Post-weld cooling device for water fire correction process of austenitic stainless steel vessel welding

Abstract

The application discloses a post-welding cooling device for an austenitic stainless steel container welding water fire correction process, which comprises a spraying machine composed of a machine base, supporting feet, a water storage tank, a water pump and a spraying channel. Concaves for lifting the spraying machine are arranged on both sides of the machine base, and weights are arranged in the concaves. Two fixed pulleys are respectively a first fixed pulley located above the concaves and a second fixed pulley located at the same height as the first fixed pulley. Rectangular housings fixedly connected to the outer wall of the spraying channel are arranged on both sides of a row of spraying heads. The second fixed pulley is rotatably arranged in the rectangular housing. The wiping mechanism comprises a wiping cloth seat connected with a hanging rope, the wiping cloth seat is provided with a plurality of pairs of wiping cloth bodies, each pair of wiping cloth bodies comprises two symmetrically arranged elastic strips. A movable baffle plate is arranged in the spraying channel, a rubber ring matched with the spraying channel is arranged on the baffle plate, a magnet or an electromagnet is arranged on the outer wall of the spraying channel, and the baffle plate is driven to move by moving the magnet or the electromagnet.

Description

Technical Field

[0001] This invention relates to a post-weld cooling device for the water-fire correction process of welding austenitic stainless steel containers. Background Technology

[0002] During the research and manufacturing of a cryogenic liquid tank, severe welding deformation occurred after welding repairs were performed on a longitudinal seam in the stainless steel container. The repaired area of ​​the longitudinal seam partially collapsed inwards. Figure 1 As shown. Measurements indicate the deformation and indentation reached 14mm, as... Figure 2 As shown in the drawing, the cylinder's roundness deflection must not exceed 2.6mm, and the current deformation and indentation do not meet the requirements. If this problem cannot be resolved, subsequent work will be hindered, negatively impacting the overall R&D and manufacturing process. The causes of the deformation are analyzed as follows: The cylinder wall thickness is 13mm, and the total length of the longitudinal seam is 1800mm. Due to welding equipment issues, incomplete fusion and porosity defects occurred within the weld, with a defect depth of 5-6mm. The repair length is 1300mm, and the repair method involves grinding the front side to remove the defects, with a grinding depth of 6-7mm, using manual argon arc welding, and an interpass temperature <100℃. Although heat input was strictly controlled according to the repair process, severe angular deformation still occurred due to the characteristics of austenitic stainless steel, such as low thermal conductivity, poor thermal conductivity, and a large coefficient of linear expansion. Welding deformation can generally be resolved through mechanical straightening or flame heating straightening. Mechanical straightening is generally suitable for simple structural shapes or thin-plate components, while flame heating straightening is generally suitable for low-carbon steel and low-alloy steel, and the heating temperature must be strictly controlled. The applicant's deformed structure is a cylindrical body. Since the multiple cylindrical sections have been assembled together, the structure is large, long, and thick-walled, making mechanical rounding correction impossible using a multi-roll mill. If flame heating correction is used, the heating temperature cannot be precisely controlled because the cylindrical body is made of SA240 304 austenitic stainless steel. If the temperature remains in the sensitive area for too long, it can easily cause intergranular corrosion of the stainless steel, which will have an adverse effect on the use of the material. Therefore, flame heating correction is not suitable.

[0003] Patent CN115446153A discloses a method for skip-type water-fire straightening of welded thin steel plates for marine applications. The method includes: first, preparing the necessary tools for water-fire straightening; second, selecting the thin steel plate to be straightened and developing a straightening plan; third, during operation, using one hand to hold a heating gun for heating and the other hand to hold a specially designed cooling nozzle for cooling, ensuring timely connection between heating and cooling; fourth, using a high-temperature flame to mark the protruding parts of the deformed steel plate as circular points, and simultaneously applying heated water for cooling, with the heating points arranged in an array and staggered between rows; fifth, heating the deformed steel plate through individual circular points, controlling the diameter and temperature of the heating points; and sixth, checking the overall straightening status and surface finish of the deformed steel plate. This patent employs a method where a certain distance is maintained between the heating gun and the cooling nozzle, allowing for simultaneous heating and water cooling. Patent CN113894181A discloses a semi-automatic water-fire straightening device for a ship's mainboard structure. The operation involves a flame nozzle in front and a water spray nozzle behind. During movement, the flame nozzle sprays fire onto the steel plate, and the water spray nozzle then sprays water onto the burned area. A certain distance is maintained between the flame nozzle and the water spray nozzle, allowing for simultaneous heating and cooling. This method is not post-weld cooling (i.e., not cooling the entire weld after each weld step), but rather cooling the weld immediately after the first section is welded. While seemingly more efficient, this method fails to utilize the post-weld air cooling mechanism. Furthermore, cooling before the weld is fully formed is not effective for deformation control. Simultaneous welding and cooling requires a connecting structure between the welding torch and the cooling torch (or cooling structure) to maintain the required distance, placing higher demands on the overall mechanism design and making it difficult to achieve. Summary of the Invention

[0004] The purpose of this invention is to overcome the deficiencies in the existing technology and provide a post-weld cooling device for austenitic stainless steel containers, which ensures that the deformed area of ​​the cylinder is basically restored, with a deflection error of 1.6mm, meeting the technical requirement of <2.6mm in the drawings. This timely resolution of the welding deformation problem ensures the orderly progress of the applicant's subsequent research and development and manufacturing work on cryogenic tanks.

[0005] To achieve the above objectives, the technical solution of the present invention is to design a post-weld cooling device for austenitic stainless steel containers, comprising the following sequential process steps:

[0006] S1: Remove the weld seam on the inside of the cylinder by grinding with a grinder to a depth of 4mm;

[0007] S2: Re-weld the inner weld seam of the cylinder;

[0008] The first weld was a self-fusion weld without filler wire, and the weld was immediately forced to cool using a cooling device after welding. Subsequent filler welds were welded with filler wire, and the welds were forced to cool immediately after each weld. Radiographic testing was performed 24 hours after welding. The welds on the inner side of the cylinder that had already undergone angular deformation were welded again, and the entire weld was forced to cool immediately after each weld, which effectively solved the problem of cylinder welding deformation.

[0009] A further technical solution is to use a sprayer as the cooling device, and to use the sprayer to spray water onto the weld to cool it down.

[0010] A further technical solution is to spray the weld seam with water and then wipe it dry, using the residual heat to dry the water vapor; after drying, measure the temperature, and control the interpass temperature to be <80℃ before welding.

[0011] A further technical solution is that, in step S2, the welding current is 140A, the welding machine voltage is 13-14V, and the welding speed is 8-12cm / min.

[0012] The present invention also provides a technical solution for a post-weld cooling device for the welding water and fire straightening process of austenitic stainless steel containers, including a spray machine. The spray machine consists of a base, support legs, a water tank, a water pump, and a spray channel. The support legs are fixedly installed below the base, and the water tank and water pump are fixedly installed on the base. The spray channel is connected to the water tank through a water pipe, and a water pump is installed on the water pipe. Several spray heads are spaced apart on the spray channel.

[0013] A further technical solution involves a spray channel with a length equal to or greater than the length of the weld to be corrected. A movable blocking plate is installed within the spray channel, with a rubber ring fitted to the channel. The length of the spray channel, being equal to or greater than the length of the weld to be corrected, allows for simultaneous cooling of the entire weld, avoiding the poor correction effect caused by a single nozzle cooling the weld sequentially along its length. The movable blocking plate allows for adjustment of its position according to the weld length, preventing waste of cooling water and ensuring that the cooling water is sprayed only onto the weld.

[0014] The advantages and beneficial effects of this invention are as follows: the inner weld of the cylinder that has already undergone angular deformation is re-welded, and the welded seam is immediately cooled down immediately after each weld is completed, which can effectively solve the problem of cylinder welding deformation.

[0015] The length of the spray channel is greater than or equal to the length of the weld to be corrected. This allows for simultaneous cooling of the entire weld, avoiding the poor correction effect caused by a single nozzle cooling the weld sequentially along its length. Furthermore, movable baffles are installed in the channel, allowing adjustment of their position according to the weld length to prevent water waste and ensure that cooling water is sprayed only onto the weld area. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the longitudinal seam welding deformation of a cryogenic liquid tank body in the prior art;

[0017] Figure 2 yes Figure 1 A schematic diagram of the deformation at the concave area;

[0018] Figure 3 This is a schematic diagram illustrating the effect of welding repair on the test plate in Example 1;

[0019] Figure 4 Yes Figure 3 A schematic diagram illustrating the effect of forced cooling of the weld area by spraying water.

[0020] Figure 5 This is a schematic diagram of the external inspection of the cylinder of a second embodiment of the post-weld cooling device for austenitic stainless steel containers according to the present invention.

[0021] Figure 6 This is a schematic diagram of the cylindrical arc detection according to Embodiment 2 of the present invention;

[0022] Figure 7 This is a schematic diagram of the deflection accuracy detection in Embodiment 2 of the present invention;

[0023] Figure 8 This is a schematic diagram of Embodiment 3 of the present invention;

[0024] Figure 9 yes Figure 8 A partially enlarged schematic diagram of the end of the central spray channel;

[0025] Figure 10 yes Figure 9 Enlarged schematic diagram of the central magnet and the blocking plate section;

[0026] Figure 11 yes Figure 8 The left view;

[0027] Figure 12 yes Figure 8 A schematic diagram showing the lifting rope, the first fixed pulley, the second fixed pulley, and the rectangular housing is added.

[0028] Figure 13 yes Figure 12 A schematic diagram of the central suspension rope, the first fixed pulley, the second fixed pulley, and the rectangular housing portion;

[0029] Figure 14 yes Figure 13 Enlarged schematic diagram of the rectangular shell section;

[0030] Figure 15 yes Figure 14A magnified view of the left end of the central cloth holder;

[0031] Figure 16 It is after a person puts their hand into the groove Figure 13 A state diagram;

[0032] Figure 17 yes Figure 16 A partially enlarged schematic diagram of the right end portion;

[0033] Figure 18 yes Figure 17 Enlarged schematic diagram of the central rag body and its surrounding components.

[0034] In the diagram: 1. Base; 2. Support leg; 3. Water tank; 4. Water pump; 5. Spray channel; 6. Spray head; 7. Blocking plate; 8. Rubber ring; 9. Magnet; 10. Groove; 11. Cuboid block; 12. Suspension rope; 13. First fixed pulley; 14. Second fixed pulley; 15. Rectangular shell; 16. Cloth holder; 17. Cloth body; 18. Elastic strip; 19. Opening. Detailed Implementation

[0035] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention. Example 1

[0036] The welding process involves uneven heating and cooling. Due to the thick wall of the cylinder and the depth of the defects, after the welder grinds away the defects, each subsequent layer of filler wire welding will cause some shrinkage deformation in the weld. After multiple layers of welding repair, the superposition of welding stress causes the entire welded area at the repair site to sag inward. Therefore, is it possible to re-weld the inner weld of the cylinder (since this invention is a correction process, "re-weld" here refers to the cylinder plate that has already been welded and has undergone angular deformation; in fact, in the correction process, this is the first weld; it's just that compared to the previously welded cylinder plate, this "fire" correction process is a re-weld) to cause angular deformation again to offset the original deformation and restore dimensional accuracy? If this method is adopted, the ensuing question is whether the same part of the stainless steel can be welded multiple times, and whether it can meet the requirements for operation at a minimum temperature of -196°C after strain strengthening.

[0037] Repeated welding repair tests were conducted using SA240 304 strain-strengthened stainless steel of the same material to verify whether its mechanical properties met the specification requirements. The test plate dimensions were 700*300*8mm. First, an automatic welding machine completed one weld. After passing RT inspection, one side of the weld was ground away to a depth of 4mm. Then, the weld was filled using manual TIG welding. This process was repeated five times. To prevent carbide precipitation sensitization and intergranular corrosion, the weld area was immediately subjected to forced cooling with water spray after each weld. Figure 3 , Figure 4 As shown. After passing the RT test, the samples were sent to a third-party testing organization for mechanical property testing in accordance with ASME BPVC VIII.1 Mandatory Appendix 44 and ASME BPVC.IX-2021. All test results met the specification requirements.

[0038] After verifying its feasibility with experimental data, a manual argon arc welding water-fire straightening process was developed for the deformed cylinder on site, as described in Example 2: Example 2

[0039] This invention relates to a welding water and fire straightening process for austenitic stainless steel containers.

[0040] 1. Welding parameters: current 140A, voltage 13~14V, welding speed 8~12cm / min.

[0041] 2. Remove the weld seams on the inside of the cylinder by grinding with a grinder to a depth of 4mm.

[0042] 3. The first weld is a self-fusion weld without wire, and water spraying should be carried out immediately after welding.

[0043] 4. Wipe away the water stains and use the residual heat to dry the moisture.

[0044] 5. Measure the temperature and control the interpass temperature to <80℃ before welding.

[0045] 6. Subsequent filler welding is performed using filler wire, and each weld is immediately cooled by water spray.

[0046] 7. RT flaw detection shall be performed 24 hours after welding is completed.

[0047] After implementing this welding water-fire straightening process, visual inspection and dimensional measurement were performed on the roundness, arc, and deflection dimensional accuracy of the cylinder. Figure 5 , Figure 6 , Figure 7 As shown, the original deformed area has been largely restored, with a deflection error of 1.6mm, meeting the technical requirement of <2.6mm in the drawings. The timely resolution of this welding deformation issue ensured the orderly progress of the company's subsequent research and development and manufacturing work on cryogenic tank containers. Example 3

[0048] like Figures 8 to 18 As shown (for ease of illustration), Figure 8 The hoisting rope, first fixed pulley, second fixed pulley, rectangular housing, and drying mechanism are not shown. Figure 11Only the obscured portion of the suspension rope is shown in dashed lines; other obscured components are not shown. A post-weld cooling device for austenitic stainless steel containers is a spray machine, consisting of a base 1, support legs 2, a water tank 3, a water pump 4, and a spray channel 5. The support legs 2 are fixedly mounted below the base 1, while the water tank 3 and water pump 4 are fixedly mounted on the base 1. The spray channel 5 is connected to the water tank 3 via a water pipe, on which the water pump 4 is mounted. Several spray heads 6 are spaced apart on the spray channel 5. The length of the spray channel 5 is greater than or equal to the length of the weld to be corrected. A movable blocking plate 7 is installed inside the spray channel 5, and a rubber ring 8 adapted to the spray channel 5 is mounted on the blocking plate 7. The blocking plate 7 is made of ferromagnetic material. A magnet 9 or an electromagnet is installed on the outer wall of the spray channel 5. The blocking plate 7 can be moved by moving the magnet 9 or the electromagnet (or the blocking plate 7 is fixedly connected to an operating rod that extends out of the spray channel 5. The spray channel 5 is provided with an opening for the horizontal movement of the operating rod. A rubber strip is fixedly connected to the operating rod. The length of the rubber strip is twice the length of the opening to ensure that the opening is sealed by the rubber strip even if the operating rod is moved to the extreme positions at both ends. The part of the operating rod that extends out of the spray channel 5 is connected to the piston rod of the hydraulic cylinder. The horizontal movement of the operating rod is achieved by driving the hydraulic cylinder to move the blocking plate 7). The base 1 has grooves 10 on both sides for lifting the sprayer. A rectangular block 11, acting as a weight, is placed inside the groove 10. A lifting rope 12 is fixedly connected to the rectangular block 11. The other end of the rope 12 passes through the base 1 and winds around two fixed pulleys before being fixedly connected to a drying mechanism. The two fixed pulleys are a first fixed pulley 13 located above the groove 10 and a second fixed pulley 14 located at the same height as the first fixed pulley 13. The first fixed pulley 13 is rotatably connected to the outer wall of the spray channel 5 or the outer wall of the water pipe. A row of spray heads 6 is arranged along the length of the spray channel 5 (which is also consistent with the length of the weld to be corrected). Rectangular housings 15 are fixedly connected to the outer wall of the spray channel 5 on both sides of the row of spray heads 6. The wheel 14 is rotatably mounted inside the rectangular housing 15. The drying mechanism includes a cuboid block-shaped cloth seat 16 fixedly connected to the hanging rope 12. The cloth seat 16 is located inside the rectangular housing 15. Several pairs of cloth bodies 17 are fixedly connected to the cloth seat 16. Each pair of cloth bodies 17 includes two symmetrically arranged elastic strips 18 (a more preferred embodiment is that each pair of cloth bodies 17 is composed of four centrally symmetrically arranged elastic strips 18, and cloth strips are fixedly pasted on the surface of the elastic strips 18). The part of the two elastic strips 18 that is further away from the cloth seat 16 is further away from the central axis of symmetry. Cloth strips are fixedly pasted on the surface of the elastic strips 18. The rectangular housing 15 has openings 19 in the same number and position as the cloth bodies 17 (for the cloth bodies 17 to extend or retract from the rectangular housing 15).

[0049] The spray channel is designed to be long enough to accommodate welds of varying lengths, allowing for simultaneous cooling of the entire weld length, unlike the sequential cooling process for long welds. For shorter welds, movable baffles provide effective adaptation, preventing water waste.

[0050] When taking the sprayer, the user's hand is inserted into the grooves on both sides of the machine body. A rectangular block is placed in the groove as a weight. The rectangular block is pressed against the upper inner wall of the groove. The drying mechanism extends to wipe the water stains at the weld seam and the sides of the weld seam (specifically: because the user's hand is inserted into the groove, the rectangular block rises to the upper inner wall of the groove, so the cloth holder is no longer lifted by the weight, i.e., the rectangular block. Therefore, the cloth holder falls due to its own weight. In this way, the cloth body on the cloth holder extends out from the opening of the rectangular shell. Thus, the elastic strip inside the cloth body is freed from the constraint of the rectangular shell opening and extends freely, spreading out. The cloth strip is also attached and fixed to the surface of the elastic strip. Therefore, the user's hand is inserted into the groove to achieve the purpose of the cloth strip extending out from the opening and spreading out to wipe the water stains). When the cooling device (sprayer) is picked up after spraying, it is wiped dry at the same time, eliminating the need for manual wiping of water stains. One action achieves two tasks, improving efficiency and reducing labor intensity. (Furthermore, when the person's hand is inserted into the grooves on both sides of the machine base to move the cooling device directly above the weld after welding and before cooling, the extension of the wiping mechanism can help to better position the weld. Therefore, the wiping mechanism not only wiping water stains at the same time as the picking action after spraying, but also achieves the purpose of positioning the weld before cooling.)

[0051] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A post-weld cooling device for a water fire straightening process of an austenitic stainless steel vessel, characterized by, An austenitic stainless steel container welding water fire correction process comprises the following process steps in sequence: S1: the inside weld of the cylinder is polished and removed by a polisher, and the polishing depth is 4mm; S2: the inside weld of the cylinder is welded again; The first weld is self-fusion welding without adding wire, and the weld is immediately cooled by a cooling device after welding; the subsequent filling is wire filling welding, and the weld is immediately cooled by a cooling device after each welding; The cooling device is a spraying machine, which comprises a machine base, supporting feet, a water storage tank, a water pump and a spraying channel. The supporting feet are fixedly arranged below the machine base, the water storage tank and the water pump are fixedly arranged on the machine base, the spraying channel is connected with the water storage tank through a water pipe, the water pump is arranged on the water pipe, a plurality of spraying heads are arranged at intervals on the spraying channel, recesses for lifting the spraying machine are arranged on both sides of the machine base, a cuboid block serving as a weight is arranged in the recess, a lifting rope is fixedly connected to the cuboid block, the other end of the lifting rope passes through the machine base, is wound around two fixed pulleys in sequence and is fixedly connected with a drying mechanism, the two fixed pulleys are a first fixed pulley located above the recess and a second fixed pulley located at the same height as the first fixed pulley, the first fixed pulley is rotatably connected to the outer wall of the spraying channel or the outer wall of the water pipe, and the length of the spraying channel is greater than or equal to the length of the weld to be corrected; a movable baffle is arranged in the spraying channel, and a rubber ring adapted to the spraying channel is arranged on the baffle; The baffle is made of ferromagnetic material, a magnet or an electromagnet is arranged on the outer wall of the spraying channel, and the baffle is driven to move by moving the magnet or the electromagnet; A rectangular shell fixedly connected to the outer wall of the spraying channel is arranged on both sides of a row of spraying heads, and the second fixed pulley is rotatably arranged in the rectangular shell; the drying mechanism comprises a cloth seat in the form of a cuboid block fixedly connected to the lifting rope, the cloth seat is arranged in the rectangular shell, a plurality of pairs of cloth bodies are fixedly connected to the cloth seat, each pair of cloth bodies comprises two symmetrically arranged elastic strips, the portions of the two elastic strips farther away from the cloth seat are farther away from the central symmetry axis, a cloth strip is fixedly attached to the surface of the elastic strip, and the rectangular shell is provided with openings corresponding in number and position to the cloth bodies.

2. The post weld cooling device for water fire straightening process of austenitic stainless steel vessel as claimed in claim 1 wherein, In the S2 step, the welding current is 140A, the welding machine voltage is 13-14V, and the welding speed is 8-12cm / min.

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