Current status and direction of boiler welding technology and equipment
2021-06-20
Over the years, domestic boiler plants have been actively carrying out technological transformations, introducing new equipment, and implementing advanced welding new processes to adapt to changes in boiler capacity, parameters and furnace types to meet the welding structure of complex boiler components and new boiler materials. Take Dongfang Boiler Company as an example to highlight the welding status of key boiler components and the progress of welding technology and welding management of the company in recent years.
1 Welding status of key components of boilers – The main key components of power station boilers include steam drums, headers, membrane walls and serpentine tubes (superheaters, reheaters and economizers). The current status of welding technology for each component is as follows:
1) The longitudinal joint of the steam drum body mainly adopts submerged arc welding, narrow gap submerged arc welding and electroslag welding; the down pipe mainly adopts saddle submerged arc automatic welding and manual arc welding; the large pipe seat mainly adopts saddle submerged arc automatic welding and Manual arc welding; other accessories use gas shielded welding and manual arc welding.
2) The ring seam welding of the header body mainly adopts the narrow gap hot wire TIG welding and submerged arc welding; the large pipe base mainly adopts the flux cored wire gas shielded welding and the manual arc welding (for the material without the flux cored wire); the heated surface seat Mainly used for internal bore argon arc welding and manual arc welding.
3) Membrane wall mainly adopts MPM gas protection automatic welding and semi-automatic CO2 gas protection welding. Our company has a total of 34 automatic welding heads, and 65 semi-automatic CO2 gas shielded weldings for the welding of membrane walls.
4) The welding of the serpentine tube is mainly the straight tube length and the butt welding after the bending. Our company mainly adopts the hot zz-TIG welding and the full position hot wire TIG welding, as well as the manual argon arc welding. The accessory welding mainly adopts gas shielded welding and manual arc welding.
2 The company's new welding technology and welding technology progress - In recent years, with the rapid increase in production and changes in boiler types, structures and materials, the previous welding processes and means can no longer meet the needs of welding manufacturing, and urgently need to add key equipment. Renovate and renovate old equipment and promote the use of new welding processes. Our company promotes the following processes:
1) Promotion and application of CO2 gas protection welding technology - gas protection welding is an advanced and efficient welding process. 20 years ago, our company began to promote the application, but because of the welding equipment, welding materials and protective gas at that time, there are certain problems. Semi-automatic gas shielded welding is not well used. Only automatic gas shielded welding is used for the membrane wall. Welding. In 2002, our company began to promote this method, and now it is widely used in various boiler pressure parts and non-pressure parts of our company. There are 120 gas shielded welders, which replace 60% of manual arc welding. The method is widely used for welding of the large header of the header, welding of the membrane wall and welding of the heating surface attachment, thereby improving the welding efficiency and the welding quality. The welding material used is a solid wire of a flux cored wire. The method will continue to be promoted in the later stages for welding other components.
2) Advanced hot wire YIG welding technology - the quality of butt welding of boiler heating surface pipe is high, the material is complex, and the quantity is quite large. The welding port of a 600MW boiler reaches 60,000 heads. The welding efficiency is the key to the boiler manufacturing. . Our company originally used three straight pipe butt welding processes, namely hot wire TIG welding, TIG+MIG welding, and no groove RRS76 TIG welding. After more than 10 years of use, it is believed that the hot wire TIG welding process is the most mature, the highest welding quality and the most adaptable welding method, which should be promoted in boiler manufacturing. After the technical transformation from 2003 to 2005, we invested nearly 40 million yuan to configure two world-class automatic welding, flaw detection, top bending and bending production lines, a double R bending production, and imported 7 advanced from the United States. Hot wire TIG welding, as shown in Figure 1. Its production welding qualification rate is over 97%, which greatly improves the company's welding technology level and product welding quality. In recent years, the hot wire TIG welding method is widely used in the boiler industry, and there are at least one hundred hot wire TIG welding equipment in the country.
3) Efficient saddle submerged arc automatic welding - 4-6 diameter ¢508-¢711 downcomers and 200 连接108-¢168 steam connecting pipes and soda water connecting pipes are often arranged on the boiler drum. The welding workload is quite large, and the labor intensity of manual welding is long, the cycle is long, and the welding quality is not guaranteed. Since 2004, various automatic welding processes for the submerged arc have been adopted, which have greatly improved the efficiency, welding quality and labor intensity of workers. Now our company has purchased 8 large saddles and 10 small saddle submerged arc automatic welding equipment. The large saddle submerged arc automatic welding equipment is used to weld the boiler drum down pipe. The small saddle submerged arc automatic welding equipment is mainly used to weld the boiler steam drum ¢ 108 and above, as shown in Figure 1. At present, the method has been widely used in the welding of boiler steam drum sockets, and the problem of welding of large and small sockets such as plug-in or riding type on boiler steam drums and containers is completely solved.
4) Gap hot wire TIG welding - narrow gap hot wire TIG welding is mainly used for welding pipes or casing ring seams during boiler manufacturing and installation. The narrow gap hot wire TIG welding has two positions: full position and fixed position. The former is mainly used for pipe welding in boiler installation instead of manual arc welding; the latter is mainly used for straight pipe splicing in header or pipe welding in boiler manufacturing. The use of workpiece rotating hot wire TIG welding needs to solve the problem of pipeline driving and the accuracy of groove processing. If the roller frame is used for driving, the synchronization, radial runout and tampering of the workpiece in the drive must be solved. During the Eighth Five-Year period, we have developed a superheated wire TIG welding equipment for the bottom of the box and the transition welding. The roller frame is driven. However, due to the low precision of the anti-rolling, the electromagnetic arc of the welding arc is beyond the range of the hood and the air hole is formed. So it has a good use. This method has special advantages for welding new materials that are difficult to weld on boilers. Because of the low impact performance of submerged arc welding of new materials such as P91/P92/P122, it is difficult to develop welding materials, and narrow gap hot wire is used. TIG welding can achieve satisfactory welding quality and good joint performance. In order to increase efficiency, the groove width must be reduced. At present, there are two welding methods of swinging and non-swinging, and the latter requires a groove width of 10 mm or less. At present, our company has imported a set of narrow gap hot wire TIG welding from France. It is driven by a chuck and can weld the ring sill of ¢ 325×80 or less. The welding groove is narrow, only 7-10mm, and does not swing during the welding process. It is mainly used for welding a large number of P91/P92 material headers in ultra-supercritical boilers. Harbin Boiler Factory also introduced a similar welding equipment. Now the method has brought breakthrough changes to the casing joint welding of the boiler plant. Each boiler plant has introduced similar equipment, as shown in Figure 3.
5) Argon arc welding of the inner hole of the header pipe socket - China's "Vapor Boiler Safety Supervision Regulations" stipulates that the short pipe joint and the box fillet weld on the header should be welded to the full groove, and argon arc welding should be adopted as much as possible. Hit low. This brings greater difficulty to manufacturing. In order to achieve full penetration, the internal hole argon arc welding process must be used, and because the diameter of the header housing is small, it is difficult to weld the inner hole. It does not use the inner wire welding of the wire, and it is easy to produce the concave and undercut defects of the root weld. Our company imported 2 internal hole argon arc welding equipment from France, with AVC voltage automatic control, pulse, wire and swing function, the root base quality is quite good, and it has been successfully used in the header pipe socket welding, which has greatly improved. The company's welding technology level.
6) Gantry-type MPM welding - At present, there are two types of submerged arc welding and gas shielded welding for the membrane wall of welding boilers at home and abroad. Our company and Harbin boiler plant are mainly gas shielded welding (MPM welding), Shanghai boiler factory and Wuhan boiler. The factory is mainly submerged arc welding, and Beijing Bawei Company has two methods. These two methods have their own advantages and disadvantages. MPM welding is welded at the same time. The efficiency is high, the deformation is small, and the penetration depth is shallow. Submerged arc welding can not achieve the simultaneous upper and lower welding needs to be turned over. The single-sided welding has large deformation, and the advantage is that the penetration is large. . In order to realize spiral water wall and cold ash bucket and triangular tube screen of supercritical and ultra-supercritical boilers, gantry welding equipment must be used. Based on the foundation and manufacturing experience of gas shielded welding and convenient workshop production management, our company has jointly developed 6 gantry welding equipments, as shown in Figure 4.
Usage of welding power source in boiler welding
At present, welding power sources used in boiler manufacturing, such as TIG welding power source, gas metal arc welding power source, coating electrode power supply, submerged arc welding power source, electroslag welding power source, etc. The company has a total of 600 welding power sources, mainly for thyristor welding power supply. In recent years, with the development of inverter welding power supply, all companies are vigorously promoting the use of inverter power. Our company has also started the trial selection in 2003, and has developed a plan for inverter welding power to replace the old power supply. Promote the use of 120 inverter power supplies. Our company is mainly optimistic about the dynamic characteristics of the power supply and energy saving, etc., according to different methods to investigate the stability and reliability of the power supply. At present, these power supplies have greatly improved in terms of reliability, stability, energy consumption and control precision, and have played an important role in improving the quality and efficiency of boiler welding, resulting in good social benefits and Economic benefits.
Development direction of boiler welding technology
1 Development of gas shielded welding on boilers - Gas shielded welding is a highly efficient, high quality, energy efficient welding process that is widely used abroad. In order to save energy and reduce consumption, there is still a lot of room for use in this process. In particular, flux-cored wire gas shielded welding and automatic gas shielded welding are the future development directions, but the development and supply of high-grade boiler material flux cored wire must be solved. At the same time, manual semi-automatic gas-shielded welding needs to be continuously improved from power supply dynamic characteristics, anti-bacterial splashing ability, arc-ignition characteristics, and specification adjustment convenience. In particular, digital control and digital display power supply are welcome by future boiler factories.
2 Automated welding and robot welding – The welding technology of boiler headers and steam drums is still relatively backward, and the level of automation is low. It is necessary to vigorously adopt a welding process with a higher level of automation to improve welding efficiency and quality. The robot or manipulator workstation is the future direction to solve the welding of the socket on the header, and the boiler manufacturer should vigorously promote it. Narrow gap hot wire TIG welding, or narrow gap hot wire zzTIG welding + submerged arc welding is the direction of the joint welding of components, pipes, steam separators and other components. Pipeline automatic scribing and automatic welding of accessories are the technological means that future boiler manufacturers need to consider.
3 Improvement of welding environment - A large number of welding operations on boilers rely on manual arc welding or gas shielded welding, welding dust is large, and the working environment is poor, especially in the container. The local soot disposal facility, the work area or the entire workshop soot treatment facility is configured to improve the future direction of the welding operation environment. With the safety and environmental protection of boiler manufacturers, the improvement of their welding environment has been put on the agenda.
4 Development of boiler welding technology requirements for welding power supply - With the development of society and the advancement of welding technology, the demand for boiler welding automation is increasing, reliability, stability, energy consumption and control accuracy of welding power supply The aspect puts forward higher requirements. The digital control inverter power supply is the development direction, the operation panel is customized, the maintenance should be simplified, the welding specification value display is convenient for monitoring and management.
5 Welding protection agent or the use of self-shielded welding wire - With the development of high-capacity and large-capacity boilers, the materials used in boilers have undergone great changes. High-alloy heat-resistant steels and stainless steels with more than 9Cr1Mo materials have been used in large quantities. The problem has become an important factor restricting production efficiency. It is particularly important to use high-quality and high-quality welding protection media and means. Our company has begun to use internal protective agents for the ring welding of the box, and is also actively exploring the use of protective agents for welding and other protection methods and media for other products.
Rubber Roller Boiler Standerand Configurations:
Automatic heating vulcanizer, temperature, pressure, and heating time, are controled by computer. Different heating program can be saved on the computer.
- Diameter 1500 * Length 4000 mm
- Material: Q345R
- Thickness of the vulcanizer: 8mm
- Thickness of the end enclosure: 8mm
- Designed pressure: 0.85mpa
- Designed temperature: 180C
- Automatic heating vulcanizer, temperature, pressure, and heating time, are controled by computer. Different heating program can be saved on the computer.
- Pressure alarm for over high, or over low
- The enclosure cannot be opened when the inside pressure reach 0.01mpa
- Total power: 48KW
Roller Boiler, Rubber Roller Boiler, Rubber Roller Vulcanization, Rubber Roller Vulcanizing Boiler
Seger Industrial Co., Ltd. http://www.powerrubberrollers.com