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    • 专利摘要:
    threaded joint for steel pipes is a screwed joint configured from a pin (10) and a housing (20). the pin (10) is provided with, in the following order from the tip end side, a shoulder surface (11), a nozzle part (12), a first sealing surface (13), a first bolted part male (14), an annular portion (15a), a second sealing surface (16) and a second male bolted portion (17). the housing (20) is provided with a shoulder surface (21), a concave part (22), a first sealing surface (23), a first female screwed part (24), an annular part (25a), a second sealing surface (26) and a second female bolted part (27). when the bolted joint is in a tight state, the shoulder surfaces (11, 21) are in contact with each other, the first sealing surfaces (13, 23) are in contact with each other, the second sealing surfaces (16, 26 ) are in contact with each other, a gap is formed between the nozzle part (12) and the concave part (22), a gap is formed between the annular parts (15a, 25a), the first male bolted part (14) and the first female bolt-on part (24) fit together and the second male bolt-on part (17) and the second female bolt-on part (27) fit together.
    公开号:BR112016026808B1
    申请号:R112016026808-3
    申请日:2015-06-16
    公开日:2021-08-17
    发明作者:Keita INOSE；Fumio Ota；Shin Ugai；Suguru Yamaguchi；Masaaki Sugino
    申请人:Nippon Steel Corporation；Vallourec Oil And Gas France；
    IPC主号:
    专利说明:

    FIELD OF TECHNIQUE
    [0001] The present invention relates to a threaded joint for use in connecting steel tubes or pipes (hereinafter referred to as "steel pipes"). TECHNICAL BACKGROUND
    [0002] In oil wells, natural gas wells and the like (hereinafter also collectively referred to as "oil wells"), oil well pipes and fittings (OCTG: oil country tubular goods) ), such as casings and pipes, are used for the extraction of underground resources. Oil field pipes and fittings are sequentially connected to each other, and threaded joints are used for the connection.
    [0003] Threaded joints for steel pipes are classified into two types: coupling-type joints and integral-type joints. A coupling-type threaded joint is made up of a pair of pipes and fittings that must be connected together, one of which is a steel pipe and the other is a coupling. In that case, the steel barrel includes male threaded portions formed on the outer peripheries at both ends thereof and the coupling includes female threaded portions formed on the inner peripheries at both ends thereof. The male threaded portion of the steel pipe is screwed into the female threaded portion of the coupling, thereby tightening the thread to complete the connection. An integral type threaded joint is made up of a pair of steel pipes like tubes and fittings that must be connected together, without a separate coupling being used. In that case, each steel pipe includes a male threaded portion formed at the outer periphery at one end thereof and a female threaded portion formed at the inner periphery at the other end thereof. The male threaded portion of one of the steel pipes is screwed into the female threaded portion of the other steel pipes, thereby tightening the thread to complete the connection.
    [0004] In general, the gasket portion at the tubular end in which a male threaded portion is disposed is referred to as a pin since it includes an element that is inserted into a female threaded portion. On the other hand, the joint at the tubular end in which a female threaded portion is disposed is called a box, as it includes an element that receives a male threaded portion. Both pins and boxes have a tubular shape, as they are made up of end portions of tubes and fittings.
    [0005] Figure 1 is a longitudinal sectional view showing an example of a typical conventional threaded joint for steel pipe. The threaded joint shown in Figure 1 is a coupling-type threaded joint and is constructed of a pin 110 and a housing 120.
    [0006] The pin 110 includes, in the order of the free end thereof to the tubular body, a shoulder surface 111, a sealing surface 113 and a male threaded portion 114. The housing 120 includes, in the order of the tubular body side to the free end, a shoulder surface 121, a sealing surface 123 and a female threaded portion 124. The shoulder surface 121, the sealing surface 123 and the female threaded portion 124 of the housing 120, corresponding to the shoulder surface, are provided. 111, sealing surface 113 and male threaded portion 114 of pin 110, respectively. The male threaded portion 114 of the pin 110 and the female threaded portion 124 of the housing 120 are configured to engage with each other and constitute a tapered threaded portion with trapezoidal threads.
    [0007] The male threaded portion 114 and the female threaded portion 124 are threadably engageable with each other and, in a tight state, engage in intimate contact with each other to have an interference fit. The sealing surfaces 113, 123 are brought into contact with each other by screwing on the pin 110 and, in a tight state, engage in intimate contact with each other to have an interference fit. Thereby, the sealing surfaces 113, 123 form a sealing portion therebetween with metal-to-metal contact. Shoulder surfaces 111, 121 are brought into contact and pressed against each other through bolt 110 bolting, and serve as plugs to restrain bolt 110 bolting. Shoulder surfaces 111, 121, in a tight state, will serve to transmit the so-called axial thread-tightening force to the load flanks of the male threaded portion 114 of the pin 110.
    [0008] With a threaded joint having this configuration, the sealing performance is ensured through the engagement and intimate contact between the sealing surfaces 113, 123, as well as the engagement and intimate contact between the male threaded portion 114 and the female threaded portion 124.
    [0009] In recent years, oil well environments have increasingly become deep underground and ultra-deep water environments, and consequently have become hostile environments with high temperatures, high pressures and high corrosivity. For application in such harsh environments, heavy wall steel pipes are widely used as oil field pipes and fittings. It is necessary that the threaded joints used to connect such steel pipes provide excellent sealing performance against both internal pressure and external pressure.
    [0010] The following examples deal with conventional techniques that have attempted to improve the sealing performance of threaded joints for heavy wall steel pipe.
    [0011] Figure 2 is a longitudinal sectional view showing an example of a conventional threaded joint for steel pipe that has been designed to provide improved sealing performance. The threaded joint shown in Figure 2 includes two metal-to-metal sealing portions (see, for example, International Publication No. WO01/029476 (Patent Literature 1)).
    [0012] Specifically, as shown in Figure 2, the pin 210 includes, in the order of the free end thereof to the tubular body, a shoulder surface 211, a first sealing surface 213, a first male threaded portion 214, a second surface seals 216 and a second male threaded portion 217. The housing 220 includes, in the order of the tubular body side to the free end, a shoulder surface 221, a first sealing surface 223, a first female threaded portion 224, a second surface seals 226 and a second female threaded portion 227. A first threaded portion comprised of the first male threaded portion 214 and the first female threaded portion 224 is a tapered threaded portion with trapezoidal threads. A second threaded portion consisting of the second male threaded portion 217 and the second female threaded portion 227 is also a tapered threaded portion with trapezoidal threads.
    [0013] Figure 3 is a longitudinal sectional view showing another example of a conventional threaded joint for steel pipe that has been designed to provide improved sealing performance. The threaded joint shown in Figure 3 is similar to the threaded joint shown in Figure 2 in that it includes two metal-to-metal sealing portions, but differs in that the locations of the shoulder surfaces have been modified (see, for example, US Patent No. 4,662,659 (Patent Literature 2)).
    [0014] Specifically, as shown in Figure 3, the pin 210 includes, in the order of the free end thereof to the tubular body, a first sealing surface 213, a first male threaded portion 214, a shoulder surface 211, a second surface seal 216 and a second male threaded portion 217. The housing 220 includes, in the order of the tubular body side to the free end, a first sealing surface 223, a first female threaded portion 224, a shoulder surface 221, a second surface seals 226 and a second female threaded portion 227. Either a first threaded portion consisting of the first male threaded portion 214 and the first female threaded portion 224, and a second threaded portion comprised of the second male threaded portion 217 and the second threaded portion female 227, are a tapered threaded portion with trapezoidal threads.
    [0015] In the case of the threaded joint shown in Figure 2, the conical surface defined by the first threaded portion and the conical surface defined by the second threaded portion are equal. In this configuration, second sealing surfaces 216, 226 are simply added between the first threaded portion and the second threaded portion. In contrast, in the case of the threaded joint shown in Figure 3, the conical surface defined by the first threaded portion is closer to the geometric axis of the barrel CL than the conical surface defined by the second threaded portion. In this configuration, shoulder surfaces 211, 221 are provided between the first threaded portion and the second threaded portion.
    [0016] In the two threaded joints shown in Figures 2 and 3, the male threaded portion 214 and the female threaded portion 224 are threadably engageable with each other and, in a tight state, they engage in intimate contact with each other to have an interference fit. Similarly, the second male threaded portion 217 and the second female threaded portion 227 have an interference fit with each other. The first sealing surfaces 213, 223 and the second sealing surfaces 216, 226 are brought into contact with each other by screwing on the pin 210 and, in a tight state, engage in intimate contact with each other to have an interference fit. Shoulder surfaces 211, 221 are brought into contact and pressed together by screwing in pin 210.
    [0017] With a threaded joint having this configuration, sealing performance primarily against internal pressure is ensured through engagement and intimate contact between the first sealing surfaces 213, 223. In addition, sealing performance primarily against internal pressure. external pressure is ensured through engagement and intimate contact between the second sealing surfaces 216, 226. CITATION LIST PATENT LITERATURE
    [0018] Patent Literature 1: International Publication No. WO01/029476
    [0019] Patent Literature 2: U.S. Patent 4,662,659 SUMMARY OF THE INVENTION PROBLEM OF THE TECHNIQUE
    [0020] Threaded gaskets for use in the harsh environments of recent years, particularly threaded gaskets for heavy wall steel pipe, are required to provide additional improved sealing performance against internal and external pressures.
    [0021] An object of the present invention is to provide a threaded joint for steel pipes that has the following feature: improved sealing performance against internal pressure and external pressure. SOLUTION TO THE PROBLEM
    [0022] A threaded joint for steel pipes according to an embodiment of the present invention includes a tubular pin and a tubular box, the pin and box being tightened by screwing the pin into the box, wherein the pin includes, in order from one end thereof, a shoulder surface, a first sealing surface, a first conical male threaded portion, a second sealing surface and a second conical male threaded portion, and the housing includes a shoulder surface, a first sealing surface, a first conical female threaded portion, a second sealing surface and a second conical female threaded portion, which correspond to the shoulder surface, the first sealing surface, the first male threaded portion, the second sealing surface and to the second male threaded portion of the pin, respectively.
    [0023] In addition, the pin includes a nozzle portion disposed between the shoulder surface and the first sealing surface, the nozzle portion being continuous with the first sealing surface, and an annular portion disposed between the first portion. male thread and the second sealing surface, the annular portion being continuous with the second sealing surface; the housing includes a recessed portion corresponding to the nose portion of the pin and an annular portion corresponding to the annular portion of the pin.
    [0024] This threaded joint is configured so that, in a tight state: the shoulder surfaces are in contact with each other; the first sealing surfaces are in contact with each other; the second sealing surfaces are in contact with each other; a clearance is provided between the nose portion of the pin and the recessed portion of the housing; a clearance is provided between the annular portion of the pin and the annular portion of the housing; the first male threaded portion engages with the first female threaded portion; and the second male threaded portion engages with the second female threaded portion.
    [0025] The above threaded joint may have the following configuration: the pin includes an auxiliary shoulder surface disposed between the first male threaded portion and the annular portion, the auxiliary shoulder surface being continuous with the annular portion; the housing includes an auxiliary shoulder surface that matches the auxiliary shoulder surface of the pin; and, in a tight state, the auxiliary shoulder surfaces are in contact with each other.
    [0026] This threaded joint may preferably have the following configuration: during thread tightening, the contact between the shoulder surfaces and the contact between the auxiliary shoulder surfaces occur simultaneously, or the contact between the auxiliary shoulder surfaces occurs before contact between the shoulder surfaces.
    [0027] In addition, the above threaded joint may preferably have the following configuration: the pin is configured so that when a tubular body having the pin has a cross-sectional area A0 in a plane perpendicular to the geometric axis of the pipe and the shoulder surface has a projected area A1 in a plane perpendicular to the geometric axis of the barrel, an area ratio A1/A0 is at least 30%.
    [0028] In addition, the above threaded joint may preferably have the following configuration: the pin is configured so that when a tubular body having the pin has a cross-sectional area A0 in a plane perpendicular to the geometric axis of the pipe , and the shoulder surface and auxiliary shoulder surface have projected areas in a plane perpendicular to the geometric axis of the barrel with a total of the projected areas designated as A2, an A2/A0 area ratio is at least 30%.
    [0029] In addition, the above threaded joint may preferably have the following configuration: the pin is configured so that when the shoulder surface and the auxiliary shoulder surface have areas projected in a plane perpendicular to the geometric axis of the barrel, with a total of the projected areas designated as A2 and the projected area of the shoulder surface designated as A1, an A1/A2 area ratio is at least 35%.
    [0030] In addition, the above threaded joint can preferably have the following configuration: the annular portion of the pin has an outer diameter greater than a diameter of a conical reference surface, with the conical reference surface being a conical surface having an outside diameter less than an outside diameter of an extension of a conical surface defined by the roots of the second male thread portion at twice a height of the threads of the second male thread portion.
    [0031] In addition, the above threaded joint can preferably have the following configuration: the annular portion of the pin has a length along the geometric axis of the barrel, the length being equal to one thread pitch of the second threaded portion male or greater than the same.
    [0032] In addition, the above threaded joint may preferably have the following configuration: the nose portion of the pin has a length along the geometric axis of the barrel, the length being at least 5 mm. ADVANTAGEOUS EFFECTS OF THE INVENTION
    [0033] A threaded joint for steel pipes of the present invention has the following significant advantage: improved sealing performance against internal pressure and external pressure. BRIEF DESCRIPTION OF THE DRAWINGS
    [0034] [Figure 1] Figure 1 is a longitudinal sectional view showing an example of a typical conventional threaded joint for steel pipe.
    [0035] [Figure 2] Figure 2 is a longitudinal sectional view showing an example of a conventional threaded joint for steel pipe that is designed to provide improved sealing performance.
    [0036] [Figure 3] Figure 3 is a longitudinal sectional view showing another example of a conventional threaded joint for steel pipe that is designed to provide improved sealing performance.
    [0037] [Figure 4A] Figure 4A is a longitudinal sectional view of a threaded joint for steel pipes according to a first embodiment of the present invention.
    [0038] [Figure 4B] Figure 4B is an enlarged longitudinal sectional view of the threaded joint for steel pipes according to the first modality, which shows a region close to the free end of the pin.
    [0039] [Figure 5] Figure 5 is an enlarged longitudinal sectional view of the threaded joint for steel pipes according to the first embodiment of the present invention showing a region in the vicinity of a second sealing portion, which is the portion external of the sealing portions.
    [0040] [Figure 6] Figure 6 is a longitudinal sectional view of a threaded joint for steel pipes according to a second embodiment of the present invention.
    [0041] [Figure 7] Figure 7 is an enlarged longitudinal sectional view of the threaded joint for steel pipes according to the second embodiment of the present invention, showing a region in the vicinity of a second sealing portion, which is a portion external of the sealing portions. DESCRIPTION OF MODALITIES
    [0042] The present inventors have conducted intensive research into a configuration that allows the sealing portion to provide maximum sealing performance. The desired threaded joint was basically of the type which includes a shoulder surface disposed at the free end of the pin and two metal-to-metal sealing portions. Specifically, the desired threaded joint was basically of the type that includes a first sealing portion, which is the inner portion that primarily contributes to the sealing performance against internal pressure, and a second sealing portion, which is the outer portion that contributes primarily for sealing performance against external pressure. Consequently, the inventors found the following.
    [0043] One method of improving sealing performance against external pressure is to increase the wall thickness of the pin. Applying external pressure to the threaded joint can cause deformation radially into the pin, which can result in loosening of the contact between the second outer sealing surfaces, but by increasing the pin wall thickness, the resistance to radial shrinkage is highlighted. However, the internal diameter of the pin is regulated by API (American Petroleum Institute) standards, while the extension of the external diameter of the pin is restricted by structural limitations of the oil well. Thus, there are limitations to increasing the wall thickness of the pin, particularly in the region of the second sealing surface.
    [0044] As a result, the pin is provided with an annular portion disposed between the second sealing surface and the first inner male threaded portion, so that the annular portion is continuous with the second sealing surface and extends in the direction of the geometric axis of the pipe. As a result of the presence of the annular portion, the pin exhibits increased resistance to radial contraction in the region of the second sealing surface. Consequently, a decrease in contact pressure between the second sealing surfaces is inhibited, resulting in improved sealing performance against external pressure. In this case, the housing is provided with an annular portion which is continuous with the second sealing surface thereof, the annular portion corresponding to the region of the annular portion of the pin. In a tight state, clearance is provided between the annular portion of the housing and the annular portion of the pin. This clearance allows an excess of grease compound (hereafter also called "thread compound"), applied to tighten the thread, to be accumulated therein, and thus makes it possible to avoid an inadvertent decrease in the contact pressure between the second sealing surfaces due to increased pressure of the screw compound.
    [0045] Furthermore, the pin and the housing can be provided with annular portions different from the annular portions above arranged between the second sealing surfaces and the second external threaded portions, so that the different annular portions are continuous with the second sealing surfaces and extend in the direction of the geometric axis of the pipe. In a tight state, clearance is provided between these annular portions. This clearance inhibits a substantial decrease in interference between the second sealing surfaces that might otherwise result from interference engagement of the second threaded portions. Consequently, a decrease in contact pressure between the second sealing surfaces is inhibited, resulting in improved sealing performance against external pressure.
    [0046] For improving sealing performance against internal pressure, the following two approaches may be possible. The first approach is as follows. The pin is provided with a cylindrical nose portion disposed between the first inner sealing surface and the shoulder surface so that the nose portion is continuous with the first sealing surface and extends in the direction of the geometric axis of the barrel. The housing is provided with a recessed portion which corresponds to the nose portion of the pin. In a tight state, clearance is provided between the recessed portion and the nozzle portion. Thus, even if the shoulder surface of the pin is separated from the shoulder surface of the box, which can cause loosening of the contact between the first sealing surfaces due to the presence of the nose portion of the pin and the recessed portion of the box, the first sealing surface of the pin elastically recovers along with the nozzle portion. Consequently, a decrease in the contact pressure between the first sealing surfaces is inhibited, so that a high sealing performance against internal pressure can be achieved even while an excessive tensile load is being applied.
    [0047] The second approach is to reduce the wall thickness of the pin in the region of the first inner male threaded portion and the first sealing surface, in addition to employing the first approach above. The pin's reduced wall thickness allows for effective radially outward deformation of the pin when internal pressure has been applied to the threaded joint, which results in the amplification of the contact pressure between the first inner sealing surfaces. However, since reducing the pin wall thickness involves decreasing the pin's rigidity, the contact between the first sealing surfaces can become loose when internal pressure is not applied to the threaded joint. This situation can be resolved with the presence of the nozzle portion according to the first approach above, whereby a decrease in the contact pressure between the first sealing surfaces is inhibited.
    [0048] The second approach can be achieved by providing the pin with an auxiliary shoulder surface disposed between the first male threaded portion and the annular portion, so that the auxiliary shoulder surface is continuous with the annular portion, and providing to the housing an auxiliary shoulder surface disposed between the first female threaded portion and the annular portion, the auxiliary shoulder surface corresponding to the auxiliary shoulder surface of the pin. When this configuration is used, due to the presence of auxiliary shoulder surfaces, it is possible to reduce the external diameter of the pin in the region of the first male threaded portion and the first sealing surface and, consequently, reduce the internal diameter of the box in the region of the first female threaded portion and the first sealing surface. As a result, it is easier to ensure a sufficient cross-sectional area of the critical cut of the box (the cross-section of the female threaded portion in a position closer to the tubular body, i.e., the cross-section of the first female threaded portion in a closer position. close to the tubular body), where a reduction of the casing outside diameter can be achieved.
    [0049] The threaded joint for steel pipes of the present invention was created based on the above findings. The threaded joint arrangements for steel pipes according to the present invention are described below. [FIRST MODE]
    [0050] Figure 4A is a longitudinal sectional view of a threaded joint for steel pipes according to a first embodiment of the present invention. Figure 4B is an enlarged longitudinal sectional view of the threaded joint for steel pipe, showing a region near the free end of the pin. Figure 5 is an enlarged longitudinal sectional view of the threaded joint for steel pipes in accordance with the first embodiment of the present invention showing a region in the vicinity of a second sealing portion, which is the outer portion of the sealing portions. As shown in Figure 4A and Figure 5, the threaded joint according to the first embodiment is a coupling-type threaded joint and is constructed of a pin 10 and a housing 20.
    [0051] The pin 10 includes, in the order of the free end thereof to the tubular body, a shoulder surface 11, a nozzle portion 12, a first sealing surface 13, a first male threaded portion 14, a first annular portion 15a a second sealing surface 16, a second annular portion 15b and a second male threaded portion 17. Both the first sealing surface 13 and the second sealing surface 16 are conical surfaces. Technically, each of the first sealing surface 13 and the second sealing surface 16 has a shape that corresponds to a shape of the peripheral surface of a truncated cone that has a diameter that decreases towards the end, or a shape that corresponds to a combined shape of the peripheral surface of a truncated cone and the peripheral surface of a solid of revolution that can be obtained by rotating a curved line such as an arc around the geometric axis of the barrel CL.
    [0052] The nozzle portion 12, which is cylindrical in shape, is continuous with the first inner sealing surface 13 and extends in the direction of the geometric axis of the barrel. It should be noted that the outer peripheral surface of the nozzle portion 12 may instead be a surface that has a taper equal to that of the first sealing surface 13, smaller (softer) than the same or larger (sharper) than the same. Technically, it has a shape that corresponds to a shape of the peripheral surface of a truncated cone that has a diameter that decreases towards the end, or a shape that corresponds to a combined shape of the peripheral surface of a truncated cone and the peripheral surface of a solid of revolution that can be obtained by rotating a curved line such as an arc around the axis of the pipe CL.
    [0053] The shoulder surface 11 is provided at one end of the nozzle portion 12. The shoulder surface 11 is an annular surface generally perpendicular to the geometric axis of the barrel CL. Technically, the shoulder surface 11 is slightly inclined such that the outer circumferential side thereof is closest to the free end of the pin 10. The first annular portion 15a is continuous with the inner side of the second outer sealing surface 16 and if extends in the direction of the axis of the pipe. The first inner male threaded portion 14 is disposed continuous with the first annular portion 15a. The second annular portion 15b is continuous with the outer side of the second outer sealing surface 16 and extends in the direction of the geometric axis of the barrel. The second outer male threaded portion 17 is disposed continuous with the second annular portion 15b. The outer peripheral surface of the first annular portion 15a can be of any shape as long as the rigidity of the same can be guaranteed. For example, it can be a cylindrical surface or a surface that has a smaller (softer) taper than that of the tapered surface defined by the first male thread portion 14, or it can be a curved surface. The same applies to the outer peripheral surface of the second annular portion 15b.
    [0054] The box 20 includes, in the order of the tubular body side to the free end, a shoulder surface 21, a recessed portion 22, a first sealing surface 23, a first female threaded portion 24, a first annular portion 25a, a second sealing surface 26, a second annular portion 25b and a second female threaded portion 27. Shoulder surface 21, recessed portion 22, first sealing surface 23, first female threaded portion 24, first portion are provided. annular 25a, the second sealing surface 26, the second annular portion 25b and the second female threaded portion 27 of the housing 20, which correspond respectively to the shoulder surface 11, the nozzle portion 12, the first sealing surface 13 to the first male threaded portion 14, the first annular portion 15a, the second sealing surface 16, the second annular portion 15b and the second male threaded portion 17 of the pin 10.
    [0055] Figures 4A and 4B show a case where the first sealing surface 23 of the box 20 protrudes towards the first sealing surface 13 of the pin 10. It should be noted that the first sealing surface 23 of the box 20 may not project. In that case, the first sealing surface 13 of the pin 10 projects towards the first sealing surface 23 of the housing 20.
    [0056] The first male threaded portion 14 of the pin 10 and the first female threaded portion 24 of the housing 20 are tapered threaded portions with trapezoidal threads that interlock with each other, and constitute a first threaded portion, which is the inner portion. The second male threaded portion 17 of the pin 10 and the second female threaded portion 27 of the housing 20 are also tapered threaded portions with trapezoidal threads that interlock with each other, and constitute a second threaded portion, which is the outer portion. In the case of the threaded joint of the first modality, the conical surface defined by the first threaded portion and the conical surface defined by the second threaded portion are equal. In this configuration, second sealing surfaces 16, 26 are simply added between the first threaded portion and the second threaded portion.
    [0057] The first male threaded portion 14 and the first female threaded portion 24 are threadably engageable with each other and, in a tight state, engage in intimate contact with each other to have an interference fit. Similarly, the second male threaded portion 17 and the second female threaded portion 27 have an interference fit with each other. Each of the first sealing surface 13, 23 and the second sealing surface 16, 26 is brought into contact with each other by screwing in the pin 10 and, in a tight state, engage in intimate contact with each other to have a fit. of interference. Thus, the first sealing surface 13, 23 and the second sealing surface 16, 26 form a first sealing portion and a second sealing portion, respectively, through metal-to-metal contact. Shoulder surfaces 11, 21 are brought into contact and pressed together through bolt 10 bolting and serve as plugs to restrict bolt 10 bolting. Furthermore, in a tight state, shoulder surfaces 11, 21 serve to impart so-called axial thread-tightening force to the loading flanks of the first male threaded portion 14 and the second male threaded portion 17 of the pin 10. In a tight state, clearance is provided between the nose portion 12 of the pin 10 and the recessed portion 22 of the housing, a gap is also provided between the first annular portion 15a of the pin 10 and the first annular portion 25a of the housing 20, and a gap is also provided between the second annular portion 15b of the pin 10 and the second annular portion 25b of box 20.
    [0058] With the threaded joint of the first mode having this configuration, the sealing performance primarily against internal pressure is ensured through the engagement and intimate contact between the first internal sealing surfaces 13, 23. In addition, the sealing performance primarily against external pressure is ensured through engagement and intimate contact between the second external sealing surfaces 16, 26.
    [0059] In particular, since the pin 10 includes the first annular portion 15a, which is continuous with the inner side of the second outer sealing surface 16, the pin 10 exhibits an increased resistance to radial contraction in the region of the second sealing surface 16 due to the rigidity of the first annular portion 15a. Thus, even in the case where an external pressure is applied to the threaded joint, the radially inward deformation of the pin 10 is inhibited, so that a decrease in the contact pressure between the second sealing surfaces 16, 26 is inhibited. As a result, the sealing performance against external pressure is improved. In the housing 20, a first annular portion 25a is provided which corresponds to the first annular portion 15a of the pin 10 and, in a tight state, a clearance is provided between the first annular portions 15a, 25a. This allows excess thread compound that has been applied to tighten the thread to accumulate in the gap. As a result, it is possible to avoid an inadvertent decrease in the contact pressure between the second sealing surfaces 16, 26 due to an increased pressure of the thread compound.
    [0060] The pin 10 and the housing 20 are provided with the second annular portion 15b and the second annular portion 25b, respectively, which are continuous with the outer side of the second outer sealing surface 16, 26. In a tight state, it is provided a gap between the second annular portions 15b, 25b. As a result, it is possible to inhibit a decrease in the contact pressure between the second sealing surfaces 16, 26 due to a substantial decrease in interference between them which may otherwise result from interference engagement of the second threaded portions. Consequently, the sealing performance against external pressure is improved.
    [0061] In addition, the pin 10 is provided with the nozzle portion 12 which is continuous with the first inner sealing surface 13. The housing 20 is provided with a recessed portion 22 corresponding to the region of the nozzle portion 12 of the pin 10. In a tight state, a gap is provided between the nozzle portion 12 and the recessed portion 22. In the case where an excessive tensile load is applied to the threaded joint, for example, the shoulder surface 11 of the pin 10 can be separated of the shoulder surface 21 of the housing 20, causing a substantial decrease in the interference between the first sealing surface 13, 23 and, therefore, a loosening of the contact between them. Even in such a case, the nozzle portion 12 elastically recovers and thereby produces the effect of amplifying the contact pressure between the first sealing surfaces 13, 23. As a result, the lowering of the contact pressure can be inhibited as a whole. and, consequently, a high sealing performance against internal pressure can be achieved even while an excessive tensile load is being applied.
    [0062] The following descriptions are additional descriptions of preferred embodiments of the threaded joint according to the first embodiment.
    [0063] With respect to pin 10, A0 is defined as a cross-sectional area of the tubular body in a plane perpendicular to the geometric axis of the barrel CL, and A1 is defined as a projected area of the shoulder surface 11 in a plane perpendicular to the geometric axis of the CL pipe. Preferably, the A1/A0 area ratio (hereinafter also referred to as the "ratio of shoulder surface area to tubular body area") is at least 30%. More preferably, the A1/A0 area ratio is at least 35%. This is due to the following. The A1/A0 area ratio is actually dependent on the area of the shoulder surface 11. In the case where the A1/A0 area ratio is smaller, due to the smaller area of the shoulder surface 11, the shoulder surface 11 cannot withstand an excessive compressive load when applied to the threaded joint. In such a case, the shoulder surface 11, and the nozzle portion 12 and the first sealing surface 13 which extend continuously from the shoulder surface 11, undergo plastic deformation, so that the contact between the first sealing surfaces 13, 23 becomes unstable. As a result, the contact pressure between the first sealing surfaces 13, 23 can be decreased. For this reason, the ratio of shoulder surface area to tubular body area A1/A0 is preferably suitably large.
    [0064] The upper limit of the ratio between the shoulder surface area and the tubular body area A1/A0 is not particularly limited. However, a very large A1/A0 area ratio means that the area of the shoulder surface 11 is too large, that is, the outer diameter of the shoulder surface 11 of the pin 10 is too large. Consequently, housing 20 has a larger inner diameter in the region of first female threaded portion 24 and first sealing surface 23. This results in the need to increase the outer diameter of housing 20 in order to ensure that the critical cut of housing 20 has a sufficient cross-sectional area. Furthermore, it is difficult to ensure sufficient lengths of engagement of the first threaded portion and the second threaded portion. Thus, for practical applications, the ratio of shoulder surface area to tubular body area A1/A0 is preferably up to 60%.
    [0065] In the pin 10, the first annular portion 15a preferably has a minimum outer diameter greater than the diameter of a conical reference surface 19b, as shown in Figure 5. The conical reference surface 19b is a conical surface having a diameter outer diameter less than an outer diameter of an extension 19a of the conical surface defined by the roots of the second male threaded portion 17 at twice the height of threads of the second male threaded portion 17. The reason for the above is as follows. The outer diameter of the first annular portion 15a is actually dependent on the wall thickness of the first annular portion 15a. When the outer diameter of the first annular portion 15a is smaller, which means that the wall thickness of the first annular portion 15a is thinner, the resistance to radial contraction in the region of the second sealing surface 16 that results from the rigidity of the first annular portion 15a will be insufficient in the case where an external pressure is applied to the threaded joint. When this occurs, the contact pressure between the second sealing surfaces 16, 26 can be decreased. For this reason, the outer diameter of the first annular portion 15a is preferably suitably large.
    [0066] The upper limit of the outer diameter of the first annular portion 15a is not particularly limited. However, it is necessary that the outer diameter of the first annular portion 15a be dimensioned so as not to interfere with the second sealing surface 26 of the housing 20 during tightening of the thread.
    [0067] In the pin 10, the first annular portion 15a preferably has a length along the geometric axis of the barrel that is equal to the thread pitch of the second male threaded portion 17 or greater than the same, the length being measured from of the inner end of the second sealing surface 16. The reason for this is that, if the length of the first annular portion 15a is shorter, the contact pressure between the second sealing surfaces 16, 26 can be decreased in the case where a pressure external is applied to the threaded joint, for the same reason for the case where the wall thickness of the first annular portion 15a is thin.
    [0068] The upper limit of the length of the first annular portion 15a is not particularly limited. It should be noted, however, that if the length of the first annular portion 15a is too long, the overall length of the joint is consequently long, which results in an increase in manufacturing costs due to increased machining time and increased material costs. Furthermore, when the length of the first annular portion 15a exceeds a certain length, the sealing performance improvement feat will no longer be substantially increased. Thus, for practical applications, the length of the first annular portion 15a is preferably at most five times the thread pitch of the second male threaded portion 17.
    [0069] In the pin 10, the second annular portion 15b preferably has a length along the geometric axis of the barrel that is equal to the thread pitch of the second male threaded portion 17 or greater than the same, the length being measured from of the outer end of the second sealing surface 16. The reason is that if the length of the second annular portion 15b is shorter, the interference engagement of the second threaded portions may cause a substantial decrease in interference between the second sealing surfaces 16, 26 , and therefore the contact pressure between the second sealing surfaces 16, 26 can be decreased.
    [0070] The upper limit of the length of the second annular portion 15b is not particularly limited. It should be noted, however, that if the length of the second annular portion 15b is too long, the overall length of the joint will consequently be long, which results in increased manufacturing costs due to increased machining time and increased costs of material. Furthermore, when the length of the second annular portion 15b exceeds a certain length, the sealing performance enhancing effect will substantially no longer be increased. Thus, for practical applications, the length of the second annular portion 15b is preferably at most five times the thread pitch of the second male threaded portion 17.
    [0071] In the pin 10, the nozzle portion 12 preferably has a length along the geometric axis of the barrel of at least 5 mm. The reason for this is as follows. If the length of the nozzle portion 12 is shorter, the elastic recovery of the first sealing surface 13 due to the nozzle portion 12 will be insufficient in the case where an excessive tensile load is applied to the threaded joint. When this occurs, the contact pressure between the first sealing surfaces 13, 23 can be decreased. For that reason, the length of the nozzle portion 12 is preferably suitably long.
    [0072] The upper limit of the length of the nozzle portion 12 is not particularly limited. It should be noted, however, that if the length of the nozzle portion 12 is too long, the overall length of the joint will consequently be long, which results in increased manufacturing costs due to increased machining time and increased costs of material. Furthermore, when the length of the nozzle portion 12 exceeds a certain length, the sealing performance enhancing effect will substantially no longer be increased. Thus, for practical applications, the length of the nozzle portion 12 is preferably at most five times the thread pitch of the first male threaded portion 14. [SECOND MODE]
    [0073] Figure 6 is a longitudinal sectional view of a threaded joint for steel pipes according to a second embodiment of the present invention. Figure 7 is an enlarged longitudinal sectional view of the threaded joint for steel pipes in accordance with the second embodiment of the present invention, showing a region in the vicinity of a second sealing portion, which is the outer portion of the sealing portions. . The threaded joint according to the second embodiment shown in Figures 6 and 7 is a variation of the threaded joint according to the first embodiment shown in Figures 4 and 5, and therefore, where appropriate, descriptions redundant to those provided in the first embodiment will not be repeated .
    [0074] As shown in Figures 6 and 7, the threaded joint of the second mode is similar to the threaded joint of the first mode in that a shoulder surface 11 is disposed at the free end of the pin 10 and two metal sealing portions with metal are provided, but differs in that an additional 18 auxiliary shoulder surface is included.
    [0075] Specifically, the pin 10 includes an auxiliary shoulder surface 18 disposed between the first internal male threaded portion 14 and the first annular portion 15a, so that the auxiliary shoulder surface 18 is continuous with the first annular portion 15a. The auxiliary shoulder surface 18 is an annular surface perpendicular to the geometric axis of the barrel CL. It is noted that the auxiliary shoulder surface 18 can be slightly angled such that the outer circumferential side thereof is closer to the free end of the pin 10, similarly to the shoulder surface 11 of the pin 10. The housing 20 includes an auxiliary shoulder surface 28 that corresponds to the auxiliary shoulder surface 18 of the pin 10.
    [0076] In the case of the threaded joint of the second modality, the conical surface defined by the first threaded portion is closer to the geometric axis of the barrel CL than the conical surface defined by the second threaded portion. This is due to the auxiliary shoulder surfaces 18, 28 provided between the first threaded portion (the first male threaded portion 14 and the first female threaded portion 24) and the second threaded portion (the second male threaded portion 17 and the second female threaded portion 27). Thus, in the threaded joint of the second embodiment, the pin 10 has a smaller outer diameter in the region of the first inner male threaded portion 14 and the first sealing surface 13 and therefore has a thinner wall thickness in that region than in the threaded joint of the first modality.
    [0077] In a tight state, the shoulder surfaces 11, 21 are in pressing contact with each other and the auxiliary shoulder surfaces 18, 28 are also in pressing contact with each other. The pressing contact between the shoulder surfaces 11, 21 transmits the axial clamping force primarily to the loading flanks of the first male threaded portion 14 of the pin 10. The pressing contact between the auxiliary shoulder surfaces 18, 28 transmits the force of axial tightening primarily to the load flanks of the second male threaded portion 17 of pin 10.
    [0078] With respect to the moment when the shoulder surfaces 11, 21 are placed in contact with each other and the moment when the auxiliary shoulder surfaces 18, 28 are placed in contact with each other in the course of tightening the thread, it is preferred. whether the two contacts occur simultaneously or that the contact between the auxiliary shoulder surfaces 18, 28 occurs before the contact between the shoulder surfaces 11, 21. With the contacts programmed in this way, the balance between the contact force of the shoulder surfaces shoulder 11, 21 and the contact force of the auxiliary shoulder surfaces 18, 28 is maintained. As a result, there is reduced damage to pin 10 and box 20.
    [0079] The threaded joint of the second mode also produces advantageous effects similar to those of the first mode described above. In the second embodiment, particularly due to the presence of the auxiliary shoulder surfaces 18, 28, the pin 10 has a reduced wall thickness in the region of the first inner male threaded portion 14 and the first sealing surface 13. As a result, the region that it has a reduced wall thickness and effectively deforms radially outward when internal pressure has been applied to the threaded joint. Consequently, the contact pressure between the first sealing surfaces 13, 23 is amplified.
    [0080] The following descriptions are additional descriptions of preferred embodiments of the threaded joint according to the second embodiment.
    [0081] With respect to pin 10, A0 is defined as a cross-sectional area of the tubular body in a plane perpendicular to the geometric axis of the barrel CL and A2 is defined as a total of projected areas of the shoulder surface 11 and the surface of auxiliary shoulder 18 in a plane perpendicular to the geometric axis of the barrel CL. Preferably, the A2/A0 area ratio (hereinafter also referred to as the "ratio of total shoulder surface area to tubular body area") is at least 30%. More preferably, the A2/A0 area ratio is at least 35%. The reason for this is as follows. The A2/A0 area ratio is actually dependent on the areas of the shoulder surface 11 and the auxiliary shoulder surface 18. In the case where the A2/A0 area ratio is smaller, due to the smaller areas of the shoulder surface 11 and of the auxiliary shoulder surface 18, the shoulder surface 11 and the auxiliary shoulder surface 18 cannot withstand an excessive compressive load when it is applied to the threaded joint. In such a case, the shoulder surface 11, and the nozzle portion 12 and the first sealing surface 13 which extend continuously from the shoulder surface 11, undergo plastic deformation, so that the contact between the first sealing surfaces 13, 23 becomes unstable. Furthermore, the auxiliary shoulder surface 18, and the first annular portion 15a and the second sealing surface 16 which extend continuously from the auxiliary shoulder surface 18, undergo plastic deformation, so that the contact between the second surfaces of seal 16, 26 becomes unstable. As a result, the contact pressure between the first sealing surfaces 13, 23 and the contact pressure between the second sealing surfaces 16, 26 can be decreased. For this reason, the ratio of the total shoulder surface area to the tubular body area A2/A0 is preferably suitably large.
    [0082] The upper limit of the ratio of the total shoulder surface area to the tubular body area A2/A0 is not particularly limited. However, a very large A2/A0 area ratio means that the areas of the shoulder surface 11 and the auxiliary shoulder surface 18 are actually very large, ie the outside diameters of the shoulder surface 11 and the auxiliary shoulder surface 18 of the 10 pin is too big. Consequently, the housing 20 has a larger inner diameter in the region of the first female threaded portion 24 and the first sealing surface 23. This results in the need to increase the outer diameter of the housing in order to ensure that the critical cut of the housing 20 has a sufficient cross-sectional area. Furthermore, it is difficult to ensure sufficient lengths of engagement of the first threaded portion and the second threaded portion. Thus, for practical applications, the ratio of shoulder surface area to tubular body area A2/A0 is preferably up to 60%.
    [0083] With respect to pin 10, A2 is defined as a total of projected areas of shoulder surface 11 and auxiliary shoulder surface 18 in a plane perpendicular to the geometric axis of the barrel CL, and A1 is defined as the projected area of shoulder surface 11 in a plane perpendicular to the geometric axis of the barrel CL. Preferably, the A1/A2 area ratio (hereinafter also referred to as the "ratio of shoulder surface area to total shoulder surface area") is at least 35%. More preferably, the A1/A2 area ratio is at least 40%. The reason for this is as follows. The A1/A2 area ratio is actually dependent on the area of the shoulder surface 11 relative to the auxiliary shoulder surface 18. In the case where the A1/A2 area ratio is smaller, due to the smaller area of the shoulder surface 11 , the shoulder surface 11 cannot withstand an excessive compressive load when it is applied to the threaded joint. In such a case, the shoulder surface 11, and the nozzle portion 12 and the first sealing surface 13 which extend continuously from the shoulder surface 11, undergo plastic deformation, so that the contact between the first sealing surfaces 13, 23 becomes unstable. As a result, the contact pressure between the first sealing surfaces 13, 23 can be decreased. For this reason, the ratio of shoulder surface area to total shoulder surface area A1/A2 is preferably suitably large.
    [0084] The upper limit of the ratio of shoulder surface area to total shoulder surface area A1/A2 is not particularly limited. However, a very large A1/A2 area ratio means that the area of the shoulder surface 11 relative to the auxiliary shoulder surface 18 is actually very large, i.e. the wall thickness of the nozzle portion 12 continuous with the surface shoulder 11 and the region of the first male threaded portion 14 and the first sealing surface 13 of the pin 10 are very thick. As a result, effective radially outward deformation does not occur in the region when internal pressure has been applied to the threaded joint and therefore it is not possible to produce the effect of amplifying the contact pressure between the first sealing surfaces 13, 23. In this case , the contact pressure between the first sealing surfaces 13, 23 can be decreased. Thus, for practical applications, the ratio of shoulder surface area to total shoulder surface area A1/A2 is preferably up to 55%.
    [0085] Outer diameters and preferred lengths of the first annular portion 15a and preferred lengths of the nozzle portion 12 of the pin 10 are similar to those of the first embodiment.
    [0086] The present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit and scope of the present invention. For example, additional techniques can be used so that the engagement and intimate contact on the first inner threaded portion can be loosened exclusively in a region close to the first sealing portion when internal pressure has been applied to the threaded joint. This allows the region of the first inner sealing surface 13 of the pin 10 to more effectively undergo a radially outward deformation so that the contact pressure between the first sealing surfaces 13, 23 is further amplified. One possible approach is to employ a configuration in which, in the first threaded portion, the first male threaded portion 14 or the first female threaded portion 24 is provided with incomplete threads of imperfect thread form, in a region close to the first sealing surface. As an example of such a configuration, the area of incomplete threads can be such that the first female threaded portion 24 of housing 20 has ridges that define a cylindrical periphery parallel to the geometric axis of the barrel CL and therefore has thread heights that are lower than the normal thread height. Thus, in the incomplete thread area, clearances are provided between the crests of the first female threaded portion 24 and the roots of the first male threaded portion 14. In this case, the length of the incomplete thread area is three to nine times the thread pitch of the first female threaded portion 24 (about 15 to 45 mm).
    [0087] The threaded joints of the above embodiments can be used as a threaded joint of the integral type or as a threaded joint of the coupling type.
    [0088] To verify the advantages of the present invention, a simulation and numerical analysis were performed using the elastic plastic finite element method. TEST CONDITIONS
    [0089] In the FEM analysis, threaded coupling type joint models for oil field pipes and fittings were prepared with the dimensions of the first annular portion, the nozzle portion and the shoulder surface (including the shoulder surface auxiliary) of the pin being varied. For the main dimensions, the following two types of steel pipe (pin) and coupling (box) have been specified.
    [0090] (1) Steel pipe size: 10 to 1/8 [inch] x 0.8 [inch] (outer diameter 257.2 mm and wall thickness 20.3 mm), Coupling outer diameter : 276.6 mm.
    [0091] (2) Steel pipe size: 7 to 5/8 [inch] x 1.2 [inch] (outer diameter 193.7 mm and wall thickness 30.5 mm), Coupling outer diameter : 217.8 mm.
    [0092] The common conditions were as follows.
    [0093] - Quality of steel pipe and coupling: API standard Q125 (carbon steel that has a yield limit of 125 [ksi]).
    [0094] - Thread shape: 1/10 taper (for 10 to 5 1/8 [inch] pipes) or 1/11 taper (for 7 to 5/8 [inch] pipes); thread height 1.575 [mm]; 5.08 thread pitch [mm]; -3° load flank angle; 10° alignment flank angle; and 0.15 [mm] alignment flank clearance.
    [0095] In the FEM analysis, the material was specified as isotropic hardening elastic plastic, and the models used were prepared to have a modulus of elasticity of 210 [GPa], and a nominal yield strength, expressed as proof stress at 0.2%, of 125 [ksi] (=862 [MPa]). Tightening was carried out to the point where the shoulder surfaces of the pin and the housing were brought into contact with each other, and continued 15 additionally to a point of 1.5/100 turns.
    [0096] The varying dimensional conditions are shown in Table 1 below.

    Comments) The symbol "*" indicates that the value is outside the range specified by the present invention.
    [0097] Test Models No. 1 through Test No. 3 are comparative examples that do not satisfy the conditions specified by the present invention, and none of these had a nozzle portion on the pin. Test Models No. 4 through Test No. 17 are examples of the invention that satisfy the conditions specified by the present invention. Among these models, Test model No. 4 was prepared based on the threaded joint of the first modality shown in Figures 4 and 5, and Test models No. 5 through Test No. 17 were prepared based on the threaded joint of the second modality shown in Figures 6 and 7. EVALUATION METHOD
    [0098] In the FEM analysis, a load sequence simulated in an ISO 13679 Series A Test was applied to the models in a tight state. To evaluate the sealing performance of the sealing surfaces, the minimum values of average contact pressures on the sealing surfaces, in the internal pressure cycle (the first and second quadrants) and in the external pressure cycle (the third and the fourth quadrants) in the charging sequence. (It is observed that the higher the minimum value of the average contact pressure, the better the sealing performance of the sealing surfaces.)
    [0099] Sealing performance ratings of the sealing surfaces were made on the following four-level scale.
    [00100] - E: Excellent. The minimum value of the average contact pressure at the sealing surfaces is 300 MPa or greater in both the internal pressure cycle and the external pressure cycle.
    [00101] - G: Good. The minimum value of the average contact pressure at the sealing surfaces is 300 MPa or greater in the external pressure cycle and is in the range of 250 MPa less than 300 MPa in the internal pressure cycle
    [00102] - A: Acceptable. The minimum value of the average contact pressure at the sealing surfaces is 300 MPa or greater in the external pressure cycle and is in the range of 200 MPa to less than 250 MPa in the internal pressure cycle.
    [00103] - NA: Not Acceptable. The minimum value of the average contact pressure at the sealing surfaces is less than 300 MPa in the external pressure cycle and less than 200 MPa in the internal pressure cycle. TEST RESULTS TEST RESULTS ARE SHOWN IN TABLE 1 ABOVE.
    [00104] In each of the tests #1 through #3, which are comparative examples, the pin did not have a nozzle portion and, as a result, the sealing performance against internal pressure was not acceptable. Among these, in test #1, in which the pin did not include the first annular portion, the sealing performance against external pressure was also not acceptable.
    [00105] In each of the tests 4 to 17, which are examples of the invention, the pin had both the nozzle portion and the first annular portion and, as a result, the sealing performances against internal pressure and pressure external have been improved. In particular, in each of tests nos. 4 to 8, 10 to 14, and 17, each of the ratio of the shoulder surface area to the tubular body area A1/A0, the ratio of the surface area shoulder surface area and tubular body area A2/A0, and the ratio of shoulder surface area to total shoulder surface area A1/A2 was large and, as a result, high sealing performances were exhibited both against internal pressure and against external pressure.
    [00106] In each of tests #9 and #15, the ratio of shoulder surface area to total shoulder surface area A1/A2 was relatively small and, as a result, the degree of improvement in the performance of sealing against internal pressure was less. Furthermore, in test #16, the ratio of the total shoulder surface area to the tubular body area A2/A0 was relatively small and, as a result, the degree of improvement in sealing performance against internal pressure was less.
    [00107] The results described above demonstrate that the threaded joints for steel pipes according to the present invention exhibit improved sealing performance against internal pressure as well as against external pressure. INDUSTRIAL APPLICABILITY
    [00108] A threaded joint according to the present invention has the ability to be used effectively in connecting heavy wall steel pipes that are used in hostile environments such as oil field pipes and fittings. LISTING OF REFERENCE SYMBOLS
    [00109] 10: pin, 11: shoulder surface, 12: nose portion,
    [00110] 13: first sealing surface, 14: first male threaded portion,
    [00111] 15a: first annular portion, 15b: second annular portion,
    [00112] 16: second sealing surface, 17: second male threaded portion,
    [00113] 18: auxiliary shoulder surface,
    [00114] 19a: extension of the conical surface defined by roots of the second male threaded portion,
    [00115] 19b: conical reference surface,
    [00116] 20: box, 21: shoulder surface, 22: recessed portion,
    [00117] 23: first sealing surface, 24: first female threaded portion,
    [00118] 25a: first annular portion, 25b: second annular portion,
    [00119] 26: second sealing surface, 27: second female threaded portion,
    [00120] 28: auxiliary shoulder surface, CL: geometric axis of the barrel.
    权利要求:
    Claims (7)
    [0001]
    1. Threaded joint for steel pipes CHARACTERIZED by the fact that it comprises: a tubular pin (10) and a tubular box (20), in which the pin (10) and the box (20) are tightened by screwing the pin ( 10) in the housing (20), the pin (10) comprising: in order from one end thereof, a shoulder surface (11); a first sealing surface (13); a first conical male threaded portion (14); a second sealing surface (16); and a second conical male threaded portion (17), the housing (20) comprising: a shoulder surface (21); a first sealing surface (23); a first conical female threaded portion (24); a second sealing surface (26); and a second conical female threaded portion (27) corresponding to the shoulder surface (11), the first sealing surface (13), the first male threaded portion (14), the second sealing surface (16) and the second male threaded portion (17) of the pin (10), respectively, wherein the pin (10) further includes: a nozzle portion (12) disposed between the shoulder surface (11) and the first sealing surface ( 13), the nozzle portion (12) being continuous with the first sealing surface (13); and an annular portion (15a) disposed between the first male threaded portion (14) and the second sealing surface (16), the annular portion (15a) being continuous with the second sealing surface (16), the housing ( 20) further includes: a recessed portion (22) corresponding to the nose portion (12) of the pin (10); and an annular portion (25a) corresponding to the annular portion (15a) of the pin (10), in a tight state: the shoulder surfaces (11, 21) are in contact with each other; the first sealing surfaces (13, 23) are in contact with each other; the second sealing surfaces (16, 26) are in contact with each other; a clearance is provided between the nose portion (12) of the pin (10) and the recessed portion (22) of the housing (20); a clearance is provided between the annular portion (15a) of the pin (10) and the annular portion (25a) of the housing (20); the first male thread portion (14) engages with the first female thread portion (24); and the second male threaded portion (17) engages with the second female threaded portion (27), and the pin (10) includes an auxiliary shoulder surface (18) disposed between the first male threaded portion (14) and the annular portion ( 15a), the auxiliary shoulder surface (18) being continuous with the annular portion (15a); the housing (20) includes an auxiliary shoulder surface (28) that corresponds to the auxiliary shoulder surface (18) of the pin (10); and, in a tight state, the auxiliary shoulder surfaces (18, 28) are in contact with each other.
    [0002]
    2. Threaded joint for steel pipes, according to claim 1, CHARACTERIZED by the fact that: during the tightening of the thread, the contact between the shoulder surfaces (11, 21) and the contact between the auxiliary shoulder surfaces ( 18, 28) occur simultaneously, or the contact between the auxiliary shoulder surfaces (18, 28) occurs before the contact between the shoulder surfaces (11, 21).
    [0003]
    3. Threaded joint for steel pipes, according to claim 1 or 2, CHARACTERIZED by the fact that: the pin (10) is configured so that when a tubular body having the pin (10) has an area of cross section A0 in a plane perpendicular to the axis of the barrel, and the shoulder surface (11) and the auxiliary shoulder surface (18) have projected areas in a plane perpendicular to the geometric axis of the barrel, a total of the projected areas is designated as A2, an A2/A0 area ratio is at least 30%.
    [0004]
    4. Threaded joint for steel pipes, according to any one of claims 1 to 3, CHARACTERIZED by the fact that: the pin (10) is configured so that when the shoulder surface (11) and the shoulder surface auxiliary (18) have projected areas in a plane perpendicular to the geometric axis of the pipe, where a total of the projected areas is designated as A2 and a projected area of the shoulder surface is designated as A1, an area ratio A1/A2 is by the minus 35%.
    [0005]
    5. Threaded joint for steel pipes, according to any one of claims 1 to 4, CHARACTERIZED by the fact that: the annular portion (15a) of the pin (10) has a minimum outside diameter greater than a diameter of a conical surface reference, wherein the reference conical surface is a conical surface that has an outside diameter less than an outside diameter of an extension (19a) of a conical surface defined by roots of the second male threaded portion (17) at twice a height of threads of the second male threaded portion (17).
    [0006]
    6. Threaded joint for steel pipes, according to any one of claims 1 to 5, CHARACTERIZED by the fact that: the annular portion (15a) of the pin (10) has a length along the geometric axis of the pipe. the length is equal to one thread pitch of the second male threaded portion (17) or greater than the same.
    [0007]
    7. Threaded joint for steel pipes, according to any one of claims 1 to 6, CHARACTERIZED by the fact that: the nozzle portion (12) of the pin (10) has a length along the geometric axis of the pipe, being that the length is at least 5mm.
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    同族专利:
    公开号 | 公开日
    AR100896A1|2016-11-09|
    EP3159591A1|2017-04-26|
    JPWO2015194160A1|2017-04-20|
    CA2952381A1|2015-12-23|
    US10774598B2|2020-09-15|
    MX2016016550A|2017-05-01|
    PL3159591T3|2019-11-29|
    AU2015275555B2|2018-01-04|
    EA033336B1|2019-09-30|
    JP6239111B2|2017-11-29|
    WO2015194160A1|2015-12-23|
    CA2952381C|2018-10-23|
    SA516380537B1|2021-05-18|
    UA118880C2|2019-03-25|
    US20170101830A1|2017-04-13|
    CN106461127A|2017-02-22|
    AU2015275555A1|2017-02-02|
    CN106461127B|2018-11-16|
    EP3159591B1|2019-04-24|
    EA201692335A1|2017-04-28|
    EP3159591A4|2018-02-14|
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    FR3098879B1|2019-07-19|2021-07-30|Vallourec Oil & Gas France|Threaded joint with asymmetrical helical profile|
    CA3140090A1|2019-08-09|2021-02-18|Keita INOSE|Threaded connection for steel pipe|
    EP3798409A1|2019-09-24|2021-03-31|Vallourec Oil And Gas France|Threaded connection including an intermediate shoulder|
    法律状态:
    2019-10-08| B25D| Requested change of name of applicant approved|Owner name: NIPPON STEEL CORPORATION (JP) ; VALLOUREC OIL AND |
    2020-01-21| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|
    2021-02-23| B07A| Application suspended after technical examination (opinion) [chapter 7.1 patent gazette]|
    2021-06-29| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|
    2021-08-17| B16A| Patent or certificate of addition of invention granted [chapter 16.1 patent gazette]|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 16/06/2015, OBSERVADAS AS CONDICOES LEGAIS. |
    优先权:
    申请号 | 申请日 | 专利标题
    JP2014127673|2014-06-20|
    JP2014-127673|2014-06-20|
    PCT/JP2015/002993|WO2015194160A1|2014-06-20|2015-06-16|Screw joint for steel piping|
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