A steel structure plant is characterized by its robust load-bearing components crafted entirely from steel, inclusive of steel columns, beams, foundations, and expansive roof trusses. Remarkably, the steel structure roofing system is predominant today. Significantly, while steel can uphold the walls, brick walls can also be utilized for certain sections. With China's booming steel production, steel structure plants are increasingly prevalent, available in both light and heavy variants. These steel marvels serve both industrial and civil construction purposes. Key features of steel structure plants include: 1. Lightweight yet high-strength with vast spanning capabilities. 2. Shortened construction periods, ensuring reduced investment costs. 3. Exceptional fire resistance and corrosion durability. 4. Ease of relocation and environmentally friendly recyclability.
Pioneering Construction Technology for Steel Structures
Scope of Application: Perfectly tailored for the intricate processing of building steel structures. This includes everything from process flow selection, lofting, marking, cutting, correction, and molding to 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 Steel, welding materials, coating materials, and fasteners employed in steel structures must come with quality certificates, meeting both design specifications and the latest industry standards.
1.1.2 Upon arrival, raw materials must be accompanied by manufacturer quality certificates. On-site witness sampling, delivery, inspection, and acceptance should be conducted under the supervision of Party A and the designated supervisor, in line with contract requirements and current standards. Detailed inspection records and reports must be furnished to both Party A and the supervisor.
1.1.3 Should any raw material defects be identified during processing, immediate analysis and corrective measures must be undertaken by inspectors and qualified technicians.
1.1.4 For material substitutions, the manufacturing unit must submit an application form (technical approval sheet) with the material certificate to Party A and the supervisor for prior approval, and receive confirmation from the design unit before proceeding.
1.1.5 Electrodes with peeling or rusted cores, damp, caked, or melted flux, and rusty wires are strictly prohibited. Studs for welding must be free from defects like cracks, striations, dents, and burrs.
1.1.6 Welding materials should be centrally managed, stored in a dedicated, dry, and well-ventilated warehouse.
1.1.7 Bolts must be preserved in a dry, ventilated environment. The acceptance of high-strength bolts must adhere to the national standard "Design, Construction and Acceptance Procedures for High-Strength Bolt Connection of Steel Structures" JGJ82. Corroded, stained, damp, bruised, or mixed batch bolts are strictly forbidden.
1.1.8 Paint must conform to design specifications and be kept in a specialized warehouse. Expired, deteriorated, caked, or ineffective paint should not be utilized.
2 Main Machinery
Steel Structure Solutions
Hai Luo Steel Structure
1.2.1 Premier Equipment
Long-Tool Production for Steel Structures.
3 Operating Conditions
1.3.1 Detailed construction drawings must be finalized and approved by the original designer.
1.3.2 Comprehensive technical preparations, including construction organization design, construction schemes, and operational instructions, must be in place.
1.3.3 All necessary process evaluation tests, process performance tests, and material procurement plans should be completed.
1.3.4 Main materials must be received and accounted for at the factory.
1.3.5 Comprehensive acceptance testing for a variety of mechanical equipment, ensuring peak performance and safety.
1.3.6 Every production worker has undergone rigorous pre-construction training and holds the relevant qualification certificates, guaranteeing expertise and reliability.
4 Operation Process
1.4.1 Process Flow
1.4.2 Operation Process
1 Lofting and Material Marking
1) Thoroughly review and familiarize yourself with the construction drawings. Address any queries by consulting the pertinent technical departments for resolution.
2) Prepare sample rods and materials. Typically, thin iron sheets and flat steel are suitable for creating samples.
3) Ensure all steel rulers used for lofting are verified and approved by the metrological department, confirming their accuracy and usability.
4) Understand the material and specifications of raw materials before quantifying them. Inspect the quality of raw materials and categorize parts by different specifications and materials. Follow the principle of processing larger items before smaller ones.
5) Mark the sample rod with processing numbers, component numbers, specifications, upper hole diameters, working lines, bending lines, and other processing symbols.
6) During lofting and marking, account for shrinkage (including on-site welding shrinkage) and machining allowances required for cutting and milling ends.
Milling end allowance: usually add 3-4mm per side after 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.
Welding shrinkage allowances are determined by the process based on the structural characteristics of the member.
7) When marking materials, ensure main force members and those needing bending are oriented as specified by the process. No sample impact points or scars should be on the exterior of bending parts.
8) Marking should facilitate cutting and maintain the quality of the parts.
9) Identify remaining materials after marking by number, specification, material, and batch number to ensure their reuse.
2 Cutting
Post-blanking line steel must be accurately cut to its specified shape and size.
1) Key considerations for cutting:
(1) With multiple parts on a steel plate and intersecting shear lines, plan a logical cutting sequence in advance.
(2) Correct any bending deformation post-shearing, and trim or polish rough or burred shear surfaces.
(3) During shearing, the metal near the incision may bend or compress. Ensure interfaces of crucial structural parts and welds are milled, planed, or ground.
2) Key points for sawing machinery construction:
(1) Straighten section steel before sawing.
(2) For single-piece sawing components, mark the line prior to cutting. For batch-processed components, use pre-installed positioning baffles.
(3) Reserve appropriate machining allowances for finishing important components post-sawing to meet high accuracy requirements.
(4) Control the perpendicularity of the cutting section during sawing.
3) Key considerations for gas cutting operations:
(1) Before commencing gas cutting, ensure that all equipment and tools within the gas cutting system are thoroughly checked for optimal operation and safety.
(2) It is crucial to select the appropriate process parameters for gas cutting. Adjust the shape of the oxygen jet (wind line) to maintain a clear outline, extended wind line, and high shooting force.
(3) Prior to gas cutting, remove dirt, oil, floating rust, and other debris from the steel surface. Leave a certain space underneath to facilitate efficient slag removal.
(4) During gas cutting, take necessary precautions to prevent tempering.
(5) To mitigate deformation during gas cutting, commence operations from the short side. Start by cutting smaller parts, then proceed to larger parts. Always cut the more complex pieces before the simpler ones.
3 Correction and Molding
1) Correction
(1) Cold correction of finished products typically employs mechanical forces using devices such as flange levelers, straighteners, hydraulic presses, and presses.
(2) Flame correction can be achieved using methods like point heating, linear heating, and triangular heating.
For thermal correction, the ideal heating temperature for low carbon steel and ordinary low alloy steel ranges between 600°C and 900°C. The optimal temperature for thermoplastic deformation is 800°C to 900°C, but it should not exceed 900°C.
Medium carbon steel is prone to cracking under deformation, hence flame correction is generally not recommended for these materials.
For ordinary low-alloy steel, gradual cooling is required post-heating correction to ensure stability.
Process Flow
2) Molding
(1) Hot Processing: Low carbon steel is typically processed at temperatures between 1000°C and 1100°C. The termination temperature should not fall below 700°C. Heating temperatures are around 500°C to 550ºC. Due to brittleness, hammering or bending is strictly prohibited to avoid breaking the steel.
(2) Cold Processing: Steel is processed at room temperature, predominantly using mechanical equipment and specialized tools.
4 Edge Machining (Including End Milling)
1) Commonly used edge processing methods encompass edge cutting, planing, milling, carbon arc gouging, gas cutting, and bevel machining.
2) For gas-cut parts requiring edge processing to eliminate the influence zone, a minimum processing allowance of 2.0mm is essential.
3) The machining edge depth must be sufficient to remove surface defects but should not be less than 2.0mm. Ensure the surface remains undamaged and crack-free post-processing, with grinding traces following the edge when using a grinding wheel.
4) After manual cutting, the surface of carbon structural steel parts should be cleaned, ensuring no roughness exceeds 1.0mm.
5) The supporting side of the member's end requires precise planing and section accuracy, regardless of the cutting method or steel type. Planing or milling is mandatory.
6) For construction drawings with specialized welding requirements, planing is necessary. However, shear edges of general plates or steel do not require planing.
7) After mechanical automatic cutting and air arc cutting, the flatness of the cutting surface must not exceed 1.0mm. For the main stress member's free edge, a processing allowance of at least 2mm on each side is required post-gas cutting. Ensure no burrs or other defects are present.
8) After the column end milling, ensure that the top tight contact surface covers more than 75% of the area close to the 0.3mm feeler. The stuffing area should not exceed 25%, and the edge gap should remain under 0.5mm to guarantee optimal structural integrity.
9) The choice of milling and the amount to be milled must align with the workpiece material and specific processing requirements. A carefully considered selection is crucial to maintaining high processing quality.
10) End processing of the component should be executed only after confirming that the correction meets the required standards.
11) Implement necessary measures according to the component's form to ensure that the milling end is precisely perpendicular to the axis, thereby enhancing accuracy and stability.
Five-hole system
1) High-strength bolts (large hexagonal head bolts, torsional shear bolts), semi-round head rivet self-tapping screws, and other holes can be produced through drilling, milling, punching, reaming, or countersinking methods.
2) Component drilling is preferred; however, punching is permissible when it can be demonstrated that the material's quality, thickness, and aperture will not be compromised, avoiding brittleness post-punching.
All ordinary structural steels under 5mm thickness and minor structures under 12mm thickness may be punched. The punched hole should not be followed by welding unless it can be proven that the material retains significant toughness post-punching. Typically, for drilling larger holes to be punched, ensure the hole is 3mm smaller than the specified diameter.
3) Prior to drilling, sharpen the drill and choose a suitable chip allowance.
4) Ensure the bolt hole is a perfect cylindrical shape, perpendicular to the steel surface at the designated location. The inclination should be less than 1/20, and the hole perimeter must be free of burrs, cracks, flares, or bumps, ensuring a clean cut.
5) The diameter of a bolt hole, made by refining or reaming, should match the diameter of the bolt rod. Post-drilling or assembly, the hole should have an H12 accuracy, and the hole wall surface roughness (Ra) should be less than 12.5μm.
6 Friction surface processing
1) High-strength bolted friction surfaces should be processed using sandblasting, shot blasting, or grinding. Note: The grinder's direction should be perpendicular to the component's force direction, with a grinding range not less than four times the bolt diameter.
2) Ensure the treated friction surface is protected from oil and physical damage.
3) Both the manufacturer and the installation unit must perform anti-slip coefficient tests on steel structure manufacturing batches. For each 2000-ton batch, divide into divisions or sub-parts. When less than 2000 tons, treat as a single batch. If multiple surface treatment processes are used, inspect each separately with three specimen groups per batch.
4) The manufacturer processes specimens for the anti-slip coefficient test. These specimens and the steel structural members they represent should be identical in material, batch, friction surface treatment process, surface state, and the same batch of high-strength bolt connections under identical environmental conditions.
5) Determine the specimen steel plate thickness based on the representative plate thickness in the steel structure project. Ensure the specimen plate surface is smooth, oil-free, and the hole and plate edges are free of flash and burrs.
6) Conduct the anti-slip coefficient test during steel structure manufacturing, and issue a detailed report. The test report should clearly state the methods and results used.
7) For retesting the anti-slip coefficient, components made from the same material and treated similarly should adhere to the current national standard "Design, Construction, and Acceptance Procedures for High-Strength Bolted Connections of Steel Structures" JGJ82 or the design document's provisions. These components must be handed over simultaneously.
7) Tube ball processing: Precision and excellence are key to our tube ball processing, ensuring that every detail meets rigorous quality standards.
1) Rod production process: Purchase steel pipe → Inspect material, specifications, surface quality (anti-corrosion treatment) → Cutting, beveling → Spot welding with cone head or seal plate assembly → Welding → Inspection → Pre-anti-corrosion treatment → Final anti-corrosion treatment. This thorough process ensures the highest quality and durability in rod production.
2) Bolt ball manufacturing process: Steel bar (or ingot) for pressure processing or round steel for machining → Forging blank → Normalizing treatment → Processing positioning thread hole (M20) and surface → Processing each thread hole and plane → Engraving worker and ball number → Anti-corrosion pretreatment → Final anti-corrosion treatment. This meticulous sequence guarantees precision and resilience in bolt ball production.
3) Cone head and sealing plate production process: Finished steel blanking → Die forging → Normalizing → Mechanical processing. Each step is optimized for quality and performance in the production of cone heads and sealing plates.
4) Welding ball joint grid manufacturing process: Purchase steel pipe → Inspect material, specifications, surface quality → Lofting → Cutting → Hollow ball production → Assembly → Anti-corrosion treatment. This detailed process ensures robust and reliable welding ball joint grids.
5) Welding hollow ball production process: Blanking (with copying cutter) → Pressing (heating) molding → Machine tool or automatic gas cutting groove → Welding → Weld non-destructive inspection → Anti-corrosion treatment → Packaging. Our precision-driven process delivers superior quality in welded hollow balls.
8) Assembly: Our assembly process is meticulously planned and executed to ensure the highest standards of product integrity and reliability.
1) Pre-assembly: Staff must be thoroughly familiar with construction drawings and technical requirements, verifying the quality of parts to be assembled in accordance with the drawings. This ensures a seamless and accurate assembly process.
2) Splicing parts: When raw materials are insufficient in size or due to technical requirements, parts must be spliced before assembly. This technique ensures that all components meet the necessary dimensions and specifications.
3) Mold assembly requirements:
(1) The selected site must be smooth and possess sufficient strength to support the assembly process.
(2) When arranging the assembly mold, consider prerelease welding shrinkage and other processing allowances based on the characteristics of the steel structure members.
(3) After assembling the first batch of components, a comprehensive inspection by the quality department is mandatory. Only upon passing this inspection can further assembly continue.
(4) Components must adhere strictly to process regulations during assembly. Any hidden welds should be completed first and covered post-inspection. For complex parts, 'welding while assembling' can be applied to ensure all aspects are addressed.
(5) To reduce deformation and streamline the assembly sequence, consider assembling parts into components first, then into the final structure.
4) Selecting the assembly method: The choice must reflect the structural characteristics, technical requirements, the manufacturer's processing capacity, and available mechanical equipment. This selection ensures quality control and high production efficiency.
5) Typical structure assembly: Employing standardized methods ensures consistency and quality in the assembly of typical steel structures.
(1) Welding H-beam construction technology: A methodical approach to H-beam welding ensures structural integrity and precision.
Process flow: A streamlined process flow is critical for efficient, high-quality production.
Cutting → Assembly → Welding → Correction → Secondary cutting → Hole making → Welding other parts → Correction and grinding. This process sequence guarantees precision and excellence at every stage.
(2) Processing technology of box section components: Cutting-edge technology ensures superior quality and durability in box section components.
(3) Processing technology of the rigid cross column: Advanced techniques provide high strength and reliability for rigid cross columns.
(4) General pipe rolling process flow chart: A detailed and efficient flow chart ensures optimal results in pipe rolling processes.
1) The number of pre-assembly operations must comply with design requirements and technical documents, ensuring every step meets required standards and specifications.
2) The selection principle of pre-assembled parts: prioritize main stress frames, complex joint connection structures, and components with tolerances near the limit that are representative of composite components.
3) Pre-assembly should be performed on a solid and stable platform tire frame. Its bearing point levelness must be ensured:
A≤300 ~ 1000m² Tolerance ≤2mm
A≤1000 ~ 5000m² Tolerance: exact measurements required< 3mm
(1) During pre-assembly, all components should be controlled according to the construction drawings. The center of gravity line of each bar should converge at the node center and remain completely free from external forces. Each member, whether column, beam, or support, should have at least two supporting points.
(2) The control basis of pre-assembled components should be clearly marked and consistent with the platform and ground baselines. The control basis must align with design requirements, and any changes in the pre-assembly basis position must be approved by process design.
(3) All components requiring pre-assembly must be individual components accepted by special inspectors and meet quality standards post-production. Identical single members should be interchangeable without affecting the overall geometry.
(4) Throughout the pre-assembly process, components must not be modified or cut using flame or machinery, nor should heavy weights be used for ballast, collision, or hammering.
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