Stainless steel corrosion-proof sucker rod

Abstract

This utility model discloses a stainless steel corrosion-resistant sucker rod, belonging to the technical field of sucker rods. The stainless steel corrosion-resistant sucker rod includes a rod body. From the outside to the inside, the end of the rod body is sequentially provided with an external thread, a transition groove, and a thickened shoulder. The two ends of the rod body are symmetrically arranged, and the two rod bodies are connected by a coupling. A clamp is detachably connected between the coupling and the thickened shoulder. This utility model, through the clamp, can limit the movement between the coupling and the thickened shoulder, distributing the force borne by the threaded portion when generating tensile and thrust forces, thereby better protecting the threaded structure, improving service life, reducing maintenance costs, and preventing the rod body and coupling from disengaging. This solves the problem of thread seizure in existing stainless steel sucker rods.

Description

Technical Field

[0001] This utility model relates to the field of sucker rods, and more particularly to a stainless steel corrosion-resistant sucker rod. Background Technology

[0002] The sucker rod is the core component of a pumping well. It is connected into a rod string by couplings. The upper end is connected to the pumping unit or screw pump motor, and the lower end is connected to the pump plunger. Its main function is to transmit power.

[0003] In practical applications, sucker rods need to have a certain degree of corrosion resistance to resist corrosion from downhole fluids (oil, water, sulfur-containing gases, etc.). Existing sucker rods are generally made of carbon steel or alloy steel and then coated with anti-corrosion materials. This type of rod can adapt to most working scenarios, but in some extreme environments, the anti-corrosion performance is insufficient. Therefore, materials with stronger anti-corrosion capabilities are needed, such as stainless steel. However, due to the different materials used, the structure must also be changed, especially the connection parts of the sucker rod. For example, the threaded parts are prone to seizing, which leads to the problem of the sucker rod being damaged too quickly. Therefore, this utility model proposes a new sucker rod structure suitable for stainless steel materials. Utility Model Content

[0004] The purpose of this invention is to solve the problem of thread seizing in existing stainless steel sucker rods, and to propose a stainless steel corrosion-resistant sucker rod.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A stainless steel corrosion-resistant sucker rod includes a rod body. The end of the rod body is provided with an external thread, a transition groove and a thickened shoulder from the outside to the inside. The two ends of the rod body are symmetrically arranged and connected by a coupling. A clamp is detachably connected between the coupling and the thickened shoulder.

[0007] Preferably, the coupling is provided with an internal thread corresponding to the external thread on the rod body, the coupling and the rod body are connected by a thread, and the tooth profile of the external thread and the internal thread is selected with a tooth profile angle of °.

[0008] Preferably, a rounded corner is provided between the transition groove and the thickened shoulder.

[0009] Preferably, the clamp includes a first buckle and a second buckle, the first buckle and the second buckle are symmetrically arranged and both are semi-circular, and the first buckle and the second buckle are connected by bolts.

[0010] Preferably, both ends of the coupling are fixedly provided with protrusions, and the first and second buckles simultaneously lock the protrusions and the thickened shoulder of the coupling.

[0011] Preferably, both ends of the coupling are provided with sealing grooves, and a sealing protrusion is fixedly provided on the outer end face of the thickened shoulder, with the sealing groove and the sealing protrusion matching each other.

[0012] Preferably, a wrench square is provided on the rod body near the inner end face of the thickened shoulder, and two symmetrical planes are provided on the outer ring surface of the coupling.

[0013] Preferably, the coupling and the thickened shoulder are sealed with fluorine-based high-temperature sealant, and the contact surfaces of the first and second buckles are sealed with a gasket and fluorine-based high-temperature sealant.

[0014] Compared with the prior art, the present invention provides a stainless steel corrosion-resistant sucker rod, which has the following beneficial effects.

[0015] 1. This utility model, through the setting of clamps, can limit the movement between the coupling and the thickened shoulder, and share the force borne by the threaded part when generating tensile and thrust forces, thereby better protecting the threaded structure, achieving the effect of improving service life and reducing maintenance costs. In addition, it can also prevent the problem of disengagement between the rod body and the coupling, thus solving the problem of thread seizure that is prone to occur in stainless steel sucker rods in the prior art.

[0016] 2. This utility model selects a thread profile with a 30° thread profile angle. Because the thread profile angle is small, the contact surface between the thread crest and the thread root is narrower, and the contact area of ​​a single thread is relatively small. Therefore, it is not easy to cause seizing, thereby further improving the protection of the thread.

[0017] 3. This utility model, by setting a thickened shoulder, can improve its load-bearing capacity and better distribute the force on the thread.

[0018] Other advantages, objectives and features of this invention will be set forth in part in the description which follows; and in part will be apparent to those skilled in the art upon examination of the following description; or may be taught from practice of this invention. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0020] Figure 2 This is a partial cross-sectional structural diagram of the present invention.

[0021] Figure 3 This is a schematic diagram of the partial explosion structure of this utility model.

[0022] Figure 4This is a schematic diagram of the structure of the rod in this utility model.

[0023] Figure 5 This is a schematic diagram of the coupling structure in this utility model.

[0024] Figure 6 This is a schematic diagram of the clamp structure in this utility model.

[0025] Figure 7 This is a schematic diagram showing the connection state of the two sucker rods in this utility model.

[0026] In the picture:

[0027] 1. Rod body; 2. Wrench square; 3. First buckle; 4. Coupling; 5. Sealing groove; 6. Second buckle; 7. Bolt; 8. Transition groove; 9. Thickened shoulder; 10. Sealing ring; 11. Rounded corner; 12. Boss. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the accompanying drawings. The drawings are simplified schematic diagrams, illustrating only the basic structure of the present invention, and therefore only show the components relevant to the present invention.

[0029] Please refer to Figures 1-7 A stainless steel corrosion-resistant sucker rod includes a rod body 1. The end of the rod body 1 is provided with an external thread, a transition groove 8 and a thickened shoulder 9 from the outside to the inside. The two ends of the rod body 1 are symmetrically arranged. The two rod bodies 1 are connected by a coupling 4. A clamp is detachably connected between the coupling 4 and the thickened shoulder 9.

[0030] In a specific embodiment of this utility model, the rod body 1 is made of 2205 duplex stainless steel, which has excellent corrosion resistance and is suitable for use in some harsh environments of oil wells. At the same time, it can simplify operation and maintenance without coating, eliminating the need for coating touch-up, corrosion inhibitor injection and other processes, thus reducing operating costs. In addition, it also has high temperature resistance. The strength retention rate of duplex steel is greater than 80% at a temperature of 350°C (the strength of carbon steel decreases by 50% at a temperature of 250°C). Furthermore, the coupling 4 and the clamp also need to be made of the same material as the rod body 1 to prevent galvanic corrosion.

[0031] It should be noted that since this rod body 1 is made of duplex stainless steel, its diameter needs to be 0.5mm-1.0mm larger than that of the carbon steel version (for example, if the diameter of a certain standard series is 22mm, it is 22.8mm when made of duplex stainless steel). This is to compensate for the strength of the stainless steel (a larger cross-sectional area is required for the same load).

[0032] The transition groove 8 is designed to allow for a margin between the external thread and the thickened shoulder 9, making it easier to machine a complete external thread (the transition groove 8 is equivalent to a relief groove).

[0033] By setting a thickened shoulder 9, its load-bearing capacity is improved, and the force on the thread is better distributed;

[0034] The clamps can limit the movement between the clamp 4 and the thickened shoulder 9. When thrust is generated between two adjacent sucker rods, the clamp 4 abuts against the thickened shoulder 9 to share part of the thrust, preventing the entire thrust from being borne by the threaded structure. When tension is generated between two adjacent sucker rods, the clamps can distribute part of the tension to the thickened shoulder 9 and the clamp 4, preventing the entire tension from being borne by the threaded structure. Therefore, this can protect the threaded structure, reduce the occurrence of thread seizure leading to difficult disassembly or significant damage to the threads after disassembly, and prevent thread failure, thereby reducing the maintenance cost of the sucker rod and increasing its service life.

[0035] The coupling 4 is provided with an internal thread corresponding to the external thread on the rod body 1. The coupling 4 and the rod body 1 are connected by threads. The tooth profile of the external thread and the internal thread is 30° tooth profile angle, which is a trapezoidal thread. The fillet is increased at the lowest point of the groove. The fillet at the root of the thread is increased from R0.13mm to 0.8mm to improve its fatigue life.

[0036] A 30° thread angle is relatively small (while the thread angle of a standard sucker rod made of carbon steel or alloy steel is generally 55° or 60°), resulting in a narrower contact area between the thread crest and root, a smaller contact area for a single thread, and less friction, thus reducing the risk of thread seizure.

[0037] A fillet 11 is provided between the transition groove 8 and the thickened shoulder 9; by providing the fillet 11 here, the strength at this point can be increased, so that the thickened shoulder 9 can exert the corresponding load-bearing capacity.

[0038] The clamp includes a first buckle 3 and a second buckle 6. The first buckle 3 and the second buckle 6 are symmetrically arranged and are both semi-circular. The first buckle 3 and the second buckle 6 are connected by a bolt 7, which is made of high strength.

[0039] Both ends of the coupling 4 are fixedly provided with protrusions 12, and the first buckle 3 and the second buckle 6 simultaneously lock the protrusion 12 and the thickened shoulder 9 of the coupling 4.

[0040] When installing the clamp, first screw one end of the coupling 4 onto one end of a rod 1, ensuring the end of the coupling 4 rests against the outer end face of the thickened shoulder 9. Note that the tightening torque should be 85% of the standard (to prevent seizing; stainless steel has good ductility but its strength is not as high as sucker rods made of standard carbon steel and alloy steel, therefore stainless steel threads are prone to seizing). After connecting the coupling 4 and the rod 1, sequentially fasten the first clip 3 and the second clip 6 onto the coupling 4 and the thickened shoulder 9. Taking the first clip 3 as an example, during engagement, one inner end face of the first clip 3 contacts the inner end face of the boss 12 on the coupling 4, and the other inner end face of the first clip 3 contacts the inner end face of the thickened shoulder 9 (i.e., the end face of the thickened shoulder 9 away from the external thread). After the first clip 3 is engaged, the same operation is performed to engage the second clip 6, forming a circle with the first clip 3. Then, the first clip 3 and the second clip 6 are connected together using bolts 7. See the attached diagram for a schematic diagram of the state after the coupling is installed. Figure 1 and attached Figure 2 ;

[0041] When two sucker rods need to be connected together, first install coupling 4 onto the first sucker rod as described above, then install the corresponding clamps. After installation, connect the end of the second sucker rod to coupling 4. Then, use another clamp to connect the other end of coupling 4 to the thickened shoulder 9 of the second sucker rod. See the attached diagram for a schematic diagram of the connected state of the two sucker rods. Figure 7 .

[0042] Both ends of the coupling 4 are provided with sealing grooves 5, and a sealing protrusion 10 is fixedly provided on the outer end face of the thickened shoulder 9. The sealing grooves 5 and the sealing protrusion 10 are matched. By setting the sealing grooves 5 and the sealing protrusion 10, when the coupling 4 is connected to the rod body 1, the sealing protrusion 10 on the thickened shoulder 9 can enter the sealing groove 5, which improves the sealing effect to a certain extent and prevents liquid from entering the threaded structure. In addition, the setting of the sealing protrusion 10 can act as a reinforcing rib to improve the strength of the thickened shoulder 9.

[0043] A wrench square 2 is provided on the rod body 1 near the inner end face of the thickened shoulder 9, and two symmetrical planes are provided on the outer ring surface of the coupling 4; the wrench square 2 provides a convenient way to fix or tighten the rod body 1 of the sucker rod, and the planes provided on the coupling 4 have the same effect as the wrench square 2.

[0044] The coupling 4 and the thickened shoulder 9 are sealed with fluorinated high-temperature grease, and the contact surfaces of the first snap 3 and the second snap 6 are sealed with a gasket and fluorinated high-temperature grease. By using fluorinated high-temperature grease, the sealing effect can be improved, and the threaded structure of the rod body 1 and the coupling 4 can be prevented from being affected by external liquids. At the same time, the use of fluorinated high-temperature grease and gasket to seal the first snap 3 and the second snap 6 can achieve a double sealing effect. One layer is the sealing of the coupling 4 and the thickened shoulder 9 by the coupling, and the other layer is the sealing structure and grease set in the coupling 4 and the thickened shoulder 9 themselves. This achieves a highly efficient sealing effect, better protects the threaded structure, and, together with the function of the coupling, can achieve maximum protection of the threaded structure, reduce maintenance costs, and improve the service life of the sucker rod. At the same time, the coupling can also play a role in preventing disengagement, preventing the sucker rod from disconnecting.

[0045] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

[0046] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0047] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A stainless steel corrosion-resistant sucker rod, comprising a rod body (1), characterized in that, The end of the rod (1) is provided with an external thread, a transition groove (8) and a thickened shoulder (9) from the outside to the inside. The two ends of the rod (1) are symmetrically arranged. The two rods (1) are connected by a coupling (4). The coupling (4) and the thickened shoulder (9) are detachably connected by a clamp.

2. The stainless steel corrosion-resistant sucker rod according to claim 1, characterized in that, The coupling (4) is provided with an internal thread corresponding to the external thread on the rod (1). The coupling (4) and the rod (1) are connected by threads. The tooth profile of the external thread and the internal thread is selected with a tooth profile angle of 30°.

3. The stainless steel corrosion-resistant sucker rod according to claim 1, characterized in that, A rounded corner (11) is provided between the transition groove (8) and the thickened shoulder (9).

4. The stainless steel corrosion-resistant sucker rod according to claim 1, characterized in that, The clamp includes a first buckle (3) and a second buckle (6). The first buckle (3) and the second buckle (6) are symmetrically arranged and are both semi-arc-shaped. The first buckle (3) and the second buckle (6) are connected by bolts (7).

5. A stainless steel corrosion-resistant sucker rod according to claim 4, characterized in that, Both ends of the coupling (4) are fixedly provided with protrusions (12), and the first buckle (3) and the second buckle (6) simultaneously lock the protrusion (12) and the thickened shoulder (9) of the coupling (4).

6. A stainless steel corrosion-resistant sucker rod according to claim 1, characterized in that, Both ends of the coupling (4) are provided with sealing grooves (5), and a sealing ring (10) is fixedly provided on the outer end face of the thickened shoulder (9). The sealing groove (5) and the sealing ring (10) are matched.

7. A stainless steel corrosion-resistant sucker rod according to claim 1, characterized in that, A wrench square (2) is provided on the rod body (1) near the inner end face of the thickened shoulder (9), and two symmetrical planes are provided on the outer ring surface of the coupling (4).

8. A stainless steel corrosion-resistant sucker rod according to claim 4, characterized in that, The coupling (4) and the thickened shoulder (9) are sealed with fluorine-based high-temperature sealant, and the contact surfaces of the first buckle (3) and the second buckle (6) are sealed with a gasket and fluorine-based high-temperature sealant.

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