1 Overview
Our company's national "863" key scientific research project undertaken in 2008 relies on the project - Huaneng Fengfeng Power Plant 2 × 660MW dry desulfurization steel structure, the project uses more than 10,000 tons of steel, of which multi-layer "ten" shaped steel The column accounted for 39.5%, a total of 128, each weighing 56.6t. Through the production and construction, good results have been achieved. For this reason, we have compiled this method according to the construction and production technology experience of this project.
2. Characteristics of this work method
The structure of the "Ten" shaped steel member is shown in Figure 1. It has the following characteristics: 1 The equipment used for making the "T" shaped member is simple and easy to operate. 2 The construction speed is fast, the construction period is short, and the efficiency is high. 3 low cost, stable performance, easy quality assurance, and good results.
Figure 1 "Ten" shaped steel member structure form 1. H-shaped steel, 2. T-shaped steel
3. Scope of application
This method is applicable to the welding of low carbon steel, high strength steel and ordinary cast steel, and is suitable for the processing and manufacturing process of building ten-shaped members of steel structure. Including process selection, stakeout, blanking, making H-beam and T-beam, correction, edge machining, assembly and welding "ten" column, welding top plate and foot plate, straightening correction, numbering tagging, shot blasting , inspection of the income bank and delivery of the factory and other processes.
4. Process principle
This method adopts H-shaped steel automatic production line, firstly processes the H-shaped steel with intermittent cuts in the web, and then cuts the reserved part of the web into T-shaped steel, and finally forms the "T" shaped member. After the steel plate is cut by CNC multi-head cutting machine, it is paired on the H-beam automatic assembly machine, and then the CO 2 base and submerged arc welding filling and cover welding are performed in the automatic ship-shaped position. After the welding inspection is completed, the H-shaped steel is completed. Corrected on the flange correcting machine. The components required for the “Ten†shape are assembled on the tire frame, and the “Ten†welds in the middle of the components are formed by CO 2 primer, submerged arc welding and cover welding.
5. Construction process
(1) Process flow chart refinement → stakeout, blanking → H-beam manufacturing → T-beam manufacturing → “Ten†shaped component assembly → “Ten†shaped component web weld welding → No. → UT test → Correction → Group Welding accessories → cleaning, derusting → painting → product inspection → storage, delivery.
The “Ten†character of Jifeng Power Plant has a single root length of 60.42m. It is difficult to manufacture and transport. It is divided into two sections by the design and owner unit. It is delivered to the site and docked on site. The factory production process is shown in Figure 2.
Figure 2 "Ten" shape steel component production process
(2) Welding method and selection of welding materials Steel components are produced in two parts in the factory and delivered to the site for docking. In order to improve the welding productivity of the factory and reduce the deformation caused by welding stress, small groove and low energy are selected. The welding method of input, namely CO 2 gas shielded welding for positioning weld and bottom welding, and submerged arc welding for cover, according to the properties of the base metal and the process evaluation results, the welding wire for gas protection tack welding and bottom welding is ER50-6 , φ1.2mm, the shielding gas is CO 2 ; the submerged arc welding wire is H08MnA, φ4.0mm, and the flux is HJ431.
6. Operating process
The assembly of the "T" shaped members is divided into three steps, namely, the production of H-shaped steel, the production of T-shaped steel, and the assembly of "T" shaped members.
The blanking and unloading 1 parts are cut and processed by a CNC flame cutting machine. 2 The wings and webs of the “Ten†shaped members are cut and cut horizontally on both sides of the CNC straight strip cutting machine (see Figure 3), and the irregular parts are cut by CNC, profiling and semi-automatic cutting machines. Track the first piece. 3 When cutting, add 30mm welding shrinkage allowance to the length of the flange plate and the web, and leave no allowance in the width direction. 4 When the length of the wing and web needs to be lengthened, the minimum length should be more than 600mm, and the number of joints of the same part should not exceed two; at the same time, it should be noted that the arrangement of the wing and the web must be ensured when placing the nesting. The distance of the seam is >200mm or more. 5 After the completion of the blanking, the color standard should be transplanted according to the material, and the engineering name, steel plate specification and part number of the good parts should be marked and stored, and the groove shape is shown in Fig. 4.
Figure 3 CNC flame straight strip cutting real scene 
Figure 4 H-shaped steel and T-shaped steel groove form and size indication 1. Flange plate 2. Web
(2) H-steel production 1H steel can be assembled and positioned by H-beam assembly machine; CO2 gas shielded welding is used for positioning, the length of the welding seam is 40~50mm, the welding feet are ≤5mm, and the interval is 300~ 400mm. The section size of 2H steel should meet the design requirements, and the error meets the requirements of GB50205-2001 for the acceptance specification of steel structure construction quality. The vertical process of H-beam automatic assembly unit is shown in Fig. 5. The welding of 3H steel adopts the gantry type submerged arc welding special machine. The flux is baked according to the process before welding, and the arc-extinguishing and arc-extinguishing plates are arranged at both ends of the member. The welding real scene is shown in Fig. 6. The correction of 4H steel mainly adopts the following methods. When the thickness of the flange plate is less than 60mm, it can be corrected by H-shaped steel flange correction machine (see Figure 7); when the flange thickness is >60mm, it should be used in the welding process. A reasonable welding sequence is supplemented by manual flame correction.
Figure 5 H-beam, double T-shaped steel assembly 
Figure 6 H-beam submerged arc welding real scene 
Figure 7 H-beam flange correction
(3) T-steel production 1 T-shaped steel web blanking: Combine the webs of two T-shaped steels into one group, and cut intermittently at the center: ie cut 1.5m, reserve 30mm without breaking, wait for H-shaped steel to double After the T-beam is welded and corrected, the reserved part is divided into two T-shaped steels. The double T-shaped steel is produced as shown in Fig. 8. 2 The process of group welding and correction of T-shaped steel is the same as that of H-beam.
Figure 8 shows the production of double T-shaped steel
(4) The selection of the equipment for the formation of the “Ten†shaped members: the assembly of the “Ten†shaped members can be assembled by artificial tires, as shown in Figure 9; The positioning of the component is CO2 gas shielded welding. The height of the positioning leg is ≤ 2/3 of the height of the designed weld bead; the length of the positioning weld is 40-60 mm, and the pitch of the bead is 400 mm. 2 The formation of the “ten†character. Determine the assembly reference line. After the H-beam and T-beam (has been formed into H-beam) are welded and corrected, the assembly reference line is established on the end web, and marked with a marker, lined, and used to support the strip. Preliminary positioning, assembly and positioning of the process support bar, and then assembled with the assembly reference line and the process support bar as a reference, the "ten" shaped member plus the support rib plate is shown in FIG. The assembly of the "T" shaped members shall be completed on the tire frame, and the jacks shall be tightly pressed between the components. The spot welding length between the components is 40 to 60 mm, the welding angle is 6 mm, and the interval is 300 to 400 mm.
Figure 9 "Ten" shaped member assembly 1. Installation platform 2. Tooling support 3. Hydraulic cylinder 4. "Ten" column 
Figure 10 Schematic diagram of the ten-shaped member ribs Note: 1 to 4 are welding sequences
The allowable deviation of the "ten" character assembly is shown in Table 1.
Table 1 "Ten" column allowable deviation
(5) Welding of the ten-character member The welding of the “ten†character is made by CO2 gas shielded welding, submerged arc welding and capping. The welding is shown in Figure 11. 2Prepare the welding preparation and add Leading and quenching the arc plate to clean the welding area. 3 The welding parameters are selected as shown in Table 2. 4 To effectively control the deformation during the welding process, the welding is generally carried out according to the welding sequence of Figure 12, and strengthened during the welding process. Check, so that the corresponding adjustment can be made at any time. After the welding of the “T†shaped members, the process ribs are removed and the components are cleaned and polished.
Figure 11 shows the welding of the ten-shaped member
Figure 12 Welding sequence of “Ten†type components Note: 1~4 is the welding sequence
Table 2 CO2 gas shielded and submerged arc welding parameters
(6) Correction of the "Ten" shaped member The correction of the "Ten" column needs to be carried out with the jack and the flame correction, and no hammering or forced correction. When the distortion is corrected, one end is fixed, and the other end is corrected by a jack. The correction method is shown in FIG. When heating, pay attention to the orientation of deformation, and the heating temperature is controlled between 600 and 800 °C.
Figure 13 “Ten†shaped steel column correction
After the correction is completed, the upper end of the "T" shaped member is cut to control the length of the member.
(7) Assembling the construction preparation of Annex 1 on the “Ten†component. When assembling the parts, make sure that they have been inspected and cleaned without burrs and gaps, and that the part numbers, directions and dimensions are correct before assembly. Check the number and specifications of the assembled "Ten" component body, and confirm that the local repair and bending and torsion deformation have been adjusted. 2 "Ten" shaped components are large. Place the steel component body on the assembly platform, determine the horizontal reference, and scribe the body on the body according to the position and size of each component on the drawing. The position includes the center line, the reference line, etc., and the position line of each component. The double-line logo should be used, and the positioning lines are clear and accurate to avoid dimensional deviation caused by blurred lines. The components to be assembled shall be assembled and welded according to their position in the structure, so that the welding of the components is completed at the optimal welding position, and the welding quality of the components is effectively controlled. On the assembly platform, the components are assembled on the body. 3 assembly method of steel component bottom plate. First, establish the horizontal platform of the assembly, and adjust the level of the platform; then, draw the "ten" centerline and the cross-sectional shape of the member on the bottom of the column. On the horizontal tire frame, the column bottom plate and the steel component body are assembled on the line, ensuring that the column bottom plate is at right angles to the body and confirmed by the wire drop. After the assembly of the 4th "Ten" component is completed, the center line of the steel column is marked with red paint on the column bottom plate as required, and the direction of assembly is accurately checked.
7. Materials and equipment
(1) Material requirements Steel materials, welding materials, coating materials, etc. used in steel structures shall have quality certificates and must meet the design requirements and current national standards.
In addition to the quality certificate of the production plant, the raw materials entering the factory shall be witnessed, sampled, tested, and inspected on the spot under the witness of the contract and the relevant current standards, and the inspection records shall be made. And provide test reports to Party A and the supervisor.
(2) The equipment required to fabricate the “Ten†shaped steel components is shown in Table 3.
Table 3 Main equipment usage
8. Quality Assurance Control
(1) Specification for welding technical specifications for standard building steel structures JGJ81-2002, J218-2002; Specification for construction quality acceptance of steel structure engineering GB50205-2001; Quality inspection and evaluation standard for steel structure engineering GB50221-1995; Carbon steel welding wire and flux for submerged arc welding GB/T5293-1999; Ultrasonic flaw detection method for steel welds and classification of flaw detection results GB11345-1989.
(2) Quality Assurance Measures 1 Strictly implement the company's quality assurance manual and procedure documents to prevent all violations of the construction process. 2 Clarify the quality responsibilities of each process, and check and implement them at all levels. 3 Welding personnel and quality inspection personnel must be certified to work. 4 Do a good job in welding process evaluation and determine process parameters. 5 Make a good spot weld test of the welder. 6 Strict welding quality, do a welding construction diary, and organize the welder files.
9. Labor organization and security protection
(1) The length of the labor organization is 1 person, 2 welders, 4 riveters, 1 lifting crane, 1 inspector, 1 milling machine, and 1 safety officer.
(2) Safety protection On-site construction personnel, in addition to strictly implementing the current national “Construction and Installation Engineering Technical Regulations†and on-site safety technical protection measures and regulations, also emphasize the following points: 1Special types of welders, cranes, etc. must be trained, After passing the examination, they will be certified to work. 2 The weight of each beam (column) is about 5t/root. Always check whether the wire rope is safe and reliable when lifting and transporting. 3 operators should prevent burns. 4 equipped with a comprehensive and skilled electrician tracking service.
10. Engineering examples and benefit analysis
In the national 11th Five-Year "863" plan key research project "600MW coal-fired power station semi-dry desulfurization and dust removal integrated technology and equipment" relying on the project - Huaneng Qifeng Power Plant 2 × 660MW dry desulfurization and dust removal integrated renovation project construction, Applying this method, the project uses more than 10,000 tons of steel, and a total of 126 "ten" shaped steel members, each weighing about 55.1t, successfully produced the "ten" shaped components and achieved excellent results.
This method effectively solves the special technical problems that need to be solved in the production of “Ten†shaped components, and provides a complete and mature construction process, which not only saves labor, improves production efficiency, shortens the construction period, and achieves very significant economic benefits. And social benefits.
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