 and the tube end inner tube user end 52 is 73.02 mm. > The inner diameter is 62.0mm and the wall thickness is 5.51mm; the outer sleeve 7 has an outer diameter of 98mm and an inner diameter of 76mm. The factory end pipe end inner pipe 51 and the customer end pipe end inner pipe 52 are sealed by an end face, and the sealing structure thereof may be an axial end face interference matching butt sealing structure as shown in FIG. 15; or the axial direction shown in FIG. 16 is selected. The combination of the end face interference butt seal and the cylindrical radial interference fit seal; or the combination structure of the axial end face interference butt seal and the conical surface radial interference fit seal shown in FIG. In this embodiment, a closed pipe end heat insulation is formed between the coupling 1 and the pipe end inner pipe 5, the pipe body pipe factory end 31, the outer pipe factory end 21, the pipe body pipe user end 32 and the outer pipe user end 22. The cavity 6 improves the thermal insulation condition at the joint of the coupling 1; since the sealing connection structure is formed between the factory end pipe end inner pipe 51 and the customer end pipe end inner pipe 52, the sealing performance of the coupling 1 joint is improved. a first seal is formed between the factory end pipe end inner pipe 51 and the customer end pipe end inner pipe 5252, and the coupling 1 forms a second seal with the outer pipe factory end 21 and the outer pipe user end 22, so the sealing effect very good.

On the basis of the foregoing structure, as shown in FIG. 4 and FIG. 5, a heat insulating sleeve 8 is provided in the closed tube end heat insulating cavity 6, and the heat insulating sleeve 8 is made of ceramic fiber, as shown in FIG. The outer circumference of the heat sleeve 87 and the inner wall of the inner hole are covered Covered with aluminum foil 9. Referring to Figures 5 and 19, a torque shoulder 10 is provided between the outer tube factory end 21 and the coupling threaded end face of the coupling 1 and/or between the outer tube user end 22 and the coupling threaded end face. The angle α between the shoulder surface of the torque shoulder 9 and the positive direction of the connecting thread axis is 90°. The torque curve diagram of the threaded connection of the insulated tubing is shown in Figure 20. As shown in Fig. 5, the axial distance between the end surface of the inner end pipe end 51 of the factory end pipe and the end surface of the outer pipe factory end 21 is Lg, and the axial distance between the end surface of the inner end pipe 52 of the user end pipe and the end surface of the outer end 22 of the outer pipe is Ly. And the axial distance Lg between the end surface of the factory end pipe inner end 51 and the end surface of the outer pipe factory end 21 and the axial distance Ly of the end surface of the end pipe end 52 of the customer end pipe and the end face of the outer end 22 of the outer pipe are greater than or equal to the connecting thread Pitch P, which is Lg+Ly P.

(Example 2)

6 and FIG. 7, this embodiment is basically the same as Embodiment 1, except that: This embodiment is a tube end inner tube 5 which is integral, one end of which is welded with the tube body 3, and the other end is sealed by abutting structure. connection.

In Fig. 6 and Fig. 7, the left end is the pipe end inner pipe factory end 53, and the right end is the pipe end inner pipe user end 54. In Fig. 6, the pipe end inner pipe factory end 53 is sealed and welded with the pipe body pipe factory end 31, and the pipe end inner pipe user end 54 and the pipe body pipe user end 32 are connected by a sealing butt joint structure; the pipe end inner pipe factory end 53 and the pipe end The sealing docking structure between the end of the tube factory 31 is provided with a butt joint with an axial length L of 2 to 50 mm at the tube factory end 31 of the tube body, and the factory end 53 of the tube end inner tube is set at the tube factory end 31 In the butt joint, the axial end faces of the two have an interference butt seal and a radial interference fit seal.

Figure 7. The end of the pipe end factory end 53 and the pipe end of the pipe body 31 are connected by a sealed butt joint structure, and the pipe end inner pipe user end 54 is sealed with the pipe inner pipe user end 32. The sealing docking structure between the end end pipe end 54 of the pipe end and the pipe end factory end 31 is such that the pipe end user end 32 is provided with a butt joint with an axial length L of 2 to 50 mm, and the pipe end inner pipe user end. 54 is placed in the butt joint of the user end 32 of the tube body, and the axial end faces of the tube are in interference with the butt seal and the radial interference fit seal.

(Embodiment 3)

8 to FIG. 13 , this embodiment is basically the same as the first embodiment, except that: The difference is that: in this embodiment, both ends of the tube end inner tube 5 are connected to the tube body 3 through the sealed butt joint structure. .

Referring to Figures 8, 9, and 10, the pipe end inner pipe 5 may be of a split type, including a factory end pipe end inner pipe 51 at the left end and a customer end pipe end inner pipe 52 at the right end; the factory end pipe end inner pipe The left end of the 51 and the inner tube factory end 31, the right end of the user end end inner tube 52 and the inner tube end 32 of the tube are connected by a sealed butt joint structure; the factory end tube end inner tube 51 and the user end tube end inner tube 52 Interspersed through the face seal structure. Referring to Figures 15, 16 and 17, the end face sealing structure between the factory end pipe end inner pipe 51 of the pipe end inner pipe 5 and the customer end pipe end inner pipe 52 is an axial end face interference butt seal structure or an axial end face. Combination of interference butt seal and radial interference fit seal Structure. The radial interference fit between the factory end pipe end inner pipe 51 and the customer end pipe end inner pipe 52 is a cylindrical radial interference fit sealing structure or a conical surface radial interference fit sealing structure. Referring to Fig. 8, Fig. 9 and Fig. 10, the sealing docking mechanism is provided with a butt joint at the tube factory end 31 and the tube body end 32 of the tube body, and the left end of the factory end tube end tube 51 of the tube end inner tube 5 The right end of the inner tube end tube 52 is fitted into the docking port of the tube body factory end 31 and the tube body tube end 32, respectively.

Referring to Figures 8, 9, and 10, there are three combinations between the axial length of the docking port, the length of the factory end pipe end tube 51, and the length of the user end pipe end tube 52: As shown in Fig. 8, the axial length of the docking port is L, the length of the factory end pipe inner pipe 51 and the length L _{2 of the} customer pipe end inner pipe 52 are larger than the axial length L of the butt joint, the factory end pipe The left end of the end inner tube 51 is fitted in the butt joint of the tube body factory end 31 in an interference fit manner, and the right end of the user end end inner tube 52 is fitted in the tube body end 32 in an interference fit manner. The docking is in the mouth. As shown in FIG. 9, the axial length of the butt joint is L, and the length L ₂ of the inner end 52 of the user end is the axial length L of the docking end is 3/10~7/]0, and The end pipe end tube 52 of the user end is fit in the butt joint of the user end 32 of the pipe body in an interference fit manner, and the two ends of the inner end pipe 51 of the factory end pipe are respectively set in the pipe body in an interference fit manner. The factory end 31 is in the docking port of the tubular body end 32 of the tube. Third, as shown in FIG. 10, the axial length of the butt joint is L, and the length 1^ of the inner end end of the factory end pipe is 3/10 7/10 of the axial length L of the butt joint, and the factory end The tube end inner tube 51 is fit in the butt joint of the tube body factory end 31 in an interference fit manner, and the two ends of the user end tube end inner tube 52 are respectively fitted in the tube body tube factory end in an interference fit manner. 31 and the docking end of the tubular body end 32 of the tube.

Referring to Fig. 11, Fig. 12, Fig. 13 and Fig. 14, the tube end inner tube 5 can also be a unitary type, the tube end inner tube factory end 53 at the left end and the tube inner tube factory end 31, and the tube end inner tube user at the right end. Both the end 54 and the tubular body end 32 are connected by a sealed docking structure.

As shown in FIG. 11, the sealing docking mechanism is provided with a butt joint at the tube factory end 31 and the tube body end 32 of the tube body, and the tube end inner tube factory end 53 and the tube end inner tube user end 54 of the tube end inner tube 5 They are respectively placed in the docking ports of the tube body factory end 31 and the tube body tube end 32.

Referring to Figures 12 and 13, the pipe end inner pipe factory end 53 is in interference fit with the butt end of the pipe body factory end 31; the pipe end inner pipe user end 54 is provided with a guide section 54-1 and a seal from right to left. In the segment 54-2, the guiding segment 54-1 is fitted in the mating end of the tubular body end 32 of the tubular body in a transition fit manner, and the sealing segment 54-2 is fitted in the tubular body end 32 of the tubular body in an interference fit manner. In the mouth. Such a structure can facilitate the cooperation of the end pipe 5 and the docking port. The axial length of the docking port is L, the axial length of the guiding section 54-1 of the pipe end inner pipe user end 54 is L ₃ , and the axial length of the sealing section 54-2 of the pipe end inner pipe user end 54 is L. _4; L ₃ is 1/10~9/10 of the length L of the butt joint. L ₄ is 1/10 to 9/10 of the length L of the butt joint.

Referring to Fig. 14, a washer 7 may also be included; the washer 7 is mounted in the tubular body end 31 or the tubular body end 32 in an interference fit manner; the length L ₅ of the washer 50 is 1 of the length of the mating tooth L /10~9/10. The pipe end inner pipe factory end 53 has an interference fit with the butt joint end of the pipe inner pipe factory end 31; the pipe end inner pipe user end 54 has an interference fit with the butt joint end of the pipe inner pipe user end 32; the axial direction of the butt joint The length L is 2 to 50 mm. The specific embodiments of the present invention have been described in detail with reference to the preferred embodiments of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and scope of the present invention are intended to be included within the scope of the present invention.

Claims

1. A joint structure of an insulated tubing, comprising a coupling (1), an outer tube (2) and an inner tube (3); the outer tube (2) comprises an outer tube factory threadedly connected to the left end of the coupling (1) End (21), outer tube user end (22) threadedly coupled to the right end of the coupling (1); tube body tube (3) including tube body factory end (31) sealed in the outer tube factory end (21) tube a tubular inner tube end end (32) welded in the outer tube user end (22) tube; a closed tube body insulating cavity (4) formed between the inner tube (3) and the outer tube (2); Between: There is a pipe end inner pipe (5) between the pipe inner pipe end (31) and the pipe inner pipe user end (32), and the two ends of the pipe end inner pipe (5) are respectively connected with the pipe inner pipe factory end ( 31), the inner tube end (32) of the tube body is sealed and fixed into one body, and the tube end inner tube (5) and the tube inner tube factory end (31), the outer tube factory end (21), the coupling (1), the tube body A closed tube end insulation chamber (6) is formed between the tube user end (32) and the outer tube user end (22).

2. The joint structure of the insulated oil pipe according to claim 1, wherein: the pipe end inner pipe (5) comprises a factory end pipe end inner pipe (51) at a left end and a user end pipe end at a right end An inner tube (52); a left end of the factory end tube end inner tube (51) and a tube inner tube factory end (31), a right end end of the user end tube end inner tube (52) and a tube inner tube user end (32) Both are sealed and welded; the factory end pipe end inner pipe (51) and the customer end pipe end inner pipe (52) are cross-linked and sealed by an end face sealing structure.

The joint structure of the insulated oil pipe according to claim 2, characterized in that: the factory end pipe end inner pipe (51) of the pipe end inner pipe (5) and the customer end pipe end inner pipe (52) The end face seal structure is a combination of an axial end face interference butt seal structure or an axial end face interference butt seal and a radial interference fit seal.

The joint structure of the insulated oil pipe according to claim 3, characterized in that: the radial interference fit between the factory end pipe end inner pipe (51) and the customer end pipe end inner pipe (52) The sealing structure is a cylindrical surface radial interference fit sealing structure or a conical surface radial interference fit sealing structure.

The joint structure of the insulated oil pipe according to claim 2, wherein: the axial distance between the end surface of the inner end pipe end of the factory end pipe (51) and the end surface of the outer pipe factory end (21) is Lg, The axial distance between the end surface of the inner end pipe (52) of the user end pipe and the end surface of the outer end of the outer pipe (22) is Ly, and the axial end of the end pipe of the factory end pipe end (51) and the end surface of the outer pipe factory end (21) The sum of the spacing Lg and the axial distance Ly of the end surface of the end pipe of the customer end pipe (52) and the end face of the outer end of the outer pipe (22) is greater than or equal to the pitch P of the connecting thread, that is, Lg+Ly P.

The joint structure of the insulated oil pipe according to claim 1, wherein: the pipe end inner pipe (5) is a unitary type, the left end is a pipe end inner pipe factory end (53), and the right end is a pipe end. The pipe end (54); the pipe end inner pipe factory end (53) is sealingly welded with the pipe body pipe factory end (31), and the pipe end inner pipe user end (54) and the pipe body pipe user end (32) are sealed. Docking structure connection; or the pipe end inner pipe factory end (53) and the pipe body pipe factory end

(31) through the sealed butt joint connection, the end end of the end of the tube end (54) and the end of the tube end of the tube (32) Pick up.

The joint structure of the insulated oil pipe according to claim 6, wherein: the sealed butt joint between the end end of the pipe end inner end (54) and the inner end pipe end end (32) is inside the pipe body The pipe user end (32) is provided with a butt joint with an axial length L of 2 to 50 mm, and the end end of the pipe end user end (54) is fitted at the end of the pipe body.

In the butt joint of (32), the axial end face of the pipe end has an interference butt seal and a radial interference fit seal; the pipe end of the pipe end inner pipe factory end (53) and the pipe body factory end (31) The structure is that the pipe end factory (31) is provided with a butt joint with an axial length of 1^2 mm, and the pipe end inner pipe factory end (53) is set to be docked at the pipe factory end (31). In the mouthpiece, the axial end faces of the two have an interference butt seal and a radial interference fit seal.

The joint structure of the insulated oil pipe according to claim 7, characterized in that: the pipe end inner pipe user end (54) and the pipe inner pipe user end (32) or the pipe end inner pipe factory end (53) The radial interference fit seal structure with the tubular body end (31) of the tube is a cylindrical radial interference fit seal or a conical radial interference fit seal.

9. The joint structure of the insulated oil pipe according to claim 7, wherein: the axial length L of the butt joint of the tubular end of the tubular body end (31) or the inner tube end of the tubular body (31) It is 5~10 mm.

10. The joint structure of the insulated oil pipe according to claim 1, wherein: the pipe end inner pipe (5) is of a split type, and includes a factory end pipe end inner pipe (51) at the left end and a right end end. User end pipe end inner pipe (52); left end of the factory end pipe end inner pipe (51) and pipe inner pipe factory end (31), user end pipe end inner pipe (52) right end and pipe inner pipe user end (32) are connected by a sealed butt joint structure; the factory end pipe end inner pipe (51) and the customer end pipe end inner pipe (52) are cross-linked and sealed by an end face sealing structure.

The joint structure of the insulated oil pipe according to claim 10, characterized in that: the factory end pipe inner pipe (51) of the pipe end inner pipe (5) and the customer end pipe end inner pipe (52) The end face seal structure is a combination of an axial end face interference butt seal structure or an axial end face interference butt seal and a radial interference fit seal.

The joint structure of the insulated oil pipe according to claim 11, characterized in that: the radial interference fit between the factory end pipe end inner pipe (51) and the customer end pipe end inner pipe (52) The sealing structure is a cylindrical surface radial interference fit sealing structure or a conical surface radial interference fit sealing structure.

The joint structure of the insulated oil pipe according to claim 12, wherein: the sealing docking mechanism has a docking port at both the pipe factory end (31) and the pipe body user end (32). The left end of the factory end pipe end pipe (51) of the pipe end inner pipe (5) and the right end end of the customer end pipe end inner pipe (52) are respectively set at the pipe body factory end (31) and the pipe body pipe user end (32) in the docking stop.

The joint structure of the insulated oil pipe according to claim 13, wherein: the axial length of the butt joint is L, the length of the inner end pipe (51) of the factory end pipe and the inner pipe end of the user end pipe end The length L _{2 of} (52) is greater than the axial length L of the butt joint, and the left end of the inner end pipe (51) of the factory end is fitted in the tube in an interference fit manner. In the docking end of the body tube factory end (31), the right end of the user end tube inner tube (52) is fitted in the butt joint of the tube body user end (32) in an interference fit manner.

The joint structure of the insulated oil pipe according to claim 13, wherein: the axial length of the butt joint is L, and the length L ₂ of the inner pipe end (52) of the user end pipe is a docking port. The axial length L is 3/10~7/10, and the end pipe end tube (52) of the user end is fit in the butt joint of the user end (32) of the pipe body in an interference fit manner, and the end of the pipe is in the factory end. The two ends of the tube (51) are respectively fit in the docking end of the tube body factory end (31) and the tube body tube end (32) in an interference fit manner; or the axial length of the docking port is L, the length of the inner end pipe end of the factory end pipe (51) is 3/10~7/10 of the axial length L of the butt joint, and the inner end pipe (51) of the factory end pipe is connected by an interference fit. The set is placed in the butt joint of the tube end of the tube body (31), and the ends of the inner end tube (52) of the user end tube are respectively fitted in the tube body factory end (31) and the tube body tube user in an interference fit manner. The docking port of the end (32).

The joint structure of the insulated oil pipe according to claim 1, wherein: the pipe end inner pipe (5) is a unitary type, and the pipe end inner pipe factory end (53) and the pipe body pipe factory at the left end The end (31), the tube end inner tube end (54) at the right end and the tube inner tube user end (32) are connected by a sealed butt joint structure.

The joint structure of the insulated oil pipe according to claim 16, wherein: the sealing docking mechanism is provided with a butt joint at the pipe factory end (31) and the pipe body end (32) of the pipe body. The pipe end inner pipe factory end (53) and the pipe end inner pipe user end (54) of the pipe end inner pipe (5) are respectively set in the pipe body pipe factory end (31) and the pipe body pipe user end (32) Docking in the mouth.

The joint structure of the insulated oil pipe according to claim 17, wherein: the pipe end inner pipe factory end (53) and the pipe inner pipe factory end (31) have an interference fit; The tube end inner tube user end (54) is provided with a guiding section (54-1) and a sealing section (54-2) from right to left, and the guiding section (54-1) is fitted in the tube body in a transitional manner. In the butt end of the end (32), the sealing section (54-2) is fitted in the butt joint of the tubular body end (32) in an interference fit.

The joint structure of the insulated oil pipe according to claim 18, wherein: the butt joint has an axial length L, and the pipe end inner pipe user end (54) has a guiding section (54-1). The axial length is L ₃ , the axial length of the sealing section (54-2) of the end end of the tube end inner tube (54) is L _{4 ;} L ₃ is 1/10~9 of the length L of the mating tooth /10, L ₄ is 1/10 to 9/10 of the length L of the butt joint.

The joint structure of the insulated oil pipe according to claim 17, further comprising: a gasket (7); the gasket (7) is installed in the pipe body factory end (31) or in an interference fit manner or The inside of the tube body end (32); the length of the washer (50) is 1/10~9/10 of the length L of the mating tooth.

21. The joint structure of an insulated oil pipe according to claim 20, wherein: said pipe end inner pipe factory The end (53) has an interference fit with the butt end of the tube end factory end (31); the end end of the tube end inner tube (54) is in interference with the butt end of the tube end user end (32); The axial length L of the butt joint is 2 to 50 mm.

The joint structure of the insulated oil pipe according to any one of claims 1 to 21, characterized in that a heat insulating sleeve (8) is provided in the closed pipe end heat insulating chamber (6).

The joint structure of the insulated oil pipe according to claim 22, wherein the heat insulating sleeve (8) is made of ceramic fiber and covered on the outer circumference and the inner wall of the heat insulating sleeve (8). There is aluminum foil (9).

The joint structure of the insulated oil pipe according to any one of claims 1 to 21, characterized in that: between the outer pipe factory end (21) and the coupling (1) connecting the thread end face and/or at the outer pipe user end ( 22) A torque shoulder (10) is provided between the end face of the coupling (1) and the threaded end.

The joint structure of the insulated oil pipe according to claim 24, characterized in that: the angle α between the shoulder surface of the torque shoulder (10) and the connecting thread axis is 55° to 90°.