Device and method for testing bonding strength of oil and gas conveying composite pipe

Abstract

The invention belongs to the technical field of oil and gas conveying composite pipes, and particularly relates to a device and a method for testing the bonding strength of an oil and gas conveying composite pipe. The device for testing the bonding strength of the oil and gas transmission composite pipe comprises a testing platform, a first through hole and a second through hole, wherein the testing platform is provided with a first through hole along the vertical direction; the at least one positioning mechanism is arranged on the testing platform and is coaxial with the first through hole, and the positioning mechanism is used for positioning the composite pipe to be tested to be coaxial with the first through hole; and the pressing die is arranged at the top of the composite pipe and is used for applying axial pressure to the lining layer of the composite pipe. According to the invention, the bonding strength of the composite pipe can be tested.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas transportation composite pipes, and in particular, relates to a bonding strength testing device for oil and gas transportation composite pipes and a bonding strength testing method for oil and gas transportation composite pipes. Background Art

[0002] With the development of oil and gas resources, fiber reinforced composite pipe (RTP) is widely used in the field of oil and gas gathering and transportation due to its advantages such as light weight, flexible coiling and corrosion resistance. RTP pipe is usually composed of an inner lining layer made of polymer material, a reinforcement layer made of continuous fiber material and an outer protective layer made of anti-aging and impact thermoplastic plastic.

[0003] The main function of the lining layer is to seal and transport materials to prevent leakage; the main function of the reinforcement layer is to provide the required pressure bearing capacity of the pipe body; the main function of the outer protective layer is to protect the entire pipe body.

[0004] The inner lining material of RTP pipe is generally made of high-density polyethylene (HDPE). HDPE has good anti-seepage performance against water vapor. Oil and gas gathering and transportation are usually medium- and high-pressure oil and gas, which often contain small molecular permeable media such as oxygen, carbon dioxide, hydrogen sulfide, and methane. HDPE has poor anti-seepage performance against oxygen, carbon dioxide, hydrogen sulfide, methane, etc. in high-pressure oil and gas.

[0005] If the bonding strength between the lining layer and the reinforcement layer material is insufficient, the infiltrated high-pressure oil and gas will gather in the secondary molding area between the lining layer and the reinforcement fiber winding layer, and wrinkling and bulging instability will easily occur under the action of external loads, which will reduce the flow area of ​​the pipeline, causing the pipeline to fail to pass normally and preventive internal inspection of the pipeline to fail to be carried out normally, affecting the normal transportation of oil and gas.

[0006] Therefore, in oil and gas gathering and transportation production, the different layers of RTP pipes need to achieve a certain bonding strength to meet usage requirements.

[0007] GB / T28897 Steel-plastic composite pipes and fittings for fluid transportation stipulates the determination of the bonding strength of composite pipes. The method described in the regulations is only an ideal situation and has great difficulties in actual implementation.

[0008] Chinese patent document CN211179484U discloses a device for detecting the plastic bonding strength of the inner lining of a steel-plastic composite pipe, comprising a press and a washer, wherein a test platform is arranged on the press, and the washer comprises an upper cylindrical part and a lower cylindrical part, wherein the upper cylindrical part and the lower cylindrical part are arranged with a common central axis, wherein the outer diameter of the lower cylindrical part is smaller than the outer diameter of the upper cylindrical part, and a groove is vertically arranged on the side wall of the upper cylindrical part, wherein the groove runs through the entire upper cylindrical part; wherein the height of the lower cylindrical part is 2-4 mm; wherein a through hole is arranged in the middle of the washer, wherein the through hole passes through the entire washer; the utility model facilitates the positioning between the test washer and the plastic inner lining pipe in the steel-plastic composite pipe, wherein the washer can be conveniently and accurately pressed completely on the plastic inner lining pipe, and there is no need for alignment between the test platform and the test piece, while effectively avoiding the test error caused by the washer pressing on the weld bead on the inner wall of the steel pipe outside the steel-plastic composite pipe.

[0009] Chinese patent document CN110501284A discloses a device and method for testing the bonding strength of composite pipes under heat loading conditions, which belongs to the technical field of composite pipe bonding strength performance testing. It includes a high-strength pressure-bearing frame, a pressure system, a heating and insulation box, and an adjustable bracket; the pressure system is fixed in the high-strength pressure-bearing frame; a variable-diameter pressure head is inserted into the heating and insulation box, and the composite pipe to be tested is placed on the variable-diameter pressure head, and the upper end face of the variable-diameter pressure head only contacts the lower end face of the inner pipe of the composite pipe to be tested, and the height of the heating and insulation box body is basically flush with the upper end face of the test pipe section, and the upper cover of the heating and insulation box is covered, and the upper cover of the heating and insulation box contacts the high-strength frame, and the lower surface of the upper cover of the heating and insulation box only contacts the upper end face of the outer pipe of the composite pipe to be tested; turn on the power of the heating and insulation box, heat it to the required test temperature, keep it warm after the temperature stabilizes, load pressure, observe the pressure change, and when the pressure reaches the maximum value and begins to drop significantly, it means that shear failure has occurred in the composite pipe, and the pressure value of this process is recorded.

[0010] Chinese patent document CN110132839A discloses a die and method for testing the interface bonding strength of a base-coated tube of a bimetallic composite tube, which relates to the field of material performance testing, including an upper die plate and a lower die seat; the upper die plate and the lower die seat are connected by a guide column; the upper die seat is installed with an upper die seat, the upper die seat is installed with a punch block, and the lower die seat is provided with a lower die blade; a stepped hole is provided at the center of the lower die blade; the outer diameter of the punch block is the same as the inner diameter of the outer tube of the base-coated tube, and the inner diameter of one hole in the stepped hole in the lower die blade is the same as the outer diameter of the punch block that matches it. The punch block and the upper die seat are detachably connected, and only the punch block can be replaced. The lower die blade adopts a one-die-multiple-blade design, and one lower die blade can perform compression shear tests on multiple samples, which is easy to operate and greatly reduces the cost; the number of mold parts is small, the structure is simple, and it is easy to use and maintain, and the mold has a long service life.

[0011] Chinese patent document CN207675563U discloses a composite pipe bonding strength test device, including a base and a plurality of test tube rings arranged on the base, the test tube rings and the base are positioned and connected by corresponding positioning magnets, the spacing between adjacent test tube rings is 0.5-1mm, and all test tube rings are provided with coaxial fixing holes. It meets the standard requirements for shear strength test devices, is easy to adjust, easy to use, and can effectively improve experimental efficiency; a single fixture can be used for testing the bonding strength of composite pipes with different wall thicknesses, all test tube rings are provided with coaxial fixing holes, which can achieve the fixation of all test tube rings, and the test tube rings are also magnetically connected and fixed to the base, which is convenient to carry; the cooperation of the positioning magnets between the test tube rings and the base can also make the fixing holes on the test tube rings instantly positioned.

[0012] Chinese patent document CN206002426U discloses a mold for testing the bonding strength between steel and plastic of a plastic-lined composite steel pipe, including a lower mold, an upper mold and a mold core, wherein the upper mold is arranged at the upper end of the lower mold, the upper mold has a slide groove, the mold core is slidably arranged in the slide groove of the upper mold, the inner wall of the lower end of the upper mold is recessed downward to form a right-angled fixed through groove, the lower mold includes a cylindrical hollow mold body, the inner side of the inner wall of the upper end of the lower mold is recessed downward to form a right-angled pressing groove, and the fixed through groove is arranged corresponding to the pressing groove position. The utility model design can cooperate with a pressure testing machine to test the bonding strength between steel and plastic of a plastic-lined composite steel pipe, supports enterprises to independently sample and test products by batch, improves production efficiency, and realizes the quality concept of not leaving the factory with unqualified products.

[0013] Chinese patent document CN205209898U discloses a plastic-lined steel pipe bonding strength test device, including a pad and a test platform, characterized in that the lower part of the pad is a steel column, the steel column has a vertical groove at the busbar position, a circular through hole is provided in the center of the test platform, and a groove is provided at the mouth of the circular through hole. The utility model first effectively solves the problem that the plastic-lined pipe is blocked from entering the hole when the test piece placed on the traditional test platform slips or is pressed and disassembled, and secondly effectively solves the problem that the traditional pad is easy to get stuck when shearing the test piece or is blocked by the protruding weld of the inner wall of the plastic-lined steel pipe and cannot be tested. Finally, the device can also be used for the bonding strength test of plastic-lined steel pipes with smooth inner walls.

[0014] It can be seen that the prior art has the following technical problems: when the composite pipe is placed on the bottom test platform, it is difficult for the composite pipe lining layer to be aligned with the holes on the test platform, which easily causes the lining layer to shift onto the platform. During the actual test, the bottom end of the lining layer is held against the test platform and is difficult to separate from the base layer, so that real and effective experimental data cannot be obtained. In addition, when the die is aligned with the upper part of the composite pipe, it is difficult to fully apply the die to the lining layer, and part of the die will shift to the base layer, resulting in the base layer and the lining layer not being subjected to completely opposite axial forces, and the base layer and the lining layer will be difficult to separate, and the true composite pipe bonding strength cannot be obtained.

[0015] Moreover, after the test is completed, because the diameter of the lining layer and the die are similar, after loading, the die is embedded in the composite pipe and is easily stuck and difficult to remove, resulting in a waste of test time and materials.

[0016] In order to solve the above problems, a simple and feasible oil and gas transportation composite pipe bonding test device is designed to better test the bonding strength of the oil and gas transportation composite pipe. Summary of the invention

[0017] In view of the above-mentioned technical problems, the present invention aims to provide a bonding strength testing device for oil and gas transmission composite pipes, which can test the bonding strength of the composite pipes.

[0018] The present invention also proposes a method for testing the bonding strength of an oil and gas transmission composite pipe. The method uses the oil and gas transmission composite pipe bonding strength testing device provided by the present invention to test the bonding strength of the composite pipe.

[0019] According to the present invention, a bonding strength testing device for a composite pipe for oil and gas transportation is provided, comprising:

[0020] A test platform, on which a first through hole is arranged in a vertical direction;

[0021] At least one positioning mechanism is disposed on the test platform and is coaxial with the first through hole, and the positioning mechanism positions the composite pipe to be tested to be coaxial with the first through hole;

[0022] and a pressing die, which is arranged on the top of the composite pipe and is used to apply axial pressure to the inner lining layer of the composite pipe.

[0023] In this embodiment, the test platform is configured to be cylindrical, and the central axis of the test platform is arranged along the vertical direction.

[0024] Furthermore, the first through hole may penetrate the test platform along the axial direction, or may only penetrate the upper end surface of the test platform upwards, as long as it can provide space for the lining layer to move downward relative to the base layer during the test process.

[0025] In a preferred embodiment, a plurality of the positioning mechanisms are coaxially arranged on the upper surface of the test platform, and a plurality of positioning mechanisms of different sizes can be adapted to a plurality of composite tubes of different sizes, thereby saving the production cost of the experimental equipment.

[0026] During the experiment, the composite pipe is first positioned on the upper end surface of the test platform by the positioning mechanism. Specifically, the lower end surface of the base layer of the composite pipe abuts against the upper end surface of the test platform, the inner lining layer of the composite pipe overlaps with the first through hole of the test platform, and the axial direction of the die abuts against the upper end surface of the inner lining layer.

[0027] The bonding strength between the base layer and the inner lining layer of the composite pipe is tested by providing axial downward pressure to the die. The die presses the inner lining layer downward, and the test platform provides an upward supporting force for the base layer. When the axial pressure applied to the die is greater than the bonding strength between the base layer and the inner lining layer, the inner lining layer separates from the base layer, and the inner lining layer moves downward into the first through hole under the action of the force.

[0028] According to the present invention, in a preferred embodiment, the positioning mechanism comprises:

[0029] At least three positioning holes are evenly arranged on the test platform along the circumferential direction;

[0030] and a positioning pin for inserting into the positioning hole.

[0031] Since there are multiple positioning mechanisms, multiple positioning mechanisms of different sizes are coaxially arranged on the upper end surface of the test platform, when facing the composite pipes with different outer diameters, the position of the positioning pin is adjusted so that the positioning pin is inserted into the positioning hole corresponding to the size of the composite pipe, thereby realizing the positioning of the composite pipes of various sizes.

[0032] In a preferred embodiment, each of the positioning mechanisms comprises four positioning holes, and the four positioning holes are evenly arranged on the upper end surface of the test platform along the circumferential direction. That is, the phase angle between two adjacent positioning holes is 90 degrees.

[0033] According to the present invention, in a preferred embodiment, the die comprises an extrusion section and a guide section which are coaxially fixedly arranged, the outer diameter of the guide section is smaller than the inner diameter of the inner lining layer, and the extrusion section is axially in contact with the inner lining layer.

[0034] According to the present invention, in a preferred embodiment, the outer diameter of the guide segment is 0.1 to 0.5 mm smaller than the inner diameter of the inner lining layer.

[0035] According to the present invention, in a preferred embodiment, the outer diameter of the extrusion section is 0.1 to 0.5 mm smaller than the outer diameter of the inner lining layer.

[0036] According to the present invention, in a preferred embodiment, an arc chamfer is provided at the connection between the guide section and the extrusion section.

[0037] According to the present invention, in a preferred embodiment, a plurality of axially arranged grooves are distributed along the circumferential direction on the outer wall of the extrusion section.

[0038] The provision of the groove can, on the one hand, reduce the weight of the die and reduce the error caused by the weight of the die during loading; on the other hand, when the die is embedded in the composite tube and is difficult to remove, the die can be quickly removed using tools, thereby avoiding wasting a lot of time in removing the die after the die is stuck in the composite tube.

[0039] In a specific embodiment, the number of the grooves is set to six, and the phase angle between two adjacent grooves is 60 degrees.

[0040] According to the present invention, in a preferred embodiment, the die further comprises an abutment section, the outer diameter of the abutment section is greater than the outer diameter of the extrusion section, and the abutment section is arranged at one end of the extrusion section away from the guide section.

[0041] In a specific embodiment, during use of the present invention, a hydraulic testing machine is required to apply a downward force to the upper end surface of the die. The setting of the abutment section can increase the contact area between the die and the hydraulic testing machine, so that the hydraulic testing machine can stably apply the load to the die, thereby improving the stability during the loading process.

[0042] Furthermore, the test platform and the die should be made of high hardness and high toughness materials to avoid deformation and cracking during the pressure application process.

[0043] According to the present invention, in a preferred embodiment, a second through hole is provided along the central axis of the die.

[0044] The provision of the second through hole can, on the one hand, reduce the weight of the die, and on the other hand, when the die is embedded in the composite pipe and is difficult to be taken out, the die can be taken out by extending a tool into the second through hole.

[0045] According to the present invention, in a preferred embodiment, the diameter of the first through hole is larger than the outer diameter of the inner lining layer of the composite pipe.

[0046] According to the present invention, in a preferred embodiment, the diameter of the first through hole is 0.1-0.5 mm larger than the outer diameter of the inner lining layer of the composite pipe.

[0047] According to the present invention, a method for testing the bonding strength of a composite pipe for oil and gas transportation is also provided. The method comprises the following steps:

[0048] Using a positioning mechanism to place the composite tube on the test platform so that the central axis of the composite tube coincides with the central axis of the first through hole;

[0049] The die is coaxially arranged at the upper end of the composite tube;

[0050] Use a hydraulic testing machine to apply pressure to the die;

[0051] Record the pressure of the hydraulic testing machine and the displacement of the die.

[0052] In a specific embodiment, the method for testing the bonding strength of a composite pipe for oil and gas transportation comprises the following steps:

[0053] Sample preparation;

[0054] Test assembly;

[0055] Loading test;

[0056] End the trial;

[0057] Calculate the bond strength;

[0058] Repeat the experiment.

[0059] Compared with the prior art, the advantages of the present application are as follows.

[0060] The present invention provides a device and method for testing the interface bonding strength of a composite pipe for oil and gas transportation. A mold is designed for commonly used composite pipes for oil and gas transportation, and accurate testing of the bonding strength between a base layer and an inner lining layer can be achieved.

[0061] The present invention arranges a plurality of positioning mechanisms on the test platform to achieve a single mold to test the bonding strength of composite pipes with the same inner liner diameter but different base diameters, which can be recycled and reduces the production cost of the present invention.

[0062] The positioning mechanism of the present invention is configured as a plurality of positioning holes uniformly arranged on the test platform along the circumferential direction, and the positioning holes cooperate with the positioning pins to realize the positioning of the composite pipe. The composite pipe is positioned by the positioning pins, so that the inner lining layer of the composite pipe can be accurately and quickly aligned with the first through hole of the test platform, avoiding errors caused by inaccurate alignment. In addition, the presence of the positioning pins also limits the relative slippage of the composite pipe and the test platform during the detection process to a certain extent.

[0063] The invention adds a guide section to the pressing die so that the pressing die can be better positioned on the inner lining layer of the composite pipe.

[0064] The present invention can reduce the weight of the die by opening a cylindrical second through hole on the die, and can also take out the die by extending a tool into the second through hole when taking out the die.

[0065] The present invention evenly opens a plurality of grooves along the circumferential direction on the backlog sheet. The arrangement of these grooves can facilitate the removal of the die from the tube after the test is completed, and can also reduce the weight of the die, thereby reducing costs and reducing the error caused by the die weight to the experiment.

[0066] The present invention can detect the bonding strength of composite pipes for oil and gas transportation, and meets the principle of composite pipe bonding strength testing in the standard. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The present invention will be described below with reference to the accompanying drawings.

[0068] Figure 1 A schematic diagram showing an embodiment of a bonding strength testing device for oil and gas transmission composite pipes according to the present invention;

[0069] Figure 2 A schematic diagram showing an embodiment of a positioning hole of a bonding strength testing device for a composite pipe for oil and gas transportation according to the present invention;

[0070] Figure 3 A schematic diagram showing an embodiment of a die of a bonding strength testing device for a composite pipe for oil and gas transportation according to the present invention;

[0071] Figure 4 A schematic diagram showing test results according to an embodiment of the present invention;

[0072] Figure 5 A schematic diagram showing test results according to another embodiment of the present invention is shown.

[0073] In the figure:

[0074] 1. Test platform; 11. First through hole;

[0075] 2. Positioning mechanism; 21. Positioning hole; 22. Positioning pin;

[0076] 3. Composite pipe; 31. Inner lining layer; 32. Base layer;

[0077] 4. die; 41. extrusion section; 411. groove; 42. guide section; 43. abutment section; 44. second through hole; 45. chamfer;

[0078] 100. Oil and gas transmission composite pipe bonding strength testing device.

[0079] In the present application, all drawings are schematic drawings, which are only used to illustrate the principles of the present invention and are not drawn according to the actual scale. DETAILED DESCRIPTION

[0080] The present invention will be described below with reference to the accompanying drawings.

[0081] It should be noted that the directional terms or qualifiers "upper" and "lower" used in this application are all directed to the referenced Figure 1 They are not intended to define the absolute positions of the components involved, but may vary depending on the specific circumstances.

[0082] With the development of oil and gas resources, fiber reinforced composite pipe (RTP) is widely used in the field of oil and gas gathering and transportation due to its advantages such as light weight, flexible coiling and corrosion resistance. In the prior art, RTP pipe is usually composed of an inner lining layer made of polymer material, a reinforcement layer made of continuous fiber material and an outer layer made of anti-aging and impact thermoplastic plastic.

[0083] In this embodiment, if Figure 1 As shown, the composite pipe 3 includes an inner lining layer 31 and a base layer 32. The main function of the inner lining layer 31 is to seal and transport materials to prevent leakage. The base layer 32 in this embodiment can be regarded as a reinforcement layer and an outer protective layer in the prior art.

[0084] The material of the inner lining layer 31 of the composite pipe 3 is generally high-density polyethylene (HDPE). HDPE has good anti-permeability to water vapor. Oil and gas gathering and transportation are usually medium- and high-pressure oil and gas, which often contain small molecular permeable media such as oxygen, carbon dioxide, hydrogen sulfide, and methane. HDPE has poor anti-permeability to oxygen, carbon dioxide, hydrogen sulfide, methane, etc. in high-pressure oil and gas.

[0085] If the bonding strength between the inner lining layer 31 and the base layer 32 is insufficient, the infiltrated high-pressure oil and gas will gather in the secondary molding area between the inner lining layer 31 and the base layer 32, and wrinkling and bulging will easily occur under the action of external loads, which will reduce the flow area of ​​the pipeline, causing the pipeline to fail to pass normally and preventive internal inspection of the pipeline to fail to be carried out normally, affecting the normal transportation of oil and gas.

[0086] Therefore, in oil and gas gathering and transportation production, the materials of the lining layer 31 and the base layer 32 need to achieve a certain bonding strength to meet the use requirements. In order to test the bonding strength between the lining layer 31 and the base layer 32, this embodiment provides an oil and gas transmission composite pipe bonding strength testing device 100.

[0087] Embodiment 1:

[0088] Figure 1 The structure of the oil and gas transmission composite pipe bonding strength testing device 100 according to the present invention is shown. Figure 1 As shown, the oil and gas transmission composite pipe bonding strength testing device 100 includes a testing platform 1, a positioning mechanism 2 and a pressing die 4.

[0089] Combination Figure 1 and Figure 2 As shown, in this embodiment, the test platform 1 is arranged in a cylindrical shape, and the central axis of the test platform 1 is arranged along the vertical direction.

[0090] A first through hole 11 is provided on the test platform 1 along the vertical direction, and the central axis of the first through hole 11 coincides with the central axial direction of the test platform 1 .

[0091] Furthermore, the first through hole 11 may penetrate the test platform 1 along the axial direction, or may only penetrate the upper end surface of the test platform 1 upwards, as long as it can provide space for the lining layer 31 to move downward relative to the base layer 32 during the test process.

[0092] According to the present invention, the diameter of the first through hole 11 is greater than or equal to the outer diameter of the inner lining layer 31 of the composite pipe 3 , and less than or equal to the outer diameter of the base layer 32 .

[0093] Preferably, the diameter of the first through hole 11 is 0.1-0.5 mm larger than the outer diameter of the inner lining layer 31 of the composite pipe 3 .

[0094] According to the present invention, the height of the test platform is 50-100 mm.

[0095] At least one positioning mechanism 2 is disposed on the test platform 1 , and the central axis of the positioning mechanism 2 coincides with the central axis of the first through hole 11 . The positioning mechanism 2 positions the composite pipe 3 to be tested to be coaxial with the first through hole 11 .

[0096] In this embodiment, the length of the composite tube 3 is 100 mm.

[0097] In a preferred embodiment, Figure 1 and Figure 2 As shown, a plurality of positioning mechanisms 2 are coaxially arranged on the upper surface of the test platform 1 , and a plurality of positioning mechanisms 2 of different sizes can be adapted to a plurality of composite tubes 3 of different sizes, thereby saving the production cost of the experimental equipment.

[0098] The pressing die 4 is disposed on the top of the composite pipe 3 and is used to apply axial pressure to the inner lining layer 31 of the composite pipe 3 .

[0099] During the experiment, the composite pipe 3 is first positioned on the upper end surface of the test platform 1 by the positioning mechanism 2. Specifically, the lower end surface of the base layer 32 of the composite pipe 3 abuts against the upper end surface of the test platform 1, the inner lining layer 31 of the composite pipe 3 coincides with the first through hole 11 of the test platform 1, and the axial direction of the die 4 abuts against the upper end surface of the inner lining layer 31.

[0100] The bonding strength between the base layer 32 and the inner lining layer 31 of the composite pipe 3 is tested by providing axial downward pressure to the die 4. The die 4 presses the inner lining layer 31 downward, and the test platform 1 provides an upward supporting force for the base layer 32. When the axial pressure applied to the die 4 is greater than the bonding strength between the base layer 32 and the inner lining layer 31, the inner lining layer 31 separates from the base layer 32, and the inner lining layer 31 moves downward into the first through hole 11 under the action of the force.

[0101] In a preferred embodiment, the positioning mechanism 2 includes a positioning hole 21 and a positioning pin 22 , and the positioning hole 21 and the positioning pin 22 can be adapted to each other.

[0102] Specifically, at least three positioning holes 21 are evenly arranged on the upper end surface of the test platform 1 along the circumferential direction, and a corresponding number of positioning pins 22 are detachably inserted into the positioning holes 21. Under this arrangement, the composite tube 3 can be aligned with the first through hole 11 under the action of the positioning pins 22.

[0103] Since there are multiple positioning mechanisms 2, multiple positioning mechanisms 2 of different sizes are coaxially arranged on the upper end surface of the test platform 1, when facing composite pipes 3 with different outer diameters, the position of the positioning pin 22 is adjusted so that the positioning pin 22 is inserted into the positioning hole 21 corresponding to the size of the composite pipe 3, thereby realizing the positioning of composite pipes 3 of multiple different sizes.

[0104] In a preferred embodiment, Figure 2 As shown, each positioning mechanism 2 includes four positioning holes 21, and the four positioning holes 21 are evenly arranged along the circumferential direction on the upper end surface of the test platform 1. That is, the phase angle between two adjacent positioning holes 21 is 90 degrees.

[0105] At the same time, a plurality of positioning mechanisms 2 of different sizes are sequentially arranged on the upper end surface of the test platform 1 .

[0106] According to the present invention, in a preferred embodiment, the die 4 includes an extrusion section 41 and a guide section 42 which are coaxially fixedly arranged.

[0107] In this embodiment, the outer diameter of the guide section 42 is smaller than the outer diameter of the extrusion section 41. The guide section 42 is used to extend into the inner lining layer 31 to play a guiding and positioning role. The extrusion section 41 is used to provide axial force for the inner lining layer 31.

[0108] In a specific embodiment, the outer diameter of the guide segment 42 is smaller than the inner diameter of the inner lining layer 31 .

[0109] Preferably, the outer diameter of the guide section 42 is 0.1-0.5 mm smaller than the inner diameter of the inner lining layer 31 .

[0110] In a specific embodiment, the extrusion section 41 is axially in contact with the inner lining layer 31 , and the outer diameter of the extrusion section 41 is smaller than the outer diameter of the inner lining layer 31 .

[0111] Preferably, the outer diameter of the extrusion section 41 is 0.1-0.5 mm smaller than the outer diameter of the inner lining layer 31 .

[0112] In this embodiment, the length of the extrusion section 41 is 50-100 mm, and the length of the guide section 42 is 5 mm.

[0113] According to the present invention, in a specific embodiment, Figure 3 As shown, a chamfer 45 is provided at the connection between the guide section 42 and the extrusion section 41 .

[0114] Preferably, the chamfer 45 is configured as an arc-shaped chamfer to better position the die 4 on the composite tube 3 .

[0115] Furthermore, the test platform 1 and the die 4 should be made of high-hardness and high-toughness materials to avoid deformation and cracking during the pressure application process.

[0116] In a specific embodiment, Figure 3 As shown, a plurality of axially arranged grooves 411 are distributed along the circumferential direction on the outer wall of the extrusion section 41 .

[0117] The setting of the groove 411 can, on the one hand, reduce the weight of the die 4 and reduce the error caused by the weight of the die 4 during loading. On the other hand, when the die 4 is embedded in the composite tube 3 and is difficult to remove, a sample removal tool can be placed in the groove 411. The removal tool has an inner protrusion, the width of the protrusion is 0.1 to 0.2 mm smaller than the width of the groove 411, and the depth of the protrusion inserted into the groove 411 is less than the depth of the groove 411 by 0.1 to 0.2 mm. The composite tube embedded in the die 4 can be removed by reverse loading the sample removal tool and the end face of the guide section.

[0118] In this embodiment, the number of the grooves 411 is set to six, and the phase angle between two adjacent grooves 411 is 60 degrees.

[0119] In a preferred embodiment, the die 4 further includes an abutment section 43, the outer diameter of which is greater than the outer diameter of the extrusion section 41, and the abutment section 43 is disposed at one end of the extrusion section 41 away from the guide section 42. During use of the present invention, a hydraulic testing machine (not shown in the figure) is required to apply a downward force to the upper end surface of the die 4. The arrangement of the abutment section 43 can increase the contact area between the die 4 and the hydraulic testing machine, so that the hydraulic testing machine can stably apply a load to the die 4, thereby improving stability during loading.

[0120] In this embodiment, the length of the abutting section is 10 mm.

[0121] In a preferred embodiment, a second through hole 44 is provided along the central axis of the die 4. With this arrangement, on the one hand, the weight of the die 4 can be reduced, and on the other hand, when the die 4 is embedded in the composite tube 3 and is difficult to be removed, the die 4 can be removed by inserting a tool into the second through hole 44.

[0122] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0123] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0124] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0125] Embodiment 2:

[0126] In one embodiment of the present invention, a method for testing the bonding strength of a composite pipe for oil and gas transportation is provided, and the method includes the following steps:

[0127] The composite tube 3 is placed on the test platform 1 using the positioning mechanism 2 so that the central axis of the composite tube 3 coincides with the central axis of the first through hole 11;

[0128] The die 4 is coaxially arranged at the upper end of the composite tube 3;

[0129] Apply pressure to the die 4 using a hydraulic testing machine;

[0130] The pressure of the hydraulic testing machine and the displacement of the die 4 are recorded.

[0131] Embodiment three:

[0132] A method for testing the bonding strength of oil and gas transmission composite pipes, using Figure 1 The oil and gas transmission composite pipe bonding strength testing device 100 is implemented by comprising the following steps:

[0133] 1. Sample preparation: Machine a composite pipe 3 with a sample length of L=100 mm and record the dimensions of the composite pipe 3, mainly including the outer diameter of the composite pipe 3 (the outer diameter of the base layer 32), the inner diameter of the composite pipe 3 (the inner diameter of the inner lining layer 31), and the thickness of the inner lining layer 31.

[0134] 2. Test assembly: first install the test platform 1 on the lower plate of the hydraulic testing machine (not shown in the figure), select a suitable positioning mechanism 2 according to the outer diameter of the composite pipe 3, insert the positioning pin 22 into the positioning hole 21 of the selected positioning mechanism 2, ensure that the inner lining layer 31 of the composite pipe 3 can be aligned with the first through hole 11 of the test platform 1, accurately position the composite pipe 3 to be tested on the test platform 1, place the die 4 with the guide section 42 on the composite pipe 3, so that the test platform 1, the composite pipe 3, and the die 4 are coaxial, slowly lower and adjust the upper chuck of the hydraulic testing machine, and when the upper chuck just lightly touches the die 4, the load and displacement are reset to zero.

[0135] 3. Loading test: Use a hydraulic testing machine to apply a vertical downward load to the die 4 to separate the base layer 32 and the inner lining layer 31 of the composite pipe 3. Load slowly at a certain loading rate, observe the force and displacement change curves, and when the force reaches the maximum value and begins to decrease significantly, it means that the composite pipe 3 has been sheared and the inner lining layer 31 has been peeled off, and record the maximum pressure.

[0136] 4. End the test, save the force and displacement curve of the hydraulic testing machine, save the data, reset the load, restore the chuck on the hydraulic testing machine to its original position, and remove the die 4 and the composite pipe 3. Remove the die 4 from the composite pipe 3 to facilitate the next test.

[0137] 5. Calculate the bonding strength. The bonding strength is calculated according to the following formula. The bonding strength is quantitatively obtained by the bonding strength obtained by the magnitude of the force when the composite pipe 3 is sheared. F is the bonding strength, in MPa; W is the maximum load when the base layer 32 and the lining layer 31 are separated, in N; D is the average inner diameter of the base layer 32 (the average outer diameter of the lining layer 31), in mm; L is the length of the sample composite pipe 3, in mm;

[0138]

[0139] 6. Repeat the test as needed, and take the average of three or more tests as the final test result.

[0140] Embodiment 4:

[0141] A method for testing the bonding strength of oil and gas transmission composite pipes, using Figure 1 The oil and gas transmission composite pipe bonding strength testing device 100 is implemented by comprising the following steps:

[0142] 1. Sample preparation: Cut the composite pipe 3 with a sample length of L=100 mm by machining, and record the dimensions of the composite pipe 3, mainly the outer diameter of the composite pipe 3, the inner diameter of the composite pipe 3, and the thickness of the inner lining layer 31. After measurement, the outer diameter of the composite pipe 3 is 98 mm, the inner diameter of the composite pipe 3 is 65 mm, the outer diameter of the inner lining layer 31 is 75 mm, and the thickness of the inner lining layer 31 is 10 mm.

[0143] 2. Test assembly: first install the test platform 1 on the lower plate of the hydraulic testing machine (not shown in the figure), select a positioning mechanism 2 with a size of 98 mm according to the outer diameter of the composite pipe 3, insert the positioning pin 22 into the positioning hole 21 of the selected positioning mechanism 2, ensure that the inner lining layer 31 of the composite pipe 3 can be aligned with the first through hole 11 of the test platform 1, accurately position the composite pipe 3 to be tested on the test platform 1, place the die 4 with the guide section 42 on the composite pipe 3, so that the test platform 1, the composite pipe 3, and the die 4 are coaxial, slowly lower and adjust the upper chuck of the hydraulic testing machine, and when the upper chuck just lightly touches the die 4, clear the load and displacement.

[0144] 3. Loading test: Use a hydraulic testing machine to apply a vertical downward load to the die 4, so that the base layer 32 of the composite pipe 3 is separated from the lining layer 31. Load slowly at a certain loading rate of 5 mm / min, and observe the force and displacement change curves, such as Figure 4 As shown, when the load applied by the hydraulic testing machine reaches 63.84363 kN, the load remains unchanged or even slightly decreases. It is believed that the inner lining layer 31 of the composite pipe 3 has been separated from the base layer 32 at this time, and the maximum load during separation is 63.84363 kN.

[0145] 4. End the test, save the force and displacement curve of the hydraulic testing machine, save the data, reset the load, restore the chuck on the hydraulic testing machine to its original position, and remove the die 4 and the composite pipe 3. Remove the die 4 from the composite pipe 3 to facilitate the next test.

[0146] 5. Calculate the bonding strength. The bonding strength is calculated according to the following formula. The bonding strength is obtained by the bonding strength obtained by the magnitude of the force when the composite pipe 3 is sheared to quantitatively obtain the bonding strength. F is the bonding strength, in MPa; W is the maximum load when the base layer 32 and the lining layer 31 are separated, in N; D is the average inner diameter of the base layer 32, in mm; L is the length of the sample composite pipe 3, in mm;

[0147]

[0148] Embodiment five:

[0149] A method for testing the bonding strength of oil and gas transmission composite pipes, using Figure 1 The oil and gas transmission composite pipe bonding strength testing device 100 is implemented by comprising the following steps:

[0150] 1. Sample preparation: Cut the composite pipe 3 with a sample length of L=100 mm by machining, and record the dimensions of the composite pipe 3, mainly the outer diameter of the composite pipe 3, the inner diameter of the composite pipe 3, and the thickness of the inner lining layer 31. After measurement, the outer diameter of the composite pipe 3 is 88 mm, the inner diameter of the composite pipe 3 is 65 mm, the outer diameter of the inner lining layer 31 is 75 mm, and the thickness of the inner lining layer 31 is 10 mm.

[0151] 2. Test assembly: first install the test platform 1 on the lower plate of the hydraulic testing machine (not shown in the figure), select a positioning mechanism 2 with a size of 88 mm according to the outer diameter of the composite pipe 3, insert the positioning pin 22 into the positioning hole 21 of the selected positioning mechanism 2, ensure that the inner lining layer 31 of the composite pipe 3 can be aligned with the first through hole 11 of the test platform 1, accurately position the composite pipe 3 to be tested on the test platform 1, place the die 4 with the guide section 42 on the composite pipe 3, so that the test platform 1, the composite pipe 3, and the die 4 are coaxial, slowly lower and adjust the upper chuck of the hydraulic testing machine, and when the upper chuck just lightly touches the die 4, clear the load and displacement.

[0152] 3. Loading test: Use a hydraulic testing machine to apply a vertical downward load to the die 4, so that the base layer 32 of the composite pipe 3 is separated from the lining layer 31. Load slowly at a certain loading rate of 5 mm / min, and observe the force and displacement change curves, such as Figure 5As shown, when the load applied by the hydraulic testing machine reaches 58.85782 kN, the load gradually decreases. It is considered that the inner lining layer 31 of the composite pipe 3 has been separated from the base layer 32 at this time, and the maximum load during separation is 58.85782 kN.

[0153] 4. End the test, save the force and displacement curve of the hydraulic testing machine, save the data, reset the load, restore the chuck on the hydraulic testing machine to its original position, and remove the die 4 and the composite pipe 3. Remove the die 4 from the composite pipe 3 to facilitate the next test.

[0154] 5. Calculate the bonding strength. The bonding strength is calculated according to the following formula. The bonding strength is obtained by the bonding strength obtained by the magnitude of the force when the composite pipe 3 is sheared to quantitatively obtain the bonding strength. F is the bonding strength, in MPa; W is the maximum load when the base layer 32 and the lining layer 31 are separated, in N; D is the average inner diameter of the base layer 32, in mm; L is the length of the sample composite pipe 3, in mm;

[0155]

[0156] Finally, it should be noted that the above is only a preferred embodiment of the present invention and does not constitute any limitation to the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for a person skilled in the art to modify the technical solutions described in the aforementioned embodiments or to replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A device for testing the bonding strength of a composite pipe for oil and gas transportation, comprising: A test platform (1), wherein a first through hole (11) is arranged in a vertical direction on the test platform (1); at least one positioning mechanism (2) disposed on the test platform (1) and coaxial with the first through hole (11), the positioning mechanism (2) positioning the composite pipe (3) to be tested to be coaxial with the first through hole (11); and a pressing die (4), wherein the pressing die (4) is arranged on the top of the composite pipe (3) and is used to apply axial pressure to the inner lining layer (31) of the composite pipe (3).

2. The oil and gas transmission composite pipe bonding strength testing device according to claim 1 is characterized in that: The positioning mechanism (2) comprises: At least three positioning holes (21) are evenly arranged on the test platform (1) along the circumferential direction; and a positioning pin (22) for inserting into the positioning hole (21).

3. The oil and gas transmission composite pipe bonding strength testing device according to claim 1 is characterized in that: The die (4) comprises an extrusion section (41) and a guide section (42) which are coaxially fixedly arranged, the outer diameter of the guide section (42) being smaller than the inner diameter of the inner lining layer (31), and the extrusion section (41) being axially abutted against the inner lining layer (31).

4. The oil and gas transmission composite pipe bonding strength testing device according to claim 3 is characterized in that: The outer diameter of the guide section (42) is 0.1 to 0.5 mm smaller than the inner diameter of the inner lining layer (31).

5. The oil and gas transmission composite pipe bonding strength testing device according to claim 3 is characterized in that: The outer diameter of the extrusion section (41) is 0.1 to 0.5 mm smaller than the outer diameter of the inner lining layer (31).

6. The oil and gas transmission composite pipe bonding strength testing device according to claim 3 is characterized in that: An arc chamfer is provided at the connection between the guide section (42) and the extrusion section (41).

7. The oil and gas transmission composite pipe bonding strength testing device according to claim 3 is characterized in that: A plurality of axially arranged grooves (411) are distributed along the circumferential direction on the outer wall of the extrusion section (41).

8. The oil and gas transmission composite pipe bonding strength testing device according to claim 3 is characterized in that: The die (4) further comprises an abutment section (43), the outer diameter of the abutment section (43) being greater than the outer diameter of the extrusion section (41), and the abutment section (43) being arranged at an end of the extrusion section (41) away from the guide section (42).

9. The oil and gas transmission composite pipe bonding strength testing device according to claim 3, characterized in that: A second through hole (44) is provided along the central axis of the die (4).

10. The oil and gas transmission composite pipe bonding strength testing device according to claim 1, characterized in that: The diameter of the first through hole (11) is greater than the outer diameter of the inner lining layer (31) of the composite pipe (3).

11. The oil and gas transmission composite pipe bonding strength testing device according to claim 10, characterized in that: The diameter of the first through hole (11) is 0.1 to 0.5 mm greater than the outer diameter of the inner lining layer (31) of the composite pipe (3).

12. A method for testing the bonding strength of a composite pipe for oil and gas transportation, characterized in that: Using the oil and gas transmission composite pipe bonding strength testing device according to any one of claims 1 to 11 comprises the following steps: Using a positioning mechanism (2) to place the composite tube (3) on the test platform (1) so that the central axis of the composite tube (3) coincides with the central axis of the first through hole (11); The die (4) is coaxially arranged at the upper end of the composite tube (3); Applying pressure to the die (4) using a hydraulic testing machine; The pressure of the hydraulic testing machine and the displacement of the die (4) are recorded.

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