Bimetal joint for RTP pipe

Abstract

The utility model belongs to the technical field of composite pipes, and particularly relates to a bimetallic joint for an RTP pipe, which comprises a metal matrix pipe fitting inner cylinder and a metal matrix pipe fitting outer cylinder, the front end of the metal matrix pipe fitting outer cylinder is welded on the outer wall of the metal matrix pipe fitting inner cylinder, and the front end of the metal matrix pipe fitting outer cylinder is welded on the outer wall of the metal matrix pipe fitting inner cylinder. An annular gap used for inserting a pipe is formed between the metal matrix pipe fitting inner cylinder and the metal matrix pipe fitting outer cylinder, and the inner wall and the end face of the metal matrix pipe fitting inner cylinder are provided with corrosion-resistant metal layers which are of an integrated structure and resistant to corrosion of sulfuration gas and chlorination gas through one-time forming machining. Conventional metal can be adopted as a pipe fitting base body, corrosion-resistant metal layers can be formed on the inner layer of the pipe fitting inner barrel, the insertion end inner barrel and the connecting end face at a time through the technologies such as thermal spraying, surfacing or hot casting, the pipe fitting can bear pressure and resist rapid corrosion of HS and the like to metal pipes, and the pipe fitting cost can be remarkably reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of composite pipe materials, and particularly relates to a bimetallic joint for RTP pipe. BACKGROUND

[0002] The crude oil extracted from oil exploitation contains H2S (hydrogen sulfide) gas with different concentrations. The existing crude oil conveying pipe starts to use RTP pipe material (enhanced thermoplastic plastic pipe), and the inner layer plastic can effectively prevent the corrosion of H2S. Although the RTP pipe can be coiled by hundreds of meters to reduce the amount of metal joints, the connection industry of the pipe material usually still uses a metal shrinkage joint (high pressure and reliability requirements, such as SY / T6662.2 Appendix A), and H2S or chlorides in the crude oil have strong corrosive properties to most metals. Therefore, the pipe joint part becomes a weak link in the entire pipeline conveying system.

[0003] In the prior art, a Chinese invention patent with the application number CN202011064648.7 and the name of "Corrosion-resistant connecting joint for oil and gas conveying non-metal pipeline and connecting method" discloses that the application relates to the technical field of oil and gas conveying pipelines, and provides a corrosion-resistant connecting joint for oil and gas conveying non-metal pipeline and a connecting method. The connecting joint is made of a bimetallic metallurgical composite pipe and includes CRA cladding, a steel base pipe, a CRA inner coating, a connecting slot, a steel coupling, and a steel clamping sleeve. In actual application, the non-metal pipe is nested between the steel base pipe and the steel clamping sleeve, so that the non-metal pipe is firmly connected with the connecting joint. The steel base pipe and the steel coupling are connected through threads, so that two non-metal pipelines are connected. The CRA inner coating of the inner wall of the joint and the CRA cladding layer at both ends significantly improve the corrosion resistance. However, the above-mentioned patent adopts a secondary forming process. After the inner layer alloy is combined with the pipe base material, first cladding and second cladding are formed. There are two kinds of metal materials for secondary welding, and the welding difficulty is large. It is difficult to ensure the welding quality and bonding performance of the thin inner layer alloy layer and the thick metal base material layer under the same process. There are problems such as poor cladding and voids. Under high internal pressure (the crude oil conveying is above 10 MPa), H2S can escape through the front and rear cladding gaps to corrode the pipe base material and the pipe reinforcing layer. In addition, the steel clamping sleeve and the connecting slot have a gap. After the steel clamping sleeve is sent into the connecting slot, it is rotated by an angle to be fixed. However, since it is movable, the reliability is poor. SUMMARY

[0004] In order to overcome the above-mentioned problems existing in the prior art, a bimetallic joint for RTP pipe is provided.

[0005] In order to achieve the above-mentioned technical effects, the technical scheme of the application is as follows:

[0006] A bimetallic joint for RTP pipe comprises a metal matrix pipe inner cylinder and a metal matrix pipe outer cylinder, the metal matrix pipe outer cylinder is welded to the outer wall of the metal matrix pipe inner cylinder at the front end, the rear end of the metal matrix pipe inner cylinder exceeds the rear end of the metal matrix pipe outer cylinder, a ring gap for pipe insertion is formed between the metal matrix pipe inner cylinder and the metal matrix pipe outer cylinder, and the inner wall and end face of the metal matrix pipe inner cylinder are processed with an integrated corrosion-resistant metal layer by one forming process.

[0007] Further, when it is a fixed flange type, the front end of the metal matrix pipe inner cylinder is provided with a metal matrix flange, the metal matrix flange and the metal matrix pipe inner cylinder are welded to each other, the front end face of the metal matrix pipe inner cylinder is provided with a corrosion-resistant metal layer, the corrosion-resistant metal layer of the front end face extends to the outside of the metal matrix flange, and the corrosion-resistant metal layer of the inner wall of the metal matrix pipe inner cylinder and the corrosion-resistant metal layer outside the metal matrix flange are processed by one forming process.

[0008] Further, when it is a fixed flange type or a loose flange type, the outside of the corrosion-resistant metal layer on the front end face of the metal matrix pipe inner cylinder is provided with a sealing groove for mounting a sealing gasket or a sealing ring.

[0009] Further, when it is a loose flange type, the front end of the metal matrix pipe inner cylinder is provided with a metal matrix flange, the loose flange is tightly attached to the inside of the metal matrix flange, the front end face of the metal matrix pipe inner cylinder is provided with a corrosion-resistant metal layer, the corrosion-resistant metal layer of the front end face extends to the outside of the metal matrix flange, the outside of the metal matrix flange is provided with a sealing groove for mounting a sealing gasket or a sealing ring, and the corrosion-resistant metal layer of the inner wall of the metal matrix pipe inner cylinder and the corrosion-resistant metal layer outside the metal matrix flange are processed by one forming process.

[0010] When it is a pipe-to-pipe direct type, each end of the metal matrix pipe inner cylinder is connected with a metal matrix pipe outer cylinder, and the corrosion-resistant metal layer of the metal matrix pipe inner cylinder extends from one end to the other end.

[0011] Further, the thickness of the corrosion-resistant metal layer is 0.2mm to 5mm.

[0012] Further, the thickness of the corrosion-resistant metal layer at the rear end of the metal matrix pipe inner cylinder is greater than or equal to the thickness of the corrosion-resistant metal layer of the inner wall of the metal matrix pipe inner cylinder, and the thickness of the corrosion-resistant metal layer outside the flange end of the front end of the metal matrix pipe inner cylinder is greater than or equal to the thickness of the corrosion-resistant metal layer of the inner wall of the metal matrix pipe inner cylinder.

[0013] Further, an O-shaped sealing ring groove is arranged on the corrosion-resistant metal layer in the ring gap, and an O-shaped sealing ring is arranged in the O-shaped sealing ring groove, so as to prevent small gas molecules from escaping along the inner wall of the pipe to corrode the metal matrix of the pipe and the metal reinforcement of the pipe.

[0014] Further, the inner diameter of the metal matrix pipe inner cylinder is D, the annular gap length for inserting the pipe material is L, and L is 3 to 8 times of D.

[0015] Further, the outer wall of the metal matrix pipe inner cylinder and the inner wall of the metal matrix pipe outer cylinder are respectively turned with U-shaped teeth in the annular gap region, the U-shaped teeth depth is ≤1.5mm, and the U-shaped teeth spacing is ≤8mm.

[0016] Further, the rear end of the metal matrix pipe inner cylinder is 5mm-20mm longer than the rear end of the metal matrix pipe outer cylinder.

[0017] Still further, the metal matrix part of the metal matrix pipe inner cylinder is shorter than the metal matrix pipe outer cylinder, and the inner side and the rear end of the metal matrix part are both the corrosion-resistant metal layer.

[0018] Further, the metal matrix pipe inner cylinder is a stainless steel matrix pipe inner cylinder, and the metal matrix pipe outer cylinder is a stainless steel matrix pipe outer cylinder.

[0019] The advantages of the present application are:

[0020] 1. The utility model can adopt conventional metal (such as stainless steel 316, carbon steel after surface passivation) as the pipe body, which is beneficial to the one-time forming of the corrosion-resistant metal layer on the inner layer of the pipe inner cylinder, the insertion end inner cylinder and the connecting end face by heat spraying, surfacing or hot casting and pressing process, so that the pipe can not only bear pressure and resist the rapid corrosion of H2S and other metal pipes, but also significantly reduce the cost of the pipe.

[0021] 2. The inner layer corrosion-resistant metal of the present application is one-piece with the corrosion-resistant metal of the front end and the rear end of the pipe, and the pipe inner cylinder insertion end has a long corrosion-resistant metal segment, and the sealing ring is arranged thereon to prevent H2S gas from escaping from the inner wall and corroding the pipe base material.

[0022] 3. One end of the pipe outer cylinder of the present application is welded with the outer surface of the pipe inner cylinder, after the RTP pipe material is inserted, the pipe is made by the inner expansion and outer contraction pipe manufacturing equipment, so that the pipe inner and outer cylinders are pressed on the inner layer plastic and outer layer plastic of the RTP pipe material, and the small and dense U-shaped teeth of the RTP pipe inner and outer cylinders stably hold the inner and outer layer plastic of the RTP pipe material, which can bear the axial tension and fluid pressure of the pipe material while avoiding the damage of the RTP pipe reinforcing layer caused by excessive extrusion. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a fixed type double metal RTP pipe joint schematic diagram of the present application.

[0024] Figure 2 It is a partial A enlarged view of Figure 1 .

[0025] Figure 3 Figure 1 is a schematic view of a pipe joint according to the present application. Figure 1 Figure 2 is a partial B enlarged view of Figure 1.

[0026] Figure 4 Figure 3 is a partial C enlarged view of Figure 1. Figure 1

[0027] Figure 5 Figure 4 is a schematic view of an active French double metal RTP pipe joint according to the present application.

[0028] Figure 6 Figure 5 is a schematic view of a pipe-to-pipe direct double metal RTP pipe joint according to the present application.

[0029] Figure 7 Figure 6 is a schematic view of a pipe and double metal fitting assembly according to the present application.

[0030] Figure 8 Figure 7 is a schematic view of a pipe end sealing according to the present application.

[0031] Figure 9 Figure 8 is a schematic view of another structure of the excess portion in Example 2.

[0032] In the drawings: 1 - metal base fitting inner cylinder, 2 - metal base fitting outer cylinder, 3 - annular gap, 4 - corrosion resistant metal layer, 5 - metal base flange, 6 - sealing groove, 7 - metal base flange, 8 - loose flange, 9 - metal base portion, 10 - O-ring groove, 11 - O-ring, 12 - U-shaped tooth, 13 - sealing gasket, 14 - plastic inner layer, 15 - plastic outer layer, 16 - metal reinforcing layer, 17 - RTP pipe, 18 - sealing ring. DETAILED DESCRIPTION

[0033] In order to make the objects, technical solutions, and advantages of the embodiments of the present application clearer, the following will be combined with the drawings for the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0034] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present application.

[0035] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. ​

[0036] In the description of the present application, it should be noted that the terms "upper", "vertical", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly understood by those skilled in the art, or the orientation or positional relationship commonly understood by those skilled in the art, or the orientation or positional relationship commonly understood by those skilled in the art, only for the convenience of describing the present application and simplifying the description, and cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" and the like are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0037] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "set", "mount", "connect" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0038] Embodiment 1

[0039] A bimetallic joint for RTP pipe comprises a metal matrix pipe inner cylinder 1 and a metal matrix pipe outer cylinder 2, the metal matrix pipe outer cylinder 2 is welded at the front end of the outer wall of the metal matrix pipe inner cylinder 1, the rear end of the metal matrix pipe inner cylinder 1 exceeds the rear end of the metal matrix pipe outer cylinder 2, an annular gap 3 for pipe insertion is formed between the metal matrix pipe inner cylinder 1 and the metal matrix pipe outer cylinder 2, and the inner wall and end face of the metal matrix pipe inner cylinder 1 are processed with an integral structure of corrosion-resistant metal layer 4 by one-time forming. The corrosion-resistant metal is, for example, duplex stainless steel 2205, 2207, nickel-based alloy UNS N06625. The pipe fittings are fixed flange type ( Figure 1 ), loose flange 8 type ( Figure 5 ), pipe-to-pipe direct type ( Figure 6 ) and other types (such as wire sleeve nut connection type, clamping connection type). A special H2S corrosion-resistant corrosion-resistant metal layer 4 (such as Figure 1 ) is arranged on the inner wall, front end face and rear end face of the metal matrix pipe. The integral structure of one-time forming mentioned here refers to the processing of the corrosion-resistant metal layer 4 to the inner wall and end face of the metal matrix pipe inner cylinder 1 by one-time forming process, rather than using two-time forming process or multiple forming process to process the corrosion-resistant metal layer 4 on the inner wall and end face of the metal matrix pipe inner cylinder 1 respectively, and finally connecting the corrosion-resistant metal layers 4 together.

[0040] Embodiment 2

[0041] As Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 7 shown, a bimetallic joint for RTP pipe comprises a metal matrix pipe inner cylinder 1 and a metal matrix pipe outer cylinder 2, the metal matrix pipe outer cylinder 2 is welded at the front end of the outer wall of the metal matrix pipe inner cylinder 1, the rear end of the metal matrix pipe inner cylinder 1 exceeds the rear end of the metal matrix pipe outer cylinder 2, an annular gap 3 for pipe insertion is formed between the metal matrix pipe inner cylinder 1 and the metal matrix pipe outer cylinder 2, and the inner wall and end face of the metal matrix pipe inner cylinder 1 are processed with an integral structure of corrosion-resistant metal layer 4 by one-time forming. The corrosion-resistant metal is, for example, duplex stainless steel 2205, 2207, and nickel-based alloy UNS N06625. The pipe fittings are divided into fixed flange type ( Figure 1 ), loose flange 8 type ( Figure 5 ), pipe-to-pipe direct type ( Figure 6 ), and other types (such as wire sleeve nut connection type, clamping connection type). A layer of special H2S corrosion-resistant metal layer 4 is provided on the inner wall, front end face, and rear end face of the metal matrix pipe. Figure 1 The one-time forming integral structure mentioned here refers to the processing of the corrosion-resistant metal layer 4 on the inner wall and end face of the metal matrix pipe inner cylinder 1 by one-time forming process, rather than using a two-time forming process or multiple forming processes to process the corrosion-resistant metal layer 4 on the inner wall and end face of the metal matrix pipe inner cylinder 1 respectively, and finally connecting the corrosion-resistant metal layers 4 together.

[0042] The thickness of the corrosion-resistant metal layer 4 is 0.2mm to 5mm.

[0043] The thickness of the corrosion-resistant metal layer 4 at the rear end of the metal matrix pipe inner cylinder 1 is greater than or equal to the thickness of the corrosion-resistant metal layer 4 on the inner wall of the metal matrix pipe inner cylinder 1, and the thickness of the corrosion-resistant metal layer 4 on the outer side of the flange end of the metal matrix pipe inner cylinder 1 is greater than or equal to the thickness of the corrosion-resistant metal layer 4 on the inner wall of the metal matrix pipe inner cylinder 1. The outer side of the flange end refers to the corrosion-resistant metal layer 4 on the outer side of the metal matrix flange 5 or the outer side of the metal matrix flange 7.

[0044] An O-ring groove 10 is provided on the corrosion-resistant metal layer 4 in the annular gap 3, and an O-ring 11 is provided in the O-ring groove 10. To prevent small gas molecules from escaping along the inner wall of the pipe and corroding the metal matrix of the pipe fitting and the metal reinforcement of the pipe. The O-ring 11 can prevent crude oil and corrosive gas from seeping in and corroding the pipe reinforcement and the pipe fitting. Among them, it is mainly to prevent the corrosion of conventional metals by strong corrosive gases such as H2S contained in crude oil production.

[0045] The inner diameter of the metal base pipe fitting inner cylinder 1 is D, the length of the annular gap 3 for inserting the pipe material is L, and L is 3 to 8 times D. The effective length of the pipe material connection in the present application is longer than that of the prior art, which can increase the contact area between the pipe fitting and the pipe material and increase the friction force, i.e. can reduce the amount of inner expansion and outer contraction when making the joint, so as to avoid excessive extrusion of the pipe wall, causing stress concentration or damage to the pipe material reinforcement, affecting the delivery pressure, and the pipe material ruptures from the pipe fitting under high pressure.

[0046] In the annular gap 3 area, the outer wall of the metal base pipe fitting inner cylinder 1 and the inner wall of the metal base pipe fitting outer cylinder 2 are respectively turned with U-shaped teeth 12, the depth of the U-shaped teeth 12 is ≤1.5mm, and the spacing of the U-shaped teeth 12 is ≤8mm. Under the premise of ensuring that the pipe fitting effectively clamps and presses the inner and outer layers of the pipe material to bear the axial tension, the extrusion damage of the pipe wall reinforcing layer by the inner expansion and outer contraction during joint making is minimized.

[0047] The rear end of the metal base pipe fitting inner cylinder 1 exceeds the rear end of the metal base pipe fitting outer cylinder 2 by 5-20mm, as shown in Figure 9 The inner side, rear end and outer wall of the excess part of the metal base pipe fitting inner cylinder 1 have an integral corrosion-resistant metal layer 4. The advantages of this arrangement are that it is convenient for the pipe material to be inserted, and the stress between the pipe fitting and the pipe material at the insertion point is not on the same plane.

[0048] The metal base part 9 of the metal base pipe fitting inner cylinder 1 is shorter than the metal base pipe fitting outer cylinder 2, and the inner side and rear end of the metal base part 9 are both corrosion-resistant metal layers 4. This can better ensure the corrosion resistance and sealing of the insertion end.

[0049] The metal base pipe fitting inner cylinder 1 is a stainless steel base pipe fitting inner cylinder, and the metal base pipe fitting outer cylinder 2 is a stainless steel base pipe fitting outer cylinder.

[0050] As shown in Figure 8 The pipe material inserted into the pipe fitting is sealed in advance, which can better avoid the entry of strong corrosive gases such as H2S into the metal reinforcement layer to corrode the reinforcement layer. The specific method is: turning a bevel on the inner and outer layers of the pipe material end face, heating the bevel and the corresponding special sealing ring hot melt butt joint surface, then fusing the special sealing ring hot melt butt joint surface and the pipe material end face bevel under certain pressure when both surfaces are in a molten state, to complete the hot melt sealing.

[0051] Example 3

[0052] As shown in Figure 5As shown, a bimetallic joint for RTP pipe comprises a metal matrix pipe inner cylinder 1 and a metal matrix pipe outer cylinder 2, the metal matrix pipe outer cylinder 2 is welded at the front end of the outer wall of the metal matrix pipe inner cylinder 1, the rear end of the metal matrix pipe inner cylinder 1 exceeds the rear end of the metal matrix pipe outer cylinder 2, an annular gap 3 for pipe insertion is formed between the metal matrix pipe inner cylinder 1 and the metal matrix pipe outer cylinder 2, and the inner wall and end face of the metal matrix pipe inner cylinder 1 are processed by one-time forming to have an integrated structure of a corrosion-resistant metal layer 4. The corrosion-resistant metal is, for example, duplex stainless steel 2205, 2207, and nickel-based alloy UNSN06625. The pipe fittings include fixed flange type ( Figure 1 ), loose flange 8 type ( Figure 5 ), pipe-to-pipe direct type ( Figure 6 ), and other types (such as a wire sleeve nut connection type, a clamping connection type). A special H2S corrosion-resistant corrosion-resistant metal layer 4 (such as Figure 1 ) is arranged on the inner wall, front end face, and rear end face of the metal matrix pipe. The integrated structure of one-time forming mentioned here refers to the corrosion-resistant metal layer 4 being processed on the inner wall and end face of the metal matrix pipe inner cylinder 1 by one-time forming process, rather than using a two-time forming process or multiple forming processes to process the corrosion-resistant metal layer 4 on the inner wall and end face of the metal matrix pipe inner cylinder 1 respectively, and finally connecting the corrosion-resistant metal layers 4 together.

[0053] When it is a loose flange 8 type, the front end of the metal matrix pipe inner cylinder 1 is provided with a metal matrix flange 7, the loose flange 8 is tightly attached to the inner side of the metal matrix flange 7, the front end face of the metal matrix pipe inner cylinder 1 is provided with a corrosion-resistant metal layer 4, the corrosion-resistant metal layer 4 of the front end face extends to the outer side of the metal matrix flange 7, and the outer side of the metal matrix flange 7 is provided with a sealing groove 6 for mounting a sealing gasket 13 or a sealing ring, and the corrosion-resistant metal layer 4 of the inner wall of the metal matrix pipe inner cylinder 1 and the corrosion-resistant metal layer 4 of the outer side of the metal matrix flange 7 are processed by one-time forming process. The loose flange 8 can be a stainless steel flange or a carbon steel flange, and the metal matrix flange 7 can be a stainless steel matrix flange. As Figure 5 , the end face is provided with a sealing gasket 13, a sealing ring, or other forms of sealing ring groove and places the corresponding sealing ring for sealing connection. Preventing the leakage of the transported liquid and the sulfurized gas contained therein from the end face.

[0054] The thickness of the corrosion-resistant metal layer 4 is 0.2mm to 5mm.

[0055] The thickness of the corrosion-resistant metal layer 4 at the rear end of the metal base pipe fitting inner cylinder 1 is greater than or equal to the thickness of the corrosion-resistant metal layer 4 on the inner wall of the metal base pipe fitting inner cylinder 1, and the thickness of the corrosion-resistant metal layer 4 on the outer side of the flange end of the metal base pipe fitting inner cylinder 1 is greater than or equal to the thickness of the corrosion-resistant metal layer 4 on the inner wall of the metal base pipe fitting inner cylinder 1. The outer side of the flange end refers to the corrosion-resistant metal layer 4 on the outer side of the metal base flange 5 or the outer side of the metal base flange 7.

[0056] An O-shaped sealing ring groove 10 is arranged on the corrosion-resistant metal layer 4 in the annular gap 3, and an O-shaped sealing ring 11 is arranged in the O-shaped sealing ring groove 10. The O-shaped sealing ring 11 can prevent small gas molecules from escaping along the inner wall of the pipe and corroding the metal reinforcement of the pipe fitting and the pipe. The O-shaped sealing ring 11 can prevent the transported crude oil and corrosive gas from seeping in from here and corroding the pipe reinforcement and the pipe fitting. Among them, it is mainly to prevent the corrosion of conventional metals by strong corrosive gases such as H2S contained in crude oil production.

[0057] The inner diameter of the metal base pipe fitting inner cylinder 1 is D, the length of the annular gap 3 for inserting the pipe is L, and L is 3 to 8 times D. The effective length of the pipe connection in the present application is longer than that of the prior art, which can increase the contact area between the pipe fitting and the pipe, increase the friction, and reduce the amount of internal expansion and external contraction during joint manufacturing, so as to prevent excessive extrusion of the pipe wall, causing stress concentration or damage to the pipe reinforcement, affecting the transportation pressure, and causing the pipe to break at the pipe fitting under high pressure.

[0058] In the annular gap 3 region, the outer wall of the metal base pipe fitting inner cylinder 1 and the inner wall of the metal base pipe fitting outer cylinder 2 are respectively turned with U-shaped teeth 12, the depth of the U-shaped teeth 12 is ≤1.5mm, and the spacing of the U-shaped teeth 12 is ≤8mm. Under the premise of ensuring that the pipe fitting effectively clamps and presses the inner and outer layers of the pipe plastic to bear the axial tension, the extrusion damage of the pipe wall reinforcement layer during joint manufacturing is minimized.

[0059] The rear end of the metal base pipe fitting inner cylinder 1 exceeds the rear end of the metal base pipe fitting outer cylinder 2 by 5mm-20mm, as shown in Figure 9 The excess part of the metal base pipe fitting inner cylinder 1 has an integral corrosion-resistant metal layer 4 on the inner side, rear end and outer wall. The advantage of this arrangement is that it is convenient for the pipe to be inserted, and the stress between the pipe fitting and the pipe at the insertion point is not on the same plane.

[0060] The metal base part 9 of the metal base pipe fitting inner cylinder 1 is shorter than the metal base pipe fitting outer cylinder 2, and the inner side and rear end of the metal base part 9 are both corrosion-resistant metal layers 4. This can better ensure the corrosion resistance and sealing of the insertion end.

[0061] The metal base pipe fitting inner cylinder 1 is a stainless steel base pipe fitting inner cylinder, and the metal base pipe fitting outer cylinder 2 is a stainless steel base pipe fitting outer cylinder.

[0062] Example 4

[0063] As shown in Figure 6 A bimetallic joint for RTP pipe comprises a metal matrix pipe inner cylinder 1 and a metal matrix pipe outer cylinder 2, the metal matrix pipe outer cylinder 2 is welded to the outer wall of the metal matrix pipe inner cylinder 1 at the front end, the rear end of the metal matrix pipe inner cylinder 1 exceeds the rear end of the metal matrix pipe outer cylinder 2, the annular gap 3 for pipe insertion is formed between the metal matrix pipe inner cylinder 1 and the metal matrix pipe outer cylinder 2, the inner wall and end face of the metal matrix pipe inner cylinder 1 are processed with an integrated corrosion-resistant metal layer 4 by one-time forming. The corrosion-resistant metal is, for example, duplex stainless steel 2205, 2207, nickel-based alloy UNSN06625. The pipe fittings include fixed flange type Figure 1 , loose flange type 8 Figure 5 , pipe-to-pipe direct type Figure 6 and other types (such as wire sleeve nut connection type, clamping connection type). A layer of special H2S corrosion-resistant metal layer 4 is arranged on the inner wall, front end face and rear end face of the metal matrix pipe. Figure 1 The integrated structure of one-time forming mentioned here refers to the corrosion-resistant metal layer 4 being processed to the inner wall and end face of the metal matrix pipe inner cylinder 1 by one-time forming process, rather than using two-time forming process or multiple forming process to process the corrosion-resistant metal layer 4 to the inner wall and end face of the metal matrix pipe inner cylinder 1 respectively, and then connecting the corrosion-resistant metal layers 4 together.

[0064] When it is a pipe-to-pipe direct type, one metal matrix pipe outer cylinder 2 is connected to each end of the metal matrix pipe inner cylinder 1, and the corrosion-resistant metal layer 4 of the metal matrix pipe inner cylinder 1 extends from one end to the other end.

[0065] The thickness of the corrosion-resistant metal layer 4 is 0.2mm to 5mm.

[0066] An O-ring groove 10 is arranged on the corrosion-resistant metal layer 4 in the annular gap 3, and an O-ring 11 is arranged in the O-ring groove 10. It can prevent small gas molecules from escaping along the inner wall of the pipe to corrode the metal matrix of the pipe fitting and the metal reinforcement of the pipe. The O-ring 11 can prevent crude oil and corrosive gas from seeping in from here to corrode the pipe reinforcement and the pipe fitting. Among them, it is mainly to prevent the corrosion of conventional metals by strong corrosive gases such as H2S contained in crude oil production.

[0067] The inner diameter of the metal matrix pipe inner cylinder 1 is D, and the length of the annular gap 3 for inserting the pipe is L, and L is 3 to 8 times of D. The effective length of the pipe connection in the present application is longer than that of the prior art, which can increase the contact area between the pipe fitting and the pipe, increase the friction, that is, it can reduce the amount of inner expansion and outer contraction when making the joint, so as to avoid excessive extrusion of the pipe wall, causing stress concentration or damage to the pipe reinforcement, affecting the conveying pressure, and the pipe may be broken from the pipe fitting under high pressure.

[0068] In the annular gap 3 region, the outer wall of the metal base inner tube 1 and the inner wall of the metal base outer tube 2 are respectively turned with U-shaped teeth 12, the depth of the U-shaped teeth 12 is ≤1.5mm, and the interval of the U-shaped teeth 12 is ≤8mm. Under the premise of ensuring that the pipe fitting effectively clamps and presses the inner and outer layers of the pipe material, so as to bear the axial tension, the extrusion damage of the pipe wall reinforcing layer caused by the inner expansion and the outer shrink during the joint manufacturing is minimized.

[0069] The rear end of the metal base inner tube 1 exceeds the rear end of the metal base outer tube 2 by 5mm-20mm, as shown in the figure, the inner side, the rear end and the outer wall of the exceeding part of the metal base inner tube 1 are provided with an integral corrosion-resistant metal layer 4, the corrosion-resistant metal layer 4 wraps the metal base part 9 of the rear end from the outside and extends to the upper surface of the metal base 9, covering the annular gap entrance part, which has the advantages of facilitating the insertion of the pipe material and the stress of the pipe fitting and the pipe material at the insertion part not being in the same plane. Figure 9

[0070] The metal base part 9 of the metal base inner tube 1 is shorter than the metal base outer tube 2, and the inner side and the rear end of the metal base part 9 are both provided with the corrosion-resistant metal layer 4, which can better ensure the corrosion resistance and sealing of the insertion end.

[0071] The metal base inner tube 1 is a stainless steel base inner tube, and the metal base outer tube 2 is a stainless steel base outer tube.​

Claims

1. A bimetallic joint for RTP tubes comprising a metal matrix tube inner cylinder (1) and a metal matrix tube outer cylinder (2), characterized in that: The metal base pipe outer cylinder (2) is welded at the front end of the metal base pipe inner cylinder (1), the rear end of the metal base pipe inner cylinder (1) is beyond the rear end of the metal base pipe outer cylinder (2), and the annular gap (3) for inserting the pipe is formed between the metal base pipe inner cylinder (1) and the metal base pipe outer cylinder (2).

2. The bimetallic joint for RTP tube according to claim 1, characterized in that: The metal base pipe inner cylinder (1) is provided with a metal base flange (5) at the front end, the metal base flange (5) and the metal base pipe inner cylinder (1) are welded with each other, the front end surface of the metal base pipe inner cylinder (1) is provided with the corrosion-resistant metal layer (4), the corrosion-resistant metal layer (4) of the front end surface extends to the outside of the metal base flange (5), and the corrosion-resistant metal layer (4) of the inner wall of the metal base pipe inner cylinder (1) and the corrosion-resistant metal layer (4) outside the metal base flange (5) are processed by one-time forming process.

3. The bimetallic joint for RTP tubes according to claim 2, characterized in that: The outside of the corrosion-resistant metal layer (4) on the front end surface of the metal base pipe inner cylinder (1) is provided with a sealing groove (6) for mounting a sealing gasket (13) or a sealing ring.

4. The bimetallic joint for RTP tubes according to claim 1, characterized in that: The metal base pipe inner cylinder (1) is provided with a metal base flange (5) at the front end, the metal base flange (5) and the metal base pipe inner cylinder (1) are welded with each other, the front end surface of the metal base pipe inner cylinder (1) is provided with the corrosion-resistant metal layer (4), the corrosion-resistant metal layer (4) of the front end surface extends to the outside of the metal base flange (5), and the corrosion-resistant metal layer (4) of the inner wall of the metal base pipe inner cylinder (1) and the corrosion-resistant metal layer (4) outside the metal base flange (5) are processed by one-time forming process.

5. The bimetallic joint for RTP tubes according to claim 1, characterized in that: The metal base pipe inner cylinder (1) is provided with a metal base flange (5) at the front end, the metal base flange (5) and the metal base pipe inner cylinder (1) are welded with each other, the front end surface of the metal base pipe inner cylinder (1) is provided with the corrosion-resistant metal layer (4), the corrosion-resistant metal layer (4) of the front end surface extends to the outside of the metal base flange (5), and the corrosion-resistant metal layer (4) of the inner wall of the metal base pipe inner cylinder (1) and the corrosion-resistant metal layer (4) outside the metal base flange (5) are processed by one-time forming process.

6. The bimetallic joint for RTP tubes according to claim 1, characterized in that: The metal base pipe inner cylinder (1) is provided with a metal base flange (5) at the front end, the metal base flange (5) and the metal base pipe inner cylinder (1) are welded with each other, the front end surface of the metal base pipe inner cylinder (1) is provided with the corrosion-resistant metal layer (4), the corrosion-resistant metal layer (4) of the front end surface extends to the outside of the metal base flange (5), and the corrosion-resistant metal layer (4) of the inner wall of the metal base pipe inner cylinder (1) and the corrosion-resistant metal layer (4) outside the metal base flange (5) are processed by one-time forming process.

7. The bimetallic joint for RTP tube according to claim 2 or 4, characterized in that: The metal base pipe inner cylinder (1) is provided with a metal base flange (5) at the front end, the metal base flange (5) and the metal base pipe inner cylinder (1) are welded with each other, the front end surface of the metal base pipe inner cylinder (1) is provided with the corrosion-resistant metal layer (4), the corrosion-resistant metal layer (4) of the front end surface extends to the outside of the metal base flange (5), and the corrosion-resistant metal layer (4) of the inner wall of the metal base pipe inner cylinder (1) and the corrosion-resistant metal layer (4) outside the metal base flange (5) are processed by one-time forming process.

8. The bimetallic joint for RTP tube according to claim 1, characterized in that: The metal base pipe inner cylinder (1) is provided with a metal base flange (5) at the front end, the metal base flange (5) and the metal base pipe inner cylinder (1) are welded with each other, the front end surface of the metal base pipe inner cylinder (1) is provided with the corrosion-resistant metal layer (4), the corrosion-resistant metal layer (4) of the front end surface extends to the outside of the metal base flange (5), and the corrosion-resistant metal layer (4) of the inner wall of the metal base pipe inner cylinder (1) and the corrosion-resistant metal layer (4) outside the metal base flange (5) are processed by one-time forming process.

9. The bimetallic joint for RTP tubes according to claim 1, characterized in that: The metal base pipe inner cylinder (1) is provided with a metal base flange (5) at the front end, the metal base flange (5) and the metal base pipe inner cylinder (1) are welded with each other, the front end surface of the metal base pipe inner cylinder (1) is provided with the corrosion-resistant metal layer (4), the corrosion-resistant metal layer (4) of the front end surface extends to the outside of the metal base flange (5), and the corrosion-resistant metal layer (4) of the inner wall of the metal base pipe inner cylinder (1) and the corrosion-resistant metal layer (4) outside the metal base flange (5) are processed by one-time forming process.

10. The bimetallic joint for RTP tubes according to claim 1, characterized in that: The metal base pipe inner cylinder (1) is provided with a metal base flange (5) at the front end, the metal base flange (5) and the metal base pipe inner cylinder (1) are welded with each other, the front end surface of the metal base pipe inner cylinder (1) is provided with the corrosion-resistant metal layer (4), the corrosion-resistant metal layer (4) of the front end surface extends to the outside of the metal base flange (5), and the corrosion-resistant metal layer (4) of the inner wall of the metal base pipe inner cylinder (1) and the corrosion-resistant metal layer (4) outside the metal base flange (5) are processed by one-time forming process.

11. The bimetallic joint for RTP tubes according to claim 1, characterized in that: The rear end of the metal base inner tube (1) is 5-20mm longer than the rear end of the metal base outer tube (2).

12. The bimetallic joint for an RTP tube according to claim 11, characterized in that: The metal base part (9) of the metal base inner tube (1) is shorter than the metal base outer tube (2), and the inner side and the rear end of the metal base part (9) are both covered by a corrosion-resistant metal layer (4).

13. The bimetallic joint for RTP tubes according to claim 1, characterized in that: The metal base inner tube (1) is a stainless steel base inner tube, and the metal base outer tube (2) is a stainless steel base outer tube.

14. The bimetallic joint for RTP tube according to claim 1, characterized in that: An RTP pipe with a metal reinforcing layer inserted in the pipe wall is inserted into the annular gap (3), and the RTP pipe is sealed by end faces. An RTP pipe with a metal reinforcing layer inserted in the pipe wall is inserted into the annular gap (3), and the RTP pipe is sealed by end faces.

Images