A full-pressure structure large-diameter floating coupling

Abstract

The present invention discloses a full-pressure structure large-diameter floating coupling, which relates to the technical field of floating casing running in extended-reach horizontal wells in oilfields. It includes: a first pipe and a second pipe sleeved with each other, with the second pipe located below the first pipe. It further includes: an inner stepped hole is formed in the inner wall of the second pipe; a sealing gasket ring is installed in the inner stepped hole; a blind plate is of a flat spherical shell structure and is installed above the sealing gasket ring, and the end face of the blind plate abuts against the top face of the sealing gasket ring; the side wall of the pressing ring is threadedly connected to the inner wall of the second pipe, and the bottom face of the pressing ring closely adheres to the end face of the blind plate. The advantages of the present invention are that this device is connected to the casing string in the horizontal well section to temporarily block the mud in the pipe and reduce the frictional resistance of the horizontal well section when the second pipe is lowered. After the second pipe reaches the position, the blind plate is broken by applying pressure at the wellhead, achieving millimeter-level particle size of the broken particles, ensuring the inner diameter size of the coupling, and then a circulation channel can be established inside and outside the casing to carry out subsequent cementing operations.

Description

Technical Field

[0001] The present invention relates to the technical field of floating casing running technology for extended reach horizontal wells in oilfields, and particularly relates to a full-pressure structure large-diameter floating collar. Background Art

[0002] The floating collar is installed in the casing string to play a role of temporary plugging. The casing between the lower part of the floating collar and the float collar is the floating section, and the floating section is filled with air or low-density drilling fluid, while the casing above the floating collar is filled with mud. Under the action of the buoyancy of the drilling fluid outside the casing, the casing in the floating section will reduce the normal pressure on the wellbore in the horizontal section, thereby reducing the friction during the casing running process and facilitating the smooth running of the casing in the extended reach horizontal well.

[0003] At present, there are mainly two types of floating collars: the sliding sleeve type floating collar and the crushing type floating collar. The sliding sleeve type floating collar mainly consists of a body, inner and outer sliding sleeves, pins, and sealing rings, etc. The outer sliding sleeve is connected to the body and the inner sliding sleeve through pins. After the casing running is completed, it is necessary to build pressure inside the casing to shear the metal pins to realize the circulation inside the casing. The internal components of the sliding sleeve type floating collar need to move to the bottom of the well, and there are many influencing factors for being blocked and stuck inside the casing, and there is a risk of blocking accidents.

[0004] The crushing type floating collar is composed of a joint body, an annular sleeve, and a flat blind plate made of toughened glass. After the casing is run, the blind plate of the toughened glass is broken into small particles by building pressure to form a normal diameter of the casing. However, for the crushing type floating collar with toughened glass, the broken particles of the flat blind plate are large, the crushing is incomplete, and it is difficult to ensure the diameter. Summary of the Invention

[0005] The present invention provides a full-pressure structure large-diameter floating collar to solve the problems in the prior art that the broken particles of the flat blind plate are large, the crushing is incomplete, and it is difficult to ensure the diameter.

[0006] The present invention provides a full-pressure structure large-diameter floating collar, including: a first pipe and a second pipe sleeved with each other, the second pipe is located below the first pipe, and further includes:

[0007] An inner stepped hole is opened on the inner wall of the second pipe;

[0008] A sealing gasket ring is installed in the inner stepped hole;

[0009] A blind plate, having a flat spherical shell structure, is installed above the sealing gasket ring, and the end face of the blind plate abuts against the top face of the sealing gasket ring;

[0010] A pressing ring, the side wall of which is threadedly connected to the inner wall of the second pipe, and the bottom face of the pressing ring closely abuts against the end face of the blind plate.

[0011] Preferably, the extension line of the end face of the blind plate passes through the center of the sphere of the blind plate, and the included angle between the extension line of the end face of the blind plate and the horizontal line is θ.

[0012] Preferably, the longitudinal section of the gasket ring is a right trapezoid, and the included angle between the hypotenuse of the right trapezoid and the horizontal line is the same as the angle of θ.

[0013] Preferably, the axial pre-tightening force of the pressing ring assembling the blind plate is F0, and the calculation method of the θ range is as follows:

[0014] D1. If the pre-tightening pressure point is in the circumferential direction where the blind plate contacts the pressing ring, the pre-tightening pressure surface is the product of the inner diameter circumference 2πr and the pressing surface arc length c, that is, 2πcr;

[0015] D2. Under the condition of not considering the friction coefficient, the normal load N and the compressive stress σ generated by the axial pre-tightening force F0 at the pre-tightening pressure point are respectively:

[0016] N = F0 / sinθ;

[0017]

[0018] D3. According to the compression strength criterion, the compressive stress at the pre-tightening pressure point does not exceed the failure strength of the blind plate material, and the range of the included angle θ between the extension line of the end face of the blind plate and the horizontal line can be determined as:

[0019]

[0020] where σ b is the failure strength of the blind plate material.

[0021] Preferably, the range of θ is 0° - 75°.

[0022] Preferably, it further includes:

[0023] Two anti-loosening bolts, symmetrically arranged, and one end of which passes through the side walls of the second pipe and the first pipe from left to right and is fixed to the first pipe.

[0024] Preferably, it further includes:

[0025] An annular groove, opened along the circumference of the first pipe;

[0026] A sealing ring, sleeved in the annular groove.

[0027] Preferably, the calculation methods of the inner and outer sphere radii SR0 and SR1 of the blind plate are as follows:

[0028] S1. Given that the diameter of the casing is 2r, the inner sphere radius SR0 of the blind plate is:

[0029] SR0 = r / cosθ;

[0030] S2. According to the Mohr's criterion, the outer spherical radius SR1 of the blind plate is as follows:

[0031]

[0032] where p is the temporary plugging pressure, and σ Cb is the expected value of the compressive failure strength of the blind plate material;

[0033] S3. When the pressure-bearing reliability of the blind plate reaches 99.7%, the expression of the outer spherical radius SR1 of the blind plate is as follows:

[0034]

[0035] where δ is the standard deviation.

[0036] Compared with the prior art, the present invention discloses a full-pressure structure large-diameter floating collar, and its beneficial effects are as follows:

[0037] The blind plate of this device has a structure of a flat spherical shell, which is different from a hemispherical shell. The flat spherical shell structure has stronger reverse pressure-bearing ability, more stable pressure-bearing, smaller particle size generated during crushing, and basically no residue on the sealing gasket ring after crushing. The crushed particles can circulate out of the wellbore with the drilling fluid, and there is no risk of sticking accident. When this device is in use, the sealing gasket ring, the blind plate and the pressing ring are installed in the second joint, and then the first joint and the second joint are installed. After installation, both ends are connected to the casing string in the horizontal well section, and the mud in the pipe is temporarily plugged to reduce the frictional resistance of the horizontal well section when the second joint is lowered. After the second joint reaches the position, the blind plate is broken by pressurizing at the wellhead. The inner diameter of the first joint and the second joint after connection is basically the same as the inner diameter of the connected casing, which belongs to a large diameter. The inner diameters of the pressing ring, the sealing gasket ring and the inner spherical diameter of the blind plate are all the same as the inner diameter of the casing. And under the hydrostatic pressure, the surface of the blind plate is all in a compressive stress state, so as to realize that when the blind plate is broken, it can be completely broken to achieve full diameter, and at the same time, the broken particle size is millimeter-level, and a circulation channel can be established inside and outside the casing to implement subsequent cementing operations. In addition, the blind plate is made of brittle material, which is easy to break, and the sealing gasket ring is made of metal composite rubber. The present invention can achieve complete breakage, reach full diameter, facilitate subsequent cementing operations, and ensure the structural reliability of the breakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to these drawings.

[0039] Figure 1Schematic diagram of the structure of the present invention;

[0040] Figure 2 Schematic diagram of the structure of the blind plate of the present invention;

[0041] Figure 3 Cross-sectional view of the second connecting pipe of the present invention;

[0042] Figure 4 Cross-sectional view of the first connecting pipe of the present invention;

[0043] Figure 5 Cross-sectional view of the gasket ring of the present invention;

[0044] Figure 6 Cross-sectional view of the pressing ring of the present invention.

[0045] The meanings of each label in the figure: 1 - second connecting pipe, 2 - gasket ring, 3 - blind plate, 4 - pressing ring, 5 - sealing ring, 6 - anti-loosening bolt, 7 - first connecting pipe, 21 - longitudinal section of gasket ring 2, 22 - top and bottom surfaces of gasket ring 2. Detailed implementation manners

[0046] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0047] The embodiment of the present invention provides a full-pressure structure large-diameter floating coupling as Figure 1 shown, including: a first connecting pipe 7 and a second connecting pipe 1 that are sleeved with each other. The second connecting pipe 1 is located below the first connecting pipe 7. The lower end side wall of the first connecting pipe 7 is provided with an external thread, and the inner wall of the upper end of the second connecting pipe 1 is provided with an internal thread. During installation, the first connecting pipe 7 and the second connecting pipe 1 are screwed tightly. This device is a short joint connected to the casing string. Therefore, in the structural design, the first connecting pipe 7 and the second connecting pipe 1 are required to have connecting interfaces with the standard casing threads, such as Figure 1 the 1:16 taper surface LC thread type shown, where the first connecting pipe 7 has a female thread interface and the second connecting pipe 1 has a male thread interface.

[0048] It further includes: an inner stepped hole, a gasket ring 2, a blind plate 3, and a pressing ring 4. As Figure 3As shown in the figure, the inner stepped hole is opened on the inner wall of the second adapter 1; the gasket ring 2 is installed in the inner stepped hole; the blind plate 3 is of a flat spherical shell structure, different from the hemispherical shell. The flat spherical shell structure has stronger reverse pressure resistance, more stable pressure bearing, smaller particle size when broken, and basically no residue on the gasket ring after breaking. The broken particles can be circulated out of the wellbore with the drilling fluid. It is installed above the gasket ring 2. The end face of the blind plate 3 abuts against the top surface of the gasket ring 2. The blind plate 3 and the gasket ring 2 are in a press-fit structure, constituting the full compressive stress state of the flat spherical shell blind plate 3 under hydrostatic pressure and the sealing support boundary condition of the gasket ring 2; as Figure 6 As shown in the figure, the side wall of the compression ring 4 is provided with an external thread that is threadedly connected to the internal thread on the inner wall of the second adapter 1. The bottom surface of the compression ring 4 closely abuts against the end face of the blind plate 3. Rotate the compression ring 4 until the bottom surface of the compression ring 4 presses the end face of the blind plate 3. When this device is in use, install the gasket ring 2, the blind plate 3 and the compression ring 4 in the second adapter 1, and then install the first adapter 7 and the second adapter 1. After installation, both ends are connected to the casing string in the horizontal well section, temporarily blocking the mud in the pipe to reduce the frictional resistance of the horizontal well section when the second adapter 1 is lowered. After the second adapter 1 is in place, then break the blind plate 3 by applying pressure from the wellhead. The inner diameter of the first adapter 7 and the second adapter 1 after connection is basically the same as the inner diameter of the connected casing, belonging to a large-diameter. The inner diameters of the compression ring 4, the gasket ring 2 and the inner spherical diameter of the blind plate 3 are all the same as the inner diameter of the casing. And under hydrostatic pressure, the surface of the blind plate 3 is all in a compressive stress state, so that when the blind plate 3 is broken, it can be completely broken to achieve a full diameter, and at the same time, the particle size of the broken particles is in millimeters, and a circulation channel can be established inside and outside the casing to implement subsequent cementing operations. In addition, the blind plate 3 is made of a brittle material for easy breaking, and the gasket ring 2 is made of a metal composite rubber material.

[0049] The second adapter 1 is designed with a minimum inner diameter 2r of the second adapter according to the inner diameter 2r of the casing, that is, the diameter of the second adapter. Inside the pipe, there are a sealing stop, an internal thread, an inner step and a through-hole in sequence; outside the pipe, there are a backstop step hole and an external thread standard for the casing, as Figure 3 shown; the outer diameter of the second adapter is 10 mm to 30 mm larger than the outer diameter of the matching casing. (When the large-diameter floating collar is actually used, it needs to be docked with the matching casing to form a casing string installed in the horizontal well. The outer diameter of the second adapter is 10 mm to 30 mm larger than the outer diameter of the casing to ensure that the second adapter has sufficient strength.)

[0050] The first adapter 7 is designed with a minimum inner diameter 2r of the first adapter according to the inner diameter 2r of the casing, that is, the diameter of the first adapter. Inside the pipe, there is an internal thread standard for the casing and a through-hole; outside the pipe, there are a pipe outer circular shaft, an outer step shaft, a backstop blind hole, two sealing grooves and an external thread in sequence. The external thread is matched with the internal thread of the second adapter 1, as Figure 4As shown; the outer diameter of the outer circle is 0 - 10 mm larger than the outer diameter of the matching casing. (Similarly, in actual use, the outer diameter of the first nozzle is 0 mm - 10 mm larger than the outer diameter of the casing to ensure that the first nozzle has sufficient strength.)

[0051] Furthermore, as Figure 2 shown, the extension line of the end face of the blind plate 3 passes through the center of the sphere of the blind plate 3, and the included angle between the extension line of the end face of the blind plate 3 and the horizontal line is θ.

[0052] Furthermore, the longitudinal section of the gasket ring 2 is a right trapezoid, and the included angle between the hypotenuse of the right trapezoid and the horizontal line is the same as the angle of θ. As Figure 5 shown, 21 is the longitudinal section of the gasket ring 2; 22 is the top surface and the bottom surface of the gasket ring 2, and its material is a vulcanized sealing rubber coating.

[0053] Furthermore, the axial pre-tightening force of the pressing ring 4 for assembling the blind plate 3 is F0, which is a risk design for supporting a certain reverse pressure (otherwise, when the drilling fluid enters from below the second nozzle and acts on the blind plate with a reverse pressure, it cannot play a role in temporary plugging). The calculation method of the θ range is as follows:

[0054] D1. If the pre-tightening pressure point is in the circumferential direction where the blind plate 3 and the pressing ring 4 are in contact, then the pre-tightening pressure surface is the product of the inner diameter circumference 2πr and the pressing surface arc length c, that is, 2πcr;

[0055] D2. Under the condition of not considering the friction coefficient, the normal load N and the compressive stress σ generated by the axial pre-tightening force F0 at the pre-tightening pressure point are respectively:

[0056] N = F0sinθ;

[0057]

[0058] D3. According to the compression strength criterion, the compressive stress at the pre-tightening pressure point does not exceed the failure strength of the material of the blind plate 3 (otherwise, it cannot play a role in temporary plugging, and the blind plate will break before cementing), and the range of the included angle θ between the extension line of the end face of the blind plate 3 and the horizontal line can be determined as:

[0059]

[0060] where σ b is the failure strength of the material of the blind plate 3.

[0061] Furthermore, the range of θ is 0° - 75°. This range is the range value of θ calculated by substituting into the above formula according to the actual working conditions. Within this range, the blind plate 3 can be completely broken when it breaks, and the broken particle size reaches the millimeter level.

[0062] Furthermore, the calculation methods of the inner and outer sphere radii SR0 and SR1 of the blind plate 3 are as follows:

[0063] S1. Given that the internal diameter of the known casing is 2r, the inner sphere radius SR0 of the blind plate 3 is (ensuring that the floating collar and the internal diameter of the casing are the same after the blind plate breaks):

[0064] SR0 = r / cosθ;

[0065] S2. Applying the Mohr's criterion, the outer sphere radius SR1 of the blind plate 3 is:

[0066]

[0067] where p is the temporary plugging pressure and σ Cb is the expected value of the compressive failure strength of the material of the blind plate 3;

[0068] S3. When the pressure-bearing reliability of the blind plate 3 reaches 99.7%, the expression of the outer sphere radius SR1 of the blind plate 3 is as follows:

[0069]

[0070] where δ is the standard deviation calculated from multiple tests of the compressive failure strength of the material of the blind plate 3. (This formula can be used to calculate the range of the outer sphere radius SR1 when the pressure-bearing reliability of the blind plate reaches 99.7% after determining the temporary plugging pressure)

[0071] Example 2

[0072] As a further improvement on the basis of Example 1, it further includes: two anti-backlash bolts 6 are symmetrically arranged, and one end of each of them passes through the side walls of the second nozzle 1 and the first nozzle 7 from left to right and is fixed to the first nozzle 7. The anti-backlash bolts 6 are provided to further fix the positions of the second nozzle 1 and the first nozzle 7. The purpose of setting the anti-backlash bolts is to ensure that the first nozzle 7 and the second nozzle 1 do not slip and become loose at the docking position during installation and use.

[0073] Among them, the other structures of this embodiment are the same as those of Example 1, except that it is an optimization of Example 1.

[0074] Example 3

[0075] As a further improvement on the basis of Example 1, as Figure 2 shown, it further includes: an annular groove and a sealing ring 5. The annular groove is formed along the circumference of the first nozzle 7; the sealing ring 5 is sleeved in the annular groove. In this embodiment, there are two sealing rings 5, both of which are standard sealing rings 5 to ensure the sealing performance of the floating collar.

[0076] Among them, the other structures of this embodiment are the same as those of Example 1, except that it is an optimization of Example 1.

[0077] Design the floating collar of this device according to the principle described in the above embodiments and the actual working conditions. For the casing with a diameter of Φ139.7mm, the internal diameter is Φ121mm, and the upper and lower joint types are LC couplings. The working condition is that the bottom hole mud column pressure is p = 45MPa. Given that the expected value of the compressive strength of the flat spherical shell blind plate material is σ cb = 385MPa, and the standard deviation δ = 92MPa. The design process of the full-bore floating collar with a full-pressure structure breaking blind plate is as follows:

[0078] 1. Dimension design of the blind plate 3

[0079] For the through-diameter size of Φ121mm, the span 2r of the blind plate 3 is 121mm, so r = 60.50mm.

[0080] Design the included angle θ = 30°, and its inner sphere radius and outer sphere radius are respectively:

[0081] SR0 = r / cosθ = 69.86mm

[0082]

[0083] The range interval determined according to the reliability of 9999.7% is:

[0084]

[0085] That is: 72.85mm ≤ SR1 ≤ 80.21mm

[0086] The rounded structural design dimensions of the blind plate 3 are obtained: SR0 is 70.00mm; SR1 is 75.00mm; the wall thickness Δ is 5.00mm; the outer conical surface included angle θ = 30°.

[0087] 2. Fit design of the gasket ring 2

[0088] For the through-diameter size of Φ121mm, the inner through-diameter 2r of the gasket ring is 121mm, so r = 60.50mm.

[0089] The outer radius R of the gasket ring 2 is not a controlled dimension, but according to the principle of compact design, R = 60.5mm + Δ = 65.65mm is rounded to 67.00mm, so the diameter is Φ134mm.

[0090] The inner conical surface angle at the upper part of the gasket ring 2 is also θ = 30° to match the flat spherical shell blind plate, and the lower part is a plane.

[0091] Both the upper inner conical surface and the lower plane of the gasket ring 2 are vulcanized with a sealing rubber coating layer about 2mm thick.

[0092] The height of the gasket ring 2 is not limited and can be adapted. Generally, it is taken as 5mm to 15mm.

[0093] 3. Matching design of clamping ring 4

[0094] The diameter size is Φ121mm, so the inner diameter of the clamping ring is 2r=121mm, and the inner radius r=60.50mm.

[0095] The outer diameter of the clamping ring 4 is required to be larger than the Φ134mm diameter of the sealing gasket ring 2, and the outer diameter adopts a shear-resistant trapezoidal straight thread, which is the commonly used standard of Tr140ⅹ5mm.

[0096] The clamping ring 4 squeezes the outer circle of the blind plate 3 through the thread, and generally has a 3×3 inner chamfer.

[0097] The height of the clamping ring 4 is not limited and can be set to 38 mm.

[0098] 4. Connection design of the second pipe 1

[0099] The diameter size is Φ121mm, so the inner diameter of the second connecting pipe 1 is also designed to be Φ121mm, and the outside is a connecting male buckle of the standard buckle type of the sleeve.

[0100] The outer diameter of the inner step hole of the second connecting pipe 1 is transitionally matched with the sealing gasket 2, and has a size of Φ134mm. The depth of the inner step hole also matches the height of the sealing gasket 2, which is 5mm to 15mm.

[0101] The internal thread of the second connecting pipe 1 connects to the external thread of the clamping ring 4, Tr140 x 5mm. The thread depth is much greater than the height of the clamping ring 4, so that the same thread will also connect to the first connecting pipe 7. Considering the shear strength of the material under the tensile load of the joint, the thread depth is generally equal to the external thread height of the clamping ring 4 + the internal thread depth of the first connecting pipe + 2mm, which is approximately 240mm.

[0102] The inner stopper surface of the second connecting pipe 1 is used for sealing and locking, and the stopper diameter is Φ145mm and the length is 120mm.

[0103] The outer diameter of the second connecting pipe 1 is Φ175 mm, taking into account the space available for the countersunk locking retaining bolt 6 and the wall thickness thereof.

[0104] The countersunk hole of the second connecting pipe 1 is matched.

[0105] 5. Docking design of the first connecting pipe 7

[0106] The diameter size is Φ121mm, so the internal diameter of the first connecting pipe 7 is also designed to be Φ121mm, and the inner hole is a connecting female buckle of the standard buckle type of the sleeve.

[0107] The outer circle corresponding to the connecting female thread of the standard thread type of the first adapter 7 casing is Φ139.7 mm according to the wall thickness of the casing outer diameter. Then, the outer circle corresponding to the inner diameter of the first adapter is designed as Φ150 mm. There are a sealing surface for docking with the inner stop of the second adapter 7, a check blind hole, and an external thread Tr140ⅹ5 mm for docking with the second adapter 7.

[0108] The assembly process of this device: First, install the sealing gasket ring 2 on the inner stepped hole of the second adapter 1; then, install the blind plate 3 and the pressing ring 4 in sequence on the upper part of the sealing gasket ring 2; the pressing ring 4 has an external thread that mates with the internal thread of the second adapter 1; by rotating the thread, the bottom surface of the pressing ring 4 presses on the outer spherical shell surface of the blind plate 3, pressing the mating surface between the blind plate 3 and the sealing gasket ring 2. Then, install two O-ring seals 5 in the external sealing groove of the first adapter 7. After connecting in place with the internal thread of the second adapter 1 through the external thread, seal the stop, squeeze the two O-ring seals 5, and then install a pair of check bolts 6 to complete the assembly process.

[0109] The advantages of the present invention are as follows:

[0110] 1. Structural reliability of pressure bearing and crushing

[0111] Based on the expected value and standard deviation of the compressive strength of the blind plate material, and according to the stress level of the oblate spherical shell structure under confining pressure conditions, calculate the structural parameters with a pressure bearing and crushing reliability of 99.7%, which is the design basis for structural reliability.

[0112] 2. Full bore with sufficient crushing and bore diameter design

[0113] The high pressure bearing characteristics exhibited by the axisymmetric structure of brittle materials are not only the characteristics of the high pressure bearing structure but also the pressure resistance characteristics of brittle materials. The designed structure uses very little material, has extremely large crushing energy storage, fully releases the fracture energy, and the particle size of the structure fracture is controllable. Coupled with the bore diameter design to ensure a full bore.

[0114] 3. Simple and stable overall structure design

[0115] The highest level of stably achieving the design function is simplicity and stability, which is the basis for ensuring the safety and reliability of the full bore floating collar.

[0116] The following table shows several common sizes of casings, and based on these sizes and basic working conditions, the parameter values and range variations of the floating collar of this device are designed.

[0117] Table 1 Variation of outer conical surface angle

[0118]

[0119]

[0120]

[0121] Table 2 Temporary plugging pressure change (cone angle 30°)

[0122]

[0123]

[0124]

[0125] Table 3 Temporary plugging pressure change (small cone angle 15°)

[0126]

[0127]

[0128]

[0129] [[ID=2,5]]Table 4 Temporary plugging pressure change (small cone angle 0°)

[0130]

[0131] [[ID=३१]]

[0132]

[0133] The above discloses only several specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto, and any changes that can be conceived by those skilled in the art should fall within the protection scope of the present invention. It should be noted that there seems to be a misspelling in "[[ID=३१]]", which should probably be "". If this is an error in the original text, please correct it for a more accurate translation.

Claims

1. A full-pressure structure large-diameter floating coupling, comprising: The first connecting pipe (7) and the second connecting pipe (1) are sleeved with each other, and the second connecting pipe (1) is located below the first connecting pipe (7), and it is characterized in that it further comprises: An inner stepped hole is opened on the inner wall of the second connecting pipe (1); A sealing gasket ring (2) is installed in the inner stepped hole; The blind plate (3), which is of a flat spherical shell structure, is installed above the gasket ring (2). The end face of the blind plate (3) abuts against the top face of the gasket ring (2). The extension line of the end face of the blind plate (3) passes through the center of the sphere of the blind plate (3), and the included angle between the extension line of the end face of the blind plate (3) and the horizontal line is ; A pressing ring (4), the side wall of which is threadedly connected to the inner wall of the second connecting pipe (1), and the bottom surface of the pressing ring (4) abuts against the end surface of the blind plate (3); The calculation methods of the inner and outer spherical radii SR0 and SR1 of the blind plate (3) are as follows: S1. Given that the inner diameter of the casing is 2r, the inner spherical radius SR0 of the blind plate (3) is: ； S2. Applying the Mohr's criterion, the outer spherical radius SR1 of the blind plate (3) is: ； Among them, is the temporary plugging pressure, is the expected value of the compressive failure strength of the material of the blind plate (3); S3. When the pressure-bearing reliability of the blind plate (3) reaches 99.7%, the expression of the outer spherical radius SR1 of the blind plate (3) is as follows: ； Among them, is the standard deviation.

2. The full-pressure structure large-diameter floating coupling according to claim 1, wherein The longitudinal section of the gasket ring (2) is a right trapezoid, and the angle between the hypotenuse of the right trapezoid and the horizontal line is the same as that of the angle of.

3. A full-pressure structure large-diameter floating coupling according to claim 1, characterized in that, The axial pre-tightening force of the pressing ring (4) for assembling the blanking plate (3) is F0, The calculation method of the range is as follows: D1. If the pre-tightening pressure point is in the circumferential direction where the blind plate (3) contacts the pressing ring (4), the pre-tightening pressure surface is the product of the inner diameter circumference 2πr and the arc length c of the pressing surface, that is, 2πcr; D2. Under the condition of neglecting the friction coefficient, the normal load and the compressive stress generated by the axial pre-tightening force F0 at the pre-tightening pressure point are respectively: ； ； D3. According to the compressive strength criterion, the compressive stress at the pre-tightening pressure point does not exceed the failure strength of the material of the blind plate (3), and the range of the angle θ between the extension line of the end surface of the blind plate (3) and the horizontal line can be determined as: ； Among them, is the breaking strength of the material of the blind plate (3).

4. A fully pressed structure large-diameter floating coupling according to claim 1, characterized in that, It further comprises: Two anti-loosening bolts (6) are symmetrically arranged, and one end of each of them passes through the side walls of the second connecting pipe (1) and the first connecting pipe (7) from left to right and is fixed to the first connecting pipe (7).

5. A full-pressure structure large-diameter floating coupling according to claim 1, characterized in that, It further comprises: An annular groove is opened along the circumference of the first connecting pipe (7); A sealing ring (5) is sleeved in the annular groove.

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