TUBULAR THREADED JOINT THAT HAS IMPROVED HIGH TORQUE MOUNTING PROPERTIES

专利摘要:
tubular threaded joint that has improved high torque mounting properties. in a tubular threaded joint made up of a pin 1 and a box 2 each having a contact surface comprising a threaded portion and a non-threaded metal contact portion including a sealing portion and a shoulder portion, a solid lubricating coating 10 which has a relatively high knoop hardness is formed into a portion that includes the shoulder portion of the contact surface (such as the non-threaded metal contact portion that includes the shoulder portion and the sealing portion) of at least one between the pin and the housing, and a solid lubricating coating 11 which has a relatively low knoop hardness is formed at least on the remaining portion of the contact surface (such as the threaded portion). the tubular threaded joint has excellent abrasion resistance, gas tightness and rust prevention properties and, since it has a large delta t, the joint is not readily subjected to deformation of the shoulder portions even when made with a torque high, thus making it possible to carry out the assembly in a stable manner.
公开号:BR112014027366B1
申请号:R112014027366-9
申请日:2013-05-21
公开日:2020-12-15
发明作者:Kunio Goto
申请人:Nippon Steel Corporation；Vallourec Oil And Gas France；
IPC主号:

专利说明:

TECHNICAL FIELD
[0001] This invention relates to a tubular threaded joint for use in connection with steel tubes and, in particular, tubes for the oil industry. A tubular threaded joint, according to the present invention, can reliably exhibit excellent abrasion resistance without the application of a lubricating grease such as compound grease that has been applied to threaded joints in the past when assembling tubes for the oil industry. As a result, a tubular threaded joint in accordance with the present invention can avoid the adverse effects of compound grease on the global environment and on humans. In addition, the joint does not readily deform even when it is formed with a high torque, so a stable metal-to-metal seal can be made with an adequate margin. BACKGROUND OF THE TECHNIQUE
[0002] Pipes for the oil industry, such as tubing and casing used to dig oil wells for crude oil or diesel are typically connected together using tubular threaded joints. In the past, the depth of oil wells was 2,000 to 3,000 at most, but sometimes reaches 8,000 to 10,000 meters in recent deep wells, such as offshore oil fields. The length of tubes for the oil industry is typically around 10 meters, and the periphery of the pipe through which the fluid, such as crude oil, flows, is surrounded by a plurality of shells. Therefore, the number of pipes for the oil industry that are connected by threaded joints reaches a large number.
[0003] In their environment of use, tubular threaded joints for pipes for the oil industry are subjected to loads in the form of axial torsional forces caused by the mass of pipes for the oil industry and the joints themselves, at compound pressures, such as , internal and external pressures, and geothermal heat. Therefore, it is necessary that the threaded joints maintain gas tightness without being damaged even in such an extreme environment.
[0004] A typical tubular threaded joint used to connect pipes for the oil industry (also referred to as a special threaded joint) has a pin and case structure. A pin, which is a joint component that has male threads, is typically formed at both ends of a tubular oil product, and a box, which is a joint component that has female threads that engage with threads with threads male, is typically formed on the inner surface of both sides of a coupling, which is a separate member. As shown in Figure 1, a sealing portion is provided on the outer peripheral surface in the vicinity of the end surface on the side closest to the end of the pin than the male threads and on the inner peripheral surface of the base portion of the female threads on the housing, and a shoulder portion (also referred to as a torque shoulder) is provided on the end surface of the pin and the corresponding rearmost portion of the box. The sealing portions and shoulder portions of the pin and housing constitute non-threaded metal contact portions of the tubular threaded joint, and the non-threaded metal contact portions and the threaded portions of the pin and housing constitute the contact surfaces. of the tubular threaded joint. Patent Document 1 identified below shows an example of such a special threaded joint.
[0005] When tapping such a tubular threaded joint, one end of a tubular oil product (a pin) is inserted into a coupling (a box), and the male threads and the female threads are tightened up to the shoulder portions of the pin and housing come into contact with each other and interfere under adequate torque. As a result, the sealing portions of the pin and the housing come in close contact with each other and form a metal-to-metal seal, so the gas tightness of the threaded joint is guaranteed.
[0006] Due to several problems when lowering the pipe or casing in an oil well, a tubular joint that was previously screwed in is sometimes broken, the joint is taken from the oil well, is screwed in again, and then is lowered again in the well. API (American Petroleum Institute) requires abrasion resistance so that severe irreparable abrasion referred to as friction does not occur and gas tightness is maintained even when screwing and breaking is performed 10 times for a pipe joint and 3 times for an enclosure joint.
[0007] In order to increase the resistance to excoriation and gas tightness, a viscous liquid lubricant (a lubricating grease) containing heavy metal powder and referred to as compound grease has been previously applied to the contact surfaces of a threaded joint each time screwing was performed. Such compound grease is prescribed by API BUL 5A2.
[0008] In order to increase the retention of compound grease and improve its sliding properties, it has been proposed to subject the contact surfaces of a threaded joint to various types of surface treatment, such as nitriding treatment, various types of deposition, such as zinc deposition or composite deposition, and chemical phosphate conversion treatment to form one or more layers on the contact surfaces. However, as described below, the use of compound grease raises concerns about an adverse effect on the environment and on humans.
[0009] Compound grease contains a large amount of powdered heavy metals, such as zinc, lead and powdered copper. When assembling a threaded joint, the applied grease is washed out or removed by compression to the outer surface, and there is the possibility of an adverse effect on the environment and especially on life, particularly due to harmful heavy metals, such as lead. . Additionally, the process of applying compound grease worsens the operating environment and operating efficiency and can cause harm to humans.
[0010] As a result of the 1998 decree of the OSPAR Convention (Oslo-Paris Convention) aimed at preventing maritime pollution in the northwest Atlantic, recently, strict environmental restrictions have been enacted on a global scale, and in some regions, the use compound grease is already regulated. Thus, in order to avoid an adverse effect on the environment and on humans in the process of digging gas wells and oil wells, there has been a demand for threaded joints that can exhibit excellent abrasion resistance without using compound grease.
[0011] As a threaded joint that can be used to connect pipes for the oil industry without application of compound grease, the present applicant proposed in Patent Document 2 identified below a threaded joint for steel pipes that has a liquid lubrication coating or viscous semi-solid formed therein, and in Patent Document 3 identified below, a threaded joint for steel tubes has been proposed that has a solid lubrication coating formed thereon.
[0012] Patent Document 4 identified below reveals the formation of a layer of high friction lubricant on the entire contact surface of a pin or a box and the formation of a layer of low friction lubricant in specified portions of the contact surface of a pin or a box (when the low friction layer and the high friction layer are placed on top of each other, the low friction layer is the top layer). The specified portions in which the low friction lubricant layer is formed are specifically a metal-to-metal sealing portion and ridge and screw roots, and it is described in that document that only the high friction lubricant layer preferably remains in one shoulder portion and screw loading flanks. However, it is very difficult to form the low-friction lubricant layer only on the perforated ridges, roots and threads of the threaded portion without forming it on the threads loading flanks.
[0013] WO 2007/063079 describes a threaded metal gasket with the thread surface of the pin and box covered by a coating comprising a first layer placed on the total surface of the pin member, and a second layer placed on part of the surfaces of any of the pin or box members. In a first aspect, the coating comprises a first layer with high friction and anti-seizing properties placed on the total surface of the pin member, and a second layer with low friction properties established on specific parts of the surfaces of any of the pin members or Cashier. Preferably, specific surfaces are those that are in reciprocal radial contact during production until the pin and the box reach the point where the shoulders touch. The second layer may contain polytetrafluoroethylene (PTFE). In a second aspect, the first layer with high friction and anti-slip properties placed on the total surface of the box member. DOCUMENTS FROM THE PREVIOUS TECHNIQUE PATENT DOCUMENTS
[0014] Patent Document 1: EP 0488912A2
[0015] Patent Document 2: EP 1350834A1
[0016] Patent Document 3: EP 2216576A1
[0017] Patent Document 4: WO 2007/063079 SUMMARY OF THE INVENTION
[0018] With a special threaded joint like the one shown in Figure 1 that has sealing portions and shoulder portions, the gas tightness is guaranteed by making a metal to metal seal between the sealing portions of the pin and the box on the assembly time.
[0019] Figure 2 shows a torque graph (ordered: torque, abscissa: number of turns) of this type of threaded joint at the time of assembly. As shown in this Figure, as the turning takes place, the threaded portions of the pin and housing make contact initially and the torque gradually increases. Subsequently, the sealing portions of the pin and housing make contact with each other and the rate of increase in torque increases. Finally, the shoulder portion at the end of the pin and the shoulder portion of the box make contact with each other and begin to interfere (the torque at the beginning of this interference is referred to as the anchoring torque and is indicated as Ts), by means of which the torque increases abruptly. Assembly is completed when the torque reaches a predetermined assembly torque. The ideal torque in Figure 2 means the ideal torque to complete the assembly in order to achieve sufficient contact pressure to guarantee gas tightness in the sealing portions between the pin and the housing. A suitable prescribed value for the ideal torque is defined previously based on the inside diameter and the type of the joint.
[0020] When a special threaded joint is used in a very deep well where compressive stresses and bending stresses are applied, the assembly is sometimes performed with an ideal torque greater than usual so that loosening does not occur with certainty . In this case, deformation or one or both of the shoulder portion on the end surface of the pin and the shoulder portion of the box that makes contact with it may occur (the torque when the deformation occurs is referred to as the deformation torque Ty ) and as shown in Figure 2, the shoulder portion (the pin shoulder portion in the illustrated case) is plastically deformed. When such deformation occurs, the rate of increase in torque decreases significantly.
[0021] In the case of a threaded joint that must be mounted with a high torque, it is advantageous that the difference between Ty and Ts or [Ty - Ts] (= ΔT: torque in the shoulder resistance) is large. However, with the tubular threaded joints described in Patent Document 2 or Patent Document 3 that have a viscous liquid or semi-solid lubrication coating or a solid lubrication coating, Ty is reduced compared to the case where conventional compound grease is applied . As a result, ΔT becomes small and the shoulder portions end up draining at a low mounting torque, through which it is sometimes not possible to perform the assembly with a high torque.
[0022] The purpose of the present invention is to provide a tubular threaded joint that does not readily deform its shoulder portions even when it is made with a high torque and that has a lubricating coating that does not contain harmful heavy metals, which it has excellent abrasion resistance, gas tightness and rust prevention properties and makes it possible to guarantee a large ΔT.
[0023] It is known that even if the composition of a lubricating coating is varied in order to change its friction coefficient, ΔT does not vary significantly because Ts and Ty generally vary in the same way. For example, if the friction coefficient of a lubricating coating increases, Ty increases, but Ts also increases (a phenomenon referred to as high berthing). As a result, in the worst case, the shoulder portions do not come into contact with each other at a prescribed mounting torque and a condition occurs as no docking in which the assembly is not completed.
[0024] The present inventors have revealed that with a tubular threaded joint that has a solid lubricating coating that does not contain harmful heavy metals that impose a burden on the global environment, forming a first solid lubricating coating on a portion of the contact surface ( the threaded portion and the non-threaded metal contact portion) of at least one of a pin and a housing, specifically a portion of the contact surface that includes the shoulder portion that experiences contact at a high pressure and, preferably, a portion of the contact surface that includes the shoulder portion and the sealing portion and forming a second solid lubricating coating that has a Knoop hardness less than the first solid lubricating coating on the other portions of the contact surface, a tubular threaded joint is obtained that has sufficient abrasion resistance, gas tightness and rust prevention properties while having a large ΔT and c with which there is no danger of any mooring occurring.
[0025] It is thought that the ΔT increase mechanism by the difference in Knoop hardness of the first and second solid lubrication coatings is generally as follows.
[0026] As a result of the investigations, the present inventors have revealed that the greater the hardness of a solid lubricating coating, the greater is Ty and, conversely, the lower the hardness, the less is Ts. This is assumed because a solid lubricating coating that has a high hardness and, therefore, a high wear resistance does not readily deform at the time of sliding under a high pressure and does not readily discharge the powder formed by abrasion, thus producing a surface sliding that has a high slip resistance. On the other hand, a solid coating that has a low hardness easily deforms at the time of sliding even under low pressure and wears out easily, so sliding of the sliding surface occurs easily.
[0027] In general, it is known from examples such as deposition of metal (high hardness) and rubber (low hardness) that there is a tendency for a solid lubricating coating that has a high hardness to have a low coefficient of friction and of a solid lubrication coating that has low hardness has a high coefficient of friction. However, the behaviors and effects described above of a solid coating that has a high hardness or a low hardness under a high pressure or a low pressure in a tubular threaded joint cannot be explained only by the magnitude of the friction coefficient. The factor that is closely related to Ts and Ty at the time of fitting a joint is thought to be the magnitude of the internal fracture force of a solid coating during wear rather than the amount of friction (ease of sliding) of the surface the coating.
[0028] Patent Document 4 mentioned above proposes the formation of a high friction lubrication coating and a low friction lubrication coating. However, the friction coefficient of a solid coating is pressure dependent and does not always correlate with the hardness of the coating. In the present invention, the hardness that does not depend on pressure and correlates with the internal fracture force of a solid coating is used to distinguish between the first and the second lubricating coatings.
[0029] The assembly of a tubular threaded joint is carried out by inserting a pin in a box and then rotating the pin or box. Initially, only the threaded portions come into contact to allow the threads to engage in a threaded manner and the mounting torque gradually increases, as shown in Figure 2. In the final assembly stage, the sealing portions and shoulder portions begin to come in in touch. The assembly is completed when the prescribed contact pressure (which is expressed by a prescribed torque such as the ideal torque) in the sealing portions between the pin and the housing is reached.
[0030] According to the present invention, for example, as shown in Figure 5, a tubular threaded joint has a first solid lubricating coating on the sealing portions and shoulder portions of the contact surfaces of a pin and a box and a second solid lubricating coating, which has a lower Knoop hardness than the first solid lubricating coating, on the other portions (primarily the threaded portions) of the contact surfaces. In this threaded joint, before the sealing portions and shoulder portions come into contact, Ts remains low due to the contact that occurs by the second solid lubricating coating that covers the threaded portions and which has a low hardness and a low internal fracture force . In the final stage of assembly, when the sealing portions and shoulder portions begin to come into contact, the first solid lubricating coating that has a higher Knoop hardness than the second solid lubricating coating and that lines these portions participates in contact . Consequently, a state occurs in which the internal fracture force of the coating is high and Ty increases. As a result, ΔT increases. An increase in ΔT due to an increase in Ty can also be achieved when the first hardest solid lubricating coating is formed only on the shoulder portions, which are exposed to a particularly high pressure during assembly.
[0031] The present invention, which is based on the above disclosure, is a tubular threaded joint composed of a pin and a housing that each have a contact surface comprising a threaded portion and an unthreaded metal contact portion which includes a sealing portion and a shoulder portion, characterized by the fact that a first solid lubricating coating is present on a portion that includes the shoulder portion of the contact surface of at least one between the pin and the housing, one second solid lubrication coating is present on at least a portion of the contact surface of at least one of the pin and housing that does not have the first solid lubrication coating, each of the solid lubricating coatings, the first and the second, are formed from an organic resin or an inorganic polymer as a film forming component, the Knoop hardness of the first solid lubrication coating is greater than the Knoop hardness of the second the solid lubricating coating and when a portion exists where both the first and the second solid lubricating coatings are present, the second solid lubricating coating is positioned below the first solid lubricating coating.
[0032] Knoop hardness (abbreviated as Hk) is a type of indentation hardness. As shown by the following equation, it is determined by dividing the test load P by the indentation surface area L2 obtained in an indentation hardness test. Hk = P / Cp / L2
[0033] where, Hk: Knoop hardness. P: load (kgf), Cp: correction factor (0.070279) and L2: indentation surface area (mm2).
[0034] The Knoop hardness value (Hk) changes consecutively according to the hardness, so it is generally used as a quantitative hardness index that can measure the surface hardness of a solid coating with comparatively good sensitivity. A method for measuring Knoop hardness is prescribed by the Knoop hardness test method (JIS B 7734 and JIS Z 2251). For example, it can be measured using a microhardness tester model HMV-200 manufactured with Shimadzu Corporation under conditions of 100 grams for 10 seconds. In the present invention, a Knoop hardness value measured under these conditions is employed.
[0035] The portion of the contact surface that has the first solid lubrication coating described above may be only the shoulder portion, but is preferably the entire non-threaded metal contact portion including the sealing portion and the portion shoulder.
[0036] The second solid lubrication coating can be provided only on the portion of the contact surface that does not have the first solid lubrication coating or can be supplied on the entire contact surface including the portion that has the first solid lubrication coating. In the latter case, there are portions in which both the first solid lubricating coating and the second solid lubricating coating are formed. In this case, the second solid lubrication coating becomes a lower layer and the first solid lubrication coating is made an upper layer.
[0037] The thicknesses of the first and the second solid lubrication coatings are each preferably in the range of 10 to 150 μm. However, in portions that have both the first and the second solid lubrication coatings, the total thickness of the coatings is preferably at most 200 μm.
[0038] When the contact surface of only one between the pin and the housing has the first solid lubrication coating and the second solid lubrication coating, there is no particular limitation on the contact surface of the other member and the same may not be treated (for example, it may be in a state after the preparatory surface treatment described below). However, from the point of view of rust prevention properties and lubrication properties, preferably at least a portion of the contact surface of the other member and preferably the entire contact surface of the other member has any of the treatment coatings following surface formed in it:
[0039] 1) a liquid lubricating coating (including a viscous liquid lubricating coating and a semi-solid lubricating coating);
[0040] 2) a solid lubricating coating (including the first or second solid lubricating coating described above);
[0041] 3) a solid corrosion protection coating; or
[0042] 4) a multilayer coating that combines at least two of the above coatings.
[0043] The solid corrosion protection coating is preferably a solid coating based on a UV-curable resin.
[0044] The contact surface of at least one of, and preferably, both the pin and the box may previously be subjected to surface treatment by one or more methods selected from sandblasting, pickling, chemical phosphate conversion treatment, chemical conversion of oxalate, treatment of chemical conversion of borate, electrodeposition, impact deposition and a combination of them in order to increase the adhesion or retention of the coating formed on top of it and / or increase the resistance to excoriation of the threaded joint.
[0045] A tubular threaded joint according to the present invention has on its contact surface a surface treatment coating that exhibits a large ΔT that is equal to or greater than this of a coating formed of a lubricating grease such as grease conventional compound containing harmful heavy metals. Therefore, it makes it possible to carry out the assembly operations without the occurrence of deformation of the shoulder portions or abrasion even when the assembly is performed with a high torque. Additionally, the coating can suppress abrasion under severe conditions such as unstable drilling operations at sea. In contrast to compound grease, the surface treatment coating contains substantially no harmful heavy metals such as lead, so it imposes almost no burden on the global environment. A tubular threaded joint in accordance with the present invention suppresses the occurrence of rust and continues to exhibit lubrication performance even when assembly and disassembly are repeated while ensuring gas tightness after assembly. BRIEF EXPLANATION OF THE DRAWINGS
[0046] Figure 1 shows schematically the non-threaded metal contact portions (shoulder portions and sealing portions) of a special threaded joint.
[0047] Figure 2 is a typical torque graph of a special threaded joint at the time of assembly.
[0048] Figure 3 shows schematically the installed structure of a steel tube and a coupling when transporting the steel tube.
[0049] Figure 4 shows schematically a cross section of a special threaded joint.
[0050] Figure 5 shows an example of the structure of the linings in a tubular threaded joint according to the present invention.
[0051] Figures 6 (A) and 6 (B) show other examples of the structure of the linings in a tubular threaded joint according to the present invention. WAYS TO CARRY OUT THE INVENTION
[0052] Below, the modalities of a tubular threaded joint according to the present invention will be explained in detail by way of example. In the following explanation, unless otherwise specified, percent means percent by mass.
[0053] Figure 3 schematically shows the state at the time of transport of a typical tubular threaded joint. A pin 1 that has a male threaded portion 3a on its outer surface is formed at both ends of a steel tube A and a box 2 that has a female threaded portion 3b on its inner surface is formed at both ends of a coupling B. Coupling B is previously connected to one end of steel tube A. Although not shown in the drawing, prior to transportation, a protector to protect the threaded portions is mounted on the pin of steel tube A and the housing of coupling B that are not connected to other members. These protectors are removed before using the threaded joint.
[0054] As shown in the drawing, with a typical tubular threaded joint, a pin is formed on the outer surface of both ends of a steel tube and a box is formed on the inner surface of a coupling, which is a separate member. There are also integral tubular threaded joints that do not use a coupling and in which one end of a steel tube is made into a pin and the other end is made into a box. A tubular threaded joint according to the present invention can be applied to both types.
[0055] Figure 4 schematically illustrates the structure of a special threaded joint (referred to below simply as a threaded joint), which is a typical tubular threaded joint used to connect pipes for the oil industry. This threaded joint comprises a pin 1 formed on the outer surface of the end of a steel tube A and a housing 2 formed on the inner surface of a coupling B. The pin 1 has a male threaded portion 3a, a sealing portion 4a positioned nearby the end of the steel tube and a shoulder portion 5a on its end surface. Correspondingly, the housing 2 has a female threaded portion 3b, a sealing portion 4b and a shoulder portion 5b on the inner side of the female threaded portion 3b.
[0056] The sealing portions and shoulder portions of pin 1 and housing 2 constitute the non-threaded metal contact portions and the non-threaded metal contact portions (i.e. the sealing portions and shoulder portions ) and the threaded portions thereof constitute the contact surfaces of the threaded joint. These contact surfaces are required to have abrasion resistance, gas tightness and rust prevention properties. In the past, for this purpose, compound grease containing heavy powdered metals has been applied to contact surfaces or a solid, semi-solid or viscous liquid lubricant coating has been formed on the contact surfaces. However, as stated above, the former has an adverse effect on humans and the environment and the latter has the problem that ΔT is small, so there is the possibility of deformation of shoulder portions before the completion of the assembly when the assembly is performed with a high torque.
[0057] In a threaded joint according to the present invention, at least one of a pin and a housing has a first solid lubrication coating on a portion of the contact surface thereof including at least the shoulder portion and a second coating of solid lubrication on at least a portion of the contact surface that lacks the first solid lubrication coating and the first solid lubrication coating is a coating that has a greater Knoop hardness than the second solid lubrication coating.
[0058] Below, the first solid lubrication coating will be referred to as a high hardness solid lubrication coating and the second solid lubrication coating will be referred to as a low hardness solid lubrication coating.
[0059] However, in locations close to the threaded portions between the threaded portions and the sealing portions of the threaded joint, a portion in which the pin and housing do not come into contact with each other even when the threaded joint is in a state assembly is usually provided with the objective of releasing lubricating components that are forced out when assembling a threaded joint. In some threaded joints, a non-contact region where the pin and housing do not come into contact is intentionally provided, for example, in a location between the sealing portions and the shoulder portions. A portion in which the pin and housing do not come into contact when a threaded joint is in an assembled state is not included in the contact surfaces and a coating according to the present invention may or may not be provided in such a portion.
[0060] The high hardness solid lubrication coating is formed only in a portion that includes the shoulder portion of the contact surface of one of or both the pin and the housing. The portion of the contact surface that has the high hardness solid lubricating coating may be only the shoulder portion, but is preferably the entire non-threaded metal contact portion including the sealing portion and the shoulder portion. That is, the solid lubrication coating of high hardness is preferably formed in the sealing portion and the shoulder portion of the contact surface. The second or low hardness solid lubrication coating is formed at least in the portion of the contact surface that does not have the high hardness solid lubrication coating. It can be formed on the entire contact surface. In that case, a portion of the contact surface has two solid lubricating coatings and the low hardness solid lubricating coating is positioned below the high hardness solid lubricating coating. It is also possible to form the low hardness solid lubricating coating only in the portion where the high hardness solid lubricating coating is not formed (such as only in the threaded portion).
[0061] When a portion of the contact surface of only one between the pin and the housing has the high hardness solid lubrication coating and the low hardness solid lubrication coating, there is no particular limitation in the surface treatment of the hard surface. contact of the other member. For example, the same or a different type of solid lubrication coating as used as the low hardness solid lubricating coating or the high hardness solid lubricating coating formed on the contact surface of one of the members, a lubricating coating liquid, a solid corrosion protection coating or a multilayer coating which is a combination of two or more of them can be formed in at least one portion and, preferably, in the entire contact surface of the other member. A liquid lubrication coating comprises a lubricating oil coating and a viscous or semi-solid lubricating coating. Alternatively, the contact surface of the other member can be left untreated or can be subjected only to the preparatory surface treatment described below for surface roughening (such as chemical phosphate conversion treatment).
[0062] Figure 5 and Figures 6 (A) and 6 (B) show several possible modalities of the coating structures formed on the contact surfaces of a pin and a box. In these figures, among the male threads formed on the threaded portion of the pin 1, the threads 3a 'at the end end adjacent to the sealing portion are shown as an incomplete thread that is seen at the beginning of the thread cut. By making the thread at the end of the pin an incomplete thread, the penetration of the pin becomes easier and the possibility of damaging the threaded portion of the box at the time of penetration of the pin decreases.
[0063] Figure 5 shows a modality in which the non-threaded metal contact portions (the sealing portions and the shoulder portions) of the contact surfaces of both the pin and the housing have a solid lubrication coating of high hardness 10 and the remaining portions of the contact surfaces of the pin and housing which are primarily the threaded portions have a solid lubrication coating of low hardness 11.
[0064] Figure 6 (A) shows an embodiment in which one of the pin and the housing (the pin in the Figure) has a high hardness solid lubrication coating 10 that covers the non-threaded metal contact portion and a coating of low hardness solid lubrication 11 that covers the remaining portion of the contact surface in the same way as in Figure 5 and the entire contact surface of the other member (the box in Figure) is covered by a low hardness solid lubrication coating 11.
[0065] Figure 6 (B) shows a modality in which one of the pin and the housing (the housing in the Figure) has a high hardness solid lubrication coating 10 that covers the non-threaded metal contact portion and a coating of low hardness solid lubrication 11 that covers the rest of the contact surface in the same way as in Figure 5 and the entire contact surface of the other member (the pin in the Figure) is covered by a solid corrosion protection coating 12.
[0066] As is understood by the person skilled in the art, a tubular threaded joint according to the present invention may have combinations of coatings other than those described above. For example, in any of the embodiments shown in Figure 5 and Figures 6 (A) and 6 (B), the low hardness solid lubrication coating 11 can also be present under the high hardness solid lubrication coating 10. Or that is, the non-threaded metal contact portion including the sealing portion and the shoulder portion of the pin and / or housing is covered by two layers consisting of the lower low hardness solid lubrication coating 11 and the solid lubrication coating of higher high hardness 10. In this case, the solid lubricating coating of low hardness 11 can be formed on the entire contact surface, but it is also possible to form this coating 11 on a portion of the contact surface. For example, the low hardness solid lubrication coating 11 can be formed to cover from the threaded portion to the sealing portion, whereby only the sealing portion is covered by the two layers mentioned above 10 and 11 and the portion of The shoulder is covered only by the high hardness solid lubrication coating 10. Furthermore, the high hardness solid lubrication coating 10 can be formed only on the shoulder portion.
[0067] In the following, various types of coatings that can cover the contact surfaces of a tubular threaded joint in accordance with the present invention will be explained. Unless otherwise specified, percent relative to the content of a coating's components means percent by weight. This content is substantially the same as the content based on the total solids content in a coating composition to form the lubrication coating (the total content of non-volatile components). [SOLID LUBRICATION COATINGS OF LOW HARDNESS AND HIGH HARDNESS]
[0068] A high hardness solid lubrication coating is a solid lubrication coating that has a Knoop hardness that is relatively high compared to that of a low hardness solid lubricating coating. It provides slip resistance in the final stage of assembling a threaded joint (from when the shoulder portions of the pin and housing begin to come into contact until the sealing portions come into close contact with a prescribed interference). It has the effect of making it difficult for deformation of the shoulder portions to occur even when the assembly is performed with a high torque.
[0069] The low hardness solid lubrication coating is a solid lubrication coating that has a relatively low Knoop hardness. This facilitates slipping in the initial stage of assembling a threaded joint (from when the pin and housing threads come into contact until the sealing portions of the pin and housing start to come in contact) and has the effect of reducing Ts .
[0070] In the present invention, the high hardness solid lubricating coating that provides the above effect is formed so as to cover a portion of the contact surface that includes at least the shoulder portion of at least one between the pin and the housing . Preferably, the entire non-threaded metal contact portion including the sealing portion and the shoulder portion is covered by the high hardness solid lubrication coating. When a threaded joint has a plurality of sealing portions, the whole of which is preferably covered by the solid, high hardness lubricating coating. However, the goal of increasing the ΔT can be achieved even if only one of the sealing portions that first comes into contact in the final stage of assembling a threaded joint is coated with the high hardness solid lubrication coating. The portion on which the high hardness solid lubricating coating is formed can be properly selected in accordance with the shape of the joint and the required properties.
[0071] A solid lubricating coating that is suitable for use in the present invention is a coating that is formed from an organic resin or an inorganic polymer as a film-forming component (a binder). In addition to a film-forming component, a solid lubricating coating may contain several common additives such as lubricating particles and an anti-corrosion agent (a corrosion resistance modifier). By varying the combination of components or component contents, two types of solid lubricating coatings that have a different Knoop hardness can be formed and these coatings are used as a high hardness solid lubricating coating and a solid lubricating coating of low hardness.
[0072] In order to increase the ΔT of a tubular threaded joint, it is desirable to satisfy the following equation: (high hardness solid lubrication coating Knoop hardness) / (low hardness solid lubrication coating Knoop hardness)> 1 ,1
[0073] This ratio is most preferably at least 1.2 and, with maximum preference, at least 1.5.
[0074] This ratio can be at least 2.0.
[0075] Both high and low hard solid lubrication coatings can be formed by uniformly dispersing as necessary various additives such as lubricating particles in a solution (or dispersion) of a film forming component and adjusting the viscosity as needed to prepare a coating composition, applying the coating composition to the contact surface of at least one of the pin and threaded joint housing and drying the coating. The coating composition can be applied by a suitable known method such as brushing, dipping, spraying or the like.
[0076] The lubricating particles have the effect of improving the lubricating properties of the lubricating coating and increasing the resistance to abrasion. Examples of lubricating particles that have such an effect are carbonates, silicates, oxides, carbides, nitrites, sulfides, fluorides, graphite (including carbon-derived nanoparticles such as carbon nanotubes and carbon onions), PTFE (polytetrafluoroethylene), soap soaps metal and the like. Carbonates include carbonates of an alkali metal and an alkaline earth metal such as Na2CO3, CaCO3, MgCO3 and the like. The silicate includes MxOySiO2 (where M is an alkali metal or alkaline earth metal). Oxides include Al2O3, TiO2, CaO, ZnO, ZrO2, SiO2, Fe2O3, Fe3O4, Y2O3 and the like. Carbides include SiC, TiC and the like, nitrites include TiN, BN, AlN, Si3N4 and the like and the sulfides include molybdenum disulfide, tungsten disulfide, PbS and the like. Fluorides include CaF2, BaF2 and the like. These can be used individually or two or more types can be mixed together for use.
[0077] There is no particular limitation on the particle diameter in the lubricating particles, but typically it is preferably in the range of 0.5 to 60 μm. If it is less than 0.5 μm, the powder particles clump easily and it becomes difficult to uniformly disperse them in a coating layer. As a result, the performance of the resulting lubricant coating may become locally unsuitable. On the other hand, if the particle diameter exceeds 60 μm, not only does the strength of a coating decrease, but its adhesion to a substrate decreases and it is sometimes not possible to suppress the occurrence of abrasion.
[0078] In addition to the lubricating particles, various additives including an anti-corrosion agent can be added to the solid lubrication coating within a range that does not worsen the abrasion resistance. For example, one or more anticorrosive agents selected from powdered zinc, a chromium pigment, silica and an alumina pigment can be added to improve the rust prevention properties of the solid lubrication coating itself. A particularly preferred anticorrosive agent is silica exchanged for calcium ion. The solid lubrication coating may contain an inorganic powder to adjust the sliding properties. Examples of such an inorganic powder are titanium dioxide and bismuth oxide. These anti-corrosion agents, inorganic powders and the like (ie powder components other than lubricating particles) can be contained in a total amount of up to 20% of the solid lubrication coating.
[0079] In addition to the above components, the solid lubrication coating may contain one or more minor additives selected from an active surface agent, a colorant, an antioxidant and the like in an amount of up to 5%, for example. In addition, it may contain an extremely small amount (maximum 2%) of an extreme pressure agent, a liquid lubricant and the like.
[0080] Both an organic resin and an inorganic polymer (also referred to as an inorganic resin) can be used as a binder (a film-forming component).
[0081] A preferred organic resin is one that has heat resistance and an adequate hardness and resistance to wear. Examples of such a resin are thermostable resins such as epoxy resins, polyimide resins, polycarbodiimide resins, phenolic resins, furan resins and silicone resins; and thermoplastic resins such as polyolefins, polystyrenes, polyurethanes, polyamides, polyesters, polycarbonates, acrylic resins, thermoplastic epoxy resins, polyamide-imide resins, poly (ether-ether-ketone) and polyethersulfone. A resin that is used can be a copolymer or a mixture of two or more resins.
[0082] A preferred binder for a high hardness solid lubrication coating is a poly (ether-ether-ketone) resin, a phenolic resin, a furan resin, a polyamide-imide resin or an epoxy resin.
[0083] As a solvent for an organic resin, several low boiling solvents that include water, hydrocarbons (such as toluene), alcohols (such as isopropyl alcohol), NMP (N-methyl pyrrolidone), y-butyrolactone and sulfoxide of dimethyl can be used individually or in the form of a mixed solvent.
[0084] One or more additives can be added to the organic resin solution and are uniformly dispersed in it to prepare a coating composition. When using a thermostable resin as a binder, from the point of view of adhesion and wear resistance of the coating, after the coating composition is applied to a contact surface of the threaded joint, it is preferably heated to cure the coating. The heating temperature is preferably at least 120 ° C and more preferably 150 to 380 ° C. The heating time can be defined based on the size of the tubular threaded joint, but is preferably at least 20 minutes and from most preferably 30 to 60 minutes.
[0085] When the binder is a thermoplastic resin, a coating composition using a solvent can be used. However, it is also possible to form a solid thermoplastic lubricating coating by the hot melt method without using a solvent. In the hot melt method, a coating composition comprising a thermoplastic resin and lubricating particles is heated to melt the thermoplastic resin and a composition that is in a low viscosity fluid state is sprayed from a spray gun that it has an ability to maintain the temperature to maintain a constant temperature (usually around the same temperature as the temperature of the composition in a molten state). The heating temperature of the composition is preferably 10 to 50 ° C higher than the melting point (the melting temperature or the softening temperature) of the thermoplastic resin. This method is suitable for use with a thermoplastic resin that has a melting point of 80 to 320 ° C and preferably 90 to 200 ° C.
[0086] In the hot melt method, the substrate that is coated (ie the contact surface of a pin and / or a box) is preferably preheated to a temperature higher than the melting point of the thermoplastic resin. As a result, good coating capacity can be obtained. When the coating composition contains a small amount (such as a maximum of 2%) of a surface active agent such as polydimethyl siloxane, a good coating can be formed even if the substrate is not preheated or if the preheating temperature is lower than the melting point of the thermoplastic resin. After application, the substrate is cooled by air cooling or natural cooling to solidify the thermoplastic resin, resulting in the formation of a solid lubricating coating on top of the substrate.
[0087] Inorganic polymers that can be used as a binder in the present invention are compounds that have a structure formed from three-dimensionally cross-linked metal-oxygen bonds such as Ti-O, Si-O, Zr-O, Mn bonds -O, Ce-O or Ba-O. Such a compound can be formed by hydrolysis and condensation of a hydrolyzable organometal compound typified by a metal alkoxide (although other hydrolyzable inorganic compounds such as titanium tetrachloride can also be used). Metal alkoxides can be a compound in which the alkoxy group is a lower alkoxy group such as methoxy, ethoxy, isopropoxy, propoxy, isobutoxy, butoxy or tert-butoxy. A preferred metal alkoxide is a silicon or titanium alkoxide and a titanium alkoxide is particularly preferred. Among these, titanium isopropoxide is preferred because of its excellent film forming properties.
[0088] An inorganic polymeric compound may contain an alkyl group which can be replaced by a functional group such as an amine or an epoxy group. For example, an organic compound such as a silane coupling agent in which one or two of the alkoxy groups of a metal alkoxide are replaced by a non-hydrolyzable alkyl group that has a functional group.
[0089] When the binder is an inorganic polymeric compound, a coating composition can be formed by dispersing lubricating particles in a solution of a metal alkoxide or its partial hydrolyzate and is applied to the contact surface of at least one among one pin and a box. After drying, a solid lubricating coating made of an inorganic polymeric compound that has metal-oxygen bonds in which the lubricating particles are dispersed is formed. After application, in order to promote film formation by hydrolysis, humidification treatment can be carried out. This treatment can be performed by leaving the coating for a certain length of time in the air, with the air having a relative humidity of at least 70% being preferred. Heating is preferably carried out after the humidification treatment. As a result of heating, hydrolysis and condensation of hydrolysates and the discharge of alcohol which is a by-product of hydrolysis are promoted, a dry coating can be formed in a short period and the adhesion of the coating that is formed is enhanced, leading to an increase in resistance to abrasion. This heating is preferably carried out after a solvent has been evaporated. The heating temperature is preferably in the range of 100 to 200 ° C which is close to the boiling point of the alcohol which is formed as a by-product and it is effective to blow hot air into the coating during heating.
[0090] In order to form a solid lubricating coating that has a high Knoop hardness, for example, a thermostable resin or an inorganic polymer can be selected as a binder and / or the content of the inorganic solid components and particularly the lubricating particles can be increased.
[0091] In the case where there is no portion in which a low hardness solid lubricating coating and a high hardness solid lubricating coating overlap, as shown in Figure 5 (for example, when a hardness solid lubricating coating low is formed in the threaded portions of the contact surfaces and a solid lubrication coating of high hardness is formed in the sealing portions and in the shoulder portions), any of the solid lubrication coatings can be formed first. In this case, the heating treatment to cure the coatings can be carried out last in a single step. That is, the heat treatment is performed after the application of the coating compositions to form the low hardness solid lubricating coating and the high hardness solid lubricating coating.
[0092] When there is a portion in which a low hardness solid lubricating coating and a high hardness solid lubricating coating overlap (for example, when a low hardness solid lubricating coating is formed on the entire contact surface ), first the low hardness solid lubricating coating is formed and then the high hardness solid lubricating coating is formed so that the low hardness solid lubricating coating becomes a lower layer.
[0093] As stated above, the thickness of each of the low hardness solid lubrication coating and the high hardness solid lubrication coating is preferably in the range of 10 to 150 μm. However, when there is a portion that has these two types of solid lubricating coatings, the total thickness of the two coatings is preferably at most 200 μm. When the two solid lubrication coatings do not overlap, the coating thickness of the high friction solid lubrication coating and the coating thickness of the low friction solid lubrication coating are preferably substantially the same (such as within ± 15 μm ) so that a large step does not form the border between the two types of coatings. [SOLID PROTECTION COATING AGAINST CORROSION]
[0094] As stated above in relation to Figure 4, in a period until a tubular threaded joint is actually used, a protector is often mounted on the pin and housing that are not used for connecting a steel pipe and coupling . It is necessary that a solid corrosion protection coating is not destroyed at least by the force applied when mounting a protector, which does not dissolve when exposed to water resulting from the condensation of water vapor by the action of the dew point during transport or storage and that does not soften readily even at a high temperature that exceeds 40 ° C. Any coating that meets these requirements can be used as a solid corrosion protection coating. For example, a solid corrosion protection coating can be a coating of a thermostable resin that optionally contains an anti-corrosion agent.
[0095] The preferred solid corrosion protection coating is a solid coating based on a UV-curable resin. The useful UV-curable resin system comprises at least one monomer, an oligomer and a photopolymerization initiator.
[0096] Some non-limiting examples of monomers include polyvalent esters (di, tri or valiant) of polyhydric alcohols with (meth) acrylic acid, various (meth) acrylate compounds, N-vinylpyrrolidone, N-vinylcaprolactam and styrene. Some non-limiting examples of oligomers include epoxy (meth) acrylates, urethane (meth) acrylates, polyester (meth) acrylates, polyether (meth) acrylates and silicone (meth) acrylates.
[0097] Useful photopolymerization initiators are compounds that have absorption at a wavelength of 260 to 450 nm, examples of which are benzoin and its derivatives, benzophenone and its derivatives, acetophenone and its derivatives, Michler's ketone, benzyl and its derivatives, tetraalkylthiuram monosulfide and thioxanes. It is particularly preferred to use thioxanes.
[0098] From the point of view of sliding properties and coating strength, a solid corrosion protection coating formed from a UV-curable resin can contain additives selected from lubricants, fibrous fillers and anti-corrosion agents. Examples of a lubricant are metal soaps such as calcium stearate and zinc stearate and polytetrafluoroethylene resin (PTFE). An example of a fibrous filler is acicular calcium carbonate such as Whiskal sold with Maruo Calcium Co., Ltd. One or more of these additives can be added in an amount of 0.05 to 0.35 part by weight with respect to one mass part of the UV curable resin. Examples of an anti-corrosion agent are aluminum tripolyphosphate and aluminum phosphite. An anti-corrosion agent can be added in a maximum amount of about 0.10 part by weight with respect to a part by mass of the UV-curable resin.
[0099] A solid corrosion protection coating formed from an anti-corrosion agent is often transparent. In order to facilitate quality inspection by visual inspection or image processing of the solid corrosion protection coating that is formed (inspecting whether or not there is a coating and inspecting the uniformity of uneven coating thickness), the solid protective coating against corrosion may contain a colorant. The dye that is used can be selected from pigments, dyes and fluorescent materials.
[00100] The amount of a pigment or dye that is added is preferably no more than 0.05 part in proportion to a part by mass of the UV-curable resin.
[0101] A fluorescent material can be any fluorescent pigments, fluorescent dyes and phosphorus used in fluorescent inks. A solid corrosion protection coating that contains a fluorescent material is transparent with or without color under visible light, but when it is irradiated with a black or ultraviolet light and develops a color, then it is possible to check for a coating and for unevenness coating thickness. Additionally, since the coating is transparent under visible light, it is possible to observe the substrate, that is, the surface of the substrate under the solid lubrication coating. Consequently, the solid corrosion protection coating does not interfere with the inspection of a threaded portion of a threaded joint for damage. The amount of the fluorescent material that is added is preferably about 0.05 parts at most in relation to a mass part of the UV-curable resin.
[0102] A preferred colorant is a fluorescent material and a fluorescent pigment is particularly preferred.
[0103] After a composition based on a UV-curable resin is applied to a contact surface of a threaded joint, the applied surface is irradiated with ultraviolet light to cure the coating, resulting in the formation of a solid corrosion protection coating based on a UV curable resin. Irradiation with ultraviolet light can be performed using a commercially available UV irradiation device that has an output wavelength in the range of 200 to 450 nm. Examples of a UV light source are high pressure mercury vapor lamps, ultra high pressure mercury vapor lamps, xenon lamps, carbon arc lamps, metal halide lamps and sunlight.
[0104] The thickness of the solid corrosion protection coating (the total thickness when it comprises two or more layers of UV-curable resin) is preferably in the range of 5 to 50 μm and most preferably in the range of 10 at 40 μm. If the thickness of the solid corrosion protection coating is very small, it does not function sufficiently as a corrosion protection coating. On the other hand, if the coating thickness of the solid corrosion protection coating is too large, when a protective member is fitted, the solid corrosion protection coating can be damaged by the force used to mount the protector, thus causing the corrosion resistance becomes inadequate.
[0105] A solid corrosion protection coating based on a UV curable resin is a transparent coating, so that the condition of the substrate can be observed without removing the coating and it is possible to inspect the threaded portions from above the coating before assembly. Consequently, by forming the solid corrosion protection coating on the contact surface of a pin that has threads formed on its outer surface and that is more easily damaged, it is possible to easily inspect for damage to the threaded portion of the pin that is easily damaged already that it is typically formed on the outer surface of the end of a steel tube by leaving the liner in place.
[0106] For this reason, such a solid corrosion protection coating is preferably formed on the contact surface of a pin, and the solid lubrication coatings of low hardness and high hardness described above are formed, preferably on the surface of contact of a box.
[0107] As is the case described above in relation to the solid lubrication coating, the solid corrosion protection coating is preferably applied by the spray coating. The spray coating includes hot melt coating. [PREPARATORY SURFACE TREATMENT]
[0108] If the contact surfaces of a tubular threaded joint according to the present invention in which a solid hard lubricating coating and a solid hard lubricating coating or, in some cases, a solid protective coating against corrosion must be formed are subjected to the preparatory surface treatment for surface roughening in order to increase the surface roughness of 3 to 5 μm which is the surface roughness after machining, the coating adhesion increases and there is a tendency that the effects that are the purpose of the coating are enhanced. Consequently, the preparatory surface treatment of a contact surface is preferably carried out to roughen the surface before forming the coatings.
[0109] When forming a coating on top of a contact surface that has a large surface roughness, the coating thickness is preferably greater than Rmax of the roughened contact surface in order to completely cover the contact surface . The coating thickness when the contact surface is rough is the average value of the coating thickness for the entire coating that can be calculated from the area, mass and density of the coating.
[0110] Examples of preparatory surface treatment for surface roughening are blasting treatment by projecting a blasting material such as granules that have a spherical shape or gravels that have an angular shape, pickling by immersion in a strongly solution acid such as a solution of sulfuric acid, hydrochloric acid, nitric or hydrofluoric acid to roughen the skin, chemical conversion treatment such as phosphate treatment, oxalate treatment and borate treatment (such as precipitated crystals that typically have acicular growth , the roughness of the crystalline surface increases), electrodeposition with a metal such as Cu, Fe, Sn or Zn or an alloy of these metals (the surface may become a little rougher due to the preferential deposition of projections) and impact deposition that can form a porous deposited coating. As an example of electrodeposition, the deposition of composite that forms a deposited coating that has small solid particles dispersed in the metal has small solid particles that protrude from the deposited coating, so it can be used as a method to transmit roughness of surface. Two or more types of preparatory surface treatment can be used in combination. Treatment can be carried out in accordance with known methods.
[0111] Regardless of which method is used for the preparatory surface treatment of a contact surface, the surface roughness Rmax after the surface roughness by the preparatory surface treatment is preferably 5 to 40 μm. If Rmax is less than 5 μm, adhesion and retention of the lubricating coating is sometimes inadequate. On the other hand, if Rmax exceeds 40 μm, friction increases, the lubricating coating cannot resist shear forces and compressive forces when it is subjected to high pressure and becomes easier than damage to the coating or peeling coating occurs.
[0112] From the point of view of adhesion of the lubricating coating, the preparatory surface treatment that can form a porous coating, that is, chemical conversion treatment and impact deposition are preferred. In that case, in order to make Rmax of a porous coating at least 5 μm, the coating thickness is preferably made at least 5 μm. There is no particular upper limit on the coating thickness, but normally it is at most 50 μm and preferably it is at most 40 μm, which is appropriate. By forming a lubricating coating on top of a porous coating that is formed by preparatory surface treatment, the adhesion of the lubricating coating is increased by the so-called anchor effect. As a result, it becomes difficult for the flaking of the solid lubrication coating to occur even when assembly and disassembly are repeated and metal-to-metal direct contact is effectively prevented, leading to further improvement in abrasion resistance, gas tightness and corrosion prevention properties.
[0113] The particularly preferential preparatory surface treatment to form a porous coating is the chemical phosphate conversion treatment (treatment with manganese phosphate, zinc phosphate, ferro-manganese phosphate or zinc-calcium phosphate) and the formation of a zinc or zinc-iron alloy coating by impact deposition. From the point of view of adhesion, a coating of manganese phosphate is preferable and from the point of view of corrosion prevention, a coating of zinc or zinc-iron alloy, which should provide a prevention effect of sacrificial corrosion by zinc.
[0114] Chemical phosphate conversion treatment can be carried out by immersion or spraying in a conventional manner. A typical acid phosphating solution used for zinc deposited materials can be used as a chemical conversion treatment solution. For example, a zinc phosphating solution that contains 1 to 150 g / l of phosphate ions, 3 to 70 g / l of zinc ions, 1 to 100 g / l of nitrate ions and 0 to 30 g / l of nickel ions can be used. A manganese phosphating solution commonly used for a threaded joint can also be used. The temperature of the solution is from room temperature to 100 ° C and the treatment time can be up to 15 minutes in accordance with the desired coating thickness. In order to promote the formation of a coating, it is possible to supply an aqueous surface modification solution containing colloidal titanium to the surface being treated before the phosphate treatment. After the phosphate treatment, washing with hot water or wound followed by drying is preferably carried out.
[0115] Impact deposition can be performed by mechanical deposition in which the particles and a material to be deposited are impacted with each other within a rotating barrel or by sandblasting in which the particles are impacted against a material to be deposited with the use of a blasting device. In the present invention, it is sufficient to perform the deposition only of the contact surfaces, so it is preferable to employ the sandblasting deposition which has the localized deposition capacity. From the point of view of preventing corrosion and adhesion, the thickness of a layer of zinc and zinc alloy formed by impact deposition is preferably 5 to 40 μm.
[0116] Jet deposition is carried out, for example, by blasting a jet material in the form of particles that have an iron-based core with its zinc-coated surface or a zinc alloy against a contact surface to be coated. The content of zinc or a zinc alloy in the particles is preferably in the range of 20 to 60%, and the diameter of the particles is preferably in the range of 0.2 to 1.5 mm. As a result of the condensation, only the zinc or zinc alloy which is the coating layer of the particles adheres to the contact surface which is a substrate, and the porous coating is made of zinc or the zinc alloy is formed on top of the contact surface. Jet deposition can form a porous metal coating that has good adhesion to a steel surface regardless of the type of steel.
[0117] Like another type of preparatory surface treatment, although it has almost no effect on roughening the surface, specific electroplating to form a single layer or multiple layers can increase the adhesion between a lubricant coating and the substrate, leading to improvement in the resistance to abrasion of a tubular threaded joint.
[0118] Examples of such a preparatory surface treatment for a lubrication coating are electrodeposition with metals, such as Cu, Sn, and Ni or alloys thereof. The deposition can be single layer deposition or multiple layer deposition with two or more layers. Specific examples of this type of electrodeposition are Cu deposition, Sn deposition, Ni deposition, Cu-Sn alloy deposition, Cu-Sn-Zn alloy deposition, two-layer deposition with Cu deposition and Sn deposition , and deposition of three layers with deposition of Ni, deposition of Cu and deposition of Sn. In particular, when a tubular threaded joint is made of steel that has a Cr content that exceeds 5%, abrasion occurs extremely easily. In this case, it is preferable to perform preparatory surface treatment by single-layer deposition with a Cu-Sn alloy or a Cu-Sn-Zn alloy or multilayer metal deposition with two or more layers selected from these alloy and deposition depositions. Cu deposition, Sn deposition and Ni deposition such as deposition of two layers with deposition of Cu and deposition of Sn, deposition of two layers with deposition of Ni and deposition of Sn, deposition of two layers with deposition of Ni and deposition of alloy Cu-Sn-Zn, and deposition of three layers with deposition of Ni, deposition of Cu and deposition of Sn.
[0119] These types of deposition can be formed by the methods presented in JP 2003-74763 A. In the case of multilayer deposition, the lower deposition layer (normally Ni deposition), which is referred to as collision deposition, is preferably an extremely thin deposition layer that has a thickness of at most 1 μm. The deposition thickness (the total thickness in the case of multiple layer deposition) is preferably in the range of 5 to 15 μm.
[0120] As another type of preparatory surface treatment, it is possible to form a solid corrosion protection coating EXAMPLES
[0121] The effects of the present invention will be illustrated by the following examples and comparative examples. In the following description, the contact surface of a pin that includes the threaded portion and the non-threaded metal contact portion will be referred to as the pin surface and the contact surface of a housing that includes the threaded portion and the Non-threaded metal contact will be referred to as the housing surface. The surface roughness is Rmax. Unless otherwise specified, percent means percent by mass.
[0122] The pin surface and the housing surface of a special VAMTOP threaded joint (17.78 cm (7 inch) outside diameter, 1.036 cm (0.408 inch) wall thickness) made of carbon steel that has the composition shown in Table 1 were subjected to the preparatory surface treatment shown in Table 2. Therefore, a high hardness solid lubrication coating and a low hardness solid lubrication coating and, in some cases, a solid corrosion protection coating as per shown in Tables 3 and 4 were formed on the pin surface and the box surface.
[0123] The treatment and coating compositions will be described in detail below. In Table 4, the non-threaded metal contact portion means the sealing portion and the shoulder portion and the threaded portion means the portion of the contact surface other than the sealing portion and the shoulder portion. When different coatings were formed on the non-threaded metal contact portion and the threaded portion, a solid lubrication coating was first formed on the non-threaded metal contact portion and then a separate solid lubrication coating was formed on the threaded portion. When forming a solid lubricating coating on the threaded portion, the coating was carried out using a shielding plate so that the lubricating coating was not formed on top of the solid lubricating coating formed previously on the non-contact metal portion threaded. However, the edge between these two coatings need not be clear and the effect of the present invention can be obtained even if there is an overlapping region of about 1 mm at the edge.
[0124] The Knoop Hk hardness of each solid lubrication coating was measured with a microhardness tester model HMV-200 manufactured with Shimadzu Corporation under conditions of 100 g for 10 seconds using a test piece that has a coating of solid lubrication formed in the same way on a steel plate made of the same material.
[0125] A high torque assembly test in which the assembly was performed with a high assembly torque was performed on tubular threaded joints that were prepared in the above manner to prepare a torque graph like the one shown in Figure 2 and Ts (torque mooring), Ty (deformation torque) and ΔT (= Ty - Ts, torque at shoulder resistance) were measured in the torque graph.
[0126] Ts was the torque when the shoulder portions started to interfere. Specifically, the torque when the change in torque after the interfered shoulder portions started to enter the linear region (region of elastic deformation) was made Ts. Ty was the torque at the beginning of the plastic deformation. Specifically, the torque after Ts was reached and when the variation in torque with the rotation started to lose linearity of the linear region it was made Ty. The relative values of ΔT (= Ty - Ts) when ΔT for Comparative Example 1 in Table 3, in which the conventional compound grease was used, a value of 100 was designated are shown in Table 5.
[0127] A repeated assembly and disassembly test was performed on each tubular threaded joint to assess abrasion resistance. In the repeated assembly and disassembly test, the assembly of a threaded joint was performed at an assembly speed of 10 rpm with an assembly torque of 20 kN-m and, after disassembly, the status of the pin surface and box surface was investigated. When seizure risks produced by the assembly were light and the assembly was possible again after the repair was carried out, the repair was carried out and the assembly and disassembly continued. The assembly was performed 10 times. TABLE 1
TABLE 2
A: surface roughness (μm), t: coating thickness (μm) Note: The preparatory surface treatment for the box in Example 2 was the same as the above preparatory surface treatment for the pin except that zinc phosphating was replaced by manganese phosphating.

EXAMPLE 1
[0128] The following preparatory surface treatment and coating formation were carried out on the pin surface and on the housing surface of a special threaded joint made of carbon steel that has the composition shown in Table 1 to form the coatings that have the structure shown in Figure 5. [BOX SURFACE]
[0129] The box surface was finished by machine grinding (3 μm surface roughness) and was then subjected to deposition by Ni bath followed by deposition of Cu-Sn-Zn alloy (Cu: 56%, Sn: 36%, a remainder of Zn, the same applies below) both performed by electrodeposition to obtain deposited coatings that have an overall thickness of 5 μm. The surface roughness after this preparatory surface treatment was 2 μm.
[0130] On the box surface that has undergone the preparatory surface treatment, the solid lubrication coating 1 shown in Table 3 (a coating of a poly (ether-ether-ketone) resin (PEEK) containing PTFE added as lubricating particles , Knoop Hk hardness of 80, coating thickness of approximately 20 μm) was formed in the non-threaded metal contact portion (the sealing portion and the shoulder portion) and then the solid lubricating coating 3 shown in Table 3 (a fluoroplastic coating with a Knoop Hk hardness of 35 and a coating thickness of approximately 20 μm) was formed on the threaded portion (the portion other than the sealing portion and the shoulder portion). [PIN SURFACE]
[0131] The pin surface was finished by machine grinding (3 μm surface roughness) and was then subjected to chemical phosphate conversion treatment by immersion for 6 minutes in a 75 to 85 zinc phosphating solution ° C to form a zinc phosphate coating (surface roughness of 10 μm) that has a thickness of 12 μm.
[0132] The pin surface that underwent this preparatory surface treatment was subjected to coating formation in the same way as for the box surface. That is, the solid lubrication coating 1 was formed on the non-threaded metal contact portions and the solid lubrication coating 3 was formed on the threaded portion. Each coating was the same thickness as the box surface.
[0133] As can be seen from Table 5, the value of ΔT in a high torque test was such that the ratio of ΔT when ΔT for Comparative Example 1 was assigned a value of 100 (referred to below as the ratio of ΔT ) was 135%. The ΔT ratio has been increased significantly compared to a ΔT ratio of 48% for Comparative Example 2 in which solid lubrication coatings formed on the seal portions and shoulder portions of the pin and case surfaces and the lubrication coatings solids formed on the threaded portions of the pin and housing surfaces were opposed to those in Example 1.
[0134] In addition, ΔT in Example 1 was increased by 35% compared to ΔT for the compound grease (Comparative Example 1), which was used as a standard since it is known that it exhibits a satisfactory value of ΔT. This verified that the threaded joint of Example 1 could be made with a high torque without the deformation of the shoulder portions occurring. In the assembly and disassembly test, assembly and disassembly could be carried out 10 times without the occurrence of abrasion. EXAMPLE 2
[0135] The preparatory surface treatment and coating formation described below were performed on the pin surface and on the housing surface of a special threaded joint made of carbon steel that has the composition shown in Table 1 to form the coatings that have the structure shown in Figure 6 (A). [BOX SURFACE]
[0136] The box surface was finished by machine grinding (3 μm surface roughness) and was subjected to the preparatory surface treatment by immersion for 20 minutes in a solution of manganese phosphating at 90 to 95 ° C to form a manganese phosphate coating (surface roughness of 14 μm) which is 18 μm thick.
[0137] On the entire box surface that underwent this preparatory surface treatment, the solid lubricating coating 3 (fluoroplastic with a Knoop Hk hardness of 35 and a coating thickness of approximately 20 μm) was formed. [PIN SURFACE]
[0138] The pin surface underwent exactly the same preparatory surface treatment and coating formation as the pin surface of Example 1. The Knoop hardness and coating thickness were exactly the same as for Example 1.
[0139] As shown in Table 5, the ratio of ΔT in a high torque test was 116%. Thus, ΔT for Example 2 was increased by 16% compared to ΔT for compound grease (Comparative Example 1), which served as a standard. That is, it was verified that the threaded joint of Example 1 could be made with a high torque without the occurrence of deformation of the shoulder portions. In the assembly and disassembly test, assembly and disassembly could be carried out 10 times without the occurrence of abrasion. EXAMPLE 3
[0140] The preparatory surface treatment and coating formation described below were performed on the pin surface and on the housing surface of a special threaded joint made of carbon steel that has the composition shown in Table 1 to form the coatings that have the structure shown in Figure 6 (B). [BOX SURFACE]
[0141] The preparatory surface treatment of the box surface was carried out in the same way as for the box surface in Example 1 (grinding and then deposition by Ni bath followed by deposition of Cu-Sn-Zn alloy). On the box surface that underwent preparatory surface treatment, the solid lubrication coating 2 shown in Table 3 (a coating of a polyamide-imide resin (PAI) and a fluoroplastic containing PTFE and MoS2 as lubricating particles, Knoop Hk hardness 62, coating thickness of approximately 22μm) was first formed in the non-threaded metal contact portion and then the solid lubrication coating 4 shown in Table 3 (a coating of an epoxy resin that contains graphite as lubricating particles, hardness Knoop Hk of 48, coating thickness of approximately 22 μm) was formed in the threaded portion. [PIN SURFACE]
[0142] The preparatory surface treatment of the pin surface was carried out in the same way as for the pin surface in Example 1 (grinding and then zinc phosphating). A solid corrosion protection coating based on a UV curable resin was formed as follows on the entire pin surface that underwent preparatory surface treatment.
[0143] The coating composition that was used was prepared by adding aluminum phosphite as an anti-corrosion agent and a polyethylene wax as a lubricant for a commercially available epoxy acrylic resin-based curable paint (solvent-free type) with Chugoku Marine Paints, Ltd. (which contains 94% of a resin, 5% of an anti-corrosion agent and 1% of a lubricant based on the total solids content). This coating composition was sprayed onto the entire pin surface and then irradiated with ultraviolet light (260 nm wavelength) from an air-cooled mercury vapor lamp with an output of 4 kW to cure the coating . The coating that was formed was 25 μm thick and was colorless and transparent, so that the male threaded portion could be seen with the naked eye or with a magnifying glass over the coating.
[0144] In the high torque test, the ΔT ratio was 110%. There was also a distinct effect of increasing the ratio of ΔT compared to Comparative Example 3 in which the solid lubricating coating formed on the sealing portion and the shoulder portion and the solid lubricating coating on the threaded portion of the housing surface was opposed to Example 3. The ratio of ΔT was also large compared to Comparative Example 1 which uses conventional compound grease. In the assembly and disassembly test, assembly and disassembly could be carried out 10 times without any problems. COMPARATIVE EXAMPLE 1
[0145] The preparatory surface treatment and lubrication treatment below were carried out on the pin surface and on the housing surface of a special threaded joint made of carbon steel that has the composition shown in Table 1. [BOX SURFACE]
[0146] The preparatory surface treatment of the box surface was carried out in the same way as for the box surface in Example 1 (grinding and then deposition by Ni bath followed by deposition of Cu-Sn-Zn alloy). A viscous liquid lubricating compound grease in accordance with API BUL 5A2 was applied to the entire box surface that underwent the preparatory surface treatment to form a lubricating coating. The total coated weight of the compound grease on the pin surface and on the box surface was 50g. The total coated area was approximately 1,400 cm2. [PIN SURFACE]
[0147] The preparatory surface treatment of the pin surface was carried out in the same way as for the pin surface in Example 1 (grinding and then zinc phosphating). The composite grease was applied to the entire pin surface that underwent the preparatory surface treatment.
[0148] In the assembly and disassembly test, in 10 assembly and disassembly cycles, there was no occurrence of abrasion through the tenth cycle. However, compound grease contains heavy metals such as lead, so it is harmful to humans and the environment.
[0149] In the high torque test, the joint had a high Ty so that the shoulder portions did not suffer deformation even when the assembly had been performed with a high torque and it exhibited a large ΔT. ΔT for this example was assigned a value of 100 and was used to calculate the ratio of ΔT. COMPARATIVE EXAMPLE 2
[0150] The preparatory surface treatment and coating formation described below were performed on the pin surface and on the housing surface of a special threaded joint made of carbon steel that has the composition shown in Table 1 to form the coatings that have the structure shown in Figure 5. However, the solid lubrication coating on the non-threaded metal contact portion and on the threaded portion were formed to be the opposite of Example 1. That is, a low hardness solid lubrication coating was formed in the non-threaded metal contact portions and a solid lubrication coating of high hardness was formed in the threaded portions. [BOX SURFACE]
[0151] The preparatory surface treatment of the box surface was carried out in the same way as for the box surface in Example 1 (grinding and then deposition by Ni bath followed by deposition of Cu-Sn-Zn alloy). On the box surface that underwent preparatory surface treatment, the solid lubricating coating 3 in Table 3 (a fluoroplastic coating with a Knoop Hk hardness of 35 and a coating thickness of approximately 20 μm) was first formed in the contact portion of non-threaded metal and then the solid lubrication coating 1 shown in Table 3 (a coating of a poly (ether-ether-ketone) resin (PEEK) containing PTFE added as lubricating particles, Knoop Hk hardness 80, thickness coating of approximately 20 μm) was formed in the threaded portion. [PIN SURFACE]
[0152] The preparatory surface treatment of the pin surface was carried out in the same way as for the pin surface in Example 1 (grinding and then zinc phosphating). The same coating formation as for the box surface was performed on the pin surface that underwent the preparatory surface treatment. That is, the solid lubrication coating 3 was formed on the non-threaded metal contact portion and the solid lubrication coating 1 was formed on the threaded portion. The coating thickness of each coating was the same as for the box surface.
[0153] In the assembly and disassembly test, there was no occurrence of abrasion in 10 assembly and disassembly cycles. However, in the high torque test, the ΔT ratio was an extremely low value of 48% compared to conventional composite grease (Comparative Example 1). That is, it was again confirmed that the ratio of ΔT increases significantly if a solid lubrication coating of low hardness is formed in the sealing portions and shoulder portions and a solid lubrication coating of high hardness is formed in the threaded portions. COMPARATIVE EXAMPLE 3
[0154] The following preparatory surface treatment and coating formation were carried out on the pin surface and on the housing surface of a special threaded joint made of carbon steel that has the composition shown in Table 1 to form the coatings that have the structure shown in Figure 6 (B). However, solid lubrication coatings were formed on the non-threaded metal contact portion and on the threaded portion of the housing surface so as to be the opposite of Example 3. That is, a solid, low hardness lubricating coating was formed on the portion of non-threaded metal contact and a solid lubrication coating of high hardness was formed on the threaded portion of the housing surface. [BOX SURFACE]
[0155] The preparatory surface treatment of the box surface was carried out in the same way as for the box surface in Example 1 (grinding and then deposition by Ni bath followed by deposition of Cu-Sn-Zn alloy). On the box surface that underwent preparatory surface treatment, the solid lubrication coating 4 shown in Table 3 (a coating of an epoxy resin containing graphite as lubricating particles, Knoop Hk hardness of 62, coating thickness of approximately 22 μm) was first formed in the non-threaded metal contact portion and then the solid lubrication coating 2 shown in Table 3 (a coating of a polyamide-imide resin and a fluoroplastic containing PTFE and MoS2 as lubricating particles, Knoop Hk hardness 62, coating thickness of approximately 22 μm) was formed in the threaded portion. [PIN SURFACE]
[0156] The pin surface has undergone preparatory surface treatment and the formation of a UV-cured solid corrosion protection coating in exactly the same way as for the pin surface of Example 3.
[0157] In the assembly and disassembly test, there was no occurrence of abrasion in 10 assembly and disassembly cycles. However, in the high torque test, the ΔT ratio was a low value of 74% compared to Comparative Example 1 in which conventional composite grease was used. Additionally, it can be seen that the ratio of ΔT was 36% less than in Comparative Example 3 in which the solid lubrication coating formed on the sealing portion and the shoulder portion and the solid lubrication coating formed on the threaded portion of the box were the opposite.
[0158] As described above, it has been found that if the Knoop hardness of a solid lubrication coating formed on the seal portion and the shoulder portion is greater than the Knoop hardness of a solid lubrication coating formed on the threaded portion in accordance with the present invention, the ratio of ΔT increases. Due to the ΔT being high, it is possible to perform assembly operations without the occurrence of deformation of the shoulder portions or abrasion even at the time of assembly with a high torque.
[0159] In order to investigate the rust prevention properties of the tubular threaded joints manufactured in Examples 1 to 3, the same preparatory surface treatment as shown for the box in Table 2 and the formation of the lubrication coatings shown for the box in the Table 3 were performed on coupon test pieces prepared separately (70 mm x 150 mm x 1.0 mm thick). The test pieces were subjected to a salt water spray test (in accordance with JIS Z 2371, which corresponds to ISO 9227, temperature of 35 ° C and length of 1,000 hours) and a humidity test (in accordance with JIS K 5600-7-2, in accordance with ISO 6270, temperature 50 ° C, relative humidity 98%, length 200 hours) to investigate the occurrence of rust. As a result, it was confirmed that there was no rust occurrence in both tests for the tubular threaded joints of Examples 1 to 3.
[0160] When a tubular threaded joint prepared in each of Examples 1 to 3 was tested by a gas tightness test and an actual use test on a real drilling rig, each exhibited satisfactory properties. ΔT was higher than for a conventional composite grease, so it was found that the assembly can be performed in a stable manner with a high assembly torque.
[0161] The present invention has been explained above in relation to the modalities that are currently considered preferable, but the present invention is not limited to the modalities described above. It is possible to make modifications within the range disclosed in the attached claims.

权利要求:
Claims (7)
[0001]
1. Tubular threaded joint made up of a pin (1) and a housing (2) that each have a contact surface comprising a threaded portion (3a, 3b) and a non-threaded metal contact portion that includes a sealing portion (4a, 4b) and a shoulder portion (5a, 5b), CHARACTERIZED by the fact that a first solid lubricating coating (10) is present in a portion including the shoulder portion (5a, 5b) of the contact surface of at least one between the pin (1) and the housing (2), a second solid lubrication coating (11) is present on at least a portion of the contact surface of the at least one of the pin (1) and the box (2) not having the first solid lubrication coating (10), each of the first and the second solid lubrication coatings (10, 11) is formed from an organic resin or an inorganic polymer as a component of film formation, the Knoop hardness of the first solid lubrication coating (10) being less than the Knoop hardness of the second solid lubrication coating (11) and, when a portion exists where both the first and the second solid lubricating coatings (10, 11) are present, the second solid lubricating coating (11 ) is positioned below the first solid lubrication coating (10).
[0002]
2. Tubular threaded joint, according to claim 1, CHARACTERIZED by the fact that the portion that includes the shoulder portion (5a, 5b) of the contact surface is the non-threaded metal contact portion of the contact surface.
[0003]
3. Tubular threaded joint, according to claim 2, CHARACTERIZED by the fact that the non-threaded metal contact portion of at least one between the pin (1) and the housing (2) has the first solid lubrication coating ( 10), and the threaded portion (3a, 3b) of the at least one between the pin (1) and the housing (2) has the second solid lubrication coating (11).
[0004]
4. Tubular threaded joint, according to claim 1, CHARACTERIZED by the fact that the contact surface of one between the pin (1) and the housing (2) has the first solid lubrication coating (10) in a portion of the same that includes the shoulder portion (5a, 5b), and the second solid lubrication coating (11) in at least a portion of it that does not have the first solid lubrication coating (10) and the contact surface of the other among the pin (1) and the housing (2) have a solid corrosion protection coating (12).
[0005]
5. Tubular threaded joint, according to claim 4, CHARACTERIZED by the fact that the solid corrosion protection coating (12) is a UV-curable resin-based coating.
[0006]
6. Tubular threaded joint according to any one of claims 1 to 5, CHARACTERIZED by the fact that the ratio between the Knoop hardness of the first solid lubricating coating (10) and the Knoop hardness of the second solid lubricating coating (11) is at least 1.1.
[0007]
7. Tubular threaded joint, according to any one of claims 1 to 6, CHARACTERIZED by the fact that the contact surface of at least one between the pin (1) and the housing (2) has undergone surface treatment by a selected method among blasting, pickling, chemical phosphate conversion treatment, chemical oxalate conversion treatment, borate chemical conversion treatment, electrodeposition, impact deposition and two or more of these methods before coating formation.

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同族专利:

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公开号 | 公开日

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IN2014DN09878A|2015-08-07|

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AU2013264676B2|2015-08-13|

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PL2852785T3|2020-02-28|

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WO2013176281A1|2013-11-28|

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CA2872848A1|2013-11-28|

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US20150192229A1|2015-07-09|

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EP2852785A4|2016-01-13|

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BR112014027366A2|2017-06-27|

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EA201492191A1|2015-04-30|

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JP2015506445A|2015-03-02|

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US10012332B2|2018-07-03|

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AR091132A1|2015-01-14|

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UA110685C2|2016-01-25|

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MX2014014207A|2015-06-04|

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EP2852785B1|2019-08-14|

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CN104334951A|2015-02-04|

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CA2872848C|2016-11-15|

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CN104334951B|2016-01-20|

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EP2852785A1|2015-04-01|

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JP5677635B1|2015-02-25|

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EA026646B1|2017-04-28|

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AU2013264676A1|2014-11-13|

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MX370934B|2020-01-09|

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法律状态:
2018-12-04| B06F| Objections, documents and/or translations needed after an examination request according art. 34 industrial property law|

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2019-07-09| B06T| Formal requirements before examination|

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2019-09-03| B25D| Requested change of name of applicant approved|Owner name: VALLOUREC OIL AND GAS FRANCE (FR) ; NIPPON STEEL C Owner name: VALLOUREC OIL AND GAS FRANCE (FR) ; NIPPON STEEL CORPORATION (JP) |

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2020-05-26| B06A| Notification to applicant to reply to the report for non-patentability or inadequacy of the application according art. 36 industrial patent law|

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2020-09-08| B09A| Decision: intention to grant|

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2020-12-15| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 21/05/2013, OBSERVADAS AS CONDICOES LEGAIS. |

优先权:

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申请号 | 申请日 | 专利标题

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JP2012117550|2012-05-23|

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JP2012-117550|2012-05-23|

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PCT/JP2013/064558|WO2013176281A1|2012-05-23|2013-05-21|Tubular threaded joint having improved high-torque makeup properties|

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