JPS59144888A - Pipe fittings for oil country tubular goods - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pipe joint for oil country tubular goods that is inserted deep underground in order to extract natural gas and crude oil produced underground, and has particularly excellent tensile strength. The present invention also relates to a lightweight pipe joint.

The depth of wells that produce crude oil is several thousand meters, and in recent years, the depth has been increasing further to reach 10,100 million meters. In such a well L/IL, the number of OCTGs that are vertically inserted and disconnected is enormous, but these are all connected in series by pipe joints, and various loads are required. A terrible force acts. Firstly, the tensile force in the axial direction is caused by the collection of the weight of the main body of pipes and pipe fittings connected in series, and the second is
The second is the compressive force between the outer jumps 1 due to earth pressure, etc., and the third is the pressing force on the inner circumferential surface due to the internal fluid. Needless to say, these forces become even more severe as the well deepens. The two most important requirements for pipe fittings that are subjected to such harsh loading conditions are to withstand strong tensile force and to maintain reliable airtight sealing performance. 0 In order to meet this demand, many proposals regarding breeding have been made.

For example, Japanese Patent Publication No. 35-7630-, Japanese Patent Publication No. 41-1
742, Japanese Patent Publication No. 45-18096, Japanese Patent Publication No. 52-27367, and US Pat.
The pipe fittings described in US Pat. No. 07589, US Pat. No. 2980451, and US Pat. is the rabbit shown in FIG. 1. The pipe joint shown in FIG. ,ru. Coupling A
In the A, P, and ■ standards, the inner diameter normally decreases with the front 6 taper as it progresses toward the center of the axial direction at both ends. On the other hand, an annular circumferential portion B that protrudes around the axis is formed inside the tube. Each 'O' has a male thread engraved at its end to be screwed into the rit J female thread of the coupling A. In Figure 1, if you enlarge the left side of the part indicated by the new song, it will be ``Nu 1'' in Figure 2.

As seen in Figure 2, beyond the part where the male thread of pipe C is cut off (to the right), there is an unthreaded lip part in an area corresponding to 1.5 to 3 threads. is provided. On the outer periphery of this lip part, there is a mark that follows the curved male thread. A curved outer circumferential seal is formed with a tabular finish, and an overhang (wax/CI/) is formed at the tip.
On the other hand, there is also a seal near the peripheral part B of the coupling A, which has an angle of approximately 10 (1') with respect to the 11IlIl line. A tapered unthreaded portion is provided, and an abutting seal surface B2 corresponding to the inner circumferential seal curvature corresponding to the outward seal portion 1) 1 and the tip seal tri+D as per ifJ lip. 0, and when the threaded state of the pipe C and the coupling fA is strongly tightened fc, the outer circumferential seal surface D1 and the inner circumferential seal surface "1", and the tip 4 seal curve D2.
and the abutment sealing surface B2 are in contact with each other to obtain an airtight sealing state in which the metal surface and the gold sheath surface form.

Since the oil country tubing "14 pipe joint is as described above, the tensile strength and sealing performance, which are the most important factors in the O1J area required for a pipe joint, are ultimately ensured by the threaded connection between the coupling and the pipe. If a problem occurs in this threaded relationship, both of the two most important points listed in IJ will not be satisfied.However, conventional pipe joints cannot be used by twisting or digging vertically deep underground. When the pipe is encased, a huge tensile force acts on it as described in tnJ, causing deformation of the threaded portion, and there is even a risk that the pipe may come loose from the coupling. This will be explained with reference to Fig. 4 and Fig. 4. Fig. 3 shows that the second
The area surrounded by a circle in the figure shows the state where deformation has occurred.

) As shown in Figure 3, a tensile force (5
0 to 100'Oton), the entire tube C is stretched and reduced in diameter, and when y<, the coupling A also exhibits a diameter expansion phenomenon in which the vicinity of its end portion warps in the direction of the black arrow. , and the j41 thread of pipe C and the female thread of coupling A become separated. Regarding such phenomena, L7
．． Considering one set of male and female threads, y, then the fourth
As shown in the figure. That is, when a tensile force in the direction of the white arrow is applied to the pipe C, a female thread A1 is formed at a point O on the thread ff1 surface where the male thread q of the pipe C contacts the female thread of the coupling.
A force of f acts on . The force f of C acts as a two-part force consisting of an axial force f1 and a force f2 perpendicular to the axis. Is the component force f1 the inner layer of coupling A? Coupling A (+- acts to expand the diameter. Coupling A (1) all l; i
l+: Since this kind of force is acting on screw A,
These are end A in Figure 3. , so that the edge'
81S An is expanded in diameter so as to warp in the direction of the black arrow. As for the action of the sword b, shown by the broken line, there is already a tendency to stretch due to the tensile force in the direction of the white arrow, and the component force f'2 in the axial direction is added to it. Incidentally, if you compare the diameter expansion force of cup link A with the contraction shaft of pipe C, the force of the diameter contraction is extremely large. In this way, the cup “ring Al7)
End A. If there is a gap between the external thread C and the external thread 1, the threaded relationship will become loose, the strength of the thread itself will decrease, the tensile strength of the entire pipe fitting will decrease, and at the same time the sealing performance will deteriorate. In view of the above-mentioned drawbacks of conventional pipe joints, the purpose of this project is to improve and eliminate this problem. By reversing the male-female relationship of both screws from the conventional one, the amount of diameter reduction deformation when a huge tensile force is applied to the pipe is reduced, making the threaded relationship even tighter. , which aims to ensure the tensile strength and sealing properties of pipe joints.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An oil country tubular talus joint (hereinafter referred to as a main pipe joint) according to the present invention will be described below based on the embodiments shown in FIGS. 5 to 7. FIG. 5 is a schematic diagram of the main pipe joint, partially shown in cross section. In the figure, l is a coupling. The coupling 1 has a flange 2 of the shape 1 that protrudes from the center outer periphery of the axis.
On both sides of the flange 2, there are joint ends 3, 3' whose outer diameter decreases with a normal taper toward the tip.
is formed, and a buttress-type male thread 4.4' is carved on the outer periphery UIU, + of the joint end 3, 3', and a male thread 4,
Lip portions 5, 5' are formed beyond the point where 4' ends. Coupling 1 made like this? The external shape of the diagonal is as shown in Fig. 6 (a, 1). In Fig. 6 (b), spline-like unevenness is provided on the outer periphery of the flange 2. 6.6' is a tube screwed together on both sides of the coupling 1.
At 6', the joint end 3.3' of the coupler 1 is screwed into the joint end 7, 7', which has its outer diameter expanded by upsetting. 7,7′
Inside the tube, the inner diameter usually decreases as you go deeper into the tube. This is the inner circumferential surface of the taper, and a female thread 8.8 corresponding to the rrin+I male thread 4.4' is attached to the inner circumference TI.
' is engraved. Then, at the end of the female threads 8, 8', the line IJg is cut 7' at the lip portions 5, 5 of the ring 1.
A corresponding shoulder 9.9' is formed.

Among the parts shown in the cross section of Fig. 5, the left side from the flange 2? It is shown in FIG. 7 when enlarged. Tsubabe 2 pieces, coupling 111! : This is the part that is gripped by the chuck when screwing the tube 6 together with power tight. Therefore, sufficient strength is required, and for this purpose, both the width W and the amount of protrusion from the surface of the tube end 7 should be large. However, if it is arranged in this way, the weight of the coupling l will inevitably increase, and there is a risk that it will not meet the objective of the present invention, which is weight reduction. Therefore, taking these things into consideration, In this example, the width W was set to 3 to 5 pitches of the ridge, and the protrusion was set to 3 to 5 wn. It is preferable that the root side surface 2a of the flange portion 2 is formed into an overhang-like inclined surface having an angle of approximately 100° with respect to the axis of the coupling l. If you do this, the screwed pipe end 7
This can prevent the tip of the tube from expanding in diameter. The outer cylindrical surface of the lip portion 5 is formed with a taper of 1/1 o, and the surface +tn is an outer circumferential sealing surface 5a finished in a more precise and smooth direction than S-6. In addition, the tip 1 of the lip portion 5
m is formed in an overbank-like inclined IM with an angle of approximately 100° to the axis, and the tip seal pofi5 is finished with a smooth surface of S-6 or higher like the outer seal surface 5a.
b. In addition, the length of the lip part 5 is in the range of 1.5 to 3 threads, and the thickness of the tip is usually in the range of 3 to 5 threads. Tip surface 7a, female thread 8. Each part of the inner circumferential seal [ill 9 a and the abutting seal surface 9 b near J'FAS 9 is the root side m 2 a, ilH of the flange 2 of the coupling 1 that corresponds to and contacts these parts.
Screw 4. It is shaped to exactly match the outer seal surface 5a of the lip portion 5 and the tip seal 11f15b. In addition, the bottom side of the tsuba part 2 in the coupling IK
] 2a and the tip 17a of the /# end portion 7 can also be used as a sealing surface to serve as a sub-seal for the main seal between the lip portion 5 and the peripheral portion 9.

In the main pipe joint made as described above, when fully screwing and tightening the pipe 6 and the coupling l, hold the pipe 6 with a chuck. (Secure 2 and fix it, then screw the joint end 3 of coupling l into this and temporarily tighten it with Hand Tight. Then, read it with Power Tight at 1 to obtain the specified torque. As the tightening progresses, the outer seal of the lip juice 95 dn 5
a Ii Inner circumference seal of cutoff ring 1 #J 9
a The VC is tapered and lowered, and as the mutual contact aU gradually increases and the surface pressure also increases to 0, the lip portion 5 causes elastic deflection in the direction of the axis of the tube 60. , stress due to blood pressure is accumulated within the lip capital 5. As the tightening progresses further, the tip seal curve 5b comes into contact with the abutting seal surface 9b of the circumferential portion 9. In this state, the tightening torque increases rapidly, and the outer seal 1fTI5a vs. the inner seal tfri 9 a, tip seal surface 5b vs. abutment seal] ■ 910 (7) Total blood pressure also increases rapidly, gold km Ir1l vs. gold stripe [(r+ provides an airtight seal.Thus, power tight tightening When the damage reaches the specified torque, it is sufficient to stop the tightening process.Even if a sealing surface is formed on the root side surface 2a of the collar portion 2 and the tip surface 7a of the tube end 7, the tip sealing surface 5b and the abutting seal ifu 9b
Of course, the same airtight seal as in the case of Ir) can be obtained by using the metal curved pair with the gold m1. However, this seal completely plays the role of a seal for the main seal of the tip seal direction 5b and the abutment seal lfI]9b. The case where the pipe (5') can be screwed and tightened to the other joint end 3' of the coupling 1 is also the same as in uiJ.

Next, we will explain the results of comparing the softness of main pipe joints and conventional pipe joints for pipes with the same performance and dimensions.Table 1 shows the results of relative softness in terms of shape, and Table 2 The table shows the tensile strength and sealing performance results.

(Hereafter the margin, θ3) Sum Y<o) As is clear from Table 1, the coupling in the main pipe joint has both a reduced overall length and an average outer diameter compared to the conventional pipe joint. Along with this, the weight is also reduced by 14 to 18%. This weight loss is larger than the weight increase due to the upsetting of the tube end. Since a large tensile force acts on the pipe joint g, from the perspective of ensuring its strength, the outer diameter and wall thickness of the coupling have traditionally been determined by the outer diameter of the contact ring; It is made thicker than the thickness of a fist, and therefore the weight of the coupling is slightly greater than the weight of the pipe ends screwed into the joint ends on both sides. Therefore, the reduction in the weight of the coupling in a non-pipe joint offsets the increase in the weight of the pipe ends screwed to the ends of the joint on both sides, and there is a surplus in the tightening force. Moreover, even if the outer diameter and wall thickness of the coupling are reduced, the tensile strength and sealing properties of the pipe joint are superior to those of conventional pipe joints. This is
This is clear from Table 2.

Table 2 (Note) The damage type marked with ○ indicates that the pipe was broken in the main body of the pipe. This shows the results of a test in which the tensile load was gradually increased until the pipe joint broke under load. All American pipe joints tend to spring out at the joint, but this Pipe fittings do not come unscrewed in cases where the main body of the pipe breaks, and the breakage is reduced to the conventional 11. - The unthreading of the fitting is 1 戊 compared to the actual load, and tensile force is not applied to the pipe. This is because the diameter-reducing effect that occurs when this occurs extends to the end of the tube that is screwed into the coupling, further tightening the screwing relationship and preventing any separation phenomenon between the Jul-thread and the female screw. If there is no loosening between the screws, sealing performance is naturally ensured. Therefore, this 'i'J+' joint was excellent in terms of sealing performance, and no water leaked even when the joint broke. In addition, water leakage occurred in 11J after screws came off with conventional pipe joints.

As described above, the present invention increases the tensile strength of a pipe joint, ensures sealing performance, and reduces the weight of the pipe joint. It is well suited to meet the demanding demands of the extractive industry sector.

[Brief explanation of the drawing]

1 to 4 explain a conventional pipe joint.
The second cause is an enlarged view of the left side of the cross-sectional view in Fig. 1, Fig. 3 is an enlarged view showing the deformation in the circled part in Fig. 2, and ':A4 Fig. Figures 5 to 1117 are schematic diagrams for explaining the phenomenon in which separation occurs in the screw threads shown in the figure. 6(a) and 6(b) are perspective views of the coupling in the non-pipe joint, and FIG. 7 is the central flange of the part facing t9■ in FIG. 5. This is a fully enlarged view of the left side. 1... Coupling 2... Flange 3... Joint end 4... Male thread 5... Lip capital 6... End
7...Pipe end 8...Female thread 9...Shoulder? To 31 Toshihiko Uchida, Patent Attorney, Sumitomo Metal Industries Co., Ltd. Figure 1 A Figure 3 Figure 5 Figure 7

Claims (1)

[Claims] 1. A coupling having a flange projecting outward in the circumferential direction of the center Q of the axis and having a joint end with a male thread carved on the outer periphery of the portion extending on both sides of the flange; It consists of two pipes with internal threads carved on the inner periphery of the pipe ends in order to be screwed into the ends of both side joints. A lip portion having an outer seal curve and a tip seal curve is formed, and an inner circumferential seal curve and an abutment seal corresponding to the outer seal crest J and the tip seal curve are formed in the inner center of the female threads of the two pipes 111. 1. A pipe joint for hydraulic pipes, characterized in that the shoulder portion thereof is hollowed out.