Welding process for miniaturized extra-high temperature heat energy equipment

Abstract

The invention relates to the technical field of welding of heat energy equipment, in particular to a welding process of miniaturized ultrahigh-temperature heat energy equipment, which comprises the following steps: S1, preparing semi-V-shaped welding grooves for base metal on two sides of a joint by adopting a pipe beveling machine, polishing the grooves and the surface of the base metal, cleaning by using an organic compound, and assembling the to-be-welded joint in a butt joint manner; s2, welding a butt welding seam of the coil pipe and the water cooling wall by adopting manual argon tungsten-arc welding; s3, a thermocouple is fixed to any side of the weld joint, the hot end of the thermocouple is tightly attached to the base metal, the cold end of the thermocouple is connected with a temperature control box, and the interlayer temperature of the weld joint is monitored in real time; s4, when the interlayer temperature is larger than the first temperature, welding is stopped, after a first time interval, a compressed air pipe is used for being matched with an air gun to cool a welding seam and the circumferential direction, and when the layer temperature of the welding seam is reduced to the second temperature, a steel wire brush is used for cleaning the welding seam; and S5, after welding is completed, a welded joint is inspected. The welding device has the beneficial effect that the welding quality and the welding efficiency can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of thermal energy equipment welding, and in particular to a welding process for miniaturized ultra-high temperature thermal energy equipment. Background Art

[0002] In the engineering application of miniaturized ultra-high temperature thermal energy equipment, the quality of welding technology is directly related to the overall performance and operational stability of the equipment. In particular, in the application scenario of ultra-supercritical austenitic heat-resistant steel in ultra-supercritical boilers, traditional welding technology faces many challenges.

[0003] In the prior art, the industry standard has not yet provided suitable welding material recommendations for the newly developed SP2215 austenitic heat-resistant steel, making the selection of welding materials a key factor restricting welding quality. Austenitic heat-resistant steel itself has a low thermal conductivity, and it is difficult to dissipate heat when welding small-diameter pipes, resulting in a rapid rise in the temperature between weld layers. According to Fourier's law, due to the small value of the thermal conductivity, under the same heat generation conditions, the temperature gradient increases, causing a significant increase in local temperature. Excessive interlayer temperature not only increases the risk of high-temperature cracks in the weld, but also reduces welding efficiency due to the need to frequently wait for cooling. In addition, when measuring weld temperature, traditional handheld infrared thermometers are affected by measurement distance, angle and environmental factors, and there are large numerical deviations, making it difficult to accurately guarantee the performance of the weld joint, resulting in poor welding quality and low welding efficiency. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present application proposes a welding process for miniaturized ultra-high temperature thermal energy equipment, which can improve welding quality and welding efficiency.

[0005] The following is a technical solution of the present invention, a welding process for miniaturized ultra-high temperature thermal energy equipment, comprising the following steps:

[0006] S1. Use a pipe beveling machine to prepare a semi-V-shaped welding groove for the parent materials on both sides of the joint, grind the groove and the surface of the parent material, and use organic compounds to clean them, and assemble the joints to be welded;

[0007] S2. Use manual tungsten inert gas arc welding to weld the butt welds of the coil and water-cooled wall;

[0008] S3. Fix a thermocouple on any side of the weld, with the hot end of the thermocouple tightly fitted to the base material and the cold end connected to the temperature control box to monitor the interlayer temperature of the weld in real time;

[0009] S4. When the interlayer temperature is greater than the first temperature, stop welding. After the first time interval, use a compressed air pipe with an air gun to cool the weld and the circumferential direction. When the weld layer temperature drops to the second temperature, use a wire brush to clean the weld.

[0010] S5. Inspect the weld joint after welding is completed.

[0011] As a preferred solution of the present invention, in S1, in the preparation of the welding groove, the groove angle is 35° to 38°, the blunt edge is 0.5-1.5 mm, and the range of the polished groove and the parent material surface is 10-15 mm.

[0012] As a preferred embodiment of the present invention, in S1, the organic compound is acetone or isopropanol.

[0013] As a preferred solution of the present invention, in S1, during the butt-joint assembly, the butt-joint clearance is 2.5-3.5 mm.

[0014] As a preferred solution of the present invention, in S2, the welding parameters of manual tungsten inert gas welding are as follows: welding current is 90-115A, welding voltage is 9-14V, welding speed is 50-90mm / min, front shielding gas flow rate is 10-15L / min, and back shielding gas flow rate is 9-13L / min.

[0015] As a preferred solution of the present invention, in S2, the thickness of each weld layer is 1.5-3.5 mm, and the width of each weld layer is 8-10 mm.

[0016] As a preferred solution of the present invention, in S3, a plurality of K-type thermocouples are fixed at 18-22 mm on any side of the weld.

[0017] As a preferred solution of the present invention, in S4, the first temperature is 150°C, the first time interval is 15-20 seconds, and the second temperature is 60-70°C.

[0018] Beneficial effects of the present invention:

[0019] 1. The present invention ensures the high quality of the welding joint through scientific material selection, precise parameter control and strict inspection standards. After 100% RT inspection, the test results are 100% qualified, meeting the stringent requirements of miniaturized ultra-high temperature thermal energy equipment on welding quality;

[0020] 2. The coil and water-cooled wall of the present invention are subjected to an integral water pressure test at P = 40 MPa according to the process requirement, and the duration is 20 minutes. There is no pressure drop during the test, and there are no water drops and water mist on the metal wall and weld of the pressure-bearing parts, and no obvious residual deformation, which complies with the relevant requirements of TSG11-2020 regulations and ensures the safe operation of the equipment under high-pressure environment;

[0021] 3. The air-cooled rapid cooling method of the present invention effectively solves the problem of low welding efficiency caused by excessively high interlayer temperature, greatly shortens the welding cycle, improves production efficiency, and reduces production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a flow chart of the welding process of the present invention;

[0023] Figure 2 Schematic diagram of groove angle of welding process of the present invention;

[0024] Figure 3 Schematic diagram of weld thickness in the welding process of the present invention;

[0025] Figure 4 Schematic diagram of weld width in the welding process of the present invention;

[0026] Figure 5 A schematic diagram of the blunt edge of the welding process of the present invention;

[0027] Figure 6 It is a schematic diagram of the butt gap of the welding process of the present invention. DETAILED DESCRIPTION

[0028] In order to make the technical problems solved by the present invention, the technical solutions adopted and the technical effects achieved clearer, the technical solutions of the embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0029] Example:

[0030] In this embodiment, the coil and water-cooled wall tubes are made of SP2215 new heat-resistant steel, and the joints are all butt joints; among them, the coil joint specifications are Φ45×12mm and Φ45×9.5mm, and the water-cooled wall tube joint specifications are Φ45×9.5mm.

[0031] The welding material is ERNiCrCoMo-1 high temperature nickel-based alloy argon arc welding wire with a diameter of φ=2.4mm, which meets the standard AWSA5.14. This welding material has excellent high temperature mechanical properties and a yield strength of σ y (T) satisfies σ y (T) ≥ 400MPa, where T is the operating temperature, 500℃ ≤ T ≤ 700℃), and it has good corrosion resistance and easy processing, and no heat treatment is required after welding.

[0032] like Figure 1 As shown, a welding process for miniaturized ultra-high temperature thermal energy equipment includes the following steps:

[0033] S1. Use a pipe beveling machine to prepare a semi-V-shaped welding groove for the parent materials on both sides of the joint, grind the groove and the surface of the parent material, and use organic compounds to clean them, and assemble the joints to be welded;

[0034] S2. Use manual tungsten inert gas welding to weld the butt welds of the coil and water-cooled wall;

[0035] S3. Fix a thermocouple on any side of the weld, with the hot end of the thermocouple tightly fitted to the base material and the cold end connected to the temperature control box to monitor the interlayer temperature of the weld in real time;

[0036] S4. When the interlayer temperature is greater than the first temperature, stop welding. After the first time interval, use a compressed air pipe with an air gun to cool the weld and the circumferential direction. When the weld layer temperature drops to the second temperature, use a wire brush to clean the weld.

[0037] S5. Inspect the weld joint after welding is completed.

[0038] In step S1, a pipe beveling machine is used to prepare a semi-V-shaped welding groove for the parent materials on both sides of the joint, the groove and the surface of the parent material are polished, and an organic compound is used to clean them, and the joints to be welded are assembled.

[0039] Using the I IP-YG-89 pipe beveling machine, semi-V-shaped welding bevels were prepared for the parent materials on both sides of the Φ45×10mm SP2215 joint. According to the welding process requirements, the groove-related parameters were calculated and controlled by the following formula:

[0040] Groove angle a: 35°≤a≤38°. The range of the groove angle is intended to ensure that the arc can effectively cover the groove area during welding and ensure the fusion quality of the weld root.

[0041] Blunt edge b: 0.5mm≤b≤1.5mm. The setting of blunt edge can prevent burn-through during welding and ensure the strength of the weld root.

[0042] Grind the surface of the base material within the groove and nearby L range, 10mm≤L≤15mm, to remove the surface oxide layer and impurities and enhance the bonding strength of the weld joint.

[0043] Clean with acetone or isopropyl alcohol to completely remove the oil.

[0044] After cleaning, the joints to be welded are assembled together, and the gap c is controlled at 2.5mm≤c≤3.5mm. A suitable gap helps to ensure the formation and filling of the molten pool during welding.

[0045] In step S2, manual tungsten inert gas arc welding is used to weld the butt welds of the coil and the water-cooled wall.

[0046] The butt welds of the coil and water-cooled wall are welded by manual tungsten inert gas welding technology, which can achieve fine control of the welding process and ensure the quality of the weld.

[0047] The welding parameters of manual tungsten inert gas arc welding are based on the welding heat input formula Optimize the settings, where q is the welding heat input, I is the welding current, U is the welding voltage, and v is the welding speed.

[0048] In this embodiment, welding current I: 90A≤I≤115A, welding voltage U: 9V≤U≤14V, welding speed v: 50mm / min≤v≤90mm / min. By reasonably adjusting these parameters, the welding heat input is ensured to be within the appropriate range to meet the metallurgical requirements of the weld.

[0049] Front shielding gas flow rate Q1: 10L / min≤Q1≤15L / min, back shielding gas flow rate Q2: 9L / min≤Q1≤13L / min. The function of shielding gas is to prevent the molten pool from contacting with air during welding to avoid oxidation and nitridation.

[0050] Interlayer temperature T in :T in ≤150℃, the thickness of each weld layer h is controlled at h=2.5mm, the width of each weld layer w is controlled at w=9mm, and precise control of interlayer temperature and weld width helps to ensure the organizational properties and appearance quality of the weld.

[0051] In step S3, a thermocouple is fixed on either side of the weld, the hot end of the thermocouple is closely attached to the base material, and the cold end is connected to the temperature control box to monitor the interlayer temperature of the weld in real time.

[0052] A K-type thermocouple is fixed with a high-precision binding device at a distance of about d = 20 mm from any side of the weld. The hot end of the thermocouple fits tightly against the base material to ensure the accuracy of temperature measurement, and the cold end is connected to the WCK-60-0306 intelligent program temperature control box, which monitors the interlayer temperature T of the weld in real time during welding. in .

[0053] In step S4, welding is stopped when the interlayer temperature is greater than the first temperature, and the weld and the circumferential direction are cooled with an air gun equipped with a compressed air pipe after a first time interval. When the weld layer temperature drops to the second temperature, the weld is cleaned with a wire brush.

[0054] When the K-type thermocouple detects the interlayer temperature T in When the temperature exceeds 150℃, stop welding immediately.

[0055] According to the heat transfer theory, after waiting for about t1 = 15-20s, use the compressed air pipe with an air gun to quickly cool the weld and its surroundings in the circumferential direction.

[0056] Assume that the convective heat transfer coefficient during the cooling process is h co , according to Newton's law of cooling q co =hco A(TT env ), where q co is the convective heat transfer, h co is the convective heat transfer coefficient, A is the heat transfer area, T is the weld temperature, T env is the ambient temperature.

[0057] By controlling the airgun parameters h co , to achieve rapid cooling. When the K-type thermocouple test results show that the weld layer temperature drops to T cool :60℃≤T cool After the temperature reaches ≤70℃, clean the weld with a wire brush to remove the oxide scale and impurities on the surface and continue the subsequent welding operation

[0058] In step S5, the welded joint is inspected after welding is completed.

[0059] Post-weld inspection: After welding is completed, 100% RT inspection is carried out on the welded joints according to NB / T47013.2-2015 standard to ensure that the internal quality of the welded joints meets the standard requirements.

[0060] Implementation plan:

[0061] The Φ45×10mm SP2215 joint is firmly fixed on the workbench of the I IP-YG-89 pipe beveling machine. Through the parameter setting system of the beveling machine, the tool position and angle are accurately adjusted to prepare a semi-V-shaped welding bevel that meets the requirements. During the grinding process, metallographic sandpaper and electric grinding tools are used to operate within the specified grinding range to ensure that the surface is flat and free of impurities. When cleaning, use a special acetone or isopropyl alcohol spray gun to spray evenly on the bevel and nearby areas, and then wipe it clean with a clean non-woven cloth. During the joint assembly process, use a high-precision caliper and feeler gauge to measure and adjust the joint gap to ensure that the gap is within the specified range.

[0062] Select manual tungsten inert gas welding equipment with stable performance, and preheat and debug it according to the equipment operating procedures. Correctly install the ERNi CrCoMo-1 high-temperature nickel-based alloy argon arc welding wire on the wire feeding mechanism, and adjust the wire feeding speed and tension to ensure smooth wire feeding. Turn on the power of the manual tungsten inert gas welding equipment, and gradually adjust the welding current, voltage, welding speed and shielding gas flow according to the pre-set welding parameters. During the welding process, closely observe the state of the welding pool and ensure stable welding quality by fine-tuning the parameters. At the same time, use a temperature sensor to monitor the interlayer temperature in real time. When the interlayer temperature is close to the upper limit, appropriately reduce the welding speed or increase cooling measures.

[0063] Use a dedicated thermocouple fixture to accurately fix the K-type thermocouple on the surface of the base material 20 mm away from the weld. Connect the thermocouple to the WCK-60-0306 intelligent program temperature control box, and calibrate and debug it to ensure that the temperature data can be accurately and real-time transmitted to the temperature control box.

[0064] When the temperature control box shows that the interlayer temperature of the weld exceeds 150℃, immediately press the stop button of the welding equipment. Start the compressed air supply system, adjust the air output and spray angle of the air gun, and evenly cool the weld and the surrounding area. During the cooling process, continue to observe the temperature data displayed by the temperature control box. When the temperature drops to 60-70℃, turn off the air gun and use a wire brush to gently clean along the direction of the weld to remove surface impurities.

[0065] After welding is completed, according to the detailed requirements of NB / T47013.2-2015 standard, prepare the equipment and materials required for RT inspection, such as radiation source, film, darkroom processing equipment, etc. According to the process specified in the standard, 100% radiation inspection is carried out on each welded joint. During the inspection process, parameters such as exposure time and focal length are strictly controlled to ensure the accuracy and reliability of the inspection results. The film after inspection is professionally processed and analyzed in the darkroom to determine whether there are defects in the welded joint.

[0066] After welding, the welded joints are subjected to 100% RT inspection in accordance with NB / T47013.2-2015 "Non-destructive testing of pressure equipment Part 2: Radiographic testing", and the test results are 100% qualified; after passing the RT inspection, the coils and water-cooled walls are subjected to a 40MPa overall water pressure test according to the process requirements, with no pressure drop for 20 minutes, no water droplets and water mist on the metal walls and welds of the pressure parts, and no obvious deformation, which complies with the relevant requirements of TSG11-2020 regulations.

[0067] The method of the present invention applies SP2215 ultra-supercritical austenitic heat-resistant steel to ultra-supercritical boilers, and innovatively selects ERNiCrCoMo-1 welding materials. The selection of this welding material is based on an in-depth study of its chemical composition, mechanical properties and metallurgical compatibility with SP2215 steel, breaking through the bottleneck that there is no corresponding welding material recommendation in the standard. The real-time monitoring method combining K-type thermocouple and intelligent program temperature control box can more accurately measure the interlayer temperature of the weld compared to the traditional handheld infrared thermometer. Through real-time feedback control, the welding heat input is effectively reduced, and the interlayer temperature is accurately controlled according to the welding thermal cycle curve to prevent the generation of high-temperature cracks in the weld and improve the performance of the weld joint. In view of the heat dissipation problem of austenitic heat-resistant steel, air cooling is adopted for rapid cooling. Through theoretical analysis and experimental verification, the optimal cooling parameters are determined, which not only avoids the generation of intergranular chromium depletion and high-temperature cracks of austenitic stainless steel at 450℃-850℃, but also significantly improves the welding efficiency. According to calculations, compared with the traditional natural cooling method, air cooling can shorten the welding cycle by about 30%-40%.

[0068] Although preferred embodiments of the present invention have been described, additional changes and modifications may be made to these embodiments by those skilled in the art once the basic inventive concepts are known. Obviously, various changes and modifications may be made to the present invention by those skilled in the art without departing from the spirit and scope of the present invention. Thus, the present invention is intended to include such changes and modifications if they fall within the scope of the technical equivalents of the present invention.

Claims

1. A welding process for miniaturized ultra-high temperature thermal energy equipment, characterized in that: The following steps are involved: S1. Use a pipe beveling machine to prepare a semi-V-shaped welding groove for the parent materials on both sides of the joint, grind the groove and the surface of the parent material, and use organic compounds to clean them, and assemble the joints to be welded; S2. Use manual tungsten inert gas welding to weld the butt welds of the coil and water-cooled wall; S3. Fix a thermocouple on any side of the weld, with the hot end of the thermocouple tightly fitted to the base material and the cold end connected to the temperature control box to monitor the interlayer temperature of the weld in real time; S4. When the interlayer temperature is greater than the first temperature, stop welding. After the first time interval, use a compressed air pipe with an air gun to cool the weld and the circumferential direction. When the weld layer temperature drops to the second temperature, use a wire brush to clean the weld. S5. Inspect the weld joint after welding is completed.

2. The welding process of a miniaturized ultra-high temperature thermal energy device according to claim 1 is characterized in that: In S1, in the preparation of welding groove, the groove angle is 35° to 38°, the blunt edge is 0.5-1.5mm, and the range of grinding groove and parent material surface is 10-15mm.

3. The welding process of a miniaturized ultra-high temperature thermal energy device according to claim 2 is characterized in that: In S1, the organic compound is acetone or isopropanol.

4. The welding process of a miniaturized ultra-high temperature thermal energy device according to claim 3 is characterized in that: In S1, during the mating assembly, the mating clearance is 2.5-3.5mm.

5. The welding process of a miniaturized ultra-high temperature thermal energy device according to claim 1 is characterized in that: In S2, the welding parameters of manual tungsten inert gas welding are as follows: welding current is 90-115A, welding voltage is 9-14V, welding speed is 50-90mm / min, front shielding gas flow rate is 10-15L / min, and back shielding gas flow rate is 9-13L / min.

6. The welding process of a miniaturized ultra-high temperature thermal energy device according to claim 5 is characterized in that: In S2, the thickness of each weld layer is 1.5-3.5 mm, and the width of each weld layer is 8-10 mm.

7. The welding process of a miniaturized ultra-high temperature thermal energy device according to claim 1 is characterized in that: In S3, several K-type thermocouples are fixed at 18-22 mm on either side of the weld.

8. The welding process of a miniaturized ultra-high temperature thermal energy device according to claim 9 is characterized in that: In S4, the first temperature is 150°C, the first time interval is 15-20 seconds, and the second temperature is 60-70°C.

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