JP4277845B2 - Oil well or gas well - Google Patents

Description

The present invention relates to an oil well pipe or a gas well pipe.

  For example, the use environment of oil wells, natural gas wells, etc. (hereinafter simply referred to as “oil wells”) is becoming stricter year by year, and threaded joints for connecting steel pipes such as oil well pipes and gas well pipes used in oil wells to each other. It is required to endure a strong axial force and to have high airtightness. There are various types of threaded joints. 7 and 8 are explanatory views partially showing an example of this type of threaded joint.

  The threaded joint shown in FIG. 7 is a buttress joint 1 having a trapezoidal screw defined in API (American Petroleum Institute) standard STD5B. As shown in the figure, a buttress joint 1 is a box having a pin portion 5 having a tapered male screw 3 and an incomplete screw portion 4 at the tip of a steel pipe 2 and tapered female screw portions 7 provided inside both ends of a coupling 6. Part 8. The taper male screw 3 is formed on a smooth outer surface that has been subjected to the outer processing.

  Further, the threaded joint shown in FIG. The special joint 9 includes a pin portion 13 having a tapered male screw 11 and an incomplete thread portion 12 at the tip of a steel pipe 10 and a box portion 16 having tapered female screw portions 15 provided inside both ends of the coupling 14. The taper male screw 11 is formed on a smooth outer surface that has been subjected to external machining. Further, a torque shoulder unthreaded portion 17 is formed at the tip of the pin portion 13, and the torque shoulder unthreaded portion 17 is in contact with the inside of the box portion 16 to prevent excessive tightening. Is formed. Further, a metal seal seal surface is formed by the metal seal portion 19 continuous to the torque shoulder unthreaded portion 17 and the box metal seal portion 20 in contact with the metal seal portion 19, thereby improving the airtightness.

However, these conventional threaded joints 1 and 9 have problems 1 and 2 listed below.
(Problem 1)
The thread provided in the incomplete thread portion 4 in the pin portion 5 of the buttress joint 1 shown in FIG. 7 or the incomplete thread portion 12 in the pin portion 13 of the special joint 9 shown in FIG. A burr occurs.

  FIG. 9A is an explanatory view showing the thread 4a (12a) where the burr 4b (12b) is generated, and FIG. 10A is a diagram where the burr 4b (12b) interferes with the taper female thread portion 7 (15). It is explanatory drawing which shows a condition. As shown in FIG. 9A, a burr 4b (12b) is generated in the thread 4a (12a) provided in the incomplete thread portion 4 (12). Further, tapered male threads 3 and 11 are formed on the pin portion 5 of the buttress joint 1 shown in FIG. 7 and the pin portion 13 of the special joint 9 shown in FIG. For this reason, the thread diameter of the incomplete thread portion 4 (12) where the burr 4b (12b) is generated exceeds the outer diameter of the pipe. As shown in FIG. 10 (a), the generated burr 4b (12b) contacts and interferes with the taper female thread portion 7 (15) particularly during use in a situation where the steel pipes 2 and 10 of the offshore oil field or the like are not stable. For this reason, an abnormal increase in the tightening torque or seizure of the threaded portion occurs.

  For this reason, when the burr 4b (12b) is generated as shown in FIG. 9A, it is necessary to grind and remove the burr 4b (12b) using a buffing grindstone or the like. FIG. 9B is an explanatory view showing the thread 4a (12a) after the burr 4b (12b) is ground and removed using a buffing wheel or the like, and FIG. 10B is a burr 4b (12b). ) Is an explanatory diagram showing a situation where the taper female thread portion 7 (15) interferes. However, even with this means, as shown in FIG. 9 (b), the burr 4b (12b) falls down in the longitudinal direction of the pipe, and as shown in FIG. 10 (b), the taper female thread portion 7 (15) and Contact and interference become stronger.

  In addition, when threading the incomplete thread portions 4 and 12, the threaded portions of the steel pipes 2 and 10 are not rounded and thus are not perfect circles, and the cutting load in the circumferential direction becomes uneven. . For this reason, the sizes of the burr 4b and 12b in the radial direction are not uniform, and it is difficult to completely remove the burr 4b and 12b even if a buffing grindstone or the like is used.

  In the conventional threaded joints 1 and 9, it was impossible to completely prevent the contact / interference between the burr 4b and 12b and the taper female thread portions 7 and 15 as described above. appear.

  FIG. 11 is a graph showing the influence of the number of tightening times on the generated torque (tightening torque) for a joint having incomplete thread portions 4 and 12 in which burr 4b and 12b are generated on the thread. As shown in the graph, if burr 4b or 12b is generated on incomplete screw parts 4 or 12, tightening torque humping (a wavy increase or decrease phenomenon) occurs, resulting in inconsistent tightening torque. Tightening occurred and seizure occurred at the thread.

Since this seizure deteriorates the thread joint performance, it is also necessary to retighten the threaded joint that has been tightened to confirm the presence or absence of seizure. For this reason, due to the occurrence of burr, the downcomer operation time in the oil well has been prolonged.
(Problem 2)

  The processing of the pin portions 5 and 13 of the threaded joints 1 and 9 is performed by rotating the steel pipes 2 and 10 on the axis without rotating the threading tool, or rotating the threading tool without rotating the steel pipes 2 and 10. Has been done by any means of However, the former means for rotating the steel pipes 2 and 10 increases the number of machining passes due to the limited number of threading tools that can be machined at the same time. Since time is required, the latter means for rotating the threading tool has been frequently used. In recent years, in these processes, in order to improve the processing efficiency, a pre-processing machine that performs all of internal machining, external machining, and rough seal processing, and finish machining that performs all of threading, external machining, and seal finishing. It has come to be performed using two processing machines. This finishing machine is provided with a centering chuck, and the centering chuck grips the inclined portion on the tip side of the steel pipes 2 and 10 so that the rotary shaft of the pre-processing machine and the finishing machine are held. And the rotation axis are made to coincide.

  However, when the pin portions 5 and 13 of the threaded joints 1 and 9 are processed by two processing machines, a pre-processing machine and a finishing processing machine, for example, screw cutting is performed between the centering chuck and the oil well pipe to be processed. There is a case where the chip is chucked in a state where the chip is misaligned and the tube main body chuck is misaligned. In this case, the core of the steel pipe when processed by the pre-processing machine and the core of the steel pipe when processed by the finishing machine are shifted from each other. Until now, there has been no method for managing the misalignment accuracy, and the control value has not been defined. For this reason, the oil well pipe joint processed in this state is highly likely to be insufficiently processed with respect to the tapered male thread portions 3 and 11 and the incomplete thread portions 4 and 12, and is airtight when used in an oil well. Performance is not ensured and the processing defect rate is increased. Moreover, even if it can somehow be processed, the tube end thickness having the seal portion becomes non-uniform, and the airtight performance is also lowered.

  As described above, in the processing of the pin portions 5 and 13 of the conventional threaded joints 1 and 9, humming of the tightening torque occurs due to the occurrence of burr, or two processes of the pre-processing machine and the finishing machine are performed. There has been a problem that a hermetic failure occurs due to misalignment when the pin portions 5 and 13 of the threaded joints 1 and 9 are machined.

  The object of the present invention is to solve these problems, specifically, to tighten the tightening torque due to the occurrence of burr, seize on the threaded portion, and lengthen the downcomer operation time in the oil well. Oil well that can solve both of misalignment, lowering of processing defect rate, and occurrence of poor airtightness when the pin part is processed by two processing machines, a pre-processing machine and a finishing machine. To provide a pipe or gas well.

As a result of intensive studies to solve the above-mentioned problems, the present inventor has performed cutting before screw cutting even in the formation range of an incomplete screw portion that has not been conventionally cut at all before screw cutting. To form an externally machined part, and by threading this externally machined part to form an incomplete thread part,
(I) The occurrence of burr on the circumference of the incomplete thread portion can be made uniform and minimized, and burr removal can be performed reliably and easily.

(Ii) Since burr removal can be performed reliably and easily, it is possible to prevent any abnormal change in tightening torque and oil thread seizure when using an oil well.
(Iii) In the conventional machining method in which the external machining is not performed in the formation range of the incomplete thread portion, the incomplete thread portion has a steel pipe skin and has discontinuous irregularities. For this reason, the threading tool was frequently damaged during threading. However, by performing external machining before threading to form the external machining part, the load acting on the threading tool during machining is stabilized, the tool life is significantly improved, and

(Iv) When processing threaded joints with two processing machines, a pre-processing machine and a finishing machine, after finishing with a pre-processing machine, leaving a certain amount of machining allowance for the seal part in the finishing machine. When centering the processing machine, use the above-mentioned external machining part to perform main body chucking, so if the center chuck misalignment occurs more than the seal part processing allowance in the finishing machine, Judging that it is possible to stop the processing and find out that the taper male thread part and the unprocessed part of the incomplete thread part can be eliminated, the present invention has been completed through further studies. .

Here, the present invention relates to an oil well in which a pipe body is fixed by a pipe body chuck and a blade rotating type pre-processing machine or a finishing machine is rotated to form a taper threaded portion at the pipe end of the oil well pipe or gas well pipe. A method of threading a pipe or a gas well pipe, wherein an inclined part whose outer diameter changes in a taper shape in order from the end face of the pipe to the axial direction using the pre-processing machine, and a horizontal part whose outer diameter is constant And a step of detecting a center position of the centering chuck by bringing a centering chuck provided in the finishing machine into contact with the horizontal portion after the preprocessing step, and the detection An oil well pipe or a gas well including a step of determining whether or not the correction of the core position of the tube main body chuck is necessary using information on the core position of the centering chuck and the core position of the tube main body chuck. This is a method for threading a tube .

According to the present invention,
(I) Since the occurrence of burr can be suppressed to the minimum, hunting of the tightening torque caused by the occurrence of burr, seizure at the threaded portion, and longer downcomering work time in the oil well, In addition to stabilizing the load acting on the threading tool and extending the life of the threading tool,
(Ii) It is possible to solve the problems of misalignment, lowering of processing defect rate, and occurrence of airtight defects when the pin part is processed by two processing machines, a pre-processing machine and a finishing processing machine. In addition, it is possible to prevent an oil well accident due to the use of an unsealed seal part in an oil well.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of an oil well pipe or a gas well pipe according to the present invention will be described in detail with reference to the accompanying drawings. In the following description, an oil well pipe is used, the joint is a buttress joint, and the threading tool is rotated to perform threading.
[Steel pipe 21]
FIG. 1A is an explanatory view showing an enlarged incomplete thread portion 22 of the steel pipe 21 of the present embodiment, and FIG. 1B is an explanatory view showing meshing of the conventional incomplete thread portion 22. FIG. 1 (c) is an explanatory view showing the meshing of the incomplete thread portion 22 of the present embodiment.

As shown in FIG. 1 (a), the steel pipe 21 of the present embodiment has an outer diameter of a d _0, the pipe end outer surface, a tapered male screw portion 23, the incomplete threaded portion adjacent the tapered male screw portion 23 22.

Since the taper male screw part 23 in this embodiment is the same as the taper male screw part of a well-known buttress joint, description is abbreviate | omitted.
The incomplete thread portion 22 is formed on the outer surface of the tube end portion adjacent to the tapered male thread portion 23 in the tube axis direction. At least a part of the incomplete thread portion 22 is formed in the outer cutting portion 24 that has been subjected to the outer cutting processing.

  That is, conventionally, the outer cutting is performed only in the formation range of the tapered male screw portion 23, and the outer cutting is not performed in the formation range of the incomplete screw portion 22. On the other hand, in the steel pipe 21 of the present embodiment, not only the formation range of the tapered male screw portion 23 but also the formation range of the incomplete screw portion 22 is subjected to external cutting.

Further, the outer cutting portion 24 in the present embodiment is formed so as to have a tube outer diameter d ₃ that is substantially the same as the maximum value d ₂ of the tube outer diameter in the formation region of the tapered male screw portion 23. The The external cutting portion 24 is formed by performing external cutting before forming the tapered male screw portion 23 and the incomplete screw portion 22.

  Further, as shown in FIG. 1A, in this embodiment, the external machining is performed not to the entire area of the incomplete thread portion 22 but to the two threads before the thread cut-up portion 25. As a result, the final position of thread engagement of the pin part and the box part can be made the same as the final position of thread engagement of the conventional buttress joint, that is, joint strength ≧ pipe body strength. Does not reduce the tensile performance. Since the portion up to two threads before the thread cut-up portion 25 comes into contact with the box screw portion at the final stage of the joint tightening, the linearity of each of the pin portion and the box portion is ensured. Therefore, the influence on the tightening state is reduced, and an abnormal change in the tightening torque or seizure of the thread portion does not occur.

Further, when the steel pipe 21 is inclined when the buttress joint of this embodiment is tightened with an oil well, the conventional incomplete thread portion 22 shown in FIG. 1B interferes with the tapered female thread portion 7. In the incomplete thread portion 22 of this embodiment shown in FIG. 1C, the height of the thread, that is, the height of the burr is reduced by the amount of external machining d ₁ (= d ₀ −d ₂ ). The incomplete thread portion 22 does not interfere with the tapered female thread portion 7.
[Threading method of steel pipe 21]
Next, the threading method of this steel pipe 21 of this embodiment is demonstrated.

  FIG. 2 schematically shows a state in which all of the inner surface machining, the outer machining and the seal portion rough machining are performed on the steel pipe 21 by the pre-machining machine 28 having the inner cutting tool 26 and the outer cutting tool 27 in the present embodiment. It is explanatory drawing. Further, FIG. 3 shows that in this embodiment, the steel pipe 21 pre-processed by the pre-processing machine 28 by the finishing machine 31 having the thread cutting tool 29 and the seal processing tool 30 is threaded, externally cut and It is explanatory drawing which shows typically the condition which performs all seal part finishing processes. Furthermore, FIG. 4 is a flowchart schematically showing the steps of the thread cutting method for the steel pipe 21 of the present embodiment.

  As shown in FIG. 2 and FIG. 4, the outer surface of the steel pipe 21 is subjected to external cutting by the pre-processing machine 28 having the internal cutting tool 26, the external cutting tool 27, and an end surface processing tool (not shown), and the inclined portion 32 and the horizontal portion. 33. That is, both the inclined portion 32 and the horizontal portion 33 constitute the outer cutting portion 24 in FIG.

By subsequent threading, the tapered male screw portion 23 is formed on the inclined portion 32 and the incomplete screw portion 22 is formed on the horizontal portion 33.
Moreover, the end surface processing and the inner surface processing of the steel pipe 21 are performed by the pre-processing machine 28. At the time of these processes, it is desirable to make the processing diameter of the seal part a certain amount larger than the finished dimension. In the present embodiment, the internal machining or the end face machining is performed by the pre-machining machine 28, but any of these machining may be performed by the finishing machine 31.

  As shown in FIGS. 3 and 4, the centering chuck 34 provided in the finishing machine 31 is brought into contact with the externally machined horizontal portion 33 as shown in FIGS. By doing so, the core position at the time of processing in the pre-processing machine 28 and the core position at the time of processing in the finishing machine 31 are matched.

  FIG. 5 is an explanatory view schematically showing a state in which the steel pipe 21 is chucked by the centering chuck 34. As shown in FIGS. 4 and 5, when the steel pipe 21 is chucked by the pipe body chuck 35 that moves in accordance with the radial movement amounts a and b of the two centering chucks 34, 34, the two centering chucks 34, 34 are aligned. By obtaining the difference (ab) between the movement amounts a and b of the chucks 34 and 34, the position of the centering chuck 34 and the radial position of the tube main body chuck 35 are determined in the pre-processing by the pre-processing machine 28. The amount of movement of the tube main body chuck 35 is managed so as not to deviate more than the remaining screw and seal part removal in the finishing machine 31.

  That is, when the difference (ab) exists more than the screw and seal part removal allowance in the finishing machine 31, first, the presence or absence of swarf in the horizontal part 33 of the steel pipe 21 is confirmed. The powder is removed and centering is performed again by the centering chuck 34. On the other hand, if there is no swarf, it is determined that there is a pre-processing defect, and the finishing process is interrupted without operating the tube main body chuck 35. The machine 28 returns to the pre-processing. In this embodiment, in this way, processing defects of the tapered male screw portion 23 and the incomplete screw portion 22 are prevented in advance.

  FIG. 6 is an explanatory view showing a centering chuck 34 attached to a conventional finishing machine. As shown in FIG. 6, conventionally, the centering chuck 34 is brought into contact with the inclined portion 32 of the steel pipe 21, and the centering is performed. However, the inclined portion 32 has a variation in the outer diameter of the tube in the axial direction. If the position where the centering chuck 34 is in contact with the inclined portion 32 of the steel pipe 21 varies even in the tube axis direction, the detected value of the amount of movement of the centering chuck 34 also varies, and the management accuracy of the center misalignment prevention device decreases. Resulting in. On the other hand, in the present embodiment, since the centering is performed using the horizontal portion 33, even if the position where the centering chuck 34 contacts the horizontal portion 33 of the steel pipe 21 varies in the tube axis direction, the pre-processing machine 28 is used. The core position at the time of machining in can be matched with the core position at the time of machining in the finishing machine 31 with high accuracy.

  In this way, after aligning the axial core of the steel pipe 21 by the pre-processing machine 28 and the finishing machine 31 using the centering chuck 34, the two left and right pipe body chucks 35 located deeper than the pipe end machining portion. Is used to chuck the steel pipe 21. Then, the finishing machine 31 having the threading tool 29 and the sealing tool 30 performs threading and sealing on the inclined part 32 and the horizontal part 33 that have been subjected to the external cutting.

The steel pipe 21 of the present embodiment having the incomplete threaded portion 22 can exhibit the effects (i) to (iv) listed below.
(I) Since the degree of occurrence of burr in the incomplete threaded portion 22 is made uniform and minimized, burr grinding and removal are performed by using a buffing wheel or the like as in the prior art, so that burr removal is reliably and easily performed. be able to.

(Ii) Since the occurrence of burr can be made uniform and minimized, burr removal can be performed reliably and easily. Both can be prevented, and the handleability of the steel pipe 21 is thereby improved.
(Iii) In the conventional machining method in which the external machining is not performed in the formation range of the incomplete thread portion 22, the incomplete thread portion 22 has a steel pipe skin and has discontinuous irregularities. For this reason, the threading tool was frequently damaged during threading. However, in the present embodiment, since the external machining portion 24 is formed when the incomplete thread portion 22 is threaded, the load acting on the threading tool during machining is reduced and stabilized, and the tool life is remarkably improved. .

(Iv) When a threaded joint is processed by two processing machines, the pre-processing machine 28 and the finishing processing machine 31, a certain amount of machining allowance for the seal part in the finishing processing machine 31 remains, and the inclined portion 32 and the horizontal After the machining by the pre-processing machine 28 leaving the portion 33, when the finishing machine 31 is centered, the steel pipe 21 is chucked by the centering chuck 34 using the horizontal part 33 that has been subjected to the external cutting. When the misalignment of the main body chuck 35 occurs beyond the seal part machining allowance in the finishing machine 31, it is determined that the pre-processing is defective and the processing can be stopped. For this reason, it is possible to remarkably reduce the incidence of processing defects in the taber male screw portion 23 and the incomplete screw portion 22.

  For this reason, according to the present embodiment, it is possible to solve both the humping of the tightening torque due to the occurrence of burr, seizure at the threaded portion, and the lengthening of the downcomering operation time in the oil well, It is possible to solve both the misalignment, the decrease in the processing defect rate, and the occurrence of the airtight defect when the pin portion is processed by two processing machines including the finishing machine.

  In the offshore oil well, the outer diameter is 177.8 mm, the thickness is 10.36 mm, and the outer diameter is the same as that of the special joint with a metal sealing surface of the conventional example in which the incomplete thread portion is not subjected to the external machining. Then, tightening work was performed on each of the special joints with metal sealing surfaces of the present invention example in which the incomplete thread portion was also subjected to external cutting. In addition, the length of the taper male screw part was 40 mm, the length of the horizontal part of the incomplete screw part was 80 mm, and the machining allowance in the finishing process was set to 0.3 mm. The management value of misalignment was 0.6 mm.

  Then, the occurrence rate (%) of the above-described humping and the downcomering efficiency (main / hour) were measured. The results are summarized in Table 1.

  As shown in Table 1, in the conventional example in which the incomplete thread portion is not subjected to external cutting, the humping rate was 75.0%, whereas the incomplete thread portion was subjected to external cutting. In the inventive example, the occurrence rate of humping was reduced to about 1/10 to 7.6%. As a result, the working time was shortened, and the downcomering efficiency was improved about twice.

  100 oil well pipes each having an outer diameter of 177.8 mm, the conventional method in which the incomplete thread portion is not subjected to external machining, and the book illustrated in FIGS. 1 to 4 in which the incomplete thread portion is also subjected to external machining. Processed according to the invention method. In the method of the present invention, the machining allowance for the seal portion in the finishing machine 31 (= difference between the external cutting dimension and the finishing dimension in the pre-processing machine) is 0.6 mm in the radial dimension. Further, the centering chuck 34 provided in the finishing machine 31 is positioned at the horizontal portion 33. Then, the number of machining defects of the Taber male screw portion 23 and the incomplete screw portion 22 was measured. The results are summarized in Table 2.

  As shown in Table 2, in the conventional method in which the external threading is not performed on the incomplete thread portion, a seal unprocessed defect occurs. It can be seen that if the method of the present invention shown is used, it is possible to prevent a seal portion unprocessed defect.

  At this time, the lifetime of the threading tool 29 of the finishing machine 31 was measured for both the conventional method and the method of the present invention. The results are summarized in Table 3.

As shown in Table 3, if the method of the present invention shown in FIG. 1 to FIG. 4 in which the incomplete thread portion is also machined is used, the life of the thread cutting tool can be improved by about 60% compared to the conventional case. You can see that it was made.
(Deformation)
In the description of the embodiments and examples, the case where the machining is performed while rotating around the steel pipe in which the machining tool is fixedly arranged is taken as an example. However, the present invention is not limited to this form, and is equally applicable even when processing is performed while rotating a steel pipe in the vicinity of a fixedly arranged processing tool.

  In the description of the embodiments and examples, the case where the joint is a buttress joint is taken as an example. However, the present invention is not limited to this embodiment, and can be applied to other joints other than buttress joints such as special joints.

  In the description of the embodiment and the example, the outer cut portion is formed so as to have a tube outer diameter that is substantially constant at the same value as the maximum value of the tube outer diameter in the formation region of the tapered male screw portion. Take the case as an example. However, the present invention is not limited to this mode, and the shape of the machining does not need to be limited as long as the outside machining is performed. In other words, the present invention is equally applicable as long as at least a part of the incomplete thread portion is provided in the external machining portion that has been subjected to external machining.

  Furthermore, in the description of the embodiment and the example, the case where the external machining is performed on the portion of the incomplete thread portion excluding the two threads is taken as an example. However, the present invention is not limited to this form, and is equally applicable as long as at least a part of the incomplete thread portion is subjected to external cutting.

FIG. 1A is an explanatory diagram showing an enlarged incomplete thread portion of the steel pipe of the embodiment, and FIG. 1B is an explanatory diagram showing meshing of the conventional incomplete thread portion. (C) is explanatory drawing which shows meshing of the incomplete thread part of embodiment. In embodiment, it is explanatory drawing which shows typically the condition which performs all of internal surface processing, external cutting, and seal part roughing to a steel pipe with the pre-processing machine which has an internal cutting tool and an external cutting tool. In the embodiment, the steel pipe that has been pre-processed by the pre-processing machine by the finishing machine having the thread-cutting tool and the seal processing tool is schematically shown as a state where all of the thread cutting, external cutting, and seal part finishing are performed. It is explanatory drawing shown in. It is a flowchart which shows typically the process of the threading method of the steel pipe of embodiment. It is explanatory drawing which shows typically the condition which chucks a steel pipe with a centering chuck. It is explanatory drawing which shows the centering chuck provided with the conventional finishing machine. It is explanatory drawing which shows an example of a buttress joint partially. It is explanatory drawing which shows an example of a special joint partially. FIG. 9A is an explanatory diagram showing a thread where burr has occurred, and FIG. 9B is an explanatory diagram showing the thread after the burr grinding and removing using a buffing wheel or the like. is there. FIG. 10A is an explanatory diagram showing a situation where the burr interferes with the tapered female screw portion, and FIG. 10B is an explanatory diagram showing a situation where the burr interferes with the tapered female screw portion. It is a graph which shows the influence of the frequency | count of fastening which has on the generated torque (tightening torque) about the coupling which has the incomplete thread part which the burr generate | occur | produced in the thread.

Explanation of symbols

21 Steel pipe 22 Incomplete thread part 23 Taper male thread part 24 External cutting part

Claims (1)

Thread cutting of an oil well or gas well pipe that forms a taper thread at the end of the oil well pipe or gas well pipe by rotating the blade rotating type pre-processing machine or finishing machine by fixing the pipe body with the pipe body chuck A method,
A pre-processing step of forming an inclined portion whose outer diameter changes in a tapered shape and a horizontal portion having a constant outer diameter in order from the end face of the tube in the axial direction using the pre-processing machine,
A step of detecting a center position of the centering chuck by bringing a centering chuck provided in the finishing machine into contact with the horizontal portion after the pre-processing step;
Determining whether or not it is necessary to correct the core position of the tube main body chuck using information on the detected core position of the centering chuck and the core position of the tube main body chuck;
A method for threading an oil well pipe or a gas well pipe, comprising:

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