Preparation method for simulating flexible riser metal layer corrosion defect structure

Abstract

The invention discloses a preparation method for simulating a flexible riser metal layer corrosion defect structure. The preparation method comprises the following steps: (1) preparing raw materials; (2) corroding raw materials of the metal layer; (3) raw material combination and the like. According to the method, the simulated corrosion defect structure can be prepared under simple conditions, and the simulated corrosion defect structure can be close to the condition of the corroded flexible riser, so that simple simulation of corrosion of the metal layer of the flexible riser is realized; the collapsing problem in the disassembling process of the multi-layer structure of the flexible vertical pipe is effectively avoided, and casualties and equipment damage are avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of flexible riser defect preparation, and in particular relates to a preparation method for simulating a corrosion defect structure of a metal layer of a flexible riser. Background Art

[0002] During the operation and maintenance process, offshore flexible risers will be affected by corrosion, resulting in corrosion and thinning of the metal armor layer. In order to find defects in the metal armor layer through non-destructive testing methods, it is necessary to prepare flexible risers with corrosion defects in the armor layer. Since it is difficult to prefabricate corrosion defects in flexible risers, it is necessary to disassemble the multi-layer structure of the flexible riser. The disassembly process may cause the flexible riser structure to collapse, and may also cause casualties or equipment damage. Therefore, it is necessary to develop a method to simulate the metal layer with corrosion defects in flexible risers. Summary of the invention

[0003] The present invention is proposed to solve the problem in the prior art that it is difficult to prefabricate corrosion defects in the metal layer of a flexible riser, and its purpose is to provide a preparation method for simulating corrosion defect structures in the metal layer of a flexible riser.

[0004] The present invention is achieved through the following technical solutions:

[0005] A method for preparing a simulated flexible riser metal layer corrosion defect structure comprises the following steps:

[0006] (I) Raw material preparation

[0007] Select metal layer raw materials and non-metal layer raw materials of the same material and thickness as the simulated target flexible riser, and cut the metal raw materials and non-metal raw materials into appropriate sizes for later use;

[0008] (II) Corrosion of metal layer raw materials

[0009] Spraying anti-corrosion material on both ends of the metal layer raw material, and after the anti-corrosion material is completely dried, immersing the entire metal layer raw material in a target corrosion environment for corrosion treatment to form a corroded metal layer raw material;

[0010] (III) Raw material combination

[0011] The non-metallic layer raw material, the metal layer raw material and the corroded metal layer raw material are respectively inserted into the corresponding U-shaped guide grooves to form material cross-sectional units. The various material cross-sectional units are stacked and combined according to the structure of the simulated target flexible riser to obtain the simulated flexible riser metal layer corrosion defect structure.

[0012] In the above technical solution, the raw materials of the metal layer include skeletons, steel strips and flat steel made of stainless steel or carbon steel.

[0013] In the above technical solution, the anti-corrosion material in step (II) is an anti-corrosion coating that is resistant to CO2 and H2S corrosion.

[0014] In the above technical solution, the length of the anti-corrosion material sprayed on both ends of the metal layer raw material in step (II) is not less than the depth of the long groove of the U-shaped guide groove.

[0015] In the above technical solution, when the metal layer raw material is made of stainless steel, before immersing the metal layer raw material as a whole in the target corrosion environment in step (II), defects are processed on the outer surface of the metal layer raw material, and the defects are grooves or blind holes.

[0016] In the above technical scheme, the target corrosion environment in step (II) is a sealed container containing a NaCl solution with a mass concentration of 2% to 6%, the pressure in the sealed container is set to 5MPa to 20MPa, and CO2 or H2S is introduced into the NaCl solution to adjust the pH of the NaCl solution to 4 to 6.

[0017] In the above technical solution, the duration of the corrosion treatment in step (II) is 100 hours to 1000 hours. When the duration of the corrosion treatment is greater than 100 hours, the target corrosion environment is replaced every 100 hours.

[0018] In the above technical solution, the U-shaped guide groove is made of non-magnetic hard material, which is a U-shaped structure composed of a crossbeam and two vertical wings perpendicular to the crossbeam, and a long groove is formed on the inner side of the vertical wings.

[0019] In the above technical solution, the long groove is a through groove, and the groove width of the long groove is greater than the thickness of the raw material.

[0020] The beneficial effects of the present invention are:

[0021] The present invention provides a preparation method for simulating the corrosion defect structure of the metal layer of a flexible riser. The simulated corrosion defect structure can be prepared under simple conditions, and the simulated corrosion defect structure can be close to the situation after the flexible riser is corroded, thereby realizing a simple simulation of the corrosion of the metal layer of the flexible riser. The collapse problem of the multi-layer structure of the flexible riser during disassembly can be effectively avoided, thereby avoiding casualties and equipment damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the U-shaped guide groove in the present invention.

[0023] in:

[0024] 1. U-shaped guide groove; 2. Vertical wing; 3. Crossbeam; 4. Long groove.

[0025] For ordinary technicians in this field, other relevant drawings can be obtained based on the above drawings without any creative work. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0027] A method for preparing a simulated flexible riser metal layer corrosion defect structure comprises the following steps:

[0028] (I) Raw material preparation

[0029] Select metal layer raw materials and non-metal layer raw materials of the same material and thickness as the simulated target flexible riser, and cut the metal raw materials and non-metal raw materials into appropriate sizes for later use;

[0030] The raw materials of the metal layer include stainless steel or carbon steel skeletons, steel strips and flat steel;

[0031] The raw materials of the non-metallic layer include HDPE board and PA board;

[0032] (II) Corrosion of metal layer raw materials

[0033] Spray 3 cm long anti-corrosion material on both ends of the metal layer raw material, wait for the anti-corrosion material to be completely dried, and then immerse the entire metal layer raw material in the target corrosion environment for corrosion treatment to form a corroded metal layer raw material;

[0034] The target corrosion environment is a sealed container containing a NaCl solution with a mass concentration of 2% to 6%, the pressure in the sealed container is set to 5MPa to 20MPa, and CO2 or H2S is introduced into the NaCl solution to adjust the pH of the NaCl solution to 4 to 6;

[0035] The duration of the corrosion treatment is 100 hours to 1000 hours. When the duration of the corrosion treatment is longer than 100 hours, the target corrosion environment is replaced every 100 hours.

[0036] (III) Raw material combination

[0037] The non-metallic layer raw material, the metal layer raw material and the corroded metal layer raw material are respectively inserted into the corresponding U-shaped guide grooves to form material cross-sectional units. The various material cross-sectional units are stacked and combined according to the structure of the simulated target flexible riser to obtain the simulated flexible riser metal layer corrosion defect structure.

[0038] The U-shaped guide groove 1 is made of non-magnetic hard material, and its structure is as follows: Figure 1As shown, the U-shaped guide groove 1 is a U-shaped structure composed of a crossbeam 3 and two vertical wings 2 perpendicular to the crossbeam 3, and a long groove 4 is formed on the inner side of the vertical wing 2; the long groove 4 is a through groove, and the groove width of the long groove 4 is greater than the thickness of the raw material.

[0039] Example 1

[0040] A method for preparing a simulated flexible riser metal layer corrosion defect structure comprises the following steps:

[0041] (I) Prepare 1 section of 316L skeleton, 4 S460MC steel strips 5 cm wide, 20 10B21 flat steels 1 cm wide, all 30 cm long, HDPE board 30 mm long, 20 cm wide, PA board 30 mm long, 20 cm wide;

[0042] (II) Spray 3cm of anti-rust paint on both ends of 316L skeleton, S460MC steel strip, and 10B21 flat steel. After they are completely dried, soak them in 3% NaCl solution, set the pressure to 10MPa, add appropriate amount of CO2 or H2S gas, and adjust the pH to 5; take them out after 168h, and replace them with the same corrosion solution after 100h;

[0043] (III) The 316L skeleton, S460MC steel strip, 10B21 flat steel, HDPE plate and PA plate are respectively inserted into the aluminum alloy U-shaped guide groove; the aluminum alloy U-shaped guide groove is combined from top to bottom according to the HDPE plate, 10B21 flat steel, PA plate, 10B21 flat steel, PA plate, S460MC steel strip and 316L skeleton to obtain a simulated flexible riser metal layer corrosion defect structure.

[0044] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a simulated flexible riser metal layer corrosion defect structure, characterized in that: The following steps are involved: (I) Raw material preparation Select metal layer raw materials and non-metal layer raw materials of the same material and thickness as the simulated target flexible riser, and cut the metal raw materials and non-metal raw materials for later use; (II) Corrosion of metal layer raw materials Spraying anti-corrosion material on both ends of the metal layer raw material, and after the anti-corrosion material is completely dried, immersing the entire metal layer raw material in a target corrosion environment for corrosion treatment to form a corroded metal layer raw material; (III) Raw material combination The non-metallic layer raw material, the metal layer raw material and the corroded metal layer raw material are respectively inserted into the corresponding U-shaped guide grooves to form material cross-sectional units. The various material cross-sectional units are stacked and combined according to the structure of the simulated target flexible riser to obtain the simulated flexible riser metal layer corrosion defect structure.

2. The method for preparing a simulated flexible riser metal layer corrosion defect structure according to claim 1, characterized in that: The raw materials of the metal layer include skeletons, steel strips and flat steel made of stainless steel or carbon steel.

3. The method for preparing a simulated flexible riser metal layer corrosion defect structure according to claim 1, characterized in that: When the metal layer raw material is made of stainless steel, before immersing the metal layer raw material as a whole in the target corrosion environment in the step (II), defects are processed on the outer surface of the metal layer raw material, and the defects are grooves or blind holes.

4. The method for preparing a simulated flexible riser metal layer corrosion defect structure according to claim 1, characterized in that: In the step (II), the length of the anti-corrosion material sprayed on both ends of the metal layer raw material is not less than the depth of the long groove of the U-shaped guide groove.

5. The method for preparing a simulated flexible riser metal layer corrosion defect structure according to claim 1, characterized in that: In the step (II), the target corrosion environment is a sealed container containing a NaCl solution with a mass concentration of 2% to 6%, the pressure in the sealed container is set to 5MPa to 20MPa, and CO2 or H2S is introduced into the NaCl solution to adjust the pH of the NaCl solution to 4 to 6.

6. The method for preparing a simulated flexible riser metal layer corrosion defect structure according to claim 1, characterized in that: The duration of the corrosion treatment in step (II) is 100 hours to 1000 hours. When the duration of the corrosion treatment is longer than 100 hours, the target corrosion environment is replaced every 100 hours.

7. The method for preparing a simulated flexible riser metal layer corrosion defect structure according to claim 1, characterized in that: The U-shaped guide groove is made of non-magnetic hard material, and is a U-shaped structure consisting of a crossbeam and two vertical wings perpendicular to the crossbeam, with a long groove formed on the inner side of the vertical wings.

8. The method for preparing a simulated flexible riser metal layer corrosion defect structure according to claim 7, characterized in that: The long groove is a through groove, and the groove width of the long groove is greater than the thickness of the raw material.

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