Method for determining the length of threaded connection collars for the butt connection of tubular bodies

Abstract

The application provides a length determination method of a threaded connection coupling for butt joint of pipe bodies, the coupling is used for connecting two pipe bodies, the length determination method comprises the following steps: processing the outer wall of a plurality of pipe bodies and the inner wall of a plurality of couplings by using the same processing program through a thread processing equipment, so as to form connecting threads on the outer wall and the inner wall respectively, the number of the pipe bodies is same as the number of the couplings; threadedly connecting the pipe bodies and the couplings by using a plurality of different torques through a pipe body connecting device, and obtaining the screwing-in lengths of the pipe bodies under the plurality of different torques; and statistically analyzing the plurality of obtained screwing-in lengths, so as to determine a target screwing-in length and a target coupling length. According to the length determination method of the threaded connection coupling for butt joint of pipe bodies, the length of the coupling can be accurately determined, and the close contact of the end faces of the two pipe bodies after the coupling connects the two pipe bodies can be ensured.

Description

Technical Field

[0001] This invention relates to the field of pipe connection technology, and in particular to a method for determining the length of a threaded connection coupling for a pipe body top-to-top connection. Background Technology

[0002] In the exploration and development of petrochemical energy sources such as oil, natural gas, and coalbed methane, the sealing and corrosion of threaded connections are critical concerns for oil well tubing. Utilizing bimetallic composite pipes to manufacture oil casing and tubing to stabilize the wellbore and create oil and gas channels is currently an effective means of addressing corrosion issues in oil well tubing. However, the corrosion resistance between the pipe body and coupling at the threaded connection of bimetallic fittings is a significant factor limiting their application, such as potential difference corrosion between the bimetallic pipe body and coupling materials.

[0003] The corrosion resistance integrity of the entire pipe string can be effectively solved by welding a corrosion-resistant alloy onto the external thread end of the bimetallic composite pipe and then using a butt-joint threaded connection. However, ensuring that the ends of the two pipe sections connected by the coupling are in good contact after the threads are engaged, i.e., ensuring the sealing of the threaded connection, is a technical challenge that the butt-joint threaded connection urgently needs to solve. Summary of the Invention

[0004] In view of the above problems, the present invention provides a method for determining the length of a threaded connection coupling for a pipe-to-pipe connection, which solves the problem of determining the length of the coupling. When using this coupling to connect two pipe sections, it can ensure good contact between the axial end faces of the two pipe sections, and avoid leakage and corrosion due to potential difference between the coupling and the pipe.

[0005] This invention provides a method for determining the length of a threaded coupling for a pipe-to-pipe connection. The coupling connects two pipe sections symmetrical about the centerline of the coupling, and the end faces of the two pipe sections abut against each other along the axial direction of the coupling. The length determination method includes the following steps: machining the outer walls of multiple pipe sections and the inner walls of multiple couplings using the same machining program with a threading machine to form connecting threads on the outer and inner walls respectively, wherein the number of pipe sections and the number of couplings are the same; threading the pipe sections and couplings together using a pipe connection device with multiple different torques, and obtaining the screw-in length of the pipe sections under the multiple different torques; and statistically analyzing the obtained screw-in lengths to determine the target screw-in length and the target coupling length.

[0006] The method for determining the length of a threaded coupling for a pipe-to-pipe connection according to the present invention involves setting the length determination logic to use multiple different torques to thread the pipe and coupling together, obtaining the screw-in length of the pipe under these different torques, and statistically analyzing the obtained screw-in lengths to determine the target screw-in length and the target coupling length. This method is highly operable and ensures that the target screw-in length of the pipe and the target coupling length are determined under the premise of a stable connection between the pipe and the coupling, with small errors and high reliability. Thus, when two pipe sections are connected by the coupling, it ensures that the two pipe sections abut against each other along the axial direction of the coupling and have a good contact state, i.e., there is no gap between the axial end faces of the two pipe sections. This prevents corrosive liquids inside the pipe, such as drilling fluid, completion fluid, oil, natural gas, etc., from flowing into the gap between the axial end faces of the two pipe sections, thereby avoiding potential difference corrosion between the pipe and the coupling. Simultaneously, the production of the pipe and coupling can be based on the above values, improving the pass rate of the pipe and coupling and reducing production costs.

[0007] According to some embodiments of the present invention, the method of connecting the pipe body and the coupling threadedly using a pipe body connection device with multiple different torques and obtaining the screw-in length of the pipe body under the multiple different torques includes the following steps: randomly pairing multiple pipe bodies and multiple couplings; threading the paired pipe bodies and couplings using the minimum upper torque of the threaded connection design, and measuring the first screw-in length of each pipe body; threading each pair of paired pipe bodies and couplings using the optimal upper torque of the threaded connection design, and measuring the second screw-in length of each pipe body; and cyclically replacing the pipe bodies and couplings, repeating the above steps so that each pipe body is connected to all the couplings.

[0008] Statistical analysis is performed on the multiple screw-in lengths obtained to determine the target screw-in length and the target coupling length, including the following steps: statistical analysis is performed on all the first screw-in lengths and second screw-in lengths obtained after pairing, wherein the target screw-in length is greater than or equal to the maximum value of the first screw-in length and less than the minimum value of the second screw-in length.

[0009] Optionally, the target screw-in length is the average of the maximum value of the first screw-in length and the minimum value of the second screw-in length.

[0010] The target coupling length is twice the target screw-in length.

[0011] In some embodiments, when fastening the pipe body and the coupling having the target coupling length at the construction site, the applied torque is greater than or equal to the optimal fastening torque of the threaded connection design.

[0012] Optionally, the pipe body includes: a body section, an external thread section, and a nose cylindrical section, wherein the connecting thread of the external thread section is a tapered thread, and the external thread section is located between the body section and the nose cylindrical section; the coupling includes an end face boring section, an internal thread section, and a middle cylindrical section, wherein the end face boring section is adapted to the body section, the internal thread section is adapted to the external thread section, and the nose cylindrical section is adapted to the middle cylindrical section.

[0013] Optionally, the length of the end face boring section in the axial direction of the coupling is greater than or equal to 18 mm.

[0014] Optionally, the length of the central cylindrical segment in the axial direction of the coupling is greater than or equal to 10 mm.

[0015] In a specific example, the pipe body is a seamless pipe or a welded pipe. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a logic diagram of a method for determining the length of a threaded connection coupling for a pipe-to-pipe top-type connection according to an embodiment of the present invention;

[0018] Figure 2 This is a schematic diagram of the threaded connection between the coupling and the pipe body provided in an embodiment of the present invention;

[0019] Figure 3 This is a schematic cross-sectional view of the coupling provided in an embodiment of the present invention;

[0020] Figure 4 This is a cross-sectional schematic diagram of the tube provided in an embodiment of the present invention.

[0021] Explanation of reference numerals in the attached figures:

[0022] 100 - Coupling; 101 - End face boring section; 102 - Internal thread section; 103 - Middle cylindrical section;

[0023] 200 - Pipe body; 201 - Body section; 202 - External thread section; 203 - Nose end cylindrical section. Detailed Implementation

[0024] To make the above-mentioned objectives, features, and advantages of the embodiments of this application more apparent and understandable, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0025] In the exploration and development of petrochemical energy sources such as oil, natural gas, and coalbed methane, the sealing and corrosion of threaded connections are critical concerns for oil well tubing. Utilizing bimetallic composite pipes to manufacture oil casing and tubing to stabilize the wellbore and create oil and gas channels is currently an effective means of addressing corrosion issues in oil well tubing. However, the corrosion resistance between the pipe body and coupling at the threaded connection of bimetallic fittings is a significant factor limiting their application, such as potential difference corrosion between the bimetallic pipe body and coupling materials.

[0026] The corrosion resistance integrity of the entire pipe string can be effectively solved by welding a corrosion-resistant alloy onto the external thread end of the bimetallic composite pipe and then using a butt-joint threaded connection. However, ensuring that the ends of the two pipe sections connected by the coupling are in good contact after the threads are engaged, i.e., ensuring the sealing of the threaded connection, is a technical challenge that the butt-joint threaded connection urgently needs to solve.

[0027] In view of this, the present invention provides a method for determining the length of a threaded coupling for a pipe-to-pipe connection. By setting the coupling length determination logic to use multiple different torques to thread the pipe and coupling together, and obtaining the screw-in length of the pipe under multiple different torques, the method performs statistical analysis on the obtained screw-in lengths to determine the target screw-in length and the target coupling length. This solves the problem of determining the coupling length. When using this coupling to connect two pipe sections, it can ensure good axial end face contact between the two pipe sections, avoiding leakage and potential difference corrosion between the coupling and the pipe.

[0028] The following is for reference. Figures 1-4 A method for determining the length of a threaded coupling for a pipe-to-pipe top-to-top connection is described according to an embodiment of the present invention.

[0029] The method for determining the length of the threaded connection coupling for a pipe-to-pipe connection according to an embodiment of the present invention, wherein the coupling 100 can be used to connect two pipe sections 200, the two pipe sections 200 are symmetrical about the center line of the coupling 100, the pipe section 200 can be an oil casing, and the two pipe sections 200 abut against each other along the axial direction of the coupling 100 inside the coupling 100, in other words, the two pipe sections 200 are in a top-to-bottom connection.

[0030] The method for determining the length of a threaded coupling for a pipe-to-pipe connection according to embodiments of the present invention can be applied to a length determination system. The entire system includes different components such as thread processing equipment and pipe connection devices. These components can be used to perform the various sub-steps of the method for determining the length of the coupling for pipe connection.

[0031] Furthermore, it should be noted that the length determination system capable of performing the length determination method for threaded connection couplings used in pipe-to-pipe connections may also include components such as a processor and a controller. The processor can be used to execute program instructions for storing and processing the obtained length data, while the controller can be used to control other parts of the length determination system, such as thread processing equipment or pipe connection devices.

[0032] The length determination method may include the following steps: S1, using a pipe threading CNC machine tool to process the outer walls of multiple pipe bodies 200 and the inner walls of multiple couplings 100 using the same machining program, so as to form connecting threads on the outer and inner walls respectively, with the number of pipe bodies 200 and the number of couplings 100 being the same; S2, using an oil casing hydraulic power clamp to thread the pipe bodies 200 and couplings 100 together with multiple different torques, and obtaining the screw-in length of the pipe bodies 200 under multiple different torques; S3, performing statistical analysis on the obtained multiple screw-in lengths to determine the target screw-in length and the target coupling length.

[0033] For example, the thread processing equipment can be a CNC machine tool for pipe threading, and the pipe connection device can be a hydraulic power clamp for oil casing. The number of pipe bodies 200 processed can be three, and correspondingly, the number of couplings 100 processed can be three. The same processing procedure is followed on the outer walls of the three pipe bodies 200 and the inner walls of the three couplings 100, ensuring that any processed pipe body 200 can be threadedly connected to any coupling 100. Here, the connecting thread can be API (American Petroleum Institute) thread or other non-API threads. Statistical analysis of the obtained multiple insertion lengths can be performed using the processor in the entire system.

[0034] Then, the pipe body 200 and the coupling 100 are threaded together one by one according to different torques, ensuring a stable connection. Since the pipe body 200 and coupling 100 are threaded together, the length by which the pipe body 200 is screwed into the coupling 100 varies depending on the applied torque. Therefore, by threading multiple pipe bodies 200 and multiple couplings 100 together with different torques, the screw-in length of each pipe body 200 under different torques can be obtained. A screw-in length measurement data table is then established to analyze the obtained data. Based on the obtained data, the fluctuation range of the screw-in length of the pipe body 200 within the coupling 100 when the connection is stable is determined. Then, the target screw-in length of the pipe body 200 is determined from this range, and finally, the target coupling length is determined based on this target screw-in length. Optionally, since the coupling 100 needs to connect two pipe sections 200 simultaneously during actual operation, the length of the coupling 100, i.e. the target coupling length, should be greater than or equal to twice the target screw-in length.

[0035] The method for determining the length of the anti-threaded coupling 100 for connecting a pipe body 200 according to an embodiment of the present invention involves setting the length determination logic to use multiple different torques to thread the pipe body 200 and the coupling 100 together, obtaining the screw-in length of the pipe body 200 under multiple different torques, and performing statistical analysis on the obtained screw-in lengths to determine the target screw-in length and the target coupling length. This method is highly operable and can ensure that the target screw-in length of the pipe body 200 and the target coupling length of the coupling 100 are determined under the premise of stable connection between the pipe body 200 and the coupling 100. It has small error and high reliability. In this way, when the two pipe sections 200 are connected by the coupling 100, it can be ensured that the two pipe sections 200 abut against each other along the axial direction of the coupling 100 and have a good contact state, that is, there is no gap between the axial end faces of the two pipe sections 200. This prevents corrosive media such as drilling fluid, injection fluid, oil, and natural gas from flowing into the gap between the axial end faces of the two pipe sections 200, thereby avoiding potential difference corrosion between the pipe section 200 and the coupling 100. At the same time, when producing the pipe section 200 and the coupling 100, production can be based on the above values, improving the pass rate of the pipe section 200 and the coupling 100 and reducing production costs.

[0036] According to some embodiments of the present invention, the pipe body 200 and coupling 100 are threaded together using a pipe body connection device with multiple different torques, and the screw-in length of the pipe body 200 under multiple different torques is obtained, which may include the following steps: S21, randomly pairing multiple pipe bodies 200 and multiple couplings 100; S22, threading each pair of paired pipe bodies 200 and couplings 100 with the minimum upper torque of the threaded connection design, and measuring the first screw-in length of each pipe body 200; S23, threading each pair of paired pipe bodies 200 and couplings 100 with the optimal upper torque of the threaded connection design, and measuring the second screw-in length of each pipe body 200; S24, sequentially cyclically pairing pipe bodies 200 and couplings 100, repeating the above steps until each pipe body 200 is paired with all couplings 100.

[0037] For example, S21: The three processed pipe bodies 200 are marked as P1, P2 and P3 respectively, and the three processed couplings 100 are marked as B1, B2 and B3 respectively. The pairing relationship when the three pipe bodies 200 and the three couplings 100 are first fastened and connected is P1-B1, P2-B2 and P3-B3.

[0038] S22: The minimum top torque of the threaded connection design is used to connect the external thread of the pipe body 200 and the internal thread of the coupling 100. The screw-in lengths of the pipe body 200 are measured as1-1, as1-2 and as1-3 respectively.

[0039] S23: Using the optimal top-pinning torque of the threaded connection design, the external thread of the pipe body 200 and the internal thread of the coupling 100 are threaded together. The screw-in lengths of the external thread of the pipe body 200 are measured to be am1-1, am1-2 and am1-3 respectively.

[0040] S24: Exchange the threaded pipe body 200 and coupling 100, and re-pair them, for example, P1-B2, P2-B3, and P3-B1. Perform threaded connections according to the minimum and optimal threading torques designed for the threaded connection, respectively. Measure the thread insertion lengths of the external thread on the pipe body 200 as2-1, as2-2, as2-3, am2-1, am2-2, am2-3, as3-1, as3-2, as3-3, and am3-1, am3-2, am3-3. It should be noted that the minimum and optimal threading torques are determined by the threaded connection designer. This allows for the acquisition of multiple thread insertion length data points. Analyzing these multiple data points results in more reliable results with less error.

[0041] Optionally, statistical analysis of the acquired multiple screw-in lengths to determine the target screw-in length and the target coupling length may include the following steps: statistical analysis of the first screw-in length and the second screw-in length acquired after each pairing, wherein the target screw-in length is greater than or equal to the maximum value among the multiple first screw-in lengths and less than the minimum value among the multiple second screw-in lengths.

[0042] Understandably, since the minimum tightening torque is less than the optimal tightening torque (typically 85% of the optimal tightening torque), the first screw-in length is less than the second screw-in length. Setting the target screw-in length to be greater than or equal to the maximum value among the multiple first screw-in lengths and less than the minimum value among the multiple second screw-in lengths makes the target screw-in length more scientific and reasonable. This avoids the target screw-in length being too small, resulting in the target coupling length being too small, which would prevent the coupling 100 from effectively and reliably connecting the two pipe bodies 200. It also avoids the target screw-in length being too large, resulting in the target coupling length being too large, which would cause gaps between the end faces of the two pipe bodies 200, allowing corrosive liquid to enter the gaps and causing potential difference corrosion between the coupling 100 and the pipe body 200.

[0043] Optionally, the target screw-in length is the average of the maximum value among multiple first screw-in lengths and the minimum value among multiple second screw-in lengths, thus making the value of the target screw-in length more scientific and reasonable.

[0044] Optionally, the target coupling length is twice the target screw-in length. This ensures that after two pipes 200 with the target screw-in length are connected by a coupling 100 with the target coupling length, the end faces of the two pipes 200 will have good contact and no gaps will appear.

[0045] In some embodiments, when fastening the pipe body 200 with a target screw-in length and the coupling 100 with a target coupling length at the construction site, the target implementation torque is greater than or equal to the optimal fastening torque. Setting the target implementation torque to be greater than or equal to the optimal fastening torque ensures that the two pipe bodies 200 are screwed in properly, with good end-face contact and no gaps. Preferably, during on-site construction, the average of the optimal fastening torque and the maximum fastening torque is used to fasten the pipe body 200 and the coupling 100.

[0046] Optionally, refer to Figures 2-4The pipe body 200 may include: a body section 201, an externally threaded section 202, and a nose-end cylindrical section 203. The connecting thread on the externally threaded section 202 is a tapered thread, and the externally threaded section 202 is located between the body section 201 and the nose-end cylindrical section 203. The coupling 100 may include: an end-face bored section 101, an internally threaded section 102, and a central cylindrical section 103. The end-face bored section 101 of the coupling 100 is adapted to the body section 201 of the pipe body 200; the internally threaded section 102 of the coupling 100 is adapted to the externally threaded section 202 of the pipe body 200; and the nose-end cylindrical section 203 of the pipe body 200 is adapted to the central cylindrical section 103 of the coupling 100.

[0047] When the tube body 200 and the coupling 100 are threaded together, the nose cylindrical section 203 of the tube body 200 can pass through the end face boring section 101 and the internal thread section 102 of the coupling 100 in sequence, and enter the middle cylindrical section 103. Meanwhile, the external thread section 202 of the tube body 200 passes through the end face boring section 101 to reach the internal thread section 102 of the coupling 100. As the tube body 200 rotates, the nose cylindrical section 203 gradually screws in and extends inward until the nose cylindrical section 203 of the tube body 200 enters the middle 1 / 2 of the coupling 100 and stops. At this time, part of the body section 201 and the end face boring section 101 are opposite to each other and cooperate with each other.

[0048] Optionally, before processing the outer walls of multiple pipe bodies 200 and the inner walls of multiple couplings 100 using the same processing procedure to form connecting threads on the outer walls of the pipe bodies 200 and the inner walls of the couplings 100 respectively, the lengths of the nose cylindrical section 203 and the end face boring section 101 can be determined first. Since the length of the nose cylindrical section 203 is part of the screw-in length of the pipe body 200, and the length of the end face boring section 101 is part of the length of the coupling 100, the nose cylindrical section 203 will affect the screw-in length of the pipe body 200, and the end face boring section 101 will affect the length of the coupling 100. After determining the target screw-in length and the target coupling length through multiple tests conducted according to the above length determination method, the axial length of the connecting thread in the pipe body 200 or the coupling 100 can also be determined, thereby providing a basis for actual processing and production.

[0049] Optionally, before determining the lengths of the nose cylindrical section 203 and the end face boring section 101, the thread type of the connecting thread can be determined first. Since the thread type of the connecting thread affects the torque required to be applied when the pipe body 200 and the coupling 100 are threaded together, namely the minimum and optimal threading torques mentioned above, determining the thread type first is beneficial to the smooth conduct of the test and makes the obtained parameters more accurate and reliable.

[0050] Optionally, the length of the central cylindrical section 103 in the axial direction of the coupling 100 is greater than or equal to 10 mm. For example, the length of the central cylindrical section 103 in the axial direction of the coupling 100 can be 10 mm, 12 mm, 14 mm or greater. The length of the central cylindrical section 103 in the axial direction of the coupling 100 can be reasonably selected within the above range according to actual needs. When the two pipe sections 200 are connected by the coupling 100, the nose cylindrical sections 203 of both pipe sections 200 are adapted to the middle cylindrical section 103 of the coupling 100. Furthermore, the end faces of the nose cylindrical sections 203 of the two pipe sections 200 need to abut against each other. Therefore, the length of the nose cylindrical sections 203 of the two pipe sections 200 is half the length of the middle cylindrical section 103 of the coupling 100. If the length of the middle cylindrical section 103 in the axial direction of the coupling 100 is greater than or equal to 10mm, it can prevent the mating length between the nose cylindrical section 203 and the middle cylindrical section 103 from being too short. This would make it difficult to effectively ensure a stable fit between the two pipe sections 200 and between the pipe section 200 and the coupling 100, which could easily lead to leakage points and, consequently, potential difference corrosion between the coupling 100 and the pipe section 200.

[0051] Optionally, the length of the end face boring section 101 of the coupling 100 in its own axial direction is greater than or equal to 18 mm. For example, the length of the boring section 101 can be 18 mm, 20 mm, 22 mm or greater.

[0052] In a specific example, the pipe body 200 is a bimetallic composite oil casing. Thus, the outer layer of the pipe body 200 ensures high structural strength and rigidity, while the inner layer provides excellent corrosion resistance. Furthermore, a 2mm thick corrosion-resistant alloy layer is welded to the end of the pipe body, specifically the cylindrical nose section. By using the above-described method to determine the length of the coupling 100, after connecting two pipe bodies 200, the end faces of both pipe bodies 200 are coated with a corrosion-resistant alloy layer, and there are no gaps between the contact surfaces. This prevents corrosive liquids such as drilling fluid, completion fluid, crude oil, and natural gas from penetrating into the gaps. Consequently, potential difference corrosion cannot form between the inner and outer layers of the pipe body 200, thereby extending the service life of the pipe body 200 to a certain extent.

[0053] Alternatively, the pipe body 200 can also be a seamless or welded pipe made of corrosion-resistant alloy or other materials. This allows for a wide range of sources for the pipe body 200, reducing costs.

[0054] The following example illustrates the method for determining the length of the coupling 100 in this embodiment, using a top-to-top threaded connection where both the pipe body 200 and the coupling 100 have 88.9*7.72mm GC threads.

[0055] S1: Select 88.9*7.72mm GC thread as the connecting thread between pipe body 200 and coupling 100, with a taper of 1:16 and a pitch of 5 threads / inch;

[0056] S2: Determine that the length of the boring section 101 of the coupling 100 is 20mm and the length of the nose cylindrical section 203 of the tube body 200 is 6mm.

[0057] S3: Machine external threads on the three pipe bodies 200 respectively, and mark the three pipe bodies 200 as P1, P2 and P3. Machine internal threads in the three couplings 100 respectively, and mark the three couplings 100 as B1, B2 and B3.

[0058] S4: During the initial threading, pair the pipe body 200 and coupling 100 respectively, with corresponding relationships of P1-B1, P2-B2, and P3-B3. Use the minimum threading torque of the GC thread to connect the pipe body 200 and coupling 100, and measure the screw-in lengths of the external thread of the pipe body 200 as1-1, as1-2, and as1-3 respectively;

[0059] S5: Use the optimal threading torque of the GC thread to connect the pipe body 200 and the coupling 100. Measure the screw-in length of the pipe body 200 as am1-1, am1-2 and am1-3 respectively.

[0060] S6: Exchange the threaded connection of pipe body 200 and coupling 100, P1-B2, P2-B3 and P3-B1, and perform threaded connection according to minimum threading torque and optimal threading torque respectively. Measure the screw-in length of pipe body 200 as2-1, as2-2, as2-3, am2-1, am2-2, am2-3, as3-1, as3-2, as3-3 and am3-1, am3-2, am3-3 respectively;

[0061] S7: Perform statistical analysis on the length values ​​of the pipe body 200 screwed into the coupling 100 to obtain the maximum screw-in length asmax of the external thread of the pipe body 200 at the minimum tightening torque, and the minimum screw-in length ammin of the external thread of the pipe body 200 at the optimal torque.

[0062] S8: Determine the length of the pipe body 200 screwed into the coupling 100 as (asmax+amv) / 2;

[0063] S9: Determine the length of coupling 100 as (asmax + amv).

[0064] The specific experimental data for this embodiment are as follows:

[0065]

[0066] From the table above, we can obtain the asmax value as 72.32 mm and the ammin value as 72.96 mm.

[0067] Therefore, the length of the pipe body 200 screwed into the coupling 100 is determined to be 72.64 mm.

[0068] Therefore, for a counter-threaded connection of 88.9*7.72mm GC thread, the length of coupling 100 is 145.28mm.

[0069] For 88.9*7.72mm GC threads with a top-fitting thread connection, the threading torque range during field threading operations is 10000N.m to 11500N.m, with the optimal threading torque value being 10750N.m.

[0070] The various embodiments or implementation methods described in this specification are presented in a progressive manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other.

[0071] It should be noted that the terms "one embodiment," "embodiment," "exemplary embodiment," "some embodiments," etc., mentioned in the specification indicate that the described embodiment may include a specific feature, structure, or characteristic, but not every embodiment necessarily includes that specific feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Moreover, when a specific feature, structure, or characteristic is described in connection with an embodiment, implementing such a feature, structure, or characteristic in conjunction with other embodiments, whether explicitly described or not, is within the knowledge scope of those skilled in the art.

[0072] Generally speaking, terms should be understood at least in part by their use in context. For example, at least in part by context, the term "one or more" as used in the text can be used to describe any feature, structure, or characteristic of the singular meaning, or a combination of features, structures, or characteristics of the plural meaning. Similarly, at least in part by context, terms such as "a" or "the" can also be understood to convey either singular or plural usage.

[0073] It should be readily understood that the terms “on,” “above,” and “on top of” in this disclosure should be interpreted in the broadest possible sense, such that “on” means not only “directly on something” but also “on something” with an intermediate feature or layer therebetween, and that “above” or “on top of” means not only “on top of something” but also “on top of something” without an intermediate feature or layer therebetween (i.e., directly on something).

[0074] Furthermore, for ease of explanation, spatially relative terms such as "below," "below," "under," "above," and "above" may be used to describe the relationship of one element or feature relative to other elements or features as shown in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation other than those shown in the figures. The device may have other orientations (rotated 90 degrees or in other orientations), and the spatially relative descriptive terms used herein may be interpreted accordingly.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for determining the length of a threaded coupling for a pipe-body top-to-top connection, characterized in that, The coupling is used to connect two pipe sections, which are symmetrical about the center line of the coupling. The end faces of the two pipe sections abut against each other along the axial direction of the coupling inside the coupling. The method for determining the length includes the following steps: The outer walls of multiple pipe bodies and the inner walls of multiple couplings are processed using the same processing procedure with a thread processing equipment to form connecting threads on the outer walls and inner walls respectively. The number of pipe bodies and the number of couplings are the same. The pipe body and the coupling are threaded together using a pipe body connection device with multiple different torques, and the screw-in length of the pipe body under the multiple different torques is obtained; Statistical analysis is performed on the multiple screw-in lengths obtained to determine the target screw-in length and the target coupling length; The method of connecting the pipe body and the coupling threadedly using a pipe body connection device with multiple different torques, and obtaining the screw-in length of the pipe body under the multiple different torques, includes the following steps: Randomly pair up the multiple pipe bodies and the multiple couplings; The minimum threading torque of the threaded connection design is used to thread each pair of paired tubes and the coupling together, and the first screw-in length of each tube is measured. The optimal threading torque of the threaded connection design is used to thread each pair of mated tubes and the coupling together, and the second screw-in length of each tube is measured. The pipe body and couplings are replaced sequentially and the above steps are repeated to ensure that each pipe body is connected to all of the couplings in the above steps. Statistical analysis is performed on the obtained screw-in lengths to determine the target screw-in length and the target coupling length, including the following steps: Statistical analysis is performed on the first and second screw-in lengths obtained after each pairing. The target screw-in length is greater than or equal to the maximum value among multiple first screw-in lengths and less than the minimum value among multiple second screw-in lengths. The target screw-in length is the average of the maximum value among a plurality of first screw-in lengths and the minimum value among a plurality of second screw-in lengths.

2. The method for determining the length of the threaded connection coupling for a pipe-body top-to-top connection according to claim 1, characterized in that, The target coupling length is twice the target screw-in length.

3. The method for determining the length of the threaded connection coupling for a pipe-body top-to-top connection according to claim 1, characterized in that, When fastening the pipe body and the coupling at the construction site, the applied torque is greater than or equal to the optimal fastening torque of the threaded connection design.

4. The method for determining the length of the threaded connection coupling for a pipe-body top-to-top connection according to claim 1, characterized in that, The tube body includes: a body section, an external thread section, and a nose cylindrical section. The connecting thread of the external thread section is a tapered thread, and the external thread section is located between the body section and the nose cylindrical section. The coupling includes an end face boring section, an internal thread section, and a middle cylindrical section. The end face boring section is adapted to the body section, the internal thread section is adapted to the external thread section, and the nose cylindrical section is adapted to the middle cylindrical section.

5. The method for determining the length of the threaded connection coupling for a pipe-body top-to-top connection according to claim 4, characterized in that, The length of the end face boring section in the axial direction of the coupling is greater than or equal to 18 mm.

6. The method for determining the length of the threaded connection coupling for a pipe-body top-to-top connection according to claim 4, characterized in that, The length of the central cylindrical section in the axial direction of the coupling is greater than or equal to 10 mm.

7. The method for determining the length of the threaded connection coupling for a pipe-body top-to-top connection according to claim 1, characterized in that, The pipe body is either a seamless pipe or a welded pipe.

Images