At Shaanxi Fanyang Construction Technology Co. Ltd, our steel structure plants are the epitome of modern engineering, tailored to meet the rigorous demands of today's industries. These structures feature primary load-bearing components crafted from high-grade steel, encompassing steel columns, steel beams, steel foundations, and expansive steel roof trusses. Notably, the steel roof trusses are designed for large spans, ensuring robustness and stability. The steel roofing is complemented by walls that can be constructed from either steel or brick, offering versatile maintenance options. As China escalates its steel production, the prevalence of steel structure plants has surged, categorized into light and heavy-duty structures. These industrial and civil facilities, constructed entirely from steel, boast remarkable attributes: 1. Exceptional light weight coupled with high strength, allowing for large spans. 2. Reduced construction periods leading to cost-effective investments. 3. Superior fire resistance and corrosion protection. 4. Ease of relocation and pollution-free recycling, setting a benchmark in sustainable construction.
Cutting-Edge Construction Technology for Steel Structures
Scope of Application: Our expertise covers the comprehensive processing of building steel structures, from selecting the ideal process flow to executing precise operations such as lofting, marking, cutting, correction, molding, edge processing, tube ball processing, hole making, friction surface processing, end processing, component assembly, round tube component processing, and pre-assembly of steel components.
1. Material Requirements
1.1.1 All materials including steel, welding, coatings, and fasteners must be certified for quality and adhere to design specifications and current industry standards.
1.1.2 Upon arrival at the factory, raw materials must be accompanied by the manufacturer's quality certificate. On-site witness sampling, inspection, and acceptance must be conducted in the presence of Party A and the supervisor, adhering to contract stipulations and relevant standards. Detailed inspection records and reports must be provided to both Party A and the supervisor.
1.1.3 Should any defects in raw materials be discovered during processing, they must be promptly addressed and resolved by qualified inspectors and technicians.
1.1.4 Any material substitution requests must be submitted in advance by the manufacturing unit, complete with the material certificate and a technical approval form. Approval must be obtained from Party A, the supervisor, and the design unit before proceeding.
1.1.5 The use of electrodes with peeling or rusted cores, damp or caked flux, melted flux, or rusty wires is strictly prohibited. Studs intended for welding must be free from defects like cracks, striations, dents, and burrs.
1.1.6 Welding materials require centralized management, stored in a dedicated, dry, and well-ventilated warehouse.
1.1.7 Bolts must be stored in a dry, ventilated space. Acceptance of high-strength bolts must comply with the national standard 'Design, Construction, and Acceptance Procedures for High-Strength Bolt Connections of Steel Structures' JGJ82. The use of corroded, stained, damp, bruised, or mixed-batch high-strength bolts is strictly forbidden.
1.1.8 Paints must meet design requirements and be stored in a specialized warehouse. Expired, deteriorated, caked, or ineffective paints must not be used.
2. Main Machinery
Steel Structure
Hai Luo Steel Structure
1.2.1 Main Equipment
Steel Structure Production Long Tool
3. Operating Conditions
1.3.1 Detailed construction drawings must be completed and approved by the original designer.
1.3.2 All technical preparations, including construction organization design, construction schemes, and operation instructions, must be thoroughly prepared.
1.3.3 Completion of various process evaluation tests, process performance tests, and material procurement plans is required.
1.3.4 Main materials must have arrived at the factory.
1.3.5 Comprehensive debugging and stringent acceptance of all types of mechanical equipment.
1.3.6 All production workers have undergone thorough pre-construction training and hold the necessary qualification certificates.
4 Operation Process
1.4.1 Process Flow
1.4.2 Operation Process
1 Lofting and Material Marking
1) Carefully review construction drawings and promptly address any queries with the relevant technical departments.
2) Prepare samples and sample rod materials; typically, thin iron sheets and flat steel are appropriate.
3) Ensure steel rulers used for lofting are checked and approved by the metrological department before use.
4) Prior to material measurement, understand the raw materials' specifications and quality. Different parts with varying specifications should be categorized accordingly, following the principle of processing larger items first.
5) Paint sample rods with processing numbers, component numbers, specifications, and mark various processing symbols like the hole diameter, working line, and bending line.
6) Reserve allowances for shrinkage (including on-site welding shrinkage) and machining, as required for cutting and milling ends:
Milling end allowance: Generally add 3-4mm per side post-cutting, and 4-5mm per side after gas cutting.
Cutting margin: Automatic gas cutting slit width is 3mm, while manual gas cutting slit width is 4mm.
Allowances for welding shrinkage are determined by the process based on the structural characteristics of the component.
7) For main force members and those needing bending, follow the specified marking directions, avoiding sample impact points and scars on the bending parts' exterior.
8) Ensure marking materials facilitate cutting and maintain the quality of parts.
9) Label remaining materials after marking with their number, specification, material, and batch number for easier reuse.
2 Cutting
The steel, post-blanking line, must be cut to the desired shape and size.
1) Key considerations during cutting:
(1) When multiple parts are laid out on a steel plate with intersecting shear lines, pre-arrange a rational cutting procedure.
(2) Correct any bending deformations post-shearing; trim and polish rough or burred shear surfaces.
(3) Due to shearing force, metal near the incision bends and squeezes; for critical structural parts and welds, milling, planing, or grinding is required.
2) During sawing, keep in mind the following points:
(1) Ensure section steel is straightened before sawing.
(2) For single-piece sawing, mark the line first, then cut. For batch processing, use pre-installed positioning baffles.
(3) For components requiring high machining accuracy, allow for a suitable machining allowance for post-sawing face finishing milling.
(4) Control the perpendicularity of the cutting section during sawing.
3) During gas cutting, adhere to the following process points:
(1) Before gas cutting, the equipment and tools of the entire gas cutting system must be checked to ensure normal operation and safety.
(2) The correct process parameters should be selected when gas cutting. When cutting, the shape of the oxygen jet (wind line) should be adjusted to achieve and maintain a clear outline, long wind line and high shooting force.
(3) Before gas cutting, the dirt, oil, floating rust and other debris on the surface of the steel should be removed, and a certain space should be left below to facilitate the blowing out of the slag.
(4) When gas cutting, tempering must be prevented.
(5) In order to prevent gas cutting deformation, the operation should start from the short side; Should cut the small parts first, then cut the large parts; The more complex ones should be cut first and the simpler ones later.
3 Correction and molding
1) Correction
(1) Cold correction of finished products, generally using mechanical forces such as flange leveler, straightener, hydraulic press, press and so on.
(2) Flame correction, heating methods are point heating, linear heating and triangular heating.
The thermal correction heating temperature of low carbon steel and ordinary low alloy steel is generally 600 ~ 900 ° C, and 800 ~ 900 ° C is the ideal temperature for thermoplastic deformation, but not more than 900 ° C.
Medium carbon steel will crack due to deformation, so medium carbon steel is generally not corrected by flame.
Ordinary low-alloy steel should be cooled slowly after heating correction.
Process flow
2) Molding
(1) hot processing: low carbon steel is generally in 1000 ~ 1100 ° C, hot processing termination temperature should not be lower than 700 ° C. The heating temperature is 500 ~ 550ºC. The steel is brittle, it is strictly prohibited to hammer and bend, otherwise it is easy to break the steel.
(2) Cold processing: Steel is processed at room temperature, most of which are carried out using mechanical equipment and special tools.
4 Edge machining (including end milling)
1) Commonly used edge processing methods are: edge cutting, planing, milling, carbon arc gouging, gas cutting and bevel machining.
2) For gas-cut parts, when the influence zone needs to be eliminated for edge processing, the minimum processing allowance is 2.0mm.
3) The depth of the machining edge should be able to ensure that the surface defects are removed, but not less than 2.0mm, the surface should not be damaged and cracked after processing, and the grinding traces should follow the edge when the grinding wheel is processed.
4) The edge of carbon structural steel parts, after manual cutting, the surface should be cleaned, and there should be no roughness of more than 1.0mm.
5) The supporting side of the end of the member requires the planing top tight and the section accuracy of the end of the member is higher, no matter what method of cutting and what kind of steel is made of, it is necessary to planing or milling.
6) The edge of the construction drawing with special requirements or provisions for welding needs to be planed, and the shear edge of the general plate or steel does not need to be planed.
7) After mechanical automatic cutting and air arc cutting of the edge of the part, the flatness of the cutting surface can not exceed 1.0mm. The free edge of the main stress member requires a processing allowance of planing or milling after gas cutting, at least 2mm on each side, and there should be no burrs and other defects.
8) After the column end milling, ensure the top tight contact surface encompasses more than 75% of the area near the 0.3mm feeler gauge. The stuffing area must not exceed 25%, and the edge gap should be kept within 0.5mm.
9) Select the milling and milling amount based on the workpiece material and processing requirements. A judicious choice guarantees processing quality and precision.
10) Perform the end processing of the component only after it passes the correction quality checks.
11) Implement essential measures according to the component's form to ensure the milling end remains perpendicular to the axis.
Five-hole system
1) High-strength bolts (large hexagonal head bolts, torsional shear bolts, etc.), semi-round head rivets, self-tapping screws, and other holes can be produced through drilling, milling, punching, reaming, or countersinking.
2) Prefer component drilling; however, punching is permissible if it can be demonstrated that the quality, thickness, and aperture of the material will not lead to brittleness.
All ordinary structural steels under 5mm thick and minor structures under 12mm thick may be punched. Ensure no welding follows the punching hole (groove shape) unless material retains considerable toughness post-punching, allowing for welding construction. For larger holes, leave a 3mm margin smaller than the specified diameter.
3) Before drilling, grind the drill properly and choose a reasonable chip allowance.
4) Bolt holes should be cylindrical and perpendicular to the steel surface, with an inclination of less than 1/20. Ensure the hole perimeter is free of burrs, cracks, flares, or bumps, and thoroughly clean the cutting.
5) For refining or reaming, the bolt hole diameter should match the bolt rod diameter, ensuring H12 accuracy post-drilling or assembly, and a surface roughness of Ra ≤ 12.5μm for the hole wall.
6) Friction surface processing
1) High-strength bolted friction surfaces can be processed via sandblasting, shot blasting, or grinding. Note: Grinding direction should be perpendicular to the component's force direction, with a grinding range at least 4 times the bolt diameter.
2) Take protective measures to prevent oil contamination and damage to the treated friction surface.
3) Both the manufacturer and the installation unit should conduct anti-slip coefficient tests for steel structure manufacturing batches. A batch can be divided into sub-parts or divisions for each 2000t batch, with inspections for each treatment process if multiple processes are used, involving three groups of specimens per batch.
4) Anti-slip coefficient test specimens must be processed by the manufacturer using the same material, batch, friction surface treatment, and environmental conditions as the steel structural members they represent. Apply the same batch of high-strength bolt connection pairs with equivalent performance grade.
5) The specimen steel plate's thickness should match the representative plate thickness in the steel structure engineering. Ensure the specimen plate surface is smooth and free of oil, with no flash or burrs on the hole and plate edges.
6) The manufacturer should conduct anti-slip coefficient tests during steel structure manufacturing and issue a detailed report, stating the test methods and results.
7) Components utilizing identical materials and treatment methods for retesting the anti-slip coefficient must adhere to the stringent requirements outlined in the national standard 'Design, Construction, and Acceptance Procedures for High-Strength Bolted Connections of Steel Structures' JGJ82 or the specific provisions within the design documents. Additionally, ensure that these components are handed over simultaneously for effective coordination.
7) Precision Tube Ball Processing
1) Rod Production Process: Initiate with steel pipe acquisition → conduct thorough inspections on material, specifications, and surface quality (including anti-corrosion treatment) → proceed to cutting and beveling → perform spot welding with cone head or seal plate assembly → execute welding → conduct inspections → pre-anti-corrosion treatment → finalize with anti-corrosion treatment.
2) Bolt Ball Manufacturing Process: Begin with a steel bar (or ingot) for pressure processing or round steel for machining → execute forging blank → normalize treatment → process positioning thread hole (M20) and its surface → continue processing each thread hole and plane → inscribe worker number and ball number → pre-anti-corrosion treatment → conclude with anti-corrosion treatment.
3) Cone Head and Sealing Plate Production Process: Start with finished steel blanking → die forging → normalizing → complete with mechanical processing.
4) Welding Ball Joint Grid Manufacturing Process: Commence with steel pipe acquisition → inspect material, specifications, and surface quality → proceed with lofting → cutting → hollow ball production → assembly → finalize with anti-corrosion treatment.
5) Welding Hollow Ball Production Process: Begin with blanking (using copying cutter) → proceed to pressing (heating) molding → perform machine tool or automatic gas cutting groove → execute welding → conduct weld non-destructive inspection → finalize with anti-corrosion treatment and packaging.
8) Precise Assembly
1) Prior to assembly, ensure staff are thoroughly familiar with the construction drawings and related technical requirements. Review the quality of all parts to be assembled according to the construction drawings' specifications.
2) If raw material size is insufficient or technical requirements necessitate splicing parts, ensure splicing is completed prior to assembly.
3) Adhere to the following guidelines when utilizing mold assembly:
(1) Select a site that is both smooth and possesses adequate strength.
(2) When arranging the assembly mold, consider prerelease welding shrinkage and other processing allowances based on the steel structure members' characteristics.
(3) Upon assembling the initial batch of components, a comprehensive inspection by the quality inspection department is required. Continue assembly only after passing this inspection.
(4) During assembly, strictly adhere to process regulations. For hidden welds, weld first and cover post-inspection. For complex assembly parts that are difficult to weld, employ a method of welding while assembling to complete the work.
(5) To minimize deformation and optimize the assembly sequence, consider first assembling components into larger sections, then integrating these sections into final components.
4) The selection of the steel structure component assembly method must be tailored to the components' structural characteristics and technical requirements, and should align with the manufacturer's processing capabilities and mechanical equipment. This ensures effective quality control and high production efficiency.
5) Assembly of Typical Structures:
(1) Welding H-Beam Construction Technology:
Process Flow:
Cutting → Assembly → Welding → Correction → Secondary Cutting → Hole Making → Welding Other Parts → Correction and Grinding
(2) Box Section Components Processing Technology
(3) Rigid Cross Column Processing Technology
(4) General Pipe Rolling Process Flow Chart
1) The required number of pre-assemblies must align with design requirements and technical documentation.
2) Selection Principle for Pre-Assembly Parts: Prioritize the main stress-bearing framework, components with intricate joint connections, and those with tolerance levels close to the limit, representing complex composite components.
3) Pre-Assembly Procedures: Conduct pre-assembly on a robust and stable platform tire frame. Ensure the bearing point levelness is maintained to the specified standards:
A ≤ 300 ~ 1000m² Tolerance ≤ 2mm
A ≤ 1000 ~ 5000m² Tolerance< 3mm
(1) During pre-assembly, adhere strictly to construction drawings. Ensure the center of gravity line of each bar converges at the node center and remains completely free of external forces. Each component, whether column, beam, or support, must have a minimum of two support points.
(2) Control Basis for Pre-Assembled Components: Clearly mark and align the center line with both the platform and ground baselines. Ensure compliance with design requirements, and seek approval from process design if any alterations to the pre-assembly basis position are necessary.
(3) Pre-Assembly Quality Assurance: Only use single components that have been inspected and meet quality standards. Ensure interchangeability of similar components without compromising the overall geometry.
(4) Pre-Assembly Precautions: Throughout the pre-assembly process, avoid modifying or cutting components using flame or machinery. Refrain from using heavy weights for ballast, collision, or hammering.
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