Method of hot work on oil-filled pipelines

Abstract

The application discloses a kind of oil-containing pipeline hot work method, belong to ship hot work technical field;Including the following steps, research and judge before construction, whether the blocking object can be removed after cutting and / or welding operation is completed according to pipeline direction to select suitable pipeline blocking mode;Cleaning, utilize the cloth or other cleaning articles and distance operation surface not less than 600MM pipeline inner wall residual oil is cleaned up;Blocking object is filled into pipeline and filled;After blocking object is filled, cooling medium is placed above blocking object;Start cutting and / or welding, when more than 50 DEG C, stop operation and take cooling measures;In ship repair, modification or disassembly operation can directly realize the hot work of oil pipeline, for different pipeline direction and the characteristics of pipeline after operation, different blocking tooling and cooling medium are used to reduce the risk in the process of hot work of oil pipeline, greatly improve work efficiency, save a lot of time.

Description

Technical Field

[0001] This invention belongs to the field of marine thermal work technology, and in particular relates to a method for thermal work on oil-containing pipelines. Background Technology

[0002] In ship repair, modification, or dismantling operations, pipeline system cutting is an extremely common yet challenging task. Cutting and welding oil-bearing pipelines is recognized as a critical operation requiring extremely stringent safety measures and technical methods due to its exceptionally high risk. The core danger lies in the complexity of the pipeline system itself; gravity drainage or simple purging is insufficient to completely remove residual oil from the pipeline, especially for pipelines containing highly adhesive heavy oil. Once the residual oil or its vapors in the pipeline reach a certain concentration, the high temperatures, sparks, or molten metal generated during cutting and welding can easily ignite it, leading to serious accidents such as explosions.

[0003] Current mainstream pipeline thermal engineering processes are mainly divided into two categories: flame construction (including thermal cutting and welding) and mechanical cutting. Flame operations, such as traditional oxyacetylene / oxypropane gas cutting, plasma cutting, and flame welding, generate temperatures of thousands of degrees Celsius, numerous sparks, molten metal splashes, and incandescent slag. These factors can all become direct ignition sources for residual oil or oil and gas. In particular, flame welding, with its continuous concentrated heat input forming a molten pool, exacerbates the risk of ignition and the possibility of secondary fires caused by dripping molten metal. For mechanical cutting, even methods often considered "cold cutting," such as abrasive wheel cutting and sawing, can generate enough heat and sparks to ignite oil and gas due to their high-speed rotation or friction. At the same time, the metal dust generated during cutting can form explosive dust clouds in confined spaces, increasing the risk of explosion. Therefore, there is an urgent need for a process method that can safely perform cutting and welding operations when oil pipes cannot be disassembled and internal residual oil cannot be completely removed. Summary of the Invention

[0004] The purpose of this invention is to provide a method for hot working of oil-containing pipelines to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution:

[0006] A method for hot working of oil-containing pipelines includes the following steps:

[0007] Step 1: Before construction, conduct an assessment and select a suitable pipeline sealing method based on the pipeline route and whether the sealing material can be removed after cutting and / or welding.

[0008] Step 2: Cleaning. Use a cloth or other cleaning tools to clean the residual oil from the inner wall of the pipe at least 600mm away from the work surface.

[0009] Step 3: Put the plug into the pipeline for filling, the distance between the plug and the working face on the working side is not less than 600MM, and the plug is in full contact with the inner side of the pipeline after filling;

[0010] Step 4: After the plug is filled, a cooling medium is placed on the side of the plug close to the working face, and the distance between the cooling medium and the working face is not less than 100MM;

[0011] Step 5: Before cutting and / or welding, the working area is tested for explosion, and after passing the test, the hot work can be carried out. During the operation, the temperature of the pipeline outside the plug position is detected, and when it exceeds 50℃, the operation is stopped and cooling measures are taken until the hot work is completed.

[0012] Further, in step 1, the pipeline direction includes vertical direction and horizontal direction, and whether the plug can be removed is that when the whole pipe is connected after the operation is completed, the plug cannot be removed, and when the flange is connected after the operation is completed, the plug can be removed by opening the flange.

[0013] Further, in step 1, the pipeline plugging mode is that when the plug can be removed after the operation is completed, the air bag plugging mode is adopted, and when the plug cannot be removed, the oil-soluble sealant rod plugging mode is adopted.

[0014] Further, when the pipeline is in horizontal direction and the plug cannot be removed, the plug can also be lithium-based grease.

[0015] Further, after the oil-soluble sealant rod or lithium-based grease is plugged, the cooling medium in step 4 is dry ice, dry ice is added on the side of the oil-soluble sealant rod or lithium-based grease close to the working face, and the dry ice is stopped after the distance from the top working face is not less than 100MM, and the height of the dry ice in the pipeline is not less than 500MM; When the temperature of the pipeline outside the plug position exceeds 50℃ in step 5, the operation is immediately stopped and dry ice is replenished again for continuous operation.

[0016] Further, in step 4, before the dry ice is added after the plug is plugged, asbestos cloth is laid between them.

[0017] Further, after the operation is completed, when the plug cannot be removed, an electric heating blanket or hot air blowing heating is used to heat the plugging position, so that the oil-soluble sealant rod or lithium-based grease melts and dissolves in the oil in the pipeline, and the pipeline system can be used normally after the dry ice automatically gasifies.

[0018] Further, when the pipeline is vertically oriented and the obturator can be removed, the cooling medium in step 4 is clean water, clean water is added into the pipeline after the air bag is inflated and expanded, the height of the clean water in the pipeline is not less than 500 MM, and the operation is performed after observing the liquid surface for five minutes to check whether the liquid surface obviously decreases; in step 5, when the temperature at the upper position of the air bag exceeds 50 DEG C, the operation is immediately stopped and the pipeline is naturally cooled before the operation is continued; after the operation is completed, the flange is opened to remove the built-in object, and then the pipeline is connected.

[0019] Further, in step 4, before clean water is added after the air bag is inflated and expanded, asbestos cloth or rubber is laid between the air bag and the clean water.

[0020] Further, when the pipeline is horizontally oriented and the obturator can be removed, the cooling medium in step 4 is dry ice.

[0021] The present application has the following beneficial effects: in ship repair, modification or disassembly operation, the hot operation of the pipeline with oil can be directly realized, different obturator and cooling medium are used for different pipeline orientations and pipeline characteristics after the operation is completed, so as to reduce the risk in the hot operation process of the pipeline with oil, greatly improve the work efficiency, and save a lot of time.

[0022] For the vertically oriented pipeline and the case that the obturator can be removed after the operation is completed, the obturator air bag is used for obturation to obturate the upward diffusion of oil gas, and the temperature outside the pipeline is detected during the hot operation to ensure that the combustible gas concentration of the welding area does not reach the critical point of combustion and explosion, water is added above the air bag to prevent the temperature of the pipeline below the air bag from rising, and the cutting operation is safely performed;

[0023] For the vertically oriented pipeline and the case that the obturator cannot be removed after the operation is completed, the oil-soluble sealing glue stick is used to obturate the upward diffusion of oil gas, and the temperature outside the pipeline is detected during the hot operation to ensure that the combustible gas concentration of the welding area does not reach the critical point of combustion and explosion, dry ice is added on the oil-soluble sealing glue stick to prevent the temperature of the pipeline below the sealing from rising, and the cutting operation is safely performed, and after the construction of the scheme, the dry ice is gasified, and the oil-soluble sealing glue stick is melted by heating, which meets the working condition that the air bag cannot be removed;

[0024] For the horizontally oriented pipeline and the case that the obturator can be removed after the operation is completed, the obturator air bag is used to form a partition to obturate the horizontal diffusion of oil gas, and the temperature outside the pipeline is detected during the hot operation to ensure that the combustible gas concentration of the welding area does not reach the critical point of combustion and explosion, dry ice is added on the hot operation side of the partition to block the temperature rise, and the cutting operation is safely performed.

[0025] For the horizontal pipeline and the work is completed, the situation can not take out the closure, using oil soluble sealant stick or lithium grease poly stack to form a partition, to block the horizontal spread of oil and gas, and in the process of hot work to detect the outside of the pipeline temperature, to ensure that the weld area of flammable gas concentration does not reach the critical point of combustion and explosion, dry ice is added to the partition side of the hot work to block the temperature rise, the cutting operation is safe, the scheme is suitable for the situation that the air bag cannot be taken out after construction;

[0026] The asbestos cloth or rubber is laid on the top of the closure to prevent the iron oxide falling into the pipeline from scalding the air bag, and can enhance the sealing of the pipeline closure and improve the safety factor during the operation.

[0027] Of course, the implementation of any product of the present application does not necessarily need to achieve all the advantages described above. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0029] Fig. 1 The flow chart of the present application;

[0030] Fig. 2 The vertical oil pipeline hot work schematic diagram of the present application;

[0031] Fig. 3 The horizontal oil pipeline hot work schematic diagram of the present application. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0033] Please refer to Figs. 1-3 The oil pipeline hot work method shown in the figure comprises the following steps:

[0034] Step 1: research and judgment before construction, according to the pipeline orientation combined with cutting and / or welding operation to select the suitable pipeline closure mode according to whether the closure can be taken out after the completion of the cutting and / or welding operation;

[0035] Step 2: cleaning, using a cloth or other cleaning items to clean the inner wall of the pipeline with a distance of not less than 600MM from the working surface;

[0036] Step 3: put the plugging material into the pipeline for filling, the plugging material is close to the working side to the working surface with a distance of not less than 600MM, and after filling, the plugging material is in full contact with the inner side of the pipeline;

[0037] Step 4: after the plugging material is filled, place the cooling medium on the side of the plugging material close to the working surface, and the cooling medium is at a distance of not less than 100MM from the working surface;

[0038] Step 5: before starting cutting and / or welding, the working area is tested for explosion, and after passing the test, the hot work can be carried out, and during the operation, the temperature of the pipeline outside the position of the plugging material is detected, and when it exceeds 50℃, the operation is stopped and cooling measures are taken until the hot work is completed.

[0039] In step 1, the pipeline direction includes vertical direction and horizontal direction, and whether the plugging material can be taken out is that when the whole pipe is connected after the operation is completed, the plugging material cannot be taken out, and when the flange is connected after the operation is completed, the flange can be opened to take out the plugging material.

[0040] In step 1, the pipeline plugging mode is that when the plugging material can be taken out after the operation is completed, the air bag plugging mode is adopted, and when the plugging material cannot be taken out, the oil-soluble sealant rod plugging mode is adopted.

[0041] When the pipeline is in horizontal direction and the plugging material cannot be taken out, the plugging material can also be lithium-based grease.

[0042] After the oil-soluble sealant rod or lithium-based grease is plugged, the cooling medium in step 4 is dry ice, dry ice is added on the side of the oil-soluble sealant rod or lithium-based grease close to the working surface, and the dry ice is stopped after the distance from the top working surface is not less than 100MM, and the length of the dry ice in the pipeline is not less than 500MM; in step 5, when the temperature of the pipeline outside the position of the plugging material exceeds 50℃, the operation is immediately stopped and dry ice is supplemented again for continuous operation.

[0043] In step 4, before the dry ice is added after the plugging material is plugged, a asbestos cloth is laid between them.

[0044] After the operation is completed, when the plugging material cannot be taken out, an electric heating blanket or hot air blowing heating is used to heat the plugging position, so that the oil-soluble sealant rod or lithium-based grease is melted and dissolved in the oil in the pipeline, and the dry ice is automatically gasified, so that the pipeline system can be used normally.

[0045] When the pipeline is vertical and the blocking object can be removed, the cooling medium in step 4 is clean water, clean water is added into the pipeline after the air bag is inflated, the height of the clean water in the pipeline is not less than 500 MM, and the operation is performed after observing the liquid surface for five minutes to check whether the liquid surface obviously drops; in step 5, when the temperature of the upper position of the air bag is higher than 50℃, the operation is immediately stopped and the pipeline is naturally cooled before the operation is continued; after the operation is completed, the flange is opened to remove the built-in object, and then the pipeline is connected.

[0046] In step 4, before the clean water is added after the air bag is inflated, asbestos cloth or rubber is laid between the air bag and the clean water.

[0047] When the pipeline is horizontal and the blocking object can be removed, the cooling medium in step 4 is dry ice. Example 1

[0048] When the pipeline is vertical and the blocking object can be removed, the following steps are included:

[0049] (1) The residual oil on the inner wall of the pipeline within a distance range of not less than 600 MM downward from the hot work surface is cleaned with a cleaning object such as a cloth;

[0050] (2) The air bag is placed into the pipeline and inflated, the top of the air bag is not less than 600 MM away from the top of the working surface after inflation, asbestos cloth or rubber is laid above the air bag after complete inflation, clean water is added into the pipeline, the water is stopped after the liquid surface is about 100 MM away from the top of the working surface, at this time, the height of the clean water in the pipeline is not less than 500 MM, and the liquid surface is observed for five minutes to check whether the liquid surface obviously drops;

[0051] (3) If the clean water liquid surface does not obviously drop, the working surface area is measured for explosion, the hot work of the working surface is started after the explosion measurement is qualified, the temperature of the upper and lower outer walls of the steel pipe of the air bag is detected during the operation, the operation is immediately stopped when the temperature of the outer side of the upper pipeline of the air bag is higher than 50℃, and the operation is continued after the steel pipe is cooled;

[0052] (4) After the operation is completed, the connecting flange is opened to clean the clean water, asbestos cloth or rubber, and the air bag and other foreign matters in the pipeline, and the site is cleaned. Example 2

[0053] When the pipeline is vertical and the blocking object cannot be removed, the following steps are included:

[0054] (1) The residual oil on the inner wall of the pipeline within a distance range of not less than 600 MM downward from the hot work surface is cleaned with a cleaning object such as a cloth;

[0055] (2) The oil-soluble sealing rubber rod matched with the inner diameter of the steel pipe is blocked in the pipeline at a position not less than 600 mm from the top working surface, after blocking, the asbestos cloth is laid, then dry ice is added into the pipeline at a position about 100 mm from the top working surface, and the process is stopped, at this time, the height of the dry ice in the pipeline is not less than 500 mm;

[0056] (3) The working surface area is tested for explosion, and after passing the test, the hot work at the working surface is started, and during the working process, the temperature of the outer wall of the pipeline above and below the oil-soluble sealing rubber rod is detected, and when the temperature at the upper position exceeds 50 DEG C, the working process is immediately stopped and dry ice is added again for the working process;

[0057] (4) After the working process is completed, the blocked position is heated by using an electric heating blanket, so that the oil-soluble sealing rubber rod is melted and dissolved in the oil in the pipeline, the dry ice is gasified, and the pipeline system can be normally used, and the working site is cleaned. Example 3

[0058] When the hot work is performed on the pipeline with a horizontal direction and the blocking object can be taken out, the following steps are included:

[0059] (1) The residual oil on the inner wall of the pipeline at a distance not less than 600 mm from the hot working surface is cleaned by using a cleaning article such as a cloth;

[0060] (2) The air bag is put into the pipeline and inflated, the air bag is inflated at a position not less than 600 mm from the working surface, after the air bag is completely inflated, the asbestos cloth or rubber is laid on the side of the air bag close to the working surface, then dry ice is added into the pipeline at a position about 100 mm from the working surface, and the process is stopped, the length of the dry ice in the pipeline is not less than 500 mm;

[0061] (3) The working surface area is tested for explosion, and after passing the test, the hot work at the working surface is started, and during the working process, the temperature of the outer wall of the pipeline above and below the oil-soluble sealing rubber rod is detected, and when the temperature at the upper position exceeds 50 DEG C, the working process is immediately stopped and dry ice is added again for the working process;

[0062] (4) After the working process is completed, the blocked position is heated by using an electric heating blanket, so that the oil-soluble sealing rubber rod is melted and dissolved in the oil in the pipeline, the dry ice is gasified, and the pipeline system can be normally used, and the working site is cleaned. Example 4

[0063] When the hot work is performed on the pipeline with a horizontal direction and the blocking object cannot be taken out, the following steps are included:

[0064] (1) The residual oil on the inner wall of the pipeline at a distance not less than 600 mm from the hot working surface is cleaned by using a cleaning article such as a cloth;

[0065] (2) The lithium-based grease or the oil-soluble sealing rubber rod matched with the inner diameter of the steel pipe is blocked in the pipeline at a position not less than 600 mm from the working surface, after blocking, the asbestos cloth is laid on the side of the lithium-based grease or the oil-soluble sealing rubber rod close to the working surface, then dry ice is added into the pipeline at a position about 100 mm from the working surface, and the process is stopped, the length of the dry ice in the pipeline is not less than 500 mm;

[0066] (3) The explosion-proof test is conducted on the working surface area, and after the test is qualified, the hot working on the working surface is started. During the working process, the temperature of the outer wall of the steel pipe at the position where the oil-soluble sealing rubber or lithium-based grease is located is detected. If the temperature near the working position exceeds 50℃, the working is immediately stopped and dry ice is added for reworking;

[0067] (4) After the working, the working site is cleaned, and the sealing position is heated by using an electric heating blanket to melt the oil-soluble sealing rubber or lithium-based grease, so that the oil-soluble sealing rubber or lithium-based grease is dissolved in the oil in the pipeline, and the dry ice is gasified. The pipeline system can be normally used.

[0068] During the ship repairing, refitting or disassembling work, the hot working of the oil-carrying pipeline can be directly realized. Different sealing tools and cooling media are used for different pipeline directions and pipeline features after the work is completed, so as to reduce the risk in the hot working process of the oil-carrying pipeline, greatly improve the working efficiency, and save a large amount of time;

[0069] For the vertically oriented pipeline and the case that the sealing material can be removed after the work is completed, a sealing air bag is used for sealing to seal the upwardly diffused oil gas. During the hot working process, the temperature outside the pipeline is detected to ensure that the flammable gas concentration in the welding area does not reach the critical point of combustion and explosion. Water is added above the air bag to prevent the temperature of the pipeline below the air bag from rising, so that the cutting work is safely carried out.

[0070] For the vertically oriented pipeline and the case that the sealing material cannot be removed after the work is completed, an oil-soluble sealing rubber is used to seal the upwardly diffused oil gas. During the hot working process, the temperature outside the pipeline is detected to ensure that the flammable gas concentration in the welding area does not reach the critical point of combustion and explosion. Dry ice is added to the oil-soluble sealing rubber to prevent the temperature of the pipeline below the sealing from rising, so that the cutting work is safely carried out. After the construction of this scheme, the dry ice is gasified, and the oil-soluble sealing rubber is melted by heating, which meets the condition that the air bag cannot be removed.

[0071] For the horizontally oriented pipeline and the case that the sealing material can be removed after the work is completed, a sealing air bag is used to form a partition to seal the horizontally diffused oil gas. During the hot working process, the temperature outside the pipeline is detected to ensure that the flammable gas concentration in the welding area does not reach the critical point of combustion and explosion. Dry ice is added to the hot working side of the partition to block the temperature rise, so that the cutting work is safely carried out.

[0072] For the horizontally oriented pipeline and the case that the sealing material cannot be removed after the work is completed, an oil-soluble sealing rubber or lithium-based grease is used to form a partition to seal the horizontally diffused oil gas. During the hot working process, the temperature outside the pipeline is detected to ensure that the flammable gas concentration in the welding area does not reach the critical point of combustion and explosion. Dry ice is added to the hot working side of the partition to block the temperature rise, so that the cutting work is safely carried out. This scheme is suitable for the condition that the air bag cannot be removed after the construction.

[0073] Cotton or rubber is laid on the plugging to prevent the iron oxide dropped into the pipeline from scalding the air bag and to enhance the sealing of the pipeline plugging and improve the safety factor during operation.

[0074] In the description of the present specification, the description referring to the terms "one embodiment", "an example", "a specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Also, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0075] The preferred embodiments of the application disclosed above are only used to help explain the application. The preferred embodiments do not describe all the details and limit the application to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of the present specification. The present specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the application, so that those skilled in the art can well understand and utilize the application. The application is limited only by the claims and their full scope and equivalents.

Claims

1. A method of hot work on an oil-filled pipeline, characterized in that, The method comprises the following steps: Step 1: cleaning, using a cloth or other cleaning items to clean the residual oil on the inner wall of the pipeline which is not less than 600MM away from the working surface; Step 2: placing the blocking material in the pipeline for filling, the distance between the blocking material close to the working side and the working surface is not less than 600MM, after filling, the blocking material is in complete contact with the inner side of the pipeline, when the pipeline is in vertical direction, the blocking material is an oil-soluble sealing rubber stick, when the pipeline is in horizontal direction, the blocking material is an oil-soluble sealing rubber stick or lithium base grease; Step 3: after the filling of the blocking material is completed, placing cooling medium on the side close to the working surface of the blocking material, the distance between the cooling medium and the working surface is not less than 100MM, and the cooling medium is dry ice; Step 4: before starting cutting and / or welding, the working area is tested for explosion, and after the test is qualified, the hot work can be carried out, during the working process, the temperature of the pipeline outside the position of the blocking material is detected, when the temperature exceeds 50℃, the work is stopped and cooling measures are taken until the hot work is completed; after the work is completed, the blocking position is heated by using an electric heating blanket or hot air blowing to melt the oil-soluble sealing rubber stick or lithium base grease, and the oil-soluble sealing rubber stick or lithium base grease is dissolved in the oil in the pipeline, and the dry ice is automatically gasified, and the pipeline system is used normally.

2. A method of hot work on an oil-filled pipeline according to claim 1, characterized in that, After the oil-soluble sealing rubber stick or lithium base grease is blocked, dry ice is added on the side close to the working surface of the oil-soluble sealing rubber stick or lithium base grease, the distance between the dry ice and the working surface is not less than 100MM, and the length of the dry ice in the pipeline is not less than 500MM; In step 4, when the temperature of the pipeline outside the position of the blocking material exceeds 50℃, the work is immediately stopped and dry ice is replenished for continuing the work.

3. A method of hot work on an oil-filled pipeline according to claim 1, characterized in that, In step 3, after the blocking material is blocked, asbestos cloth is laid between the blocking material and the dry ice before the dry ice is added.

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