Stainless steel pipe welding cooling device and its cooling welding method

Abstract

A stainless steel pipe welding cooling device and its cooling welding method, having a first baffle plate and a second baffle plate, the first baffle plate and the second baffle plate are connected and fixed by two or more than two long strip connecting plates, one end of the connecting plate is welded and fixed with the first baffle plate, and the other end is movably connected with the second baffle plate through a connecting piece. The first baffle plate is fixed with a lead-in mechanism in the center, the lead-in mechanism includes a fastening base and a rotating body, the inlet pipeline and the outlet pipeline pass through the center of the rotating body to enter the inside of the first baffle plate. The device is located inside the pipe to be welded, argon enters the sealed space at a flow rate of 10L / min-15L / min, when the purity of argon in the sealed space is not more than 50ppm, welding is carried out, after 2-3 welding passes, cooling water is input into the sealed space, after forming a cooling water circulation, subsequent welding is carried out. The present application can be arranged on both sides of the weld of the welded pipe body, without the need for additional reinforcement, the inflated air bag is in close contact with the pipe to be welded, and the friction generated can ensure that the device is stably fixed inside the pipe to be welded.

Description

Technical Field

[0001] This invention belongs to the field of welding technology, and specifically relates to a cooling device for welding stainless steel pipes. Background Technology

[0002] In the welding process of austenitic stainless steel, the weld temperature can rise to about 200℃ after every 2-3 welding passes. Excessively high temperatures will severely reduce the weld joint's resistance to intergranular corrosion. Intergranular corrosion will not occur when the interpass temperature is below 150℃. Therefore, controlling the interpass temperature during welding plays a crucial role in ensuring weld quality. Previously, the following methods were mainly used for interpass temperature control in stainless steel welding:

[0003] Method 1: Natural cooling, that is, before welding the next weld, the weld temperature is cooled down to below 150℃ by natural ambient air cooling.

[0004] Method 2: Water cooling, which means cooling the weld temperature to below 150℃ by directly spraying water onto the weld before welding the next weld.

[0005] There is no dedicated cooling device for welding stainless steel pipes in the existing technology, and the existing cooling methods have the following shortcomings:

[0006] First, because stainless steel has a low thermal conductivity, the heat generated by the previous weld cannot be quickly dissipated through natural cooling before the subsequent weld is applied. Therefore, it takes a very long time for the interpass temperature to drop below 150°C, which will greatly reduce the construction efficiency for stainless steel pipe welding.

[0007] Secondly, the method of cooling the previous weld by spraying water before the subsequent weld is cumbersome on site. The water sprayed on the weld cannot be effectively controlled and recovered, and there is also a safety hazard of leakage caused by the cable coming into contact with water. Summary of the Invention

[0008] To address the aforementioned problems, this invention provides a stainless steel pipe welding cooling device and a cooling welding method thereof, aiming to achieve cooling of the pipe fittings to be welded during the welding process. The technical solution adopted is as follows:

[0009] A stainless steel pipe welding cooling device includes a circular first end plate and a second end plate. The first end plate and the second end plate are connected and fixed by two or more elongated connecting plates. The connecting plates are arranged horizontally. One end of the connecting plate is welded and fixed to the first end plate, and the other end is movably connected to the second end plate through a connector. The two or more connecting plates are arranged at equal intervals along the circumference of the end plate.

[0010] A continuous square groove is provided on the outer side of the first and second blocking plates, along the circumferential edge of the first and second blocking plates. An airbag is placed in the square groove, with the opening of the square groove facing outward, and the airbag is in contact with the inner surface of the pipe to be welded.

[0011] The first blocking plate has an inlet mechanism fixed at its center. The inlet mechanism includes a fastening base and a rotating body. One end of the rotating body has a limit stop. The end of the rotating body away from the limit stop passes through the first waterproof bearing, the fastening base, the second waterproof bearing, and the nut in sequence. The inlet mechanism is fixed to the first blocking plate through the fastening base. The inlet and outlet pipes pass through the center of the rotating body and enter the interior of the first blocking plate, located between the first blocking plate and the second blocking plate.

[0012] Furthermore, in the aforementioned stainless steel pipe welding cooling device, a square connecting hole is provided at the end of the connecting plate. One end of the L-shaped connector is welded to the second blocking plate, and the other end passes through the connecting hole and is fixed. When the first blocking plate and the second blocking plate are placed opposite each other, the free end of the connector is aligned with the connecting hole on the connecting plate. When the first blocking plate is rotated relative to the second blocking plate, the free end of the connector is inserted into the connecting hole and fixed.

[0013] Furthermore, in the aforementioned stainless steel pipe welding cooling device, the fastening base is connected to the first blocking plate by bolts, a ring of bolts is provided along the circumferential edge of the fastening base, and a through hole is opened in the center of the fastening base, through which the rotating body passes and can rotate.

[0014] Furthermore, in the aforementioned stainless steel pipe welding cooling device, the airbag is an integrally circular airbag placed in a square groove. The airbag has a valve, and a round hole is opened on the wall of the square groove, through which the valve protrudes.

[0015] Furthermore, in the aforementioned stainless steel pipe welding cooling device, the first waterproof bearing has a first bearing outer ring and a first bearing inner ring, and the second waterproof bearing has a second bearing outer ring and a second bearing inner ring. The first bearing outer ring is rotatable relative to the first bearing inner ring, and the second bearing outer ring is rotatable relative to the second bearing inner ring. The first and second bearing outer rings are fixedly connected to a fastening base, and the first and second bearing inner rings are fixedly connected to a rotating body. The first bearing inner ring is circumferentially rotatable relative to the first and second bearing inner rings, and the first and second bearing inner rings are fixedly connected to the rotating body. The first and second bearing outer rings are fixedly connected to the fastening base, thereby driving the rotating body to rotate circumferentially relative to the fastening base. This structure avoids the tooling from becoming entangled in the inlet and outlet pipes during use.

[0016] Furthermore, in the aforementioned stainless steel pipe welding cooling device, a sealing gasket is provided between the fastening base and the first waterproof bearing and the second waterproof bearing.

[0017] Furthermore, in the aforementioned stainless steel pipe welding cooling device, a sealing gasket is provided between the stop block and the second waterproof bearing.

[0018] Furthermore, in the aforementioned stainless steel pipe welding cooling device, there is a 20-30cm gap between the first and second blocking plates.

[0019] A method for cooling welding using a stainless steel pipe welding cooling device involves inserting a first blocking plate and a second blocking plate into the two ends of the pipe to be welded, then rotating the first blocking plate and the second blocking plate in opposite directions until the connecting member aligns with the connecting hole of the connecting plate. The connecting member is inserted into the connecting hole, and the first blocking plate and the second blocking plate are connected and fixed by connecting the connecting plate and the connecting member.

[0020] The weld is located at the center of the cooling device. The air bladder is inflated until it contacts the inner wall of the pipe to be welded and presses the pipe to be welded. The first blocking plate, the second blocking plate, and the pipe to be welded form a sealed space.

[0021] The inlet pipe is connected to the argon gas supply pipe, and argon gas is continuously introduced into the sealed space at a flow rate of 10L / min-15L / min. Air is discharged from the outlet pipe. When the purity of argon gas in the sealed space is not greater than 50ppm, welding is performed. After welding 2-3 weld passes, the inlet pipe is replaced with a water inlet pipe, and the outlet pipe is connected to a water outlet pipe to introduce cooling water into the sealed space. After cooling water circulation is formed in the sealed space, subsequent welding is performed.

[0022] Furthermore, in the above-mentioned method of using a stainless steel pipe welding cooling device, a circulating pump is connected to the water inlet pipe.

[0023] This invention can be installed on both sides of the weld seam of a welded pipe without additional reinforcement. The inflated airbags are in close contact with the pipe to be welded, and the resulting friction ensures that the device is firmly fixed inside the pipe. During welding, an external circulator injects and discharges cooling water through a circulating water inlet device into and out of the closed cavity formed by the plug plate and the welded pipe. Through the cooling effect of the circulating water, heat is circulated and exchanged, achieving the purpose of cooling the weld metal, effectively reducing the interpass temperature, improving welding efficiency, and ensuring weld quality. It is especially suitable for automatic welding methods where the welded pipe rolls on a rotating platform, allowing for continuous welding and significantly improving welding efficiency. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the cooling device of the present invention;

[0025] Figure 2 This is a schematic diagram of the circulating water pipe inlet device;

[0026] Figure 3This is a schematic diagram of the connecting plate structure;

[0027] Figure 4 This is a schematic diagram of the first blocking plate structure;

[0028] Figure 5 This is a schematic diagram of the second blocking plate structure;

[0029] Figure 6 This is a schematic diagram of the front structure of the fastening base;

[0030] Wherein: 100-First blocking plate, 101-Second blocking plate, 102-Square groove, 103-Valve nozzle, 104-Airbag, 106-Metal round tube, 107-Connecting hole, 108-Round hole, 300-Circulating water pipe inlet device, 301-Rotator, 302-Nut, 303-First waterproof bearing, 304-Fastening base, 305-Second waterproof bearing, 306-Discharge pipe, 307-Inlet pipe, 308-Limiting block, 309-Sealing gasket, 400-Pipe fitting to be welded. Detailed Implementation

[0031] The invention will be further described with reference to the accompanying drawings.

[0032] like Figure 1 The device illustrates a stainless steel pipe welding cooling system. It comprises a circular first and second blocking plate, connected and fixed to the second blocking plate by two elongated connecting plates. The connecting plates are evenly spaced along the circumference of the blocking plate and are placed horizontally. One end of each connecting plate is welded to the first blocking plate, and the other end is movably connected to the second blocking plate via an L-shaped connector. A connection hole (e.g., ...) is provided at the end of each connecting plate. Figure 3 As shown, one end of the L-shaped connector is welded to the second blocking plate, and the other end passes through the connecting hole for fixation.

[0033] A continuous square groove (e.g., ...) is provided on the outer side of the first and second blocking plates, along the circumferential edges of the first and second blocking plates. Figure 4 , 5 As shown, an airbag is placed inside a square groove, with the opening of the groove facing outwards. The airbag is in contact with the inner surface of the pipe to be welded. The square groove is made of angle steel, with the opening facing outwards (in this case, outwards refers to the direction away from the center of the blocking plate). The airbag is a circular airbag placed inside the square groove. The airbag has a valve, and a round hole is made in the web of the angle steel through which the valve protrudes.

[0034] One of the blocking plates has an inlet mechanism fixed in its center, such as Figure 2 As shown, the introduction mechanism includes a fastening base and a rotating body. The introduction mechanism is fixed to the first blocking plate via the fastening base, and the fastening base and the first blocking plate are connected by bolts. A ring of bolts is provided along the circumferential edge of the fastening base (e.g., ...). Figure 4 ,6 (As shown). One end of the rotating body has a limit stop. The end of the rotating body away from the limit stop passes sequentially through the first waterproof bearing, the fastening base, the second waterproof bearing, and the nut. The entry and exit pipes pass through the center of the rotating body and enter the interior of the first blocking plate, located between the first and second blocking plates. The first waterproof bearing has a first bearing outer ring and a first bearing inner ring, and the second waterproof bearing has a second bearing outer ring and a second bearing inner ring. The first bearing outer ring is rotatable relative to the first bearing inner ring, and the second bearing outer ring is rotatable relative to the second bearing inner ring. The rotating body is fixedly connected to the first and second bearing inner rings, and the fastening base is fixedly connected to the first and second bearing outer rings, thus allowing the rotating body to rotate relative to the fastening base. Because the weld of the welded pipe is a circumferential weld, to improve welding efficiency, the welding torch position remains stationary, and the welded pipe rotates on the rotating body to achieve continuous welding. The function of the rotating body is to ensure that the entry and exit pipes are relatively stationary when the welded pipe and the blocking plate are rotating, preventing the entry and exit pipes from tangling. The first waterproof bearing, the second waterproof bearing, and the fastening base are fixed together by nuts and a stop block, which serves as a limit. A circulation pump is connected to the inlet and outlet pipelines. Sealing gaskets are installed between the fastening base and the first and second waterproof bearings, and a sealing gasket is installed between the stop block and the second waterproof bearing.

[0035] In use, insert the first and second blocking plates into the two ends of the pipe fitting to be welded, respectively. Rotate the first and second blocking plates in opposite directions until the connecting piece aligns with the connecting hole of the connecting plate. Insert the connecting piece into the connecting hole and connect the first and second blocking plates through the connection of the connecting plate and the connecting piece to fix the first and second blocking plates.

[0036] The weld is located at the center of the cooling device. The air bladder is inflated until it contacts the inner wall of the pipe to be welded and presses the pipe to be welded. The first blocking plate, the second blocking plate, and the pipe to be welded form a sealed space.

[0037] The inlet pipe is connected to the argon gas supply pipe, and argon gas continuously enters the sealed space at a flow rate of 10L / min-15L / min. Air is discharged from the outlet pipe. When the purity of argon gas in the sealed space is no more than 50ppm, welding is carried out. After welding 2-3 weld passes, the inlet pipe is replaced with a water inlet pipe, and the outlet pipe is connected to a water outlet pipe. Cooling water is introduced into the sealed space through the water inlet pipe and discharged through the water outlet pipe, forming a circulation. After the cooling water circulation is formed in the sealed space, subsequent welding is carried out.

[0038] Connect the inlet and outlet pipes of the circulating water inlet device to the inlet and outlet pipes of the circulating machine, respectively, and inject cooling water. The cooling water circulates in the closed cavity. Welding can begin after the circulating water is formed.

[0039] To achieve controllable and adjustable cooling performance, the following methods can be used:

[0040] A. This can be achieved by adjusting the rotational speed or effective output displacement of the circulating machine.

[0041] B. Use a coolant with better cooling performance.

[0042] C. Adjust the size of the plug plate according to the size of the pipe fitting to be welded.

[0043] D. Adjust the diameter of the inlet and outlet pipes.

[0044] This device was used for welding simulation verification of stainless steel pipes. Multiple layers and passes of continuous welding were performed on a 508mm diameter, 20mm thick test pipe, with interpass temperatures controlled below 100℃ to maintain the weld joint's resistance to intergranular corrosion. Welding a 20mm thick pipe requires multiple layers and passes. Experiments have shown that using traditional natural cooling methods, each 2-3 passes requires approximately 20-30 minutes of cooling to below 150℃, taking about 5-6 hours in total. However, using this device allows for continuous, uninterrupted welding with the interpass temperature controlled below 100℃, reducing the total time to approximately 1.5 hours, increasing efficiency by about three times.

Claims

1. A method for cooling the welded stainless steel pipe, characterized in that: A cooling device is used, which has a circular first blocking plate (100) and a second blocking plate (101). The first blocking plate and the second blocking plate are connected and fixed by two or more long strip connecting plates (106). The connecting plates are arranged horizontally. One end of the connecting plate is welded and fixed to the first blocking plate, and the other end is movably connected to the second blocking plate through a connector (105). The two or more connecting plates are arranged at equal intervals along the circumference of the blocking plate. A continuous square groove (102) is provided on the outside of the first and second blocking plates and along the circumferential edge of the first and second blocking plates. An air bag (104) is placed in the square groove. The opening of the square groove faces outward and the air bag is in contact with the inner surface of the pipe fitting (400) to be welded. The first blocking plate is fixed with an inlet mechanism (300). The inlet mechanism includes a fastening base (304) and a rotating body (301). One end of the rotating body is equipped with a limit stop (308). The end of the rotating body away from the limit stop passes through the first waterproof bearing (303), the fastening base, the second waterproof bearing (305), and the nut (302) in sequence. The inlet mechanism is fixed to the first blocking plate through the fastening base. The inlet pipe (307) and the outlet pipe (306) pass through the center of the rotating body and enter the interior of the first blocking plate, located between the first blocking plate and the second blocking plate. Insert the first and second blocking plates into the pipe fittings to be welded from both ends, then rotate the first and second blocking plates in opposite directions and connect them through the connecting plate and connecting piece to fix the first and second blocking plates together. The weld is located at the center of the cooling device. The air bag is inflated until it contacts the inner wall of the pipe to be welded and presses the pipe to be welded. The first blocking plate, the second blocking plate, and the pipe to be welded form a sealed space. The inlet pipe is connected to the argon gas supply pipe, and argon gas is continuously introduced into the sealed space at a flow rate of 10L / min-15L / min. Air is discharged from the outlet pipe. When the purity of argon gas in the sealed space is not greater than 50 ppm, welding is performed. After welding 2-3 weld passes, the inlet pipe is replaced with a water inlet pipe, and the outlet pipe is connected to a water outlet pipe to introduce cooling water into the sealed space. After cooling water circulation is formed in the sealed space, subsequent welding is performed.

2. The method for cooling stainless steel pipe welding according to claim 1, characterized in that: The end of the connecting plate has a square connecting hole (107). The connector is L-shaped. One end of the L-shaped connector is welded to the second blocking plate, and the other end passes through the connecting hole for fixation.

3. The method for cooling stainless steel pipe welding according to claim 1, characterized in that: The fastening base is connected to the first blocking plate by bolts. A ring of bolts is provided along the circumferential edge of the fastening base. A through hole is opened in the center of the fastening base. The rotating body passes through the through hole and can rotate within the through hole.

4. The method for cooling stainless steel pipe welding according to claim 1, characterized in that: The airbag is a circular airbag placed in a square groove. The airbag has a valve and a round hole (108) is opened on the wall of the square groove. The valve protrudes from the round hole.

5. The method for cooling stainless steel pipe welding according to claim 1, characterized in that: The first waterproof bearing has a first bearing outer ring and a first bearing inner ring, and the second waterproof bearing has a second bearing outer ring and a second bearing inner ring. The first bearing outer ring is rotatable relative to the first bearing inner ring, and the second bearing outer ring is rotatable relative to the second bearing inner ring. The first bearing outer ring and the second bearing outer ring are fixedly connected to the fastening base, and the first bearing inner ring and the second bearing inner ring are fixedly connected to the rotating body.

6. The method for cooling stainless steel pipe welding according to claim 1, characterized in that: A sealing gasket is provided between the fastening base and the first waterproof bearing and the second waterproof bearing.

7. The method for cooling stainless steel pipe welding according to claim 1, characterized in that: A sealing gasket is provided between the stop block and the first waterproof bearing.

8. The method for cooling stainless steel pipe welding according to claim 1, characterized in that: There is a 20-30cm gap between the first and second blocking plates.

9. A method for cooling stainless steel pipe welding according to claim 1, characterized in that: A circulation pump is connected to the water inlet pipe.

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