A conical stress joint for a flanged riser

Abstract

This utility model discloses a tapered stress joint for flange-connected risers, belonging to the field of marine oil and gas resource extraction equipment. It includes a suspension body with an upper connecting flange fixed at its top for connection to a marine oil and gas resource extraction platform. The inner diameter of the suspension body remains constant. The outer wall of the suspension body is thicker in the middle and thinner at both ends, with a concave arc transition from the thickest point of the outer wall to the top and bottom. A deformable cone is sleeved on the lower part of the suspension body, with a lower connecting flange fixed at its lower end for connection to a marine oil and gas riser. The deformable cone has the same inner diameter as the suspension body, and its inner diameter remains constant while its outer wall thickness gradually decreases from top to bottom. This design solves the problems of insufficient anti-peeling capacity and limited applicability of stress joints in existing technologies, and can be widely used in various marine oil and gas extraction environments, especially complex working conditions with large bending loads.

Description

Technical Field

[0001] This utility model belongs to the field of marine oil and gas resource extraction equipment, specifically relating to a tapered stress joint for flange-connected risers. Background Technology

[0002] In offshore subsea oil and gas exploration and development systems, riser systems, serving as the connection channel between surface platforms and subsea equipment, are the "throat" for media transmission between the platform and the seabed, and a crucial component of the subsea production system. Steel catenary risers (SCRs) are an important riser type for deepwater oil and gas development. Stress joints, as key devices in the SCR system, connect the riser to the platform, bearing the constant tension of hundreds of tons while also enduring the long-term swaying of the riser under environmental loads. Due to the complex loads borne by stress joints and the special properties of their materials, stress joints are a weak point in the SCR system, posing a risk of structural failure and leakage.

[0003] Patent application number 202421812068.5 discloses a flange-connected riser. The tapered stress joint, constructed of alloy metal materials, includes a main tube with a constant inner diameter. One end of the main tube is fixed with an upper connecting flange for connection to an offshore oil and gas resource extraction platform, and the other end is fixed with a lower connecting flange for connection to an offshore oil and gas riser. The outer surface of the main tube is metallurgically coated with a titanium alloy outer reinforcing layer with progressively decreasing thickness. This design enhances the strength of the main tube, making it less prone to breakage while withstanding constant riser tension. However, the outer reinforcing layer is only metallurgically attached to the outer surface. When the tube is subjected to bending deformation, the interface can only transmit shear force through metallurgical bonding, lacking an auxiliary load-bearing mechanism. This further reduces its anti-peeling ability, making it only suitable for offshore oil and gas extraction scenarios where constant tension is the primary load and bending load is relatively small. Utility Model Content

[0004] To overcome the shortcomings of the prior art, the purpose of this utility model is to provide a tapered stress joint for flange-connected risers, which solves the problems of insufficient anti-peeling ability and limited application scenarios of the outer reinforcing layer attached by metallurgy on the outer surface.

[0005] This utility model is achieved through the following technical solution: A tapered stress joint for flange-connected risers includes a suspension body. An upper connecting flange for connection to an offshore oil and gas resource extraction platform is fixed to the top of the suspension body. The inner diameter of the suspension body remains constant. The outer wall of the suspension body is thicker in the middle and thinner at both ends. The thickest part of the outer wall transitions to a concave arc surface at the top and to an arc surface at the bottom. A deformable cone is sleeved on the lower part of the suspension body. A lower connecting flange for connection to an offshore oil and gas riser is fixed to the lower end of the deformable cone. The inner diameter of the deformable cone is the same as that of the suspension body. The inner diameter of the deformable cone remains constant, while the outer wall thickness gradually decreases from top to bottom.

[0006] Furthermore, the ratio of the outer diameter of the upper end to the outer diameter of the lower end of the deformed vertebra is 1.1-2.1.

[0007] Furthermore, the lower inner wall of the suspension body is provided with an internal thread, and the upper part of the deformable cone is provided with an external thread adapted to the internal thread. A first rubber sealing ring is provided between the suspension body and the deformable cone and they are fixedly connected by a first connecting thread.

[0008] Furthermore, the upper connecting flange and the suspension body are integrally formed, and the deformable cone and the lower connecting flange are integrally formed.

[0009] Furthermore, the upper connecting flange is fixed to the suspension body, and the lower connecting flange is fixed to the deformed cone by welding.

[0010] Furthermore, the upper connecting flange is fixed to the suspension body by welding, and a second rubber sealing ring is provided between the lower connecting flange and the deformed cone and fixedly connected by a second connecting thread.

[0011] Furthermore, the first connecting thread and the second connecting thread are API standard round threads or trapezoidal threads.

[0012] Furthermore, the upper connecting flange and the suspension body are made of ASTM A694 F56 forging or F70 forging, and the deformed cone and the lower connecting flange are made of ASTM B 265 Gr-23 or Gr-29 titanium.

[0013] Furthermore, the upper connecting flange, the suspension body, and the lower connecting flange are made of ASTM A694 F56 forging or F70 forging, and the deformable cone is made of ASTM B 265 Gr-23 or Gr-29 titanium.

[0014] Compared with the prior art, the beneficial effects of this utility model are as follows: This invention optimizes the outer wall structure of the suspension body, making it thicker in the middle and thinner at both ends with a curved transition, effectively dispersing stress concentration caused by riser tension and environmental loads, and improving the fatigue resistance of the overall structure. The deformable cone adopts a conical design, with its outer wall thickness gradually decreasing from top to bottom. When the riser swings, it can buffer bending stress through its own elastic deformation, avoiding excessive stress concentration at the connection point. At the same time, the combined structure of the suspension body and the deformable cone, combined with the threaded connection fixing method, ensures the sealing and stability of the connection, taking into account both structural strength and corrosion resistance in the marine environment. It solves the problems of insufficient anti-peeling ability of stress joints and limited application scenarios in the prior art, and can be widely used in various marine oil and gas extraction environments, especially complex working conditions with large bending loads. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the present utility model; Figure 2 This is a schematic diagram of the structure of Embodiment 2 of the present invention; Figure 3 This is a structural schematic diagram of Embodiment 3 of the present invention.

[0016] In the figure: 1-Upper connecting flange, 2-Suspension body, 3-First rubber sealing ring, 4-First connecting thread, 5-Deformed cone, 6-Lower connecting flange, 7-Upper butt weld, 8-Lower butt weld, 9-Second rubber sealing ring, 10-Second connecting thread. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to specific embodiments. The description is for explanation and not limitation of the present invention.

[0018] Example 1 refer to Figure 1As shown, this utility model provides a tapered stress joint for flange-connected risers, including a suspension body 2. An upper connecting flange 1 for connection to an offshore oil and gas resource extraction platform is fixed to the top of the suspension body 2. The upper connecting flange 1 and the suspension body 2 are integrally formed. The inner diameter of the suspension body 2 remains constant. The outer wall of the suspension body 2 is thicker in the middle and thinner at both ends. The thickest part of the outer wall transitions to a concave arc surface at the top and to an arc surface at the bottom. An internal thread is provided on the lower inner wall of the suspension body 2. A deformable cone is sleeved on the lower part of the suspension body 2. 5. The deformable cone 5 and the suspension body 2 have the same inner diameter. The inner diameter of the deformable cone 5 remains unchanged, while the outer wall thickness gradually decreases from top to bottom. The ratio of the outer diameter of the upper end to the outer diameter of the lower end of the deformable cone 5 is 1.1. The upper part of the deformable cone 5 is provided with an external thread that matches the internal thread. A first rubber sealing ring 3 is provided between the suspension body 2 and the deformable cone 5 and fixedly connected by a first connecting thread 4. The lower end of the deformable cone 5 is fixed with a lower connecting flange 6 for connecting to the offshore oil and gas riser. The deformable cone 5 and the lower connecting flange 6 are integrally formed structures.

[0019] The first connecting thread 4 is a round thread according to the API standard.

[0020] The upper connecting flange 1 and the suspension body 2 are made of ASTM A694 F56 forging material, and the deformable cone 5 and the lower connecting flange 6 are made of ASTM B 265 Gr-23 titanium material.

[0021] A tapered stress joint for flange-connected risers, the manufacturing method of which includes the following steps: Step 1: The upper connecting flange 1 and the suspension body 2 are manufactured by forging process, and the connecting flange 1 and the suspension body 2 are integrally forged; Step 2: The deformed cone 5 and the lower connecting flange 6 are manufactured by forging process. The deformed cone 5 and the lower connecting flange 6 are integrally forged. Step 3: Machining matching API standard round threads on the lower end of the suspension body 2 and the upper end of the deformed cone 5 respectively, and connecting the suspension body 2 and the deformed cone 5 together using a torque wrench.

[0022] Example 2 refer to Figure 2As shown, this utility model provides a tapered stress joint for flange-connected risers, including a suspension body 2. An upper connecting flange 1 for connection to an offshore oil and gas resource extraction platform is fixed to the top of the suspension body 2. The upper connecting flange 1 and the suspension body 2 are fixedly connected by welding, with the connection being an upper butt weld 7. The inner diameter of the suspension body 2 remains unchanged. The outer wall of the suspension body 2 is thicker in the middle and thinner at both ends. The thickest part of the outer wall transitions to a concave arc surface at the top and to an arc surface at the bottom. Internal threads are provided on the lower inner wall of the suspension body 2, and a deformable cone is sleeved on the lower part of the suspension body 2. 5. The deformable cone 5 and the suspension body 2 have the same inner diameter. The inner diameter of the deformable cone 5 remains unchanged, while the outer wall thickness gradually decreases from top to bottom. The ratio of the outer diameter of the upper end to the outer diameter of the lower end of the deformable cone 5 is 1.6. The upper part of the deformable cone 5 is provided with an external thread that matches the internal thread. A first rubber sealing ring 3 is provided between the suspension body 2 and the deformable cone 5 and fixedly connected by a first connecting thread 4. The lower end of the deformable cone 5 is fixed with a lower connecting flange 6 for connecting to the offshore oil and gas riser. The lower connecting flange 6 and the deformable cone 5 are fixedly connected by welding, and the connection is a lower butt weld 8.

[0023] The first connecting thread 4 is a trapezoidal thread according to the API standard.

[0024] The upper connecting flange 1 and the suspension body 2 are made of ASTM A694 F70 forging material, and the deformable cone 5 and the lower connecting flange 6 are made of ASTM B 265 Gr-29 titanium material.

[0025] A tapered stress joint for flange-connected risers, the manufacturing method of which includes the following steps: Step 1: The upper connecting flange 1 and the suspension body 2 are manufactured by forging. Before forging and finishing, the two can be welded together by argon arc welding. After welding heat treatment, they are then finished. Step 2: The deformed cone 5 and the lower connecting flange 6 are manufactured by forging. Before forging and finishing, the two can be welded together by argon arc welding. After welding heat treatment, they are then finished. Step 3: Machining matching API standard trapezoidal threads on the lower end of the suspension body 2 and the upper end of the deformed cone 5 respectively, and connecting the suspension body 2 and the deformed cone 5 together using a torque wrench.

[0026] Example 3 refer to Figure 3As shown, this utility model provides a tapered stress joint for flange-connected risers, including a suspension body 2. An upper connecting flange 1 for connection to an offshore oil and gas resource extraction platform is fixed to the top of the suspension body 2. The upper connecting flange 1 and the suspension body 2 are fixedly connected by welding, with the connection being an upper butt weld 7. The inner diameter of the suspension body 2 remains unchanged. The outer wall of the suspension body 2 is thicker in the middle and thinner at both ends. The thickest part of the outer wall transitions to a concave arc surface at the top and to an arc surface at the bottom. An internal thread is provided on the lower inner wall of the suspension body 2. A deformable cone 5 is sleeved on the lower part of the suspension body 2. The deformable cone 5 and the suspension body 2... The inner diameter of the hanging body 2 is the same, the inner diameter of the deformable cone 5 remains unchanged, and the outer wall thickness gradually decreases from top to bottom. The ratio of the outer diameter of the upper end to the outer diameter of the lower end of the deformable cone 5 is 2.1. The upper part of the deformable cone 5 is provided with an external thread that matches the internal thread. A first rubber sealing ring 3 is provided between the hanging body 2 and the deformable cone 5 and it is fixedly connected by a first connecting thread 4. The lower end of the deformable cone 5 is fixed with a lower connecting flange 6 for connecting with the offshore oil and gas riser. The lower part of the deformable cone 5 is provided with an external thread. A second rubber sealing ring 9 is provided between the lower connecting flange 6 and the deformable cone 5 and it is fixedly connected by a second connecting thread 10.

[0027] The first connecting thread 4 and the second connecting thread 10 are trapezoidal threads according to API standards.

[0028] The upper connecting flange 1, the suspension body 2, and the lower connecting flange 6 are made of ASTM A694 F56 forging material, and the deformable cone 5 is made of ASTM B 265 Gr-23 titanium material.

[0029] A tapered stress joint for flange-connected risers, the manufacturing method of which includes the following steps: Step 1: The upper connecting flange 1 and the suspension body 2 are manufactured by forging. The upper connecting flange 1 and the suspension body 2 are formed by separate forging. Before forging and finishing, the two are welded into one piece by argon arc welding. After welding heat treatment, they are then finished. API standard trapezoidal threads are machined in the lower end inner hole of the suspension body 2. Step 2: The deformed cone 5 is manufactured using a forging process, and API standard trapezoidal threads are machined at both ends of the deformed cone 5. Step 3: Manufacture the lower connecting flange 6 using forging technology, and machine an API standard trapezoidal thread into the inner hole of one end of the lower connecting flange 6; Step 4: Connect the suspension body 2 and the deformed cone 5 together using a torque wrench, and connect the deformed cone 5 and the lower connecting flange 6 together.

[0030] This invention enables the connection between the offshore oil and gas resource extraction platform and the offshore oil and gas riser. While bearing the constant tension of hundreds of tons of riser, it also withstands the long-term swaying of the riser under environmental loads, ensuring the safety and service life of the offshore resource extraction equipment.

Claims

1. A tapered stress joint for flange-connected risers, characterized in that, The system includes a suspension body (2), with an upper connecting flange (1) fixed at the top of the suspension body (2) for connecting to an offshore oil and gas resource extraction platform. The inner diameter of the suspension body (2) remains unchanged. The outer wall of the suspension body (2) is thicker in the middle and thinner at both ends. The thickest part of the outer wall of the pipe transitions to the top with a concave arc surface, and the thickest part of the outer wall of the pipe transitions to the bottom with an arc surface. A deformable cone (5) is sleeved on the lower part of the suspension body (2). A lower connecting flange (6) is fixed at the lower end of the deformable cone (5) for connecting to an offshore oil and gas riser. The inner diameter of the deformable cone (5) is the same as that of the suspension body (2), and the inner diameter of the deformable cone (5) remains unchanged while the outer wall thickness gradually decreases from top to bottom.

2. The tapered stress joint for a flanged riser according to claim 1, characterized in that, The ratio of the outer diameter of the upper end to the outer diameter of the lower end of the deformed vertebra (5) is 1.1-2.

1.

3. The tapered stress joint for a flange-connected riser according to claim 1, characterized in that, The lower inner wall of the suspension body (2) is provided with an internal thread, and the upper part of the deformable cone (5) is provided with an external thread that is compatible with the internal thread. A first rubber sealing ring (3) is provided between the suspension body (2) and the deformable cone (5) and they are fixedly connected by a first connecting thread (4).

4. The tapered stress joint for a flanged riser according to claim 1, characterized in that, The upper connecting flange (1) and the suspension body (2) are integrally formed, and the deformable cone (5) and the lower connecting flange (6) are integrally formed.

5. The tapered stress joint for a flanged riser according to claim 1, characterized in that, The upper connecting flange (1) is fixed to the suspension body (2), and the lower connecting flange (6) is fixed to the deformed cone (5) by welding.

6. The tapered stress joint for a flanged riser according to claim 1, characterized in that, The upper connecting flange (1) is fixed to the suspension body (2) by welding, and a second rubber sealing ring (9) is provided between the lower connecting flange (6) and the deformed cone (5) and fixedly connected by the second connecting thread (10).

7. A tapered stress joint for a flanged riser according to claim 3, characterized in that, The first connecting thread (4) and the second connecting thread (10) are API standard round threads or trapezoidal threads.

8. A tapered stress joint for a flanged riser according to claim 4 or 5, characterized in that, The upper connecting flange (1) and the suspension body (2) are made of ASTM A694 F56 forging or F70 forging, and the deformable cone (5) and the lower connecting flange (6) are made of ASTM B 265 Gr-23 or Gr-29 titanium.

9. A tapered stress joint for a flanged riser according to claim 6, characterized in that, The upper connecting flange (1), the suspension body (2), and the lower connecting flange (6) are made of ASTM A694 F56 forging or F70 forging, and the deformable cone (5) is made of ASTM B 265 Gr-23 or Gr-29 titanium.

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