Welding construction method for large-thickness and large-diameter steel pipe penetrating through soil layer based on working well

Abstract

The invention relates to the technical field of pipe jacking welding construction, in particular to a welding construction method for a large-thickness steel pipe penetrating through a soil layer based on a working well. The welding construction method comprises the steps of excavation of a pit groove in the bottom of a working well, laying of steel rails, butt joint of steel pipes, erection of a steel pipe internal platform, welding of positioning steel plates, installation of ceramic gaskets, welding of welding seams, welding of the inner tops and the outer bottoms of the steel pipes, post-welding treatment of the welding seams and pushing of the steel pipes into a water pipeline. By digging a pit groove in the bottom of the working well, overhead welding construction can be conducted on the outer arc face of the bottom of the steel pipe, and it is guaranteed that welding of welding seams meets the quality requirement. And through the erected platform, a worker can conveniently stand on the platform to carry out overhead welding on a welding seam at the inner top of the two steel pipes. The method has the advantages that butt joint dislocation of the steel pipes can be avoided through positioning welding of the steel pipes, the welding fusion degree is good, in addition, back gouging treatment is carried out on the welding seams after first welding during welding seam welding, air holes and slag inclusion can be avoided at the roots of the welding seams, and reworking is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of pipe jacking welding construction, and in particular to a welding construction method for a thick steel pipe that penetrates a soil layer based on a working well. Background Art

[0002] At present, in drainage projects, especially those that penetrate the soil layer of a mountain, each section of steel pipe needs to be welded outside the water pipe opening and pushed into the water pipe. Among them, welding of steel pipes and penetration between multiple wells are very critical processes.

[0003] In addition, steel pipes that penetrate the soil layer of the mountain must withstand the pressure of the mountain, so they are usually made of thick and large-diameter steel pipes. At present, the thickness of such steel pipes is generally 40mm and the diameter is generally 3m. Therefore, such steel pipes are heavy and cannot be turned over during welding and jacking of water pipes. As a result, welding between each two sections of steel pipes is difficult, and it is easy for the steel pipes to be misaligned, the welding fusion is poor, and the root of the weld is prone to slag inclusions and pores, which is not conducive to rework. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a welding construction method for thick steel pipes that penetrate the soil layer based on a working well. The welding construction method can avoid the misalignment of the steel pipes, and has the advantages of good welding fusion, avoiding the generation of pores and slag inclusions at the root of the weld, and is conducive to rework.

[0005] In order to achieve the purpose of the above invention, the technical solution adopted by the present invention is as follows:

[0006] The present invention provides a welding construction method for a thick steel pipe penetrating a soil layer in a working well, comprising the following steps:

[0007] S1. Excavating a soil pit at the bottom of the working pit: excavating a soil pit on the bottom plane of the working pit;

[0008] S2. Laying rails: Laying rails on the bottom plane of the working pit at a position outside the water pipe opening to facilitate the steel pipe to push the water pipe, and the rails pass above the soil pit;

[0009] S3, butt joint of steel pipes and setting up internal platform of steel pipes: hoist two sections of steel pipes into the working pit and place them on the steel rails, place the butt joint of the two sections of steel pipes to be welded on the soil pit, and set up a platform for welding at the end of one section of the steel pipe near the butt joint, and adjust the butt joint interval of the two sections of steel pipes;

[0010] S4. Positioning steel plate welding: Positioning steel plates are welded at the relative positions of the two ends of each steel pipe, and the positioning steel plates are connected respectively with plumb bobs to perform elevation compensation and verticality control;

[0011] S5. Install ceramic liner: Install ceramic liner at the butt joint of two steel pipes;

[0012] S6. Steel pipe positioning welding: Under the protection of carbon dioxide gas, use a welding machine and welding wire to weld the midpoints of the left and right sides and the upper and lower midpoints of the steel pipe at the same time to fix the steel pipe;

[0013] S6. Welding: The weld types on the left and right sides of the steel pipe weld adopt double-sided V-shaped grooves, and after the first welding of the inner and outer base layers of the weld, the weld is first cleaned and then the second welding is performed;

[0014] Among them, when implementing the weld, first check whether the ceramic liner and the steel pipe are tightly fitted, so as to facilitate the weld. In addition, after the first welding, the weld root cleaning is to clean the oxide scale, welding slag, oil stains and other impurities formed after the weld is welded, exposing the surface of the parent material for the second welding work. The weld root cleaning is to ensure the quality and strength of the weld.

[0015] S7, welding the inner top and outer bottom of the steel pipe: using the platform set up in step S3 to perform overhead welding on the welds on the inner top of the two sections of the steel pipe, and using the soil pit excavated in step S1 to perform overhead welding on the welds on the outer bottom of the two sections of the steel pipe;

[0016] Among them, due to the limitation of the working surface in the working pit, the steel pipe is placed on the rail and cannot be turned over or moved during welding. Welding requires the steel pipe to be pushed flat into the water pipe. Therefore, by digging a pit, the outer arc surface at the bottom of the steel pipe can be welded overhead. In addition, the platform is set up to facilitate workers to stand on the platform to weld the welds on the top of the two sections of steel pipes overhead.

[0017] S8. Post-weld treatment of welds: Grind the surface of the welds of the steel pipes, and then perform ultrasonic testing on the welds. After the ultrasonic testing is qualified, apply anti-corrosion coating to the welds for protection;

[0018] S9, pushing the steel pipe into the water pipeline: using a top iron to push the steel pipe after completing step S8 into the water pipeline, and making the end of the steel pipe stay on the earth pit, and then continue to weld with the next section of the steel pipe.

[0019] Furthermore, in the step S1, a soil pit is excavated on the bottom plane of the working well at a distance of 5m to 7m from the water pipe opening. The diameter of the working well is generally more than 20 meters. A soil pit is excavated on the bottom plane of the working well at a distance of 5m to 7m from the water pipe opening to facilitate the welding of the steel pipe and the advancement to the water pipe after welding. The excavated soil pit can realize overhead welding construction of the outer arc surface of the bottom of the steel pipe and ensure that the welding of the weld meets the quality requirements. During the construction process, the workers enter the soil pit and perform overhead welding construction on the outer arc surface of the bottom of the steel pipe.

[0020] Furthermore, in step S1, the length, width and depth of the earth pit are (1.4-1.6) m, (1.1-1.3) m and (1.1-1.3) m respectively. The earth pit of this size is convenient for workers to enter the earth pit to perform overhead welding on the outer arc surface of the bottom of the steel pipe.

[0021] Furthermore, in step S2, the steel rail includes two parallel steel bars, and when the steel pipe is placed on the steel rail, the two parallel steel bars are respectively located on both sides of the symmetry axis of the steel pipe. The steel rail can facilitate the smooth advancement of the steel pipe.

[0022] Furthermore, in the step S3, the butt joint interval of the steel pipe is 9.5 mm to 10.5 mm. The butt joint interval of the steel pipe is reserved to facilitate the welding of the steel pipe.

[0023] Furthermore, in step S3, the length of each section of the steel pipe is 5m to 7m, which is convenient for welding between each section of the steel pipe and for pushing the steel pipe into the water pipe after welding.

[0024] Furthermore, in the step S4, the positioning steel plate is provided with bolt holes, and the plumb bob is connected to the positioning steel plate by bolts. The plumb bob is connected to the positioning steel plate to facilitate the positioning of the steel pipe in terms of elevation and verticality.

[0025] Furthermore, in the step S5, the thickness of the ceramic liner is set to 9.5 mm to 10.5 mm. The ceramic liner used plays an important protective role in the welding process. Due to the high temperature and thermal stress during welding, the ceramic liner can effectively isolate the weldment and other materials to prevent them from being damaged. In addition, the ceramic liner can also help maintain the shape and size of the weld, improve welding quality and production efficiency, and will not cause harm to the human body and the environment. In addition, the use of ceramic liners can avoid the generation of pores and slag in the weld, and will not affect the material of the steel pipe.

[0026] Furthermore, in step S6, the current of the welding machine is 240A to 280A, and the voltage of the welding machine is 24V to 28V; and / or

[0027] The diameter of the welding wire is 1.1 mm to 1.3 mm.

[0028] Furthermore, in the step S8, the grinding process is to grind the surface of the weld of the steel pipe with a hand grinding wheel. In addition, the ultrasonic testing is ultrasonic testing of the weld of the steel structure, so as to detect whether there are defects such as penetration (i.e., whether the depth is reached), slag inclusion, pores, undercut, etc. inside the steel pipe.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The present invention provides a welding construction method for thick steel pipes that penetrate the soil layer in a working well, including digging a soil pit at the bottom of the working well, laying steel rails, butting steel pipes and setting up an internal platform for steel pipes, welding positioning steel plates, installing ceramic liners, welding seams, welding the inner top and outer bottom of steel pipes, post-weld treatment of welds, and pushing steel pipes into water pipes. By digging a soil pit at the bottom of the working well, it is possible to perform overhead welding on the outer arc surface of the bottom of the steel pipe, and ensure that the welding of the weld meets the quality requirements. By setting up a platform, it is convenient for workers to stand on the platform to perform overhead welding on the welds at the inner tops of two sections of steel pipes. Positioning welding of steel pipes can avoid misalignment of steel pipe butts, and has the advantage of better welding fusion. In addition, when welding the weld seams, the weld seams are cleaned at the root after the first weld, so that the weld root can avoid the formation of pores and slag inclusions, and it is also conducive to rework.

[0031] (2) The present invention provides a welding construction method for thick steel pipes penetrating the soil layer in a working well. By welding the positioning steel plates, the positioning steel plates can be connected respectively using plumb bobs to perform elevation compensation and verticality control, thereby ensuring better positioning and welding between the two sections of steel pipes and avoiding misalignment of the steel pipes.

[0032] (3) The present invention is a welding construction method for thick steel pipes that penetrate the soil layer in a working well. The ceramic liner used plays an important protective role in the welding process. Due to the high temperature and thermal stress during welding, the ceramic liner can effectively isolate the weldment and other materials to prevent them from being damaged. In addition, the ceramic liner can also help maintain the shape and size of the weld, improve welding quality and production efficiency, and will not cause harm to the human body and the environment. In addition, the use of ceramic liners can avoid the generation of pores and slag in the weld, and will not affect the material of the steel pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 paying creative work.

[0034] Figure 1 It is a schematic structural diagram of two sections of steel pipes after welding in a welding construction method of a thick steel pipe penetrating a soil layer in a working well according to the present invention.

[0035] Figure 2 It is a structural schematic diagram of a welding construction method of a thick steel pipe penetrating a soil layer in a working well according to the present invention, in which a top iron is used to push a water pipe after two sections of steel pipes are welded.

[0036] Figure 3 The present invention is a structural schematic diagram of butt-jointing two sections of steel pipes in a welding construction method of a thick steel pipe penetrating a soil layer in a working well.

[0037] Reference numerals:

[0038] Working well 1, earth pit 2, water pipe opening 3, steel pipe 4, outer arc surface 41, inner top 42, weld 5, platform 6, docking interval 7, positioning steel plate 8, top iron 9. DETAILED DESCRIPTION

[0039] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0040] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. In the present invention, the singular forms "a", "said" and "the" used in the embodiments and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0041] The following describes the invention in conjunction with specific embodiments.

[0042] Example 1

[0043] This embodiment is based on a welding construction method for a thick steel pipe penetrating the soil layer in a working well, please refer to Figures 1 to 3 , including the following steps:

[0044] S1, excavating a soil pit at the bottom of the working pit: excavating a soil pit 2 on the bottom plane of the working pit 1;

[0045] Among them, in step S1, a soil pit 2 is excavated at a distance of 6m from the water pipe opening 3 on the bottom plane of the working well 1. Among them, the diameter of the working well 1 is generally more than 20 meters. The soil pit 2 is excavated at a distance of 6m from the water pipe opening 3 on the bottom plane of the working well 1, which is convenient for welding the steel pipe 4 and advancing it to the water pipe after welding. The excavated soil pit 2 can realize overhead welding construction of the outer arc surface 41 at the bottom of the steel pipe 4, and ensure that the welding of the weld 5 meets the quality requirements. During the construction process, the workers enter the soil pit 2 and perform overhead welding construction on the outer arc surface 41 at the bottom of the steel pipe 4.

[0046] In this embodiment, the length, width and depth of the earth pit 2 are 1.5m, 1.2m and 1.2m respectively. The earth pit 2 of this size is convenient for workers to enter the earth pit 2 to perform overhead welding on the outer arc surface 41 at the bottom of the steel pipe 4.

[0047] S2. Laying rails: Laying rails (not shown) on the bottom plane of the working pit 1 relative to the position outside the water pipe opening 3 to facilitate the steel pipe 4 to push the water pipe, and the rails pass above the soil pit 2;

[0048] In this embodiment, the steel rail includes two parallel steel bars. When the steel pipe 4 is placed on the steel rail, the two parallel steel bars are respectively located on both sides of the symmetry axis of the steel pipe 4. The steel rail can facilitate the steel pipe 4 to be smoothly pushed forward.

[0049] S3, butt joint of steel pipes and setting up internal platform of steel pipes: hoist two sections of steel pipes 4 into the working well 1 and place them on the rails, and place the butt joint of the two sections of steel pipes 4 to be welded on the earth pit 2, and set up a platform 6 for easy welding at the end of one section of the steel pipe 4 near the butt joint, and adjust the butt joint interval 7 of the two sections of steel pipes 4;

[0050] In this embodiment, the butt joint interval 7 of the steel pipe 4 is 10 mm. The butt joint interval 7 of the steel pipe 4 is reserved to facilitate welding of the steel pipe 4. In this embodiment, the length of each section of the steel pipe 4 is 6 m. The steel pipe 4 of this length is convenient for welding between each section of the steel pipe 4, and is easy to push into the water pipe after welding.

[0051] S4, welding of positioning steel plates: welding positioning steel plates 8 at the relative positions of the two ends of each section of steel pipe 4, and connecting the positioning steel plates 8 with plumb bobs to perform elevation compensation and verticality control;

[0052] Among them, the positioning steel plate 8 is provided with bolt holes, and the plumb bob hanging wire is connected to the positioning steel plate 8 by bolts. Among them, the plumb bob hanging wire is connected to the positioning steel plate 8, which is convenient for positioning the elevation and verticality of the steel pipe 4.

[0053] S5, installing ceramic liner: installing a ceramic liner (not shown in the figure) at the butt interval 7 between the two sections of steel pipe 4;

[0054] In this embodiment, the thickness of the ceramic liner is set to 10 mm. Among them, the ceramic liner used plays an important protective role in the welding process. Due to the high temperature and thermal stress during welding, the ceramic liner can effectively isolate the weldment and other materials to prevent them from being damaged. In addition, the ceramic liner can also help maintain the shape and size of the weld, improve the welding quality and production efficiency, and will not cause harm to the human body and the environment. In addition, the use of ceramic liners can avoid the generation of pores and slag in the weld, and will not affect the material of the steel pipe.

[0055] S6. Steel pipe positioning welding: Under the protection of carbon dioxide gas, a welding machine and welding wire are used to simultaneously weld the midpoints of the left and right sides and the upper and lower midpoints of the steel pipe 4 to fix the steel pipe 4;

[0056] S6. Welding: The weld types on the left and right sides of the steel pipe weld adopt double-sided V-shaped grooves, and after the first welding of the inner and outer base layers of the weld, the weld is first cleaned and then the second welding is performed;

[0057] When welding the weld, first check whether the ceramic liner and the steel pipe 4 are tightly fitted, so as to facilitate the welding of the weld. In addition, after the first welding, the weld is cleaned to remove the scale, welding slag, oil stains and other impurities formed after the welding of the weld, exposing the surface of the parent material for the second welding. The purpose of cleaning the weld is to ensure the quality and strength of the weld.

[0058] In this embodiment, the current of the welding machine is 260A, the voltage of the welding machine is 26V; and the diameter of the welding wire is 1.2mm.

[0059] S7, welding the inner top and outer bottom of the steel pipe: using the platform 6 set up in step S3, the weld seams 5 of the inner tops 42 of the two sections of the steel pipe 4 are welded overhead, and using the soil pit 2 excavated in step S1, the weld seams of the outer bottoms of the two sections of the steel pipe 4 are welded overhead;

[0060] Among them, due to the limitation of the working surface in the working pit 1, the steel pipe 4 is placed on the rail and cannot be turned over or moved during welding. Welding requires the steel pipe to be pushed flat into the water pipe. Therefore, by excavating the soil pit 2, the outer arc surface 41 at the bottom of the steel pipe 4 can be welded overhead. In addition, by setting up the platform 6, it is convenient for workers to stand on the platform 6 to weld the welds of the inner top 42 of the two sections of the steel pipe 4 overhead.

[0061] S8, post-weld treatment of the weld: use a hand grinding wheel to grind the surface of the weld 5 of the steel pipe 4, and then perform ultrasonic testing on the weld 5. After the ultrasonic testing is qualified, the weld 5 is coated with an anti-corrosion coating for protection;

[0062] Among them, ultrasonic testing is ultrasonic testing of steel structure welds to detect whether there are defects such as weld penetration (i.e. whether the depth has been reached), slag inclusions, pores, and undercuts inside the steel pipe.

[0063] S9, pushing the steel pipe into the water pipeline: the steel pipe 4 after completing step S8 is pushed into the water pipeline using the top iron 9, and the end of the steel pipe 4 is allowed to stay on the earth pit 2, and then continue to be welded with the next section of the steel pipe.

[0064] Example 2

[0065] This embodiment is based on a welding construction method for a thick steel pipe penetrating the soil layer in a working well, please refer to Figures 1 to 3 , including the following steps:

[0066] S1, excavating a soil pit at the bottom of the working pit: excavating a soil pit 2 on the bottom plane of the working pit 1;

[0067] Among them, in step S1, a soil pit 2 is excavated at a distance of 5m from the water pipe opening 3 on the bottom plane of the working well 1. Among them, the diameter of the working well 1 is generally more than 20 meters. The soil pit 2 is excavated at a distance of 5m from the water pipe opening 3 on the bottom plane of the working well 1, which is convenient for welding the steel pipe 4 and advancing it to the water pipe after welding. The excavated soil pit 2 can realize overhead welding construction of the outer arc surface 41 at the bottom of the steel pipe 4, and ensure that the welding of the weld 5 meets the quality requirements. During the construction process, the workers enter the soil pit 2 and perform overhead welding construction on the outer arc surface 41 at the bottom of the steel pipe 4.

[0068] In this embodiment, the length, width and depth of the earth pit 2 are 1.4m, 1.1m and 1.1m respectively. The earth pit 2 of this size is convenient for workers to enter the earth pit 2 to perform overhead welding on the outer arc surface 41 at the bottom of the steel pipe 4.

[0069] S2. Laying rails: Laying rails (not shown) on the bottom plane of the working pit 1 relative to the position outside the water pipe opening 3 to facilitate the steel pipe 4 to push the water pipe, and the rails pass above the soil pit 2;

[0070] In this embodiment, the steel rail includes two parallel steel bars. When the steel pipe 4 is placed on the steel rail, the two parallel steel bars are respectively located on both sides of the symmetry axis of the steel pipe 4. The steel rail can facilitate the steel pipe 4 to be smoothly pushed forward.

[0071] S3, butt joint of steel pipes and setting up internal platform of steel pipes: hoist two sections of steel pipes 4 into the working well 1 and place them on the rails, and place the butt joint of the two sections of steel pipes 4 to be welded on the earth pit 2, and set up a platform 6 for easy welding at the end of one section of the steel pipe 4 near the butt joint, and adjust the butt joint interval 7 of the two sections of steel pipes 4;

[0072] In this embodiment, the butt joint interval 7 of the steel pipe 4 is 9.5 mm. The butt joint interval 7 of the steel pipe 4 is reserved to facilitate welding of the steel pipe 4. In this embodiment, the length of each section of the steel pipe 4 is 5 m. The steel pipe 4 of this length is convenient for welding between each section of the steel pipe 4, and is easy to push into the water pipe after welding.

[0073] S4, welding of positioning steel plates: welding positioning steel plates 8 at the relative positions of the two ends of each section of steel pipe 4, and connecting the positioning steel plates 8 with plumb bobs to perform elevation compensation and verticality control;

[0074] Among them, the positioning steel plate 8 is provided with bolt holes, and the plumb bob hanging wire is connected to the positioning steel plate 8 by bolts. Among them, the plumb bob hanging wire is connected to the positioning steel plate 8, which is convenient for positioning the elevation and verticality of the steel pipe 4.

[0075] S5, installing ceramic liner: installing a ceramic liner (not shown in the figure) at the butt interval 7 between the two sections of steel pipe 4;

[0076] In this embodiment, the thickness of the ceramic liner is set to 9.5 mm. Among them, the ceramic liner used plays an important protective role in the welding process. Due to the high temperature and thermal stress during welding, the ceramic liner can effectively isolate the weldment and other materials to prevent them from being damaged. In addition, the ceramic liner can also help maintain the shape and size of the weld, improve the welding quality and production efficiency, and will not cause harm to the human body and the environment. In addition, the use of ceramic liner can avoid the generation of pores and slag in the weld, and will not affect the material of the steel pipe.

[0077] S6. Steel pipe positioning welding: Under the protection of carbon dioxide gas, a welding machine and welding wire are used to simultaneously weld the left and right midpoints and the upper and lower midpoints of the steel pipe 4 to fix the steel pipe 4;

[0078] S6. Welding: The weld types on the left and right sides of the steel pipe weld adopt double-sided V-shaped grooves, and after the first welding of the inner and outer base layers of the weld, the weld is first cleaned and then the second welding is performed;

[0079] When welding the weld, first check whether the ceramic liner and the steel pipe 4 are tightly fitted, so as to facilitate the welding of the weld. In addition, after the first welding, the weld is cleaned to remove the scale, welding slag, oil stains and other impurities formed after the welding of the weld, exposing the surface of the parent material for the second welding. The purpose of cleaning the weld is to ensure the quality and strength of the weld.

[0080] In this embodiment, the current of the welding machine is 240A, the voltage of the welding machine is 24V; and the diameter of the welding wire is 1.1mm.

[0081] S7, welding the inner top and outer bottom of the steel pipe: using the platform 6 set up in step S3, the weld seams 5 of the inner tops 42 of the two sections of the steel pipe 4 are welded overhead, and using the soil pit 2 excavated in step S1, the weld seams of the outer bottoms of the two sections of the steel pipe 4 are welded overhead;

[0082] Among them, due to the limitation of the working surface in the working pit 1, the steel pipe 4 is placed on the rail and cannot be turned over or moved during welding. Welding requires the steel pipe to be pushed flat into the water pipe. Therefore, by excavating the soil pit 2, the outer arc surface 41 at the bottom of the steel pipe 4 can be welded overhead. In addition, by setting up the platform 6, it is convenient for workers to stand on the platform 6 to weld the welds of the inner top 42 of the two sections of the steel pipe 4 overhead.

[0083] S8, post-weld treatment of the weld: use a hand grinding wheel to grind the surface of the weld 5 of the steel pipe 4, and then perform ultrasonic testing on the weld 5. After the ultrasonic testing is qualified, the weld 5 is coated with an anti-corrosion coating for protection;

[0084] Among them, ultrasonic testing is ultrasonic testing of steel structure welds to detect whether there are defects such as weld penetration (i.e. whether the depth has been reached), slag inclusions, pores, and undercuts inside the steel pipe.

[0085] S9, pushing the steel pipe into the water pipeline: the steel pipe 4 after completing step S8 is pushed into the water pipeline using the top iron 9, and the end of the steel pipe 4 is allowed to stay on the earth pit 2, and then continue to be welded with the next section of the steel pipe.

[0086] Example 3

[0087] This embodiment is based on a welding construction method for a thick steel pipe penetrating the soil layer in a working well, please refer to Figures 1 to 3 , including the following steps:

[0088] S1, excavating a soil pit at the bottom of the working pit: excavating a soil pit 2 on the bottom plane of the working pit 1;

[0089] Among them, in step S1, a soil pit 2 is excavated at 7m away from the water pipe opening 3 on the bottom plane of the working well 1. Among them, the diameter of the working well 1 is generally more than 20 meters. The soil pit 2 is excavated at 5m to 7m away from the water pipe opening 3 on the bottom plane of the working well 1, which is convenient for welding the steel pipe 4 and advancing it to the water pipe after welding. The excavated soil pit 2 can realize overhead welding construction of the outer arc surface 41 at the bottom of the steel pipe 4, and ensure that the welding of the weld 5 meets the quality requirements. During the construction process, the workers enter the soil pit 2 and perform overhead welding construction on the outer arc surface 41 at the bottom of the steel pipe 4.

[0090] In this embodiment, the length, width and depth of the earth pit 2 are 1.6m, 1.3m and 1.3m respectively. The earth pit 2 of this size is convenient for workers to enter the earth pit 2 to perform overhead welding on the outer arc surface 41 at the bottom of the steel pipe 4.

[0091] S2. Laying rails: Laying rails (not shown) on the bottom plane of the working pit 1 relative to the position outside the water pipe opening 3 to facilitate the steel pipe 4 to push the water pipe, and the rails pass above the soil pit 2;

[0092] In this embodiment, the steel rail includes two parallel steel bars. When the steel pipe 4 is placed on the steel rail, the two parallel steel bars are respectively located on both sides of the symmetry axis of the steel pipe 4. The steel rail can facilitate the steel pipe 4 to be smoothly pushed forward.

[0093] S3, butt joint of steel pipes and setting up internal platform of steel pipes: hoist two sections of steel pipes 4 into the working well 1 and place them on the rails, and place the butt joint of the two sections of steel pipes 4 to be welded on the earth pit 2, and set up a platform 6 for easy welding at the end of one section of the steel pipe 4 near the butt joint, and adjust the butt joint interval 7 of the two sections of steel pipes 4;

[0094] In this embodiment, the butt joint interval 7 of the steel pipe 4 is 10.5 mm. The butt joint interval 7 of the steel pipe 4 is reserved to facilitate welding of the steel pipe 4. In this embodiment, the length of each section of the steel pipe 4 is 7 m. The steel pipe 4 of this length is convenient for welding between each section of the steel pipe 4, and is easy to push into the water pipe after welding.

[0095] S4, welding of positioning steel plates: welding positioning steel plates 8 at the relative positions of the two ends of each section of steel pipe 4, and connecting the positioning steel plates 8 with plumb bobs to perform elevation compensation and verticality control;

[0096] Among them, the positioning steel plate 8 is provided with bolt holes, and the plumb bob hanging wire is connected to the positioning steel plate 8 by bolts. Among them, the plumb bob hanging wire is connected to the positioning steel plate 8, which is convenient for positioning the elevation and verticality of the steel pipe 4.

[0097] S5, installing ceramic liner: installing a ceramic liner (not shown in the figure) at the butt interval 7 between the two sections of steel pipe 4;

[0098] In this embodiment, the thickness of the ceramic liner is set to 10.5 mm. Among them, the ceramic liner used plays an important protective role in the welding process. Due to the high temperature and thermal stress during welding, the ceramic liner can effectively isolate the weldment and other materials to prevent them from being damaged. In addition, the ceramic liner can also help maintain the shape and size of the weld, improve the welding quality and production efficiency, and will not cause harm to the human body and the environment. In addition, the use of ceramic liners can avoid the generation of pores and slag in the weld, and will not affect the material of the steel pipe.

[0099] S6. Steel pipe positioning welding: Under the protection of carbon dioxide gas, a welding machine and welding wire are used to simultaneously weld the midpoints of the left and right sides and the upper and lower midpoints of the steel pipe 4 to fix the steel pipe 4;

[0100] S6. Welding: The weld types on the left and right sides of the steel pipe weld adopt double-sided V-shaped grooves, and after the first welding of the inner and outer base layers of the weld, the weld is first cleaned and then the second welding is performed;

[0101] When welding the weld, first check whether the ceramic liner and the steel pipe 4 are tightly fitted, so as to facilitate the welding of the weld. In addition, after the first welding, the weld is cleaned to remove the scale, welding slag, oil stains and other impurities formed after the welding of the weld, exposing the surface of the parent material for the second welding. The purpose of cleaning the weld is to ensure the quality and strength of the weld.

[0102] In this embodiment, the current of the welding machine is 280A, the voltage of the welding machine is 28V; and the diameter of the welding wire is 1.3mm.

[0103] S7, welding the inner top and outer bottom of the steel pipe: using the platform 6 set up in step S3, the weld seams 5 of the inner tops 42 of the two sections of the steel pipe 4 are welded overhead, and using the soil pit 2 excavated in step S1, the weld seams of the outer bottoms of the two sections of the steel pipe 4 are welded overhead;

[0104] Among them, due to the limitation of the working surface in the working pit 1, the steel pipe 4 is placed on the rail and cannot be turned over or moved during welding. Welding requires the steel pipe to be pushed flat into the water pipe. Therefore, by excavating the soil pit 2, the outer arc surface 41 at the bottom of the steel pipe 4 can be welded overhead. In addition, by setting up the platform 6, it is convenient for workers to stand on the platform 6 to weld the welds of the inner top 42 of the two sections of the steel pipe 4 overhead.

[0105] S8, post-weld treatment of the weld: use a hand grinding wheel to grind the surface of the weld 5 of the steel pipe 4, and then perform ultrasonic testing on the weld 5. After the ultrasonic testing is qualified, the weld 5 is coated with an anti-corrosion coating for protection;

[0106] Among them, ultrasonic testing is ultrasonic testing of steel structure welds to detect whether there are defects such as weld penetration (i.e. whether the depth has been reached), slag inclusions, pores, and undercuts inside the steel pipe.

[0107] S9, pushing the steel pipe into the water pipeline: the steel pipe 4 after completing step S8 is pushed into the water pipeline using the top iron 9, and the end of the steel pipe 4 is allowed to stay on the earth pit 2, and then continue to be welded with the next section of the steel pipe.

[0108] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A welding construction method for thick steel pipes penetrating soil layers in a working well, characterized in that: The following steps are involved: S1. Excavating a soil pit at the bottom of the working pit: excavating a soil pit on the bottom plane of the working pit; S2. Laying rails: Laying rails on the bottom plane of the working pit at a position outside the water pipe opening to facilitate the steel pipe to push the water pipe, and the rails pass above the soil pit; S3, butt joint of steel pipes and setting up internal platform of steel pipes: hoist two sections of steel pipes into the working pit and place them on the steel rails, place the butt joint of the two sections of steel pipes to be welded on the soil pit, and set up a platform for welding at the end of one section of the steel pipe near the butt joint, and adjust the butt joint interval of the two sections of steel pipes; S4. Positioning steel plate welding: Positioning steel plates are welded at the relative positions of the two ends of each steel pipe, and the positioning steel plates are connected respectively with plumb bobs to perform elevation compensation and verticality control; S5. Install ceramic liner: Install ceramic liner at the butt joint of two steel pipes; S6. Steel pipe positioning welding: Under the protection of carbon dioxide gas, use a welding machine and welding wire to weld the midpoints of the left and right sides and the upper and lower midpoints of the steel pipe at the same time to fix the steel pipe; S6. Welding: The weld types on the left and right sides of the steel pipe weld adopt double-sided V-shaped grooves, and after the first welding of the inner and outer base layers of the weld, the weld is first cleaned and then the second welding is performed; S7, welding the inner top and outer bottom of the steel pipe: using the platform set up in step S3 to perform overhead welding on the welds on the inner top of the two sections of the steel pipe, and using the soil pit excavated in step S1 to perform overhead welding on the welds on the outer bottom of the two sections of the steel pipe; S8. Post-weld treatment of welds: Grind the surface of the welds of the steel pipes, and then perform ultrasonic testing on the welds. After the ultrasonic testing is qualified, apply anti-corrosion coating to the welds for protection; S9, pushing the steel pipe into the water pipeline: using a top iron to push the steel pipe after completing step S8 into the water pipeline, and making the end of the steel pipe stay on the earth pit, and then continue to weld with the next section of the steel pipe.

2. A welding construction method for thick steel pipes based on a working well penetrating the soil layer as claimed in claim 1, characterized in that: In the step S1, a soil pit is excavated on the bottom plane of the working well at a distance of 5m to 7m from the water pipe opening.

3. A welding construction method for thick steel pipes penetrating soil layers based on a working well as claimed in claim 1, characterized in that: In the step S1, the length, width and depth of the soil pit are (1.4-1.6) m, (1.1-1.3) m and (1.1-1.3) m respectively.

4. A welding construction method for thick steel pipes based on a working well penetrating the soil layer as claimed in claim 1, characterized in that: In the step S2, the steel rail includes two parallel steel bars. When the steel pipe is placed on the steel rail, the two parallel steel bars are respectively located on both sides of the symmetry axis of the steel pipe.

5. A welding construction method for thick steel pipes based on a working well penetrating the soil layer as claimed in claim 1, characterized in that: In the step S3, the butt joint interval of the steel pipes is 9.5 mm to 10.5 mm.

6. A welding construction method for thick steel pipes penetrating soil layers based on a working well as claimed in claim 1, characterized in that: In the step S3, the length of each section of the steel pipe is 5m to 7m.

7. A welding construction method for thick steel pipes based on a working well penetrating the soil layer as claimed in claim 1, characterized in that: In the step S4, the positioning steel plate is provided with bolt holes, and the plumb bob wire is connected to the positioning steel plate via bolts.

8. A welding construction method for thick steel pipes based on a working well penetrating the soil layer as claimed in claim 1, characterized in that: In the step S5, the thickness of the ceramic liner is set to 9.5 mm to 10.5 mm.

9. A welding construction method for thick steel pipes penetrating soil layers based on a working well as claimed in claim 1, characterized in that: In step S6, the current of the welding machine is 240A-280A, and the voltage of the welding machine is 24V-28V; and / or The diameter of the welding wire is 1.1 mm to 1.3 mm.

10. A welding construction method for thick steel pipes based on a working well penetrating a soil layer as claimed in claim 1, characterized in that: In the step S8, the grinding process is to grind the surface of the weld of the steel pipe using a hand grinding wheel.

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