LLDPE three-layer composite pipe pressure testing equipment

Abstract

This invention relates to the field of pressure testing technology for new material composite pipes, specifically, to a pressure testing device for LLDPE three-layer composite pipes. The device includes a pressure testing body and a pressure output section mounted thereon. The pressure output section includes a first pressure output end and a second pressure output end mounted on the pressure testing body. Both the first and second pressure output ends are equipped with sealing joints. Each sealing joint includes a first compression ring with an output port at its center. Several sets of clamping components are arranged in a circumferential array on the first compression ring. The sealing joint also includes sealing components. This solution utilizes a triple mechanism of radial bidirectional clamping, adaptive gap filling, and axial pressure transfer to construct a highly reliable sealing testing system specifically for multi-layer composite pipe structures. The overall operating logic is clear: first, the pipe body is securely clamped and protected; then, the sealing is strengthened step by step.

Description

Technical Field

[0001] This invention relates to the field of pressure testing technology for new material composite pipes, and more specifically, to a pressure testing device for LLDPE three-layer composite pipes. Background Technology

[0002] According to the publication number CN212748539U, which discloses a pressure testing device for HDPE hollow wall plastic-steel spiral wound pipes, this utility model discloses a pressure testing device for HDPE hollow wall plastic-steel spiral wound pipes, including a base, a top plate, and a supporting base plate. A weighing instrument is centrally mounted on the upper surface of the base. The top plate has a U-shaped structure, and its bottom corners are welded to the base via four sets of pillars arranged in a rectangular array. Two sets of fixing blocks are symmetrically welded to the middle of the inner top wall of the top plate, directly above the weighing instrument. A transmission rod is installed between the two sets of fixing blocks, and a slider is slidably mounted on the transmission rod. A pressure mechanism is installed at the bottom end of the slider. This pressure testing device for HDPE hollow wall plastic-steel spiral wound pipes allows for both electric and manual adjustment of the limiting plate when it is tightly attached to the plastic-steel spiral wound pipe, resulting in better sealing and improved testing accuracy. It can also be used for pressure testing of plastic-steel spiral wound pipes of different sizes.

[0003] The aforementioned patents still have shortcomings in practical use. Ordinary clamps mainly rely on friction or simple mechanical compression. For new material composite pipes, due to the special nature of the material, since the middle layer of LLDPE three-layer composite pipe is a "ceramic insulation layer", the bonding force between the layers may not be as strong as that of homogeneous pipes. Under high pressure, interlayer peeling or the pipe slipping out of the clamp can easily occur. If the clamping force is not properly controlled, excessive radial compressive stress may also cause local crushing of the pipe wall, resulting in test failure.

[0004] Based on this, the present invention discloses a pressure testing device for LLDPE three-layer composite pipe. Summary of the Invention

[0005] To address the problem that conventional clamps, which rely on friction or simple mechanical compression for sealing and fixing, are unsuitable for LLDPE three-layer composite pipes, which contain a ceramic insulating interlayer and have lower interlayer bonding strength than homogeneous pipes, making them prone to interlayer peeling or slippage under high pressure, and excessive clamping force can lead to pipe wall crushing, causing intriguing failures and test failures, this invention provides an LLDPE three-layer composite pipe pressure testing device. The device includes a pressure testing body and a pressure output section mounted thereon. The pressure output section includes a first pressure output end and a second pressure output end mounted on the pressure testing body. Both the first and second pressure output ends are equipped with sealing joints. Each sealing joint includes a first compression ring with an output port at its center. Several sets of clamping components are arranged in a circular array on the first compression ring. The sealing joint also includes sealing components. Traditional pressure testing devices often seal composite pipes by clamping or mechanically compressing both ends. This method is prone to slippage or peeling, and under increased pressure, it may even cause the pipe wall to collapse. In other words, traditional pressure testing devices apply pressure to the composite pipe in one direction to seal it, either by applying pressure radially outward, similar to inserting a plug into the end of the test pipe, or by applying pressure radially inward, similar to clamping. However, due to the limited pressure that can be applied to the pipe wall thickness and tension threshold, this method is prone to leakage at the seal point during pressure testing. This invention transfers pressure from the test tube wall to a clamping plate with higher rigidity. First, the test tube is clamped by the clamping plate, and then the clamping plate is pressurized and sealed to achieve pressure transfer, allowing for greater pressure to be applied for sealing. Secondly, the clamping plate in this invention clamps the test tube simultaneously from both sides radially along both sides, overcoming the drawbacks of traditional single-direction force application. Simultaneous clamping of the inner and outer sides of the tube wall protects it while applying greater pressure to ensure a seal at the tube wall edges. As a further improvement to this technical solution, the clamping assembly includes two sets of opposing pressure plates. The first extrusion ring has a groove corresponding to the pressure plate. Pressure pads are provided on the opposite side of the two pressure plates, and several isolation grooves are provided tangentially inside the pressure pads.

[0006] Based on this, in order to further improve the sealing performance, and on the basis of achieving bidirectional clamping and sealing of the tube wall under test, this application continues to increase the axial sealing pressure, that is, to apply dual sealing pressure to the tube wall in both the radial and axial directions to ensure the seal; moreover, the radial direction is a bidirectional seal; secondly, the axial sealing pressure is also transferred from the end wall of the tube under test to the clamping assembly, which can further increase the axial pressure to improve the sealing performance and solve the problem of insufficient sealing that may occur in the clamping assembly. Moreover, an annular butt joint is formed between the inner pressure plate and the first extrusion ring. First, this annular joint must be sealed, and then one side of the entire clamping assembly must be sealed. As a further improvement to this technical solution, the sealing assembly includes a second compression ring, on which a sealing cone ring is provided, and an elastic sealing gasket is also provided.

[0007] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. In this pressure testing device for LLDPE three-layer composite pipes, symmetrically arranged arc-shaped pressure plates and elastic pressure pads with isolation grooves, combined with an inclined symmetrical sliding groove drive mechanism, enable simultaneous bidirectional force application along the pipe wall during the clamping process. During clamping, the pressure pads initially contact the pipe wall, gradually compressing as pressure increases to form multiple independent sealing chambers, effectively blocking leakage paths. Compared to traditional unidirectional clamping methods, this not only avoids composite pipe crushing or interlayer peeling due to localized stress concentration but also significantly improves sealing reliability, making it particularly suitable for LLDPE three-layer composite pipes with an intermediate ceramic insulation layer and low interlayer bonding strength.

[0008] 2. In this pressure testing equipment for LLDPE three-layer composite pipe, a conical sealing cone is added at the joint of adjacent pressure plates. Utilizing its structural characteristics of a wider front end and a narrower rear end, as well as its material deformation capability, the cone automatically fills the gap during the clamping process of the pressure plates and enhances the tightness of the fit as the pressure increases. This design specifically solves the risk of gap leakage that inevitably occurs when the multi-lobed clamping structure is closed, ensuring continuous and complete circumferential sealing in the clamping area. This further enhances the sealing stability under high pressure testing and makes up for the shortcomings of traditional clamps in terms of structural continuity.

[0009] 3. In this LLDPE three-layer composite pipe pressure testing equipment, an independent axial sealing assembly is introduced, including a conical sealing ring and an elastic sealing gasket with a clearance groove. This axial seal acts on the entire clamping assembly rather than directly on the pipe end, thus transferring the sealing force from the pipe body under test to the high-rigidity clamping structure. The axial seal is activated after radial clamping, first sealing the butt joint between the pressure plate and the compression ring, and then applying uniform axial pressure to the entire side of the clamping assembly, forming a dual radial and axial sealing system. This not only avoids deformation or damage caused by direct pressure on the pipe end but also allows for the application of a higher sealing load, solving the problem of premature test termination due to seal failure in traditional testing devices. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the pressure output section of the present invention; Figure 3 This is a schematic diagram of the sealing joint of the present invention; Figure 4 This is a schematic diagram of the internal pressure pad of the present invention; Figure 5 This is a cross-sectional view of the sealing joint of the present invention; Figure 6 This is one of the structural schematic diagrams of the clamping assembly of the present invention; Figure 7 This is a second schematic diagram of the clamping assembly of the present invention; Figure 8 This is a schematic diagram of the sealing assembly of the present invention; Figure 9 This is a schematic diagram of the sealing joint of the present invention; Figure 10 This is a schematic diagram of the clamping assembly of the present invention.

[0011] The meanings of the labels in the diagram are as follows: 1. Pressure test body; 2. First pressure output end; 3. Second pressure output end; 4. First compression ring; 5. Output port; 6. Clamping assembly; 7. Sealing assembly; 61. First connecting rod; 62. Second connecting rod; 63. First sliding groove; 64. Second sliding groove; 65. First clearance groove; 66. Outer pressure plate; 67. Outer pressure pad; 68. Inner pressure plate; 69. Inner pressure pad; 610. Isolation groove; 611. Outer sealing cone; 612. Inner sealing cone; 613. Support rod; 71. Second compression ring; 72. Sealing cone ring; 73. Elastic sealing gasket; 74. Expansion groove; 75. Second clearance groove; 76. Slot; 77. Third clearance groove. Detailed Implementation

[0012] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0013] The LLDPE three-layer composite pipe of this invention has a three-layer structure. The inner reinforcing layer incorporates carbon black into the LLDPE substrate to improve wear resistance, corrosion resistance, and lubrication properties, while also enhancing the flame retardant performance of the composite pipe to adapt to complex high-temperature and high-pressure environments and ensure rapid fluid flow within the pipe. The middle insulation layer is filled with ceramic insulating filler, which can significantly block external high-temperature or low-temperature conduction, ensuring stable fluid temperature inside the pipe, reducing energy consumption, and increasing the compressive strength of the composite pipe. The outermost protective layer is made of linear low-density polyethylene (LLDPE) with added high reflectivity. The white masterbatch forms a dense protective layer; its white surface can reflect more than 85% of sunlight, effectively reducing the surface temperature of the pipe, preventing ultraviolet aging, and extending its service life. Due to its unique heat-insulating filler, the pipe does not easily dissipate heat in winter, and the white exterior of the pipe in summer can avoid most of the direct sunlight, maintaining a constant water temperature in agricultural irrigation applications. The linear low-density polyethylene (LLDPE) granules have a particle size of 20-50μm, the masterbatch granules have a particle size of 0.2-0.5μm, the carbon black granules have a particle size of 20-40nm, and the heat-insulating filler (alumina) has a particle size of 0.05-0.5μm.

[0014] Existing conventional clamps rely on friction or simple mechanical compression for sealing and fixing, which is difficult to apply to LLDPE three-layer composite pipes. These pipes contain a ceramic thermal insulation intermediate layer, and the interlayer interface bonding strength is lower than that of homogeneous pipes. Under high pressure, interlayer peeling or slippage is prone to occur, and excessive clamping force can cause the pipe wall to collapse, leading to intriguing failures and test failures.

[0015] Therefore, this invention provides a pressure testing device for LLDPE three-layer composite pipes. See [link / reference] Figures 1-4 As shown, it includes a pressure testing body 1 and a pressure output section disposed thereon. The pressure output section includes a first pressure output end 2 and a second pressure output end 3 disposed on the pressure testing body 1. Both the first pressure output end 2 and the second pressure output end 3 are provided with sealing joints. The sealing joints include a first compression ring 4. The first compression ring 4 has an output port 5 at its center. Several sets of clamping components 6 are arranged in a circumferential array on the first compression ring 4. The sealing joints also include sealing components 7. Furthermore, both the first pressure output end 2 and the second pressure output end 3 are provided with hydraulic telescopic rods for driving the first compression ring 4 and the sealing components 7 to extend and retract.

[0016] During operation, the composite tube is placed on the sealing joint between the first pressure output end 2 and the second pressure output end 3. Then, the first extrusion ring 4 is extended by the hydraulic telescopic rod, which causes the clamping assembly 6 to expand, allowing the wall of the composite tube to fit inside the clamping assembly 6. Then, the first extrusion ring 4 contracts, causing the clamping assembly 6 to fit tightly against the wall of the composite tube and form the first layer of sealing protection. Next, the sealing assembly 7 extends to provide a second layer of sealing protection on one side of the clamping assembly 6. After this process, the pressure inside the composite tube is pressurized through the first pressure output end 2 to test the pressure threshold of the composite tube.

[0017] For details, see Figures 5-7 As shown, traditional pressure testing devices often seal the ends of composite tubes by clamping or mechanically compressing them during pressure testing. This method is prone to slippage or peeling, and under increased pressure, it may even cause the tube wall to collapse. In other words, traditional pressure testing devices apply pressure to the composite tube in one direction to seal it, either by applying pressure radially outward, similar to inserting a plug into the end of the test tube, or by applying pressure radially inward, similar to clamping. However, due to the limited pressure that can be applied to the tube wall thickness and tension threshold, this method is prone to leakage at the seal point during pressure testing. This invention transfers pressure from the test tube wall to a clamping plate with higher rigidity. First, the test tube is clamped by the clamping plate, and then the clamping plate is pressurized and sealed to achieve pressure transfer, allowing for greater pressure to be applied for sealing. Secondly, the clamping plate in this invention clamps the test tube simultaneously from both sides radially along both sides, overcoming the drawbacks of traditional single-direction force application. Simultaneous clamping of the inner and outer sides of the tube wall protects it while applying greater pressure to ensure a seal at the tube wall edges.

[0018] Specifically, the clamping assembly 6 includes two sets of opposing pressure plates. The first compression ring 4 has inclined grooves corresponding to the pressure plates. Pressure pads are provided on opposite sides of both pressure plates, and several isolation grooves 610 are tangentially formed within the pressure pads. The clamping assembly 6 also includes a first connecting rod 61 and a second connecting rod 62. Support rods 613 are fixedly connected to both the first connecting rod 61 and the second connecting rod 62. The first connecting rod 61 and the second connecting rod 62 are slidably connected to the output end of the pressure output section via the support rods 613. The inclined grooves are a first sliding groove 63 and a second sliding groove 64, and the pressure plates are an outer pressure plate 66 and an inner pressure plate 68 with an arc-shaped structure. The pressure pads are an outer pressure pad 67 and an inner pressure pad 69; one end of the first connecting rod 61 is slidably connected in the second slide groove 64, and the other end of the first connecting rod 61 is fixedly connected to the outer pressure plate 66. A first clearance groove 65 is provided on the first extrusion ring 4 on the moving path of the first connecting rod 61. The first connecting rod 61 is slidably connected in the first clearance groove 65. The second connecting rod 62 is slidably connected in the first connecting rod 61. One end of the second connecting rod 62 is slidably connected in the first slide groove 63, and the other end of the second connecting rod 62 is fixedly connected to the inner pressure plate 68. The outer pressure pad 67 is fixedly connected to the outer pressure plate 66, and the inner pressure pad 69 is fixedly connected to the inner pressure plate 68. The first slide groove 63 and the second slide groove 64 are both inclined and symmetrically arranged to ensure that the first connecting rod 61 and the second connecting rod 62 move in both directions synchronously. Next, the isolation groove 610 is opened on the opposite side of the outer pressure pad 67 and the inner pressure pad 69, and the isolation grooves 610 on the outer pressure pad 67 and the inner pressure pad 69 correspond one-to-one. The isolation grooves 610 on the outer pressure pad 67 and the inner pressure pad 69 form a number of sealed chambers, and the pressure pad has deformation characteristics. Secondly, when the outer pressure plate 66 and the inner pressure plate 68 move towards each other, a gap will appear at the joint of the pressure plates. This gap will affect the sealing performance. The present invention adopts a sealing cone with a conical structure to be added to the gap. Specifically, an outer sealing cone 611 is fixedly connected to both sides of the outer pressure plate 66, and an inner sealing cone 612 is fixedly connected to both sides of the inner pressure plate 68 in a symmetrical arrangement with the outer sealing cone 611. Both the outer sealing cone 611 and the inner sealing cone 612 are conical structures. The outer sealing cone 611 is fixedly connected to the outer pressure pads 67 on both sides, and the inner sealing cone 612 is fixedly connected to the inner pressure pads 69 on both sides. The outer sealing cone 611 and the inner sealing cone 612 have deformation characteristics. The width of the opposite end of the outer sealing cone 611 and the inner sealing cone 612 is greater than the width of the opposite end of the outer sealing cone 611 and the inner sealing cone 612.

[0019] At work, such as Figure 10As shown, the tube to be tested is inserted between the outer pressure pad 67 and the inner pressure pad 69. The first compression ring 4 retracts inward under the control of the hydraulic telescopic rod in the pressure output section. Due to the inclined and symmetrical layout of the first slide groove 63 and the second slide groove 64, the first connecting rod 61 moves radially inward, and the second connecting rod 62 moves radially outward within the first connecting rod 61. The first connecting rod 61 and the second connecting rod 62 move towards each other, thus clamping the wall of the tube to be tested. During this process, through... Figure 5 As can be seen, the protrusions on the outer pressure pad 67 and the inner pressure pad 69 will first adhere to the wall of the pipe to be tested, and then continue to clamp. The pressure pads in contact with the wall of the pipe to be tested will be compressed until all the protrusions are tightly adhered to each other. Then the isolation grooves 610 opened on the outer pressure pad 67 and the inner pressure pad 69 will connect with each other to form several sets of sealing chambers. The remaining protrusions in contact with the wall of the pipe to be tested will also form another kind of sealing chamber with the pipe wall. These several sets of sealing chambers will form a series of defenses to ensure the sealing of the inner and outer sides of the pipe wall. Moreover, the several sets of sealing chambers formed by the isolation grooves 610, compared with the traditional method of the rubber pad directly and completely adhering to the wall of the pipe to be tested, make leakage require to break through multiple defenses before it can occur, thereby improving the isolation and sealing performance from a structural point of view. Secondly, the pressure is changed from the traditional single radial pressure to simultaneous pressure on both sides of the pipe wall. This is to avoid damage to the pipe wall under test caused by pressure in one direction. The bidirectional pressure allows for higher pressure to be applied to improve sealing. Secondly, the multiple seals on the inner and outer sides further improve the sealing performance. Next, since there will be a gap between the pressure plates, this gap may become a risk point for leakage when the pipe wall to be tested is clamped in opposite directions. In this invention, sealing cones, namely outer sealing cone 611 and inner sealing cone 612, are added at the gap. When the outer pressure plate 66 and inner pressure plate 68 clamp the pipe wall in opposite directions, the wider end of the outer sealing cone 611 and inner sealing cone 612 will first adhere to the pipe wall to be tested. Then, as the outer pressure plate 66 and inner pressure plate 68 clamp the pipe wall, the gap between the pressure plates will close. The sealing cones on the sides fit together, thereby achieving automatic filling of the gap between the sealing cones and the corresponding clamping plates; that is, when the outer pressure plate 66 and the inner pressure plate 68 clamp each other, the gap between the outer pressure plates 66 and the gap between the inner pressure plates 68 will be filled by the corresponding outer sealing cones 611 and inner sealing cones 612. As the pressure increases, the clamping force with the sealing cones will also increase. Moreover, the sealing cones have deformation characteristics, and the part of its conical structure that contacts the pipe wall to be tested will spread due to compression, thereby further improving the sealing performance of the gap.

[0020] Further, see Figures 8-9As shown, in order to further improve the sealing performance, and on the basis of achieving bidirectional clamping and sealing of the tube wall under test, this application continues to increase the axial sealing pressure, that is, to implement dual sealing pressure on the radial and axial sides of the tube wall to ensure the seal; and the radial side is a bidirectional seal; secondly, the axial sealing pressure is also transferred from the end wall of the tube under test to the clamping assembly 6, which can further increase the axial pressure to improve the sealing performance and solve the problem of insufficient sealing that may occur in the clamping assembly 6. Moreover, an annular butt joint is formed between the inner pressure plate 68 and the first extrusion ring 4. First, this annular joint must be sealed, and then one side of the clamping assembly 6 as a whole must be sealed. Specifically, the sealing assembly 7 includes a second compression ring 71, a sealing cone ring 72, and an elastic sealing gasket 73. Several inner pressure plates 68 and outer pressure plates 66 form circular structures, and the circular structure formed by the inner pressure plates 68 forms a mating ring seam with the first compression ring 4. The sealing cone ring 72 has a conical structure and is fitted onto the front end of the second compression ring 71. The outer diameter of the rear end of the sealing cone ring 72 is larger than the outer diameter of the mating ring seam, and the second connecting rod 62 has deformation characteristics. Furthermore, the elastic sealing gasket 73 is fixedly connected to the rear end of the second compression ring 71. In the initial state, the front end of the elastic sealing gasket 73 extends beyond the rear end of the sealing cone ring 72, so that the front end of the elastic sealing gasket 73 can have a certain compressibility, so that it can pressurize and seal one side of the entire clamping assembly 6. Several telescopic grooves 74 are provided on the periphery of the elastic sealing gasket 73 to avoid the first connecting rod 61. The sealing cone ring 72 and the second extrusion ring 71 are provided with a second clearance groove 75 that is adapted to the first connecting rod 61. The elastic sealing gasket 73 is provided with a slot 76 that is adapted to the first connecting rod 61 on one side. The elastic sealing gasket 73 is also provided with a third clearance groove 77 that is adapted to the support rod 613.

[0021] At work, such as Figure 9 As shown, the second extrusion ring 71 extends via a corresponding hydraulic telescopic rod. First, the second extrusion ring 71, carrying the sealing cone ring 72 at its front end, inserts into the mating annular gap, specifically the annular gap between the circular structure formed by the inner pressure plate 68 and the first extrusion ring 4. Because the sealing cone ring 72 has a conical structure, as the second extrusion ring 71 advances with the sealing cone ring 72, it first seals the annular gap. Then, referring to… Figure 8 and Figure 9As shown, the side of the elastic sealing gasket 73 opposite to the first connecting rod 61 will fit against the first connecting rod 61, that is, the groove 76 on the elastic sealing gasket 73 will engage with the first connecting rod 61 and wrap around the first connecting rod 61. The remaining part of the elastic sealing gasket 73 will fit against one side of the outer pressure plate 66, outer pressure pad 67, inner pressure plate 68 and inner pressure pad 69, sealing the entire side. At this time, the axial pressure is applied to the entire clamping assembly 6, not the tube to be tested, so the pressure can be increased for sealing. Secondly, due to the opening of the expansion groove 74 and its own characteristics, the elastic sealing gasket 73 has deformation and compression characteristics. The front end of the elastic sealing gasket 73 extends beyond the end of the sealing cone ring 72. Therefore, the elastic sealing gasket 73 will eventually be tightly compressed and fitted against one side of the entire clamping assembly 6 to seal it. Thus, the first layer of sealing is achieved by applying radial pressure to the wall of the tube to be tested through the pressure plate and pressure pad. Then, the second layer of sealing is achieved by applying axial pressure to the tube to be tested through the elastic sealing gasket 73 and sealing cone ring 72. The cooperation between the elastic sealing gasket 73 and sealing cone ring 72, as well as the pressure pad and sealing cone, achieves all-round sealing around the end of the tube to be tested and also realizes pressure transfer, avoiding the crushing of the tube to be tested. After sealing is completed, the tube is pressurized through the output port 5 for testing.

[0022] Furthermore, it is worth mentioning that during the sealing stage of this invention, the first compression ring 4 and the second compression ring 71 move in opposite directions. The first compression ring 4 contracts inward to achieve clamping. Since the entire clamping assembly 6 is slidably connected to the output end of the pressure output section through the support rod 613, if the first compression ring 4 extends outward to apply pressure, the support rod 613 will be under excessive pressure and may fall off or be damaged over time. However, applying pressure inward avoids excessive pressure on the support rod 613, and the rigidity of its own material can provide support. Secondly, after the first compression ring 4 has completed its task, when the second compression ring 71 extends to seal one side of the clamping assembly 6, the pressure body becomes the clamping assembly 6. The clamping assembly 6 can be further supported by the first compression ring 4, ensuring the stability of the clamping assembly 6 when the second compression ring 71 applies pressure.

[0023] In summary, a highly reliable sealing test system specifically designed for multi-layer composite pipes was constructed through the coordinated operation of three mechanisms: radial bidirectional clamping, adaptive gap filling, and axial pressure transfer. This effectively solves the problem that existing conventional clamps rely on friction or simple mechanical compression for sealing and fixing, which is unsuitable for LLDPE three-layer composite pipes containing ceramic insulation interlayers. The interlayer interface bonding strength is lower than that of homogeneous pipes, making them prone to interlayer peeling or slippage under high pressure. Furthermore, excessive clamping force can lead to pipe wall crushing, causing intriguing failures and test failures.

[0024] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0025] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A pressure testing device for LLDPE three-layer composite pipe, comprising a pressure testing body (1) and a pressure output section disposed thereon, wherein sealing joints are symmetrically arranged on the pressure output section, characterized in that: The sealing joint includes a first compression ring (4), an output port (5) is provided in the center of the first compression ring (4), and several sets of clamping components (6) are arranged in a circular array on the first compression ring (4). The sealing joint also includes a sealing component (7). The clamping assembly (6) includes two sets of opposing pressure plates. The first extrusion ring (4) has a groove corresponding to the pressure plate. Pressure pads are provided on the opposite side of the two pressure plates. Several isolation grooves (610) are provided in the pressure pads along the tangential direction. The sealing assembly (7) includes a second compression ring (71), on which a sealing cone ring (72) is provided, and on which an elastic sealing gasket (73) is also provided.

2. The LLDPE three-layer composite pipe pressure testing equipment according to claim 1, characterized in that: The pressure output section includes a first pressure output end (2) and a second pressure output end (3) disposed on the pressure test body (1). Both the first pressure output end (2) and the second pressure output end (3) are provided with sealing joints, and both the first pressure output end (2) and the second pressure output end (3) are provided with hydraulic telescopic rods for driving the first compression ring (4) and the second compression ring (71) to extend and retract.

3. The LLDPE three-layer composite pipe pressure testing equipment according to claim 1, characterized in that: The clamping assembly (6) further includes a first connecting rod (61) and a second connecting rod (62), the inclined grooves are a first sliding groove (63) and a second sliding groove (64), the pressure plates are an outer pressure plate (66) and an inner pressure plate (68) with an arc-shaped structure, and the pressure pads are an outer pressure pad (67) and an inner pressure pad (69); one end of the first connecting rod (61) is slidably connected in the second sliding groove (64), the other end of the first connecting rod (61) is fixedly connected to the outer pressure plate (66), and a first clearance groove (65) is provided on the first extrusion ring (4) on the moving path of the first connecting rod (61), the first connecting rod (61) is slidably connected in the first clearance groove (65), the second connecting rod (62) is slidably connected in the first connecting rod (61), one end of the second connecting rod (62) is slidably connected in the first sliding groove (63), and the other end of the second connecting rod (62) is fixedly connected to the inner pressure plate (68); The outer pressure pad (67) is fixedly connected to the outer pressure plate (66), and the inner pressure pad (69) is fixedly connected to the inner pressure plate (68).

4. The LLDPE three-layer composite pipe pressure testing equipment according to claim 3, characterized in that: The first slide (63) and the second slide (64) are both inclined and are arranged symmetrically.

5. The LLDPE three-layer composite pipe pressure testing equipment according to claim 3, characterized in that: The isolation groove (610) is formed on the opposite side of the outer pressure pad (67) and the inner pressure pad (69), and the isolation grooves (610) on the outer pressure pad (67) and the inner pressure pad (69) correspond one-to-one. The isolation grooves (610) on the outer pressure pad (67) and the inner pressure pad (69) form a plurality of sealed chambers, and the pressure pad has deformation characteristics.

6. The LLDPE three-layer composite pipe pressure testing equipment according to claim 3, characterized in that: The outer pressure plate (66) is fixedly connected to the outer sealing cone (611) on both sides, and the inner pressure plate (68) is fixedly connected to the inner sealing cone (612) which is symmetrically arranged with the outer sealing cone (611) on both sides. The outer sealing cone (611) and the inner sealing cone (612) are both conical structures. The outer sealing cone (611) is fixedly connected to the outer pressure pads (67) on both sides, and the inner sealing cone (612) is fixedly connected to the inner pressure pads (69) on both sides. The outer sealing cone (611) and the inner sealing cone (612) have deformation characteristics. The width of the opposite end of the outer sealing cone (611) and the inner sealing cone (612) is greater than the width of the opposite end of the outer sealing cone (611) and the inner sealing cone (612).

7. The LLDPE three-layer composite pipe pressure testing equipment according to claim 6, characterized in that: A support rod (613) is fixedly connected to both the first connecting rod (61) and the second connecting rod (62). The first connecting rod (61) and the second connecting rod (62) are slidably connected to the output end of the pressure output section through the support rod (613).

8. The LLDPE three-layer composite pipe pressure testing equipment according to claim 7, characterized in that: The inner pressure plates (68) and outer pressure plates (66) are respectively formed into circular structures, and the circular structure formed by the inner pressure plates (68) forms a butt joint with the first extrusion ring (4).

9. The LLDPE three-layer composite pipe pressure testing equipment according to claim 8, characterized in that: The sealing cone ring (72) has a conical structure and is sleeved on the front end of the second extrusion ring (71). The outer diameter of the rear end of the sealing cone ring (72) is larger than the outer diameter of the mating ring seam, and the second connecting rod (62) has deformation characteristics.

10. The LLDPE three-layer composite pipe pressure testing equipment according to claim 9, characterized in that: The elastic sealing gasket (73) is fixedly connected to the rear end of the second compression ring (71), and in the initial state, the front end of the elastic sealing gasket (73) extends beyond the rear end of the sealing cone ring (72), and a plurality of expansion grooves (74) are provided on the periphery of the elastic sealing gasket (73). The sealing cone ring (72) and the second extrusion ring (71) are provided with a second clearance groove (75) that is adapted to the first connecting rod (61). The elastic sealing gasket (73) is provided with a slot (76) that is adapted to the first connecting rod (61) on one side. The elastic sealing gasket (73) is also provided with a third clearance groove (77) that is adapted to the support rod (613).

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