Thermal working method for oil-containing pipeline

Abstract

The invention discloses a thermal working method for an oil-containing pipeline, and belongs to the technical field of ship thermal working. Comprising the following steps that study and judgment are conducted before construction, and a proper pipeline plugging mode is selected by combining whether a plugging object can be taken out or not after cutting and / or welding operation is completed according to the pipeline trend; cleaning: cleaning residual oil on the inner wall of the pipeline, which is not less than 600MM away from the working surface, by using a rag or other cleaning articles; the plugging object is put into the pipeline to be filled; after the plugging object is filled, a cooling medium is placed above the plugging object; cutting and / or welding are / is started, and when the temperature exceeds 50 DEG C, operation is stopped, and cooling measures are taken; the thermal work with the oil pipeline can be directly achieved in ship repair, modification or disassembly operation, different plugging tools and cooling media are used according to different pipeline trends and the characteristics of the pipeline after operation is completed, risks in the thermal work process with the oil pipeline are reduced, the working efficiency is greatly improved, and a large amount of time is saved.

Description

Technical Field

[0001] The invention belongs to the technical field of ship thermal work, and in particular relates to a thermal work method for oil-containing pipelines. Background Art

[0002] Cutting pipelines is a common yet challenging task during ship repair, modification, or dismantling operations. Cutting and welding pipelines containing (or carrying) oil are considered critical operations due to their high risk, requiring stringent safety measures and technical expertise. The core risk lies in the complexity of the pipeline system itself. Gravity drainage or simple purging alone is difficult to completely remove residual oil from the pipeline, especially in heavily adherent heavy oil pipelines. Once residual oil or its vapors reach a certain concentration, the high temperatures, sparks, or molten metal generated by the cutting and welding operations can easily ignite them, leading to serious accidents such as explosions.

[0003] Currently, mainstream pipeline thermal processes are categorized as flame cutting (including thermal cutting and welding) and mechanical cutting. Flame operations, such as traditional oxyacetylene / oxypropane cutting, plasma cutting, and flame welding, generate temperatures exceeding thousands of degrees Celsius, numerous sparks, molten metal splashes, and incandescent slag. These factors can serve as direct ignition sources for residual oil or gas. Flame welding, in particular, creates a molten pool through continuous, concentrated heat input, increasing the risk of ignition and the potential for secondary fires caused by molten metal dripping. Mechanical cutting, even with methods often considered "cold cutting" like abrasive cutting and sawing, can generate heat and sparks high enough to ignite oil and gas due to high-speed rotation or friction. Furthermore, the metal dust generated by cutting can form explosive dust clouds in confined spaces, increasing the risk of explosion. Therefore, a process is urgently needed to safely cut and weld oil pipes when disassembly and complete removal of residual oil are not possible. Summary of the Invention

[0004] The object of the present invention is to provide a method for hot working of oil-containing pipelines to solve the problems raised by the above-mentioned background technology.

[0005] To solve the above technical problems, the present invention is achieved through the following technical solutions: A method for hot working an oil-containing pipeline comprises the following steps: Step 1: Before construction, conduct research and judgment, and select the appropriate pipeline blocking method based on the pipeline direction and whether the blocking material can be removed after the cutting and / or welding work is completed; Step 2: Cleaning: Use a rag or other cleaning items to clean the residual oil on the inner wall of the pipe at a distance of not less than 600mm from the working surface; Step 3: Place the plugging material into the pipeline for filling. The distance between the plugging material and the working surface should be no less than 600mm. After filling, the plugging material should be in full contact with the inside of the pipeline. Step 4: After the plugging material is filled, place a cooling medium on top of the plugging material. The distance between the cooling medium and the working surface should be no less than 100mm. Step 5: Before starting cutting and / or welding, conduct explosion test on the working area. Hot work can only be carried out after the explosion test is qualified. During the operation, check the temperature of the outer pipeline above and below the blockage. If it exceeds 50℃, stop the operation and take cooling measures until the hot work is completed.

[0006] Furthermore, in step 1, the direction of the pipeline includes vertical direction and horizontal direction. Whether the blockage can be removed is specifically determined by the following: when the operation is completed and the pipeline is connected into a whole pipe, the blockage cannot be removed; when the operation is completed and the pipeline is connected with a flange, the flange can be opened to remove the blockage.

[0007] Furthermore, the pipeline blocking method in step 1 is specifically: when the blocking object can be removed after the operation is completed, an air bag blocking method is adopted; when the blocking object cannot be removed, an oil-soluble sealant stick blocking method is adopted.

[0008] Furthermore, when the pipeline is horizontal and the plugging material cannot be removed, the plugging material is lithium-based grease.

[0009] Furthermore, after the oil-soluble sealant rod or lithium-based grease is used for sealing, the cooling medium in step 4 is dry ice, and dry ice is added to one side of the oil-soluble sealant rod or lithium-based grease. The process stops when the dry ice is at least 100 mm away from the top working surface, and the height of the dry ice in the tube is not less than 500 mm. In step 5, when the temperature at the upper part of the sealing object exceeds 50°C, the operation is immediately stopped and the dry ice is replenished before continuing the operation.

[0010] Furthermore, in step 4, asbestos cloth is laid between the two after the sealing material is sealed and before the dry ice is added.

[0011] Furthermore, after the operation is completed, if the blockage cannot be removed, the blockage position is heated by an electric heating blanket or hot air blowing to melt the oil-soluble sealant stick or lithium-based grease and dissolve it in the oil in the pipeline. After the dry ice automatically vaporizes, the pipeline system can be used normally.

[0012] Furthermore, when the pipeline is vertical and the blockage can be removed, the cooling medium in step 4 is clean water. After the airbag is inflated, clean water is added to the pipeline. The height of the clean water in the pipe is not less than 500 MM. The liquid level is observed for five minutes to check whether the liquid level has dropped significantly before the operation is carried out; in step 5, when the temperature at the upper position of the airbag exceeds 50°C, the operation is stopped immediately and wait for the pipeline to cool down naturally before continuing the operation; after the operation is completed, the flange is opened to remove the built-in object and the pipeline is connected completely.

[0013] Furthermore, in step 4, after the airbag is inflated and before clean water is added, asbestos cloth or rubber is laid between the airbag and the clean water.

[0014] Furthermore, when the pipeline is a horizontal pipeline and the blockage can be removed, the cooling medium in step 4 is dry ice.

[0015] The present invention has the following beneficial effects: hot work on oil pipelines can be directly performed during ship repair, modification or dismantling operations. Different plugging tools and cooling media are used according to different pipeline directions and pipeline characteristics after the operation is completed, thereby reducing the risks during hot work on oil pipelines, greatly improving work efficiency and saving a lot of time. For vertical pipelines where the plugging material can be removed after the operation is completed, a plugging airbag is used to block the oil and gas that spreads upward. During the hot work, the temperature outside the pipeline is detected to ensure that the concentration of combustible gas in the welding area does not reach the critical point of combustion and explosion. Water is added above the airbag to prevent the temperature of the pipeline below the airbag from rising, ensuring safe cutting operations. For vertical pipelines where the blockage cannot be removed after the operation is completed, oil-soluble sealing sticks are used to block the upward diffusion of oil and gas. The temperature of the outer side of the pipeline is monitored during the hot work to ensure that the concentration of combustible gas in the welding area does not reach the critical point of combustion and explosion. Dry ice is added to the oil-soluble sealing stick to prevent the temperature of the pipeline under the seal from rising, ensuring safe cutting operations. After construction, the dry ice vaporizes and the oil-soluble sealing stick melts after heating, meeting the working condition where the airbag cannot be removed. For horizontal pipelines where the plugging material can be removed after the operation is completed, a blocking airbag is used to form a partition to block the horizontal diffusion of oil and gas. During the hot work, the temperature outside the pipeline is monitored to ensure that the concentration of combustible gas in the welding area does not reach the critical point of combustion and explosion. Dry ice is added on the hot work side of the partition to prevent the temperature from rising, ensuring safe cutting operations. For horizontal pipelines where the blockage cannot be removed after the operation is completed, use oil-soluble sealant sticks or lithium-based grease to form a partition to block the horizontal diffusion of oil and gas. During the hot work, the temperature outside the pipeline is monitored to ensure that the concentration of combustible gas in the welding area does not reach the critical point of combustion and explosion. Dry ice is added on the hot work side of the partition to prevent the temperature from rising, ensuring safe cutting operations. This solution is suitable for tooling conditions such as where the air bag cannot be removed after construction. Asbestos cloth or rubber is laid on the plugging object to prevent iron oxide and other substances from falling into the pipeline and scalding the airbag. It can also enhance the sealing of the pipeline plugging and improve the safety factor during the operation.

[0016] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 is a flow chart of the present invention; Figure 2 This is a schematic diagram of the hot working operation of a vertical oil-containing pipeline according to the present invention; Figure 3 It is a schematic diagram of the thermal operation of the horizontal oil-containing pipeline of the present invention. DETAILED DESCRIPTION

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0020] See also Figure 1-3 As shown, a method for hot working of an oil-containing pipeline comprises the following steps: Step 1: Before construction, conduct research and judgment, and select the appropriate pipeline blocking method based on the pipeline direction and whether the blocking material can be removed after the cutting and / or welding work is completed; Step 2: Cleaning: Use a rag or other cleaning items to clean the residual oil on the inner wall of the pipe at a distance of not less than 600mm from the working surface; Step 3: Place the plugging material into the pipeline for filling. The distance between the plugging material and the working surface should be no less than 600mm. After filling, the plugging material should be in full contact with the inside of the pipeline. Step 4: After the plugging material is filled, place a cooling medium on top of the plugging material. The distance between the cooling medium and the working surface should be no less than 100mm. Step 5: Before starting cutting and / or welding, conduct explosion test on the working area. Hot work can only be carried out after the explosion test is qualified. During the operation, check the temperature of the outer pipeline above and below the blockage. If it exceeds 50℃, stop the operation and take cooling measures until the hot work is completed.

[0021] In step 1, the pipeline direction includes vertical direction and horizontal direction. Whether the blockage can be removed is determined by: when the operation is completed and the pipeline is connected into a whole pipe, the blockage cannot be removed; when the operation is completed and the pipeline is connected with a flange, the flange can be opened to remove the blockage.

[0022] The pipeline blocking method in step 1 is specifically to use an airbag blocking method when the blocking object can be removed after the operation is completed, and to use an oil-soluble sealing stick blocking method when the blocking object cannot be removed.

[0023] When the pipeline is horizontal and the plugging material cannot be removed, the plugging material is lithium-based grease.

[0024] After the oil-soluble sealant stick or lithium-based grease is used for sealing, the cooling medium in step 4 is dry ice. Dry ice is added to one side of the oil-soluble sealant stick or lithium-based grease. The process stops when the dry ice is at least 100 mm away from the top working surface, and the height of the dry ice in the tube is not less than 500 mm. In step 5, when the temperature at the upper part of the sealant exceeds 50°C, the process is stopped immediately and the dry ice is replenished before continuing the process.

[0025] In step 4, asbestos cloth is laid between the two after the plugging material is sealed and before the dry ice is added.

[0026] After the operation is completed, if the blockage cannot be removed, the blockage position is heated with an electric heating blanket or hot air blowing to melt the oil-soluble sealant stick or lithium-based grease and dissolve it in the oil in the pipeline. After the dry ice automatically vaporizes, the pipeline system can be used normally.

[0027] When the pipeline is vertical and the obstruction can be removed, the cooling medium in step 4 is clean water. After the airbag is inflated, clean water is added to the pipeline. The height of the clean water in the pipe is not less than 500 MM. The liquid level is observed for five minutes to check whether the liquid level has dropped significantly before the operation is carried out; in step 5, when the temperature at the upper part of the airbag exceeds 50°C, the operation is stopped immediately and the pipeline is allowed to cool down naturally before continuing the operation; after the operation is completed, the flange is opened to remove the built-in object and the pipeline is connected completely.

[0028] In step 4, after the air bag is inflated and before clean water is added, asbestos cloth or rubber is laid between the air bag and the clean water.

[0029] When the pipeline is horizontal and the blockage can be removed, the cooling medium in step 4 is dry ice.

[0030] Example 1 When hot work is performed on a vertical pipeline and the obstruction can be removed, the following steps are included: (1) Use a rag or other cleaning items to clean the residual oil on the inner wall of the pipe at a distance of not less than 600mm downward from the hot work surface; (2) Place the airbag in the pipeline and inflate it. After the airbag is inflated, the top should be at least 600mm away from the top working surface. After it is fully inflated, lay asbestos cloth or rubber on top of the airbag. Then add clean water to the pipeline. When the liquid level is about 100mm away from the top working surface, stop the water supply. At this time, the height of the clean water in the pipe should be at least 500mm. Observe the liquid level for 5 minutes to check whether the liquid level has dropped significantly. (3) If the clean water level does not drop significantly, conduct explosion test on the working surface area. After the explosion test is qualified, start the hot work on the working surface. During the operation, check the temperature of the outer wall of the upper and lower steel pipes of the airbag. If the temperature at the outer side of the upper pipe of the airbag exceeds 50℃, stop the operation immediately and wait for the steel pipe to cool down before continuing the operation until the operation is completed; (4) After the operation is completed, open the connecting flange to clean out foreign objects such as water, asbestos cloth or rubber, and air bags in the pipe, and clean up the site.

[0031] Example 2 When hot work is performed on a vertical pipeline and the obstruction cannot be removed, the following steps are included: (1) Use a rag or other cleaning items to clean the residual oil on the inner wall of the pipe at a distance of not less than 600mm downward from the hot work surface; (2) Seal the pipe with an oil-soluble sealant stick that matches the inner diameter of the steel pipe at a position not less than 600mm from the top working surface. After sealing, lay asbestos cloth and then add dry ice into the pipe. Stop about 100mm from the top working surface. At this time, the height of dry ice in the pipe is not less than 500mm. (3) Conduct explosion test on the working surface area. After passing the test, start hot work on the working surface. During the operation, detect the temperature of the outer wall of the pipeline above and below the oil-soluble sealant stick. When the temperature at the upper position exceeds 50℃, stop the operation immediately and refill dry ice before continuing the operation; (4) After the operation is completed, the sealing position is heated with an electric heating blanket to melt the oil-soluble sealant stick and dissolve it in the oil in the pipeline. The dry ice is vaporized, and the pipeline system can be used normally. The operation site is then cleaned up.

[0032] Example 3 When hot work is performed on a horizontal pipeline and the plugging material can be removed, the following steps are included: (1) Use rags or other cleaning items to clean the residual oil on the inner wall of the pipe within a distance of not less than 600mm from the hot working surface; (2) Place the airbag in the pipeline and inflate it. After the airbag is inflated, the top should be at least 600mm away from the working surface. After it is fully inflated, lay asbestos cloth or rubber on top of the airbag and add dry ice into the pipeline. Stop about 100mm away from the working surface. The length of dry ice in the pipe should be at least 500mm. (3) Conduct explosion test on the working surface area. After passing the test, start hot work on the working surface. During the operation, test the temperature of the outer wall of the steel pipe around the oil-soluble sealant stick. If the temperature near the working position exceeds 50℃, stop the operation immediately and replenish dry ice before continuing the operation; (4) After the operation, remove and clean out foreign objects such as air bags in the pipe and clean up the site.

[0033] Example 4 When hot work is performed on a horizontal pipeline and the obstruction cannot be removed, the following steps are included: (1) Use rags or other cleaning items to clean the residual oil on the inner wall of the thermal pipe within a distance of not less than 600mm from the working surface; (2) Seal the pipeline with lithium-based grease or an oil-soluble sealant stick that matches the inner diameter of the steel pipe at a position not less than 600mm from the working surface. After sealing, lay asbestos cloth above the lithium-based grease or oil-soluble sealant stick, and then add dry ice into the pipeline and stop about 100mm away from the working surface. The height of dry ice in the pipe should not be less than 500mm; (3) Conduct explosion test on the working surface area. After passing the test, start hot work on the working surface. During the operation, test the temperature of the outer wall of the steel pipe where the oil-soluble sealant stick or lithium-based grease is located. If the temperature near the working position exceeds 50°C, stop the operation immediately and refill dry ice before continuing the operation; (4) After the operation, clean the work site and use an electric heating blanket to heat the blocking position to melt the oil-soluble sealing glue stick or lithium-based grease and dissolve it in the oil in the pipeline. The dry ice will vaporize and the pipeline system can be used normally.

[0034] During ship repair, modification or dismantling operations, hot working of oil pipelines can be directly carried out. Different plugging tools and cooling media are used according to different pipeline directions and pipeline characteristics after the operation is completed to reduce the risks during hot working of oil pipelines, greatly improve work efficiency and save a lot of time; For vertical pipelines where the plugging material can be removed after the operation is completed, a plugging airbag is used to block the oil and gas that spreads upward. During the hot work, the temperature outside the pipeline is detected to ensure that the concentration of combustible gas in the welding area does not reach the critical point of combustion and explosion. Water is added above the airbag to prevent the temperature of the pipeline below the airbag from rising, ensuring safe cutting operations. For vertical pipelines where the blockage cannot be removed after the operation is completed, oil-soluble sealing sticks are used to block the upward diffusion of oil and gas. The temperature of the outer side of the pipeline is monitored during the hot work to ensure that the concentration of combustible gas in the welding area does not reach the critical point of combustion and explosion. Dry ice is added to the oil-soluble sealing stick to prevent the temperature of the pipeline under the seal from rising, ensuring safe cutting operations. After construction, the dry ice vaporizes and the oil-soluble sealing stick melts after heating, meeting the working condition where the airbag cannot be removed. For horizontal pipelines where the plugging material can be removed after the operation is completed, a blocking airbag is used to form a partition to block the horizontal diffusion of oil and gas. During the hot work, the temperature outside the pipeline is monitored to ensure that the concentration of combustible gas in the welding area does not reach the critical point of combustion and explosion. Dry ice is added on the hot work side of the partition to prevent the temperature from rising, ensuring safe cutting operations. For horizontal pipelines where the blockage cannot be removed after the operation is completed, use oil-soluble sealant sticks or lithium-based grease to form a partition to block the horizontal diffusion of oil and gas. During the hot work, the temperature outside the pipeline is monitored to ensure that the concentration of combustible gas in the welding area does not reach the critical point of combustion and explosion. Dry ice is added on the hot work side of the partition to prevent the temperature from rising, ensuring safe cutting operations. This solution is suitable for tooling conditions such as where the air bag cannot be removed after construction. Asbestos cloth or rubber is laid on the plugging object to prevent iron oxide and other substances from falling into the pipeline and scalding the airbag. It can also enhance the sealing of the pipeline plugging and improve the safety factor during the operation.

[0035] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these 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 any one or more embodiments or examples.

[0036] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for hot working of oil-containing pipelines, characterized in that: The following steps are involved: Step 1: Before construction, conduct research and judgment, and select the appropriate pipeline blocking method based on the pipeline direction and whether the blocking material can be removed after the cutting and / or welding work is completed; Step 2: Cleaning: Use a rag or other cleaning items to clean the residual oil on the inner wall of the pipe at a distance of not less than 600mm from the working surface; Step 3: Place the plugging material into the pipeline for filling. The distance between the plugging material and the working surface should be no less than 600mm. After filling, the plugging material should be in full contact with the inside of the pipeline. Step 4: After the plugging material is filled, place a cooling medium on top of the plugging material. The distance between the cooling medium and the working surface should be no less than 100mm. Step 5: Before starting cutting and / or welding, conduct explosion test on the working area. Hot work can only be carried out after the explosion test is qualified. During the operation, check the temperature of the outer pipeline above and below the blockage. If it exceeds 50℃, stop the operation and take cooling measures until the hot work is completed.

2. The oil-containing pipeline hot working method according to claim 1, characterized in that: In step 1, the pipeline direction includes vertical direction and horizontal direction. Whether the blockage can be removed is determined by: when the operation is completed and the pipeline is connected into a whole pipe, the blockage cannot be removed; when the operation is completed and the pipeline is connected with a flange, the flange can be opened to remove the blockage.

3. The oil-containing pipeline hot working method according to claim 2, characterized in that: The pipeline blocking method in step 1 is specifically to use an airbag blocking method when the blocking object can be removed after the operation is completed, and to use an oil-soluble sealing stick blocking method when the blocking object cannot be removed.

4. The oil-containing pipeline hot working method according to claim 3, characterized in that: When the pipeline is horizontal and the plugging material cannot be removed, the plugging material is lithium-based grease.

5. The oil-containing pipeline hot working method according to claim 4, characterized in that: After the oil-soluble sealant stick or lithium-based grease is used for sealing, the cooling medium in step 4 is dry ice. Dry ice is added to one side of the oil-soluble sealant stick or lithium-based grease. The dry ice is stopped when it is at least 100 mm away from the top working surface. The height of the dry ice in the tube is not less than 500 mm. In step 5, when the temperature of the upper portion of the blocking material exceeds 50° C., the operation is immediately stopped and the dry ice is replenished before the operation is continued.

6. The oil-containing pipeline hot working method according to claim 5, characterized in that: In step 4, asbestos cloth is laid between the two after the plugging material is sealed and before the dry ice is added.

7. The oil-containing pipeline hot working method according to claim 6, characterized in that: After the operation is completed, if the blockage cannot be removed, the blockage position is heated with an electric heating blanket or hot air blowing to melt the oil-soluble sealant stick or lithium-based grease and dissolve it in the oil in the pipeline. After the dry ice automatically vaporizes, the pipeline system can be used normally.

8. The oil-containing pipeline hot working method according to claim 3, characterized in that: When the pipeline is vertical and the blockage can be removed, the cooling medium in step 4 is clean water. After the airbag is inflated, clean water is added into the pipeline. The height of the clean water in the pipeline should be no less than 500 mm. The liquid level is observed for five minutes to check whether the liquid level has dropped significantly before the operation is carried out; In step 5, if the temperature of the upper portion of the airbag exceeds 50°C, the operation is stopped immediately and the operation is continued after the pipeline cools down naturally. After the operation is completed, open the flange, remove the internal objects, and then connect the pipeline completely.

9. The oil-containing pipeline hot working method according to claim 8, characterized in that: In step 4, after the air bag is inflated and before clean water is added, asbestos cloth or rubber is laid between the air bag and the clean water.

10. The oil-containing pipeline hot working method according to claim 2, characterized in that: When the pipeline is horizontal and the blockage can be removed, the cooling medium in step 4 is dry ice.

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