JP2001082644A - Manufacturing method of threaded joint for oil country tubular goods - Google Patents

Abstract

(57) [Problem] To design the dimensions of each part in order to actually manufacture the threaded joint for oil country tubular goods according to the invention proposed in Japanese Patent Application No. 10-193119 requires a great deal of labor. According to a design procedure of a threaded joint for oil country tubular goods shown in FIG.
To manufacture.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to oil, natural gas,
For producing oil wells, gas wells, geothermal wells for exploring and producing steam and hot water, and oil well pipes for forming industrial wells, gas and water, etc. The present invention relates to an optimum method for manufacturing a threaded joint having a resistance to various external forces equal to or higher than that of the pipe body.

[0002]

2. Description of the Related Art Conventionally, a threaded joint has been used as a joint for such an oil country tubular good. Currently, API thread (American Petroleum Institute standard) round thread joints and buttress thread joints (hereinafter referred to as “API joints”) are most frequently used. In recent years, with the deepening of oil wells, gas wells, etc., as well as in-well pressures, temperatures, and corrosive environments, etc., the joints with high strength against breakage due to their own weight and excellent airtightness have been developed. I have been asked.

FIG. 1 (a) shows, as an example, a coupling 20 having two box portions 21 and 21 at both ends and tubes 10 and 10 having pin portions 11 and 11 at each end. FIG. 1 is a cross-sectional view (hereinafter, simply referred to as “cross-sectional view”) including a pipe shaft showing a coupling type threaded joint for oil country tubular goods 25 to be used. Also,
FIG. 1B is an enlarged sectional view of the box portion 21 of the coupling 20, and FIG. 1C is an enlarged sectional view of the pin portion 11 of the pipe 10.

As shown in FIG. 1A, a steel pipe as an oil well pipe
10 and 10 are screw-connected by a coupling 20. Box portions 21 and 21 are provided at both ends of the coupling 20, and a tube is provided.
Pin portions 11, 11 are provided at the tips of 10, 10, respectively.

As shown in FIG. 1B, a female screw 22 is formed on the inner peripheral surface of the box portion 21. Further, as shown in FIG. 1 (c), a male screw 12 is engraved on the outer peripheral surface of the pin portion 11.

As described above, a coupling type screw joint is described.
25 is a pin portion 11 having an external thread 12 provided at the end of the tube 10.
And a box part 21 having a female screw 22 provided inside the coupling 20 by screwing them together.
Connect 10 and 10.

However, as described above, to meet the demand for a threaded joint 25 having high strength against tensile stress generated by the weight of the pipe 10 and high airtightness, simply use a male screw 12 such as an API joint. A joint consisting only of a screw element consisting of the female screw 22 and the female screw 22 has not been sufficient. Therefore, as shown in FIGS. 1 (b) and 1 (c), each of the box portion 21 and the pin portion 11 has a metal seal portion.
A threaded joint 25 provided with both 13, 23 and torque shoulder portions 14, 24 has been used.

In the metal seal portions 13 and 23, the amount of interference in the radial direction of the pipe 10, that is, the outer diameter of the metal seal portion 13 of the pin portion 11 is larger than the inner diameter of the metal seal portion 23 of the box portion 21 (this difference Is referred to as an “interference amount”.)
Screwed into the two metal seals 1
Surface pressure is generated on the contact surfaces 3 and 23, and good airtightness is expected to be maintained by the surface pressure.

On the other hand, the torque shoulder portions 14 and 24 are
By abutting this part of the box part 11 and the box part 21 with an appropriately controlled pressure, a high contact surface pressure that causes excessive plastic deformation does not occur in the metal seal parts 13 and 23, and sufficient screwing is performed. Secure the amount of threaded joint
This is to ensure the fastening of 25.

In addition to the metal seal portions 13 and 23, not only the metal seal portions 13 and 23 but also the screw portions 12 and 22 are formed in the same manner as the metal seal portions 13 and 23 in order to ensure that the tapered screws are securely fastened and not loosened. Many have the amount of interference,
Due to the regulation of the torque shoulders 14 and 24, this screw 1
The amount of interference between 2 and 22 is also limited to the safe range, and the occurrence of excessive stress in the box portion 21 is suppressed.

For this reason, the threaded joint 25 shown in FIGS. 1 (a) to 1 (c) has a structure suitable for use in a corrosive environment. The inclination angle theta ₁ with respect to the vertical plane of the torque shoulder portion 14, 24 of the shoulder angle.

[0012]

In recent years, the well depth has become larger and the development environment and well environment have deteriorated. On the other hand, the development technology of oil wells and gas wells has been developed. Such severe requirements have come to be required for joints.

[0013] Able to withstand the tensile force in the axial direction due to the weight of the connected pipes. Able to withstand the internal pressure due to the internal fluid or the external pressure due to the external fluid. The pipe has sufficient strength against the compressive and torsional forces applied to the pipe during the development of the well or during the operation of the well. Withstand pressure seals.

In order to meet such a demand, conventionally,
Many inventions have been made to improve the fastening condition of the threaded joint 25 shown in FIGS. 1 (a) to 1 (c). The applicant also filed a patent application
No. 10-193119 was proposed.

This proposal has the following four items (a) to (d),
Alternatively, by satisfying (a) to (c) and (e), a threaded joint capable of having a proof stress and a resistance equal to or higher than that of the pipe body for all loads assumed to be applied to the threaded joint is provided. Yes, this allows Vom Mises
API5C3 with the entire range of internal pressure and axial force expressed by the equivalent stress ellipse of
Satisfies the entire range of external pressure and axial force expressed by the equation of the tube collapse, and maintains airtightness even after receiving a load of high compressive force of 95% of the tube strength, especially under fluctuation of the axial force, It is another object of the present invention to provide a threaded joint for oil country tubular goods having a high resistance to loosening torque, which is difficult to loosen even under fluctuations in axial force of tension and compression.

(A) The flank angle of the screw load surface is -20 ° or more and less than 0 °, the flank angle of the insertion surface is more than 25 ° and 45 ° or less,
In addition, the screw interference amount defined by the difference between the pitch inner diameters of the male screw and the female screw has a positive value, and the load surface and the insertion surface of the male screw and the female screw come into contact with each other during and after completion of the joint. In addition, a gap must be provided between the top surface and the bottom surface of the screw.

(B) The following (18) or
Of the values calculated for the total length of the thread using Equation (19),
Double the smallest value as the upper limit, and 5% of the upper limit
Is the lower limit.

[0018]

(Equation 18)

Here, δ ₁ , δ ₂ : apparent screw interference amount by radius (mm), σy: yield strength of joint material (kgf / mm ² ) E: Young's modulus of joint material (kgf / mm ² ), D : Box outer diameter
(mm) d: Pin inner diameter (mm), dp: Pitch circle diameter of screw (mm) La ² : (dp ² -d ² ) Lb ² : (D ² -dp ² ) Smaller than the interference amount.

(C) The engagement length of the complete screw between the male screw of the pin portion and the female screw of the box portion is (a) at least three times the wall thickness of the pipe body at the time of fastening: the pipe wall thickness to pipe outer diameter ratio is 0.096 or more. (B) 4 times or more: と き When it is 0.084 or more and less than 0.096, (c) 5 times or more: When other than (a) and (b) above, However, if the ratio of the pipe wall thickness to the pipe outer diameter is 0.052 or less, the inner diameter of the seal lip of the pin portion is set to the pipe inner diameter or less as much as possible.

(D) The shoulder angle of the torque shoulder is θ: 5 to 20 °, and is defined by the following equation between the root thickness (lt) of the lip of the seal lip and the pipe wall thickness (Wt). The lip thickness ratio (X) is set to 0.52 or more.

(Lt / DB) / (Wt / OD) ≧ 0.52 Here, DB: outer diameter at the base of the lip portion OD: outer diameter of the tube However, when Wt / OD is small and Wt is thin, the tube end swage is used. The pre-processing such as satisfies the above defined rib ratio of ≧ 0.52.

(E) Factors that determine the shape of the threadless portion at the tip of the pin portion and the threadless portion at the back of the box portion, lip length: We (mm): seal length: S (mm), seal taper: Ts,
The shoulder angle: θ (°) and the lip thickness ratio (X) are in the following ranges, respectively, and the function f, which is a first-order polynomial, satisfies f> 1.2.

6 mm ≦ We (mm) ≦ 30 mm, 3 mm ≦ S (mm) ≦ 10 mm 1/16 ≦ Ts ≦ 1, 0 ° ≦ θ (°) ≦ 20 °, 0.25 ≦ X ≦
0.75 where f = −3.26 × 10 ^-1 + 3.19 × 10 ^-2 (1 / °) × θ (°) +1.4
3 x X-4.67 x 10 ^-4 (1 / mm) x We (mm) + 8.39 x 10 ^-2 (1 / mm)
× S (mm) −6.22 × 10 ⁻¹ × Ts X = ｛(wall thickness at the root of the pin side lip) / (outer diameter of the root of the lip)｝ / ｛(wall thickness of the pipe body) / (tube body (Outer diameter)｝ According to the invention proposed by the present applicant in Japanese Patent Application No. 10-193119, it is possible to provide a threaded joint for oil country tubular goods having surely desired performance. However, designing the dimensions of each part in order to actually manufacture the oil country tubular goods threaded joint according to this proposal requires an extremely large amount of labor.

An object of the present invention is to enable a person skilled in the art to easily manufacture a threaded joint for an oil country tubular good, specifically, a threaded joint having a resistance to various external forces equal to or higher than that of the pipe body. It is to provide a specific method that can be used.

The object of the present invention is also disclosed in Japanese Patent Application No. 10-193119.
All the load conditions that a threaded joint for oil country tubular goods receives, such as (i) tensile force, compressive force, and internal and external pressures (bending is where the tensile force is outside the curvature, As long as the compressive force is generated and the cross-sectional shape is not deformed, it can be uniquely treated as being equivalent to the load of the axial force.)
Includes the entire inside of the ellipse with an equivalent stress of 100%, and the external pressure area is the API collapse pressure specified by API5C3 (considering axial force) 100
% Or within the ellipse with a Von Mises equivalent stress of 100%, under a composite load condition that includes all the smaller areas.
It can maintain the internal / external pressure leakage resistance and the joint strength, and (ii) No matter how the load changes repeatedly inside the ellipse with 100% equivalent stress of Von Mises and the API5C3 collapse value ellipse It is an object of the present invention to provide a method of designing and manufacturing a threaded joint which can sufficiently maintain its leak resistance and joint strength, and which can be reused repeatedly.

[0027]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventor has analyzed and reconstructed a threaded joint proposed in Japanese Patent Application No. 10-193119, so that the design procedure of this threaded joint has been improved. Once constructed, the present invention has been completed. By determining the dimensions of each part according to this design procedure, a person skilled in the art can easily design a threaded joint proposed in Japanese Patent Application No. 10-193119.

Here, as shown in FIG. 2 to be described later, the present invention comprises a pin portion having a male thread having a substantially trapezoidal tapered thread and a tapered thread having a generally trapezoidal thread. A box portion having a female screw engaged with the male screw portion, a screwless portion for forming a metal seal portion provided on the pin portion, and abutting against the screwless portion for forming the metal seal portion provided on the box portion. A metal seal portion formed by a screwless portion for forming a metal seal portion; a screwless portion for forming a torque shoulder portion provided at the tip of the pin portion; and the torque shoulder portion provided to the box portion. When manufacturing a threaded joint for an oil country tubular good comprising: a torque shoulder portion formed by a torque shoulder portion for forming a torque shoulder portion and a torque shoulder portion for contacting the threadless portion for formation. Outer diameter of the pipe having a pin portion (OD)
And the pipe wall thickness (t), and based on the determined pipe outer diameter (OD) and pipe wall thickness (t), the allowable range of the screw length (L) of the completely engaged screw between the pin section and the box section. The complete engagement screw length (L) is provisionally determined based on the allowable range of the provisionally determined complete engagement screw length (L), and the lip inner diameter (D2) of the pin portion is determined and determined. Lip inside diameter of the pin part (D2)
The inner diameter (D1) of the box portion is determined based on the lip thickness ratio (X), and the lip thickness ratio (X) is provisionally determined. The outer diameter (DB) of the box portion is temporarily determined, the screw engagement height (h) is temporarily determined, the determined tube outer diameter (OD), and the temporarily determined outer diameter (DB) of the box portion and the Based on the complete engagement screw length (L), the screw taper (Tt) and the complete engagement screw length (L) are provisionally determined, and the provisionally determined lip thickness of the pin portion (lt) and the box portion are determined. Lip length (l) based on outer diameter (DB)
, Pin seal length (Sp), seal taper (Ts), shoulder angle (θ ₁ ) and the lip thickness ratio (X),
Tentatively determined to be> 1.2, and tentatively determined lip length
(l), based on the pin seal length (Sp), seal taper (Ts), shoulder angle (θ ₁ ) and lip thickness ratio (X),
Determine the pin lip shape, determine the bevel angle (θ ₂ ) and the pin inner surface shaving angle (θ ₃ ) at the beginning of the threading of the pin, and determine the lip thickness (lt) of the pin and the outer diameter of the pin lip. (DB), the tip lip diameter (Papex), the pin seal parallel part R (R ₁ ) and the pin seal tip R (R ₂ ) are determined, and the determined lip thickness of the pin part ( lt) and the pin portion lip root outer diameter (DB), determine the screw taper (Tt) and the complete meshing screw length (L), and determine the box portion screw parallel portion diameter (DA),
Determine the load surface angle (α), stub surface angle (β), stubbing clearance (δ), and crest clearance (γ), determine the screw pitch (P), determine the screw shape, and seal the box. Determine the length (S _B ), determine the pitch diameter (Dp), determine the box outer diameter (W) and the pin pitch diameter position (LPt), and set the screw based on the determined pitch diameter (Dp). Interference (It)
Is determined, the box shoulder depth (LB) is determined, and the box shoulder length (IRes) is determined based on the determined pipe outer diameter (OD) and pipe wall thickness (t). Determine the box length (NL) based on the shoulder length (IRes) and shoulder depth (LB), determine the box pitch diameter position (LBt), and based on the determined lip tip diameter (Papex). To determine the box seal tip R (R ₂ ) based on the determined box seal seal tip diameter (Bapex) so as to be smaller than the determined pin seal seal tip R (R ₂ ). A method for manufacturing a threaded joint for oil country tubular goods, characterized in that dimensions of each part are determined by determining R ₃ ).

Further, from another viewpoint, the present invention, as shown in FIG. 3, includes a pin portion having an external thread formed of a taper screw having a substantially trapezoidal shape and a taper screw having a substantially trapezoidal shape. A box portion having a female screw engaged with the male screw portion, a screwless portion for forming a metal seal portion provided on the pin portion, and a screwless portion for forming the metal seal portion provided on the box portion. A metal seal portion formed by a screwless portion for forming a metal seal portion that abuts on the screw portion; a screwless portion for forming a torque shoulder portion provided at the tip of the pin portion; When manufacturing a threaded joint for an oil country tubular good comprising: a torque shoulder portion constituted by a torque shoulder portion-forming threadless portion that abuts a torque shoulder portion-forming threadless portion. , By performing the from the following first step to the following fifth step, a method of manufacturing a threaded joint for oil well pipes, characterized in that to determine the various dimensions.

First step A: A pipe outer diameter (OD) and a pipe wall thickness (t) of a pipe having the pin portion are determined, and the determined pipe outer diameter is determined.
Determine the thread pitch (P) based on (OD) and pipe wall thickness (t).

Second step B: Based on the determined pipe outer diameter (OD) and pipe wall thickness (t), the allowable range of the complete meshing screw length (L) between the pin section and the box section is provisionally determined. Then, the complete meshing screw length (L) is temporarily determined based on the allowable range of the temporarily determined complete meshing screw length (L), and the determined pipe outer diameter (OD) is determined.
Based on the pipe wall thickness (t), the provisionally determined complete engagement screw length (L), and the provisionally determined pin portion lip outer diameter (DB), a screw taper (Tt) and the complete engagement screw Length (L)
Provisional decision.

Third step C: The lip inner diameter (D2) of the pin portion is determined based on the determined outer diameter (OD) and wall thickness (t) of the tube, and the determined lip inner diameter (D2) of the pin portion is determined. ) Is determined based on the inner diameter (D1) of the box portion, and the determined outer tube diameter (O
The lip thickness ratio (X) is provisionally determined on the basis of (D) and the pipe wall thickness (t), and based on the provisionally determined lip thickness ratio (X), the lip thickness (lt) of the pin portion and the lip thickness of the pin portion are determined. The outer diameter (DB) is provisionally determined, and based on the provisionally determined lip thickness (lt) of the pin portion and the pin portion lip outer diameter (DB), the pin portion lip outer diameter (DB) is provisionally determined, The lip length (l), the pin seal length (Sp), the seal taper (Ts), the shoulder angle (θ ₁ ) and the lip thickness ratio (X) are provisionally determined so that the function f> 1.2. Based on the function f and the lip inner diameter (D2) of the pin portion, a lip length (l), a pin portion seal length (Sp),
The pin lip shape including the seal taper (Ts), the shoulder angle (θ ₁ ) and the lip thickness ratio (X) is determined, and based on the determined pin lip shape, (i) the pin portion seal tip R (R ₂ ) Is determined, the box seal tip R (R ₃ ) is determined based on the pin seal tip R (R ₂ ), (ii) the pin seal seal R (R ₁ ) is determined, and (iii) the lip Tip diameter (Papex)
Is determined based on the lip tip diameter (Papex), and the box seal tip diameter (Bapex) is determined. (Iv) Pin part threading start bevel part angle (θ ₂ ) and pin part inner surface grinding angle (θ ₃ ) and (iv) the lip thickness of the pin
(lt) and the pin portion lip outer diameter (DB) are determined, and the box portion screw parallel portion diameter (DA) is determined based on the lip thickness (lt) and the pin portion lip outer diameter (DB), Screw taper
(Tt) and the full mesh screw length (L) are determined, and based on the screw taper (Tt) and the full mesh screw length (L), a box part pitch diameter position (LBt) is determined. v) Determine the box seal length (S _B ).

Fourth step D: A screw engagement height (h) is determined based on the determined pipe outer diameter (OD) and pipe wall thickness (t), and a pitch is determined based on the screw engagement height (h). The diameter (Dp) is determined, and based on the pitch diameter (Dp), (i) the box outer diameter (W) and the pin pitch diameter position (LPt) are determined, and (ii) the screw interference amount.
(It) is determined, and (iii) the box portion shoulder depth (LB) and the box portion shoulder length (IRes) are determined, and the box portion shoulder depth (LB) and the box portion shoulder length (IRe) are determined.
Determine the box length (NL) based on s).

Fifth step E: Determining the load surface angle (α), stub surface angle (β), stubbing surface clearance (δ) and thread crest clearance (γ).

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a method for manufacturing a threaded joint for oil country tubular goods according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 2 is a flowchart illustrating an example of a design procedure of the threaded joint for an oil country tubular good in the present embodiment.

The threaded joint for oil country tubular goods in this embodiment is as follows.
A threaded joint proposed by Japanese Patent Application No. 10-193119, that is, (i) a pin portion having a male thread having a generally trapezoidal tapered thread and a threaded thread having a generally trapezoidal tapered thread, A box portion having an internal thread that meshes with the portion, (ii) a screwless portion provided on the pin portion for forming a metal seal portion, and a metal contacting the screwless portion provided on the box portion for forming a metal seal portion. A metal seal portion constituted by a screwless portion for forming a seal portion,
(iii) A screwless portion for forming a torque shoulder portion provided at the tip of the pin portion, and a screwless portion for forming a torque shoulder portion provided on the box portion and abutting against the screwless portion for forming the torque shoulder portion. This is a threaded joint for an oil country tubular good having a torque shoulder portion constituted by:

In the present embodiment, when designing this threaded joint, the following steps (hereinafter simply referred to as "S").
1 to S29.

At S1, the outer diameter of the pipe having the pin portion
(OD) and pipe wall thickness (t) are determined. The pipe outer diameter (OD) and pipe wall thickness (t) are subject to the required pin part outer diameter and its corresponding, depending on the outer diameter and wall thickness of the pipe body that requires this threaded joint. It is determined by the pipe wall thickness.

In S2, the allowable range of the length (L) of the complete meshing screw between the pin portion and the box portion is provisionally determined based on the determined tube outer diameter (OD) and tube thickness (t). The allowable range of the length of the complete meshing screw (L) between the pin and the box is, for example,
3 or more when {wall thickness (t) / outside diameter (OD)} is 0.096 or more, 4 or more when {wall thickness (t) / outside diameter (OD)} is 0.084 or more, 5 or more when {wall thickness (t) / outside diameter (OD)} is 0.052 or more, 5 or more when {wall thickness (t) / outside diameter (OD)} is less than 0.052 Therefore, the inner diameter of the lip of the pin portion (D2) ≦ the inner diameter of the pipe (ID) is set.

In step S3, based on the allowable range of the complete meshing screw length (L) determined in S2, the length of the complete meshing screw length (L) is determined.
(L) is provisionally determined. In S4, the lip inside diameter of the pin part (D2)
To determine. This determination is made by the processor making a judgment based on the processing capability.

In S5, based on the lip inner diameter (D2) determined in S4, the inner diameter (D1) of the box portion is obtained as the lip inner diameter (D2) + α. Here, the symbol α is a set value related to the seal interference amount, and is uniquely determined by a designer.

In S6, the lip thickness ratio (X) is provisionally determined.
In S7, the lip thickness ratio (X = t / O) provisionally determined in S6
Based on D), the lip thickness (lt) of the pin portion and the outer diameter (DB) of the lip portion are provisionally determined. Specifically, the lip thickness (lt) of the pin portion is obtained by the following equation (20).

[0043]

(Equation 20)

The lip outer diameter (DB) of the pin portion is as shown in the following (2).
It can be obtained by equation (1).

[0045]

(Equation 21)

In S8, the screw engagement height (h) is temporarily determined. The screw engagement height (h) is independently set by the designer as a constant based on the pipe outer diameter (OD) of the pipe, or the pipe outer diameter (OD) and the pipe wall thickness (t). For example, OD ≦
In the case of 4-1 / 2 '', h = 1.016, 4-1 / 2 ''<OD ≦ 7
In the case of −3/4 ″, h = 1.575, 7−3 / 4 ″ <OD ≦ 14 ″
In the case of, h = 1.982 is set.

At S9, the determined pipe outer diameter (OD) and the temporarily determined pin lip outer diameter (DB), which is the pin lip root position, are determined.
The screw taper (Tt) is tentatively determined based on the full engagement screw length (L). The screw taper (Tt) is obtained, for example, by the following equation (22).

[0048]

(Equation 22)

However, the symbol C is a constant indicating the tolerance between the screw bottom and the outer periphery of the lip at the lip root position, and is determined by the designer. Symbol ε is the difference (radius difference) between the screw top diameter at the lip root position and the screw bevel top.

In S10, the length (L) of the complete meshing screw is provisionally determined. Specifically, it is determined by the following equation (23), and the condition in S2 is satisfied.

[0051]

(Equation 23)

In S11 and S12, the lip length (l) and the pin portion seal length (Sp) are determined based on the tentatively determined lip thickness (lt) of the pin portion and the pin lip outer diameter (DB) which is the pin lip base outer diameter. ), Seal taper (Ts), shoulder angle (θ ₁ )
And the lip thickness ratio (X) are provisionally determined so that the function f> 1.2. Specifically, the function f is obtained by the following equation (24).

[0053]

(Equation 24)

However, 5 ° ≦ θ ₁ ≦ 20 °, 0.52 ≦ X ≦ 0.
75, 6 ≦ l ≦ 30, 3 ≦ Sp ≦ 10, 1 ≦ Ts ≦ 16.

In S13, S14 and S15, the lip length (l), the pin portion seal length (Sp), the seal taper (Ts), the shoulder angle (θ ₁ ) and the lip thickness ratio temporarily determined in S12
Based on (X), the pin lip shape is determined, and the bevel angle (θ ₂ ) and the inner surface cutting angle (θ ₃ ) of the pin portion at the beginning of threading are determined.

In S16, the lip length provisionally determined in S12
(l), based on the pin seal length (Sp), seal taper (Ts), shoulder angle (θ ₁ ) and lip thickness ratio (X),
Determine the pin lip thickness (lt) and the pin lip (root) outer diameter (DB).

In step S17, the screw taper (Tt) and the completely meshing screw length (L) are determined based on the lip thickness (lt) of the pin portion and the outer diameter (DB) of the pin portion lip (root) determined in step S16.
To determine.

In step S18, the box part screw parallel part diameter (DA) is determined based on the pin part lip thickness (lt) and the pin part lip outer diameter (DB) determined in step S16. Specifically, the diameter DA of the box part screw parallel part is obtained by the following equation (25).

[0059]

(Equation 25)

The symbol d is a constant indicating the difference between the pin parallel portion and the box portion screw parallel portion DA.
For example, d is determined to be 0.2 mm. In S19, the load surface angle (α), stub surface angle (β), stubbing surface clearance
(δ) and the crest of the thread crest (γ) are determined. Specifically, the stub plane angle β is obtained by the following equation (26).

[0061]

(Equation 26)

However, 0>α> −20 ° C., γ: a value as small as possible, 25 <β <45, δ: a positive value as small as possible by the processor in consideration of cost and performance. In S20,
Determine the thread pitch (P). Specifically, screw pitch
(P) is set as a constant based on the pipe external pressure (OD) or the pipe external pressure (OD) and the pipe wall thickness (t). For example, if OD is 2 "or more and less than 2-7 / 8", P
= 8 and P when 2-7 / 8 '' or more and less than 4-1 / 2 ''
= 6, and if P is less than 4-1 / 2 '' and less than 8-5 / 8 '', P
= 5, and in the case of 8-5 / 8 '' or more and 14 '' or less, P = 4.

In S21, the box seal length (S _B ) is determined. Specifically, the box seal length (S _B )
In the case of S _B> S _P is a S _B> S _P +2.0, and determined by the following equation (27), when in the case of S _B ≦ S _P is the following (28) It is obtained by the formula.

[0064]

[Equation 27]

[0065]

[Equation 28]

[0066] However, the code Is denotes a seal interference amount, reference numeral T _D indicates the taper of the pin lip portion (not seal portion), reference numeral theta ₅ shows the box seal portion inlet angle.

In S22, the pitch diameter (Dp) is determined. Specifically, the pitch diameter Dp is obtained by the following equation (29).

[0068]

(Equation 29)

Where the symbol ε is a value according to the API,
For example, when OD ≤ 4-1 / 2 '', 0.009 ''
In the case of ≦ 14 ″, it is 0.016 ″. In S23, the box outer diameter (W) is determined. The box outer diameter W is set so that the box dangerous cross section (A _BC ) is larger than the pipe standard cross section (A _PC ). The box dangerous cross-sectional area (A _BC ) is determined by each designer because the method of determining the box dangerous cross section differs depending on the concept of where the dangerous cross section is to be set. S
At 24, the pin pitch diameter position (LPt) is determined. Specifically, the pin portion pitch diameter position LPt is obtained by the following equation (30).

[0070]

[Equation 30]

In S25, the amount of screw interference (It) is determined. Specifically, the screw interference amount It is obtained by the following equation (31) or (32).

[0072]

(Equation 31)

Where the symbol δy is the material yield strength (kgf / m
m ² ), the symbol E indicates the Young's modulus (kgf / mm ² ) of the joint material, the symbol D indicates the box outer diameter (mm), the symbol d indicates the pin inner diameter (mm), and the symbol dp indicates the thread. The pitch circle diameter of (mm), the symbol La ² indicates (dp ² −d ² ), and the symbol Lb ² indicates
(D ² −dp ² ). In S26, the shoulder depth of the box
(LB) is determined. Specifically, the shoulder depth of the box
LB is obtained by the following equation (33).

[0074]

[Equation 33]

Here, the symbol θ ₄ indicates the bevel angle in the end face of the box portion. In S27, the box shoulder length (I
Res). In S28, the entire box portion length (NL) is determined based on the determined box portion shoulder length (IRes). Specifically, the box portion total length NL is obtained by the following equation (34).

[0076]

(Equation 34)

In step S29, the box part pitch diameter position (LBt)
To determine. Specifically, box pitch diameter position (LB
t) is obtained by the following equation (35).

[0078]

(Equation 35)

On the other hand, at S30, the lip tip diameter (Papex)
, The pin seal parallel part R (R ₁ ) and the pin seal tip R (R ₂ ) are determined. Specifically, the lip tip diameter (Pape
x) is determined by the following equation (36) or (36 ′).

[0080]

[Equation 36]

However, the expression (36) is applied to the case where the portion other than the seal portion of the pin seal lip portion is parallel (when the pin seal parallel portion is provided), and the expression (36 ') is applied to the portion other than the seal portion of the pin seal lip portion. In the case of having a taper (applied in the case of having a tapered portion instead of the pin seal parallel portion, or in the case of having both a parallel portion and a tapered portion).

The pin sealing portion R (R ₁ ) has the following (37)
It is obtained by the equation or the equation (37 ').

[0083]

(37)

Furthermore, the pin seal tip R (R ₂ ) is set more uniquely by the designer. In S31, the box part seal tip diameter (Bapex) is determined based on the determined lip part tip diameter (Papex), the pin part seal parallel part R (R ₁ ) and the pin part seal tip R (R ₂ ). Is, the tip diameter Bapex of the box seal is obtained by the following equation (38).

[0085]

(38)

Here, the symbol Is indicates a seal interference amount.
In S32, to determine the determined pin seal tip R (R ₂₎ box part so as to be smaller than the sealing tip R (R _3).
In S33, if necessary, to determine the box seal original R (R _4).

In the present embodiment, the dimensions of each part of the threaded joint are determined in this manner. By setting the dimensions of each part of the threaded joint according to the procedure of this embodiment, Japanese Patent Application No.
Those skilled in the art can easily and reliably design and manufacture the threaded joint for oil country tubular goods proposed by 193119.

[0088]

EXAMPLES The present invention will be further described with reference to examples. The oil well pipe threaded joint was designed in accordance with the oil well pipe threaded joint design procedure shown in FIG. 2 described in the above embodiment.

FIG. 4 shows the box portion, the metal seal portion, and the torque shoulder portion of the threaded joint for oil country tubular goods thus designed. In the figure, L = 5, a = 0.3
, C = 0.19, h = 1.475, θ ₁ = 15 °, X = 0.57, l
= 11.0, Sp = 6, Ts = 4, α = −3 °, γ = 0.1, β =
35 °, δ = 0.06, P = 5, d = 0.3, R ₂ = 1.0, l Res
= 50.8, Is = 0.60, R ₃ = 0.9, and R ₄ = 4.0.

The threaded joint for oil country tubular goods can withstand the tensile force in the axial direction due to the weight of the connected pipe, the internal pressure of the internal fluid, or the external pressure of the external fluid, and can be used repeatedly. There is,
Have sufficient strength against the compressive and torsional forces applied to the pipe during the well development process or during the operation of the well;
And have the characteristics of withstanding internal and external pressure seals even when repeatedly subjected to the above-mentioned loads.
It has been found that it has all the requirements presented in the issue.

[0091]

As described in detail above, according to the present invention, a person skilled in the art can easily produce a threaded joint for oil country tubular goods, specifically, a threaded joint having a resistance to various external forces equal to or greater than that of the pipe body. A method that can be manufactured in a specific manner can be provided specifically.

More specifically, according to the present invention, a threaded joint proposed by Japanese Patent Application No. 10-193119, specifically, (i) for oil country tubular goods such as a tensile force and a compressive force, and an internal pressure and an external pressure. Any load condition that the threaded joint receives (bending has a tensile force on the outside of its curvature and a compressive force on the inside,
As long as the cross-sectional shape is not deformed, it can be uniquely treated as equivalent to the load of the axial force. ), For the internal pressure region, includes the entire inside of the ellipse with 100% Von Mises equivalent stress, and for the external pressure region, within 100% of the API collapse pressure (considering axial force) specified by API5C3, or 100% Von Mises equivalent stress.
%, The inner / external pressure leakage resistance and the joint strength can be maintained, and (ii) the equivalent stress of 100 Von Mises under the combined load condition including all of the smaller area in the inside of the ellipse. % Of the ellipse and the API5C3 collapsed ellipse, no matter how the load fluctuates repeatedly, the leak resistance and the joint strength can be sufficiently maintained, and further, the threaded joint can be reused repeatedly. Could be easily provided by those skilled in the art. The significance of the present invention having such an effect is extremely remarkable.

[Brief description of the drawings]

FIG. 1 (a) shows a pipe shaft of a coupling type oil country tubular good threaded joint for connecting a coupling having two box parts at both ends and a pipe having a pin part at each end. FIG. 1 (b) is an enlarged sectional view of a box portion of the coupling, and FIG. 1 (c) is an enlarged sectional view of a pin portion of the tube.

FIG. 2 is a flowchart showing an example of a design procedure of a threaded joint for an oil country tubular good of the embodiment.

FIG. 3 is a flowchart showing another example of the design procedure of the threaded joint for oil country tubular goods in the embodiment.

FIG. 4 is an explanatory diagram showing a design result of the example.

[Explanation of symbols]

 10 Steel pipe 11 Pin part 12 Male thread part 20 Coupling 21 Box part 22 Female thread part 23 Metal seal part 24 Torque shoulder part 25 Screw joint

Claims (21)

[Claims] 1. A pin portion having a male screw having a substantially trapezoidal tapered thread, a box portion having a substantially trapezoidal tapered screw, and having a female screw meshing with the male screw portion; And a screwless portion for forming a metal seal portion provided on the box portion and contacting the screwless portion for forming the metal seal portion provided on the box portion. A metal seal portion, a screwless portion for forming a torque shoulder portion provided at the tip of the pin portion, and a torque shoulder portion for forming a torque shoulder portion provided on the box portion and in contact with the screwless portion for forming the torque shoulder portion. When manufacturing a threaded joint for an oil country tubular good having a torque shoulder portion constituted by a threadless portion of the present invention, the following first step to the following fifth step are performed. Than,
A method for manufacturing a threaded joint for oil country tubular goods, comprising determining dimensions of each part. First step: The pipe outer diameter (OD) and the pipe wall thickness (t) of the pipe having the pin portion are determined, and based on the determined pipe outer diameter (OD) and the pipe wall thickness (t), a screw pitch ( P). 2nd process: Based on the determined pipe outer diameter (OD) and pipe wall thickness (t), the allowable range of the complete meshing screw length (L) between the pin part and the box part is provisionally determined and provisionally determined. Based on the allowable range of the full mesh screw length (L)
(L) is provisionally determined, the determined pipe outer diameter (OD) and the pipe wall thickness (t), the provisionally determined complete meshing screw length (L), and the provisionally determined pin part lip outer diameter ( DB), and temporarily determine the screw taper (Tt) and the length of the completely meshing screw (L). Third step: A lip inner diameter (D2) of the pin portion is determined based on the determined pipe outer diameter (OD) and pipe wall thickness (t), and based on the determined lip inner diameter (D2) of the pin portion. The inner diameter (D1) of the box portion is determined, the lip thickness ratio (X) is provisionally determined based on the determined tube outer diameter (OD) and the tube wall thickness (t), and the tentatively determined lip thickness ratio (X ), The lip thickness (lt) and the pin portion lip outer diameter (DB) of the pin portion are provisionally determined, and the tentatively determined lip thickness (lt) and the pin portion lip outer diameter (DB) of the pin portion are determined. Tentatively determines the pin portion lip outer diameter (DB) based on the lip length (l)
, Pin seal length (Sp), seal taper (Ts), shoulder angle (θ ₁ ) and the lip thickness ratio (X),
> 1.2, and based on the function f and the lip inner diameter (D2) of the pin portion, a lip length (l), a pin portion seal length (Sp), a seal taper (Ts), Shoulder angle
(θ ₁ ) and the lip thickness ratio (X) are determined, and based on the determined pin lip shape, (i) a pin seal tip R (R ₂ ) is determined, and the pin seal tip is determined. R (R ₂ ), the box seal tip R (R ₃ ) is determined, (ii) the pin seal R (R ₁ ) is determined, and (iii) the lip tip diameter (Pa)
pex) and the tip diameter of the box seal (Bapex) based on the tip diameter of the lip (Papex). (iv) Bevel angle (θ ₂ ) and pin inner surface grinding angle at the start of threading of the pin (θ ₃ ) is determined, and (iv) the lip thickness (lt) and the pin portion lip outer diameter (DB) of the pin portion are determined, and the lip thickness (lt) and the pin portion lip outer diameter (DB) are determined. Based on this, while determining the box part screw parallel part diameter (DA), the screw taper (Tt) and the full mesh screw length (L) are determined, and the screw taper (Tt) and the full mesh screw length (L) are determined. Based on L), determine the box pitch diameter position (LBt), and (v) determine the box seal length (S _B ). Fourth step: The screw engagement height (h) is determined based on the determined pipe outer diameter (OD) and pipe wall thickness (t), and the screw engagement height (h) is determined.
Based on the pitch diameter (Dp), based on the pitch diameter (Dp), (i) box part outer diameter (W) and pin part pitch diameter position (LPt) are determined, and (ii) screw interference Determine the amount (It),
(iii) Determine the box portion shoulder depth (LB) and the box portion shoulder length (IRes), and determine the box portion shoulder depth
(LB) and the length of the box part (NL) based on the box part shoulder length (IRes). Fifth step: load surface angle (α), stub surface angle (β),
Determine the stubbing clearance (δ) and the crest clearance (γ). 2. A pin portion having a male screw having a substantially trapezoidal tapered screw shape, a box portion having a substantially trapezoidal tapered screw shape, and having a female screw meshing with the male screw portion; And a screwless portion for forming a metal seal portion provided on the box portion and contacting the screwless portion for forming the metal seal portion provided on the box portion. A metal seal portion, a screwless portion for forming a torque shoulder portion provided at the tip of the pin portion, and a torque shoulder portion for forming a torque shoulder portion provided on the box portion and in contact with the screwless portion for forming the torque shoulder portion. When manufacturing a threaded joint for an oil country tubular good having a torque shoulder portion constituted by a threadless portion of the pipe, the pipe outer diameter (OD) of the pipe having the pin portion and the pipe Thickness
(t), and, based on the determined pipe outer diameter (OD) and pipe wall thickness (t), tentatively determine the allowable range of the completely meshing screw length (L) between the pin portion and the box portion. Tentatively determining the complete meshing screw length (L) based on the tentatively determined allowable range of the full meshing screw length (L), and determining the determined pipe outer diameter (OD) and the determined pipe wall thickness (t). The inner diameter (D2) of the box is determined based on the lip inner diameter (D2) of the pin portion based on the determined lip inner diameter (D2) of the pin portion, and the lip thickness ratio (X) is provisionally determined. Tentatively determined lip thickness ratio (X)
Tentatively determines the lip thickness (lt) of the pin portion and the lip outer diameter (DB) of the pin portion, based on the determined pipe outer diameter (OD) and the determined pipe wall thickness (t). The height (h) is tentatively determined, and based on the determined pipe outer diameter (OD) and the tentatively determined lip outer diameter (DB) and the completely meshing screw length (L) of the pin portion, a screw is formed. Taper (Tt) and full mesh screw length (L)
Based on the provisionally determined lip thickness (lt) of the pin portion and the lip outer diameter (DB) of the pin portion, a lip length (l), a pin portion seal length (Sp), a seal The taper (Ts), the shoulder angle (θ ₁ ) and the lip thickness ratio (X) are calculated by the function f> 1.2
Based on the tentatively determined lip length (l), pin part seal length (Sp), seal taper (Ts), shoulder angle (θ ₁ ) and lip thickness ratio (X), Determine the pin lip shape, determine the bevel angle (θ ₂ ) and the pin inner surface shaving angle (θ ₃ ) at the beginning of the threading of the pin, and determine the lip thickness (lt) of the pin and the outer diameter of the pin lip. (DB), the lip tip diameter (Papex), the pin seal R (R ₁ ) and the pin seal tip R (R ₂ ), and the determined lip thickness (lt ) And the pin portion lip outer diameter (DB), determine the screw taper (Tt) and the fully engaged screw length (L), determine the box portion screw parallel portion diameter (DA), and load surface. Angle (α), stub surface angle (β), stubbing surface clearance (δ), and thread crest clearance (γ) were determined and determined. Determine the thread pitch (P) on the basis of the outer diameter (OD) and pipe wall thickness (t), the pin seal length (Sp) and the pin portion based on the various dimensions box seal lengths (S _B) The pitch diameter (Dp) is determined from the determined pipe outer diameter (OD), pipe wall thickness (t) and screw engagement height (h), and the box part outer diameter (W) and pin part pitch diameter position ( L
Pt), determine the amount of screw interference (It) based on the determined pitch diameter (Dp), determine the box shoulder depth (LB), determine the box shoulder length (IRes), Based on the determined box shoulder length (IRes) and box shoulder depth (LB), the overall length of the box (NL) is determined, and the length of the complete meshing screw (L) and the length of the pin seal lip (l) are determined. ) To determine the box part pitch diameter position (LBt), the box part seal tip diameter (Bapex) based on the determined lip part tip diameter (Papex), and determine the determined pin part seal tip R (R ₂ ). A method for manufacturing a threaded joint for oil country tubular goods, characterized in that the dimensions of each part are determined by determining the tip R (R ₃ ) of the box part seal so as to be smaller than that. 3. The permissible range of the length (L) of the completely meshing screw between the pin portion and the box portion is as follows: pipe wall thickness (t) / tube outer diameter (O
D) 3 or more when 96 is 0.096 or more, 4 or more when ｛pipe wall thickness (t) / outside diameter (OD) 0.0 0.084 or more, ｛pipe wall thickness (t) /
5 or more when the pipe outer diameter (OD) is 0.052 or more;
3. When (t) / outer pipe diameter (OD) is less than 0.052, it is 5 or more, and the lip inner diameter (D2) of the pin portion is set to be equal to or less than the pipe inner diameter (ID). The method for producing a threaded joint for oil country tubular goods described in the above. 4. The lip thickness (lt) of the pin portion is as follows:
The method for manufacturing a threaded joint for oil country tubular goods according to any one of claims 1 to 3, which is obtained by an equation. (Equation 1) 5. The lip outer diameter (DB) of the pin portion is as follows:
The method for manufacturing a threaded joint for oil country tubular goods according to any one of claims 1 to 4, wherein the method is obtained by equation (2). (Equation 2) 6. The thread engagement height (h) may be determined based on the pipe outer diameter (OD), or the pipe outer diameter (OD) and the pipe wall thickness.
The method for manufacturing a threaded joint for oil country tubular goods according to any one of claims 1 to 5, wherein the method is set based on (t). 7. The method for manufacturing a threaded joint for an oil country tubular good according to claim 1, wherein the thread taper (Tt) is obtained by the following equation (3). (Equation 3) Here, the symbol C is a constant indicating the tolerance between the screw bottom and the lip outer diameter at the lip root position, and the symbol ε is the radius difference between the screw top and the screw bevel top at the lip root position. 8. The length of the completely meshing screw (L) is as follows:
The method for manufacturing a threaded joint for oil country tubular goods according to any one of claims 1 to 7, which is obtained by an equation. (Equation 4) 9. The method of manufacturing a threaded joint for oil country tubular goods according to claim 1, wherein the function f is obtained by the following equation (5). (Equation 5) However, 5 ° ≦ θ ₁ ≦ 20 °, 0.52 ≦ X ≦ 0.75, 6 ≦ l ≦
30, 3 ≦ Sp ≦ 10 and 1 ≦ Ts ≦ 16. 10. The method for manufacturing a threaded joint for oil country tubular goods according to claim 1, wherein the Papex is obtained by the following equation (6). (Equation 6) 11. The pin part seal R (R ₁ ) is formed by the following (7)
2. The method according to claim 1, wherein the value is obtained by the expression or the expression (7 ').
0. The method for manufacturing a threaded joint for oil country tubular goods according to any one of 0 to 0. However, equation (7) shows a case where the pin lip portion other than the seal portion is parallel, and equation (7 ') shows a case where the adjacent portion of the seal portion has a taper (T _D ). (Equation 7) 12. The method for manufacturing a threaded joint for oil country tubular goods according to claim 1, wherein the stub surface angle β is obtained by the following equation (8). (Equation 8) However, 5>α> −20 ° C., γ: as small as possible, 25 ° <β
<45 °, δ: Positive value as small as possible by the processor, considering cost and performance 13. The pipe pitch (P) is a pipe outer diameter (OD) or a pipe outer diameter (OD) and a pipe wall thickness.
The method for manufacturing a threaded joint for oil country tubular goods according to any one of claims 1 to 12, wherein the method is set based on (t). 14. The box seal length (S _B) in the case of S _B> S _P is a S _B> S _P +2.0, and determined by the following equation (9), S If in the case of _B ≦ S _P is claim 1 claim 1, obtained by the following (10)
3. The method for producing a threaded joint for an oil country tubular good according to any one of 3 to 3. (Equation 9) (Equation 10) However, the code Is denotes a seal interference amount, reference numeral T _D indicates the taper of the pin lip tapered portion, reference numeral theta ₅ shows the box seal portion inlet angle. 15. The method according to claim 1, wherein the pitch diameter Dp is determined by the following equation (11). [Equation 11] Here, the symbol ε is a constant set based on the pipe outer diameter (OD). 16. The box outer diameter W is set such that the box dangerous cross section (A _BC ) is larger than a predetermined ratio of the pipe standard cross section (A _PC ). The method for producing a threaded joint for oil country tubular goods according to any one of the above. 17. The method for manufacturing a threaded joint for oil country tubular goods according to claim 1, wherein the screw interference amount It is obtained by the following equation (12) or (13). However, among the values calculated over the entire length of the screw by the expression (12) or (13), the minimum value is the upper limit of the screw interference amount It, and 5% of the upper limit is the lower limit of the screw interference amount It. (Equation 12) Here, the symbol δy indicates the material yield strength (kgf / mm ² ), the symbol E indicates the Young's modulus of the joint material (kgf / mm ² ), the symbol D indicates the box outer diameter (mm), and the symbol d indicates the pin. Indicates the inner diameter (mm), the symbol dp indicates the pitch circle diameter (mm) of the screw, and the symbol La ²
Indicates (dp ² −d ² ), and the symbol Lb ² indicates (D ² −dp ² ). 18. The method of manufacturing a threaded joint for oil country tubular goods according to claim 1, wherein the shoulder depth LB of the box portion is obtained by the following equation (14). [Equation 14] However, reference numeral theta ₄ shows a box section end plane bevel angle. 19. The box part pitch diameter position LBt is:
The method for manufacturing a threaded joint for oil country tubular goods according to any one of claims 1 to 18, which is obtained by the following equation (15). (Equation 15) 20. The tip diameter Bapex of the box part seal.
Is calculated by the following equation (16).
9. The method for producing a threaded joint for oil country tubular goods according to any one of 9 to 9. (Equation 16) Here, the symbol Is indicates the seal interference amount. 21. The pin part pitch diameter position LPt is as follows:
The method for manufacturing a threaded joint for oil country tubular goods according to any one of claims 1 to 20, which is obtained by the equation (17). [Equation 17]