Steel structure plants are defined by their primary load-bearing components being composed of steel. This includes steel columns, beams, foundations, and roof trusses. Modern plants predominantly feature steel roof trusses, and walls can be optionally maintained with brick. With China's booming steel production, the adoption of steel structure plants has surged and can be categorized into light and heavy. Both industrial and civil construction facilities fabricated from steel fall under this category. Key features of steel structure plants: 1. Lightweight yet strong with vast spanning capabilities. 2. Shorter construction periods, leading to reduced investment costs. 3. High fire resistance and formidable corrosion resistance. 4. Easy to relocate and recyclable with zero pollution.
Advanced Construction Technology for Steel Structures
Scope of Application: This technology is ideal for processing building steel structures, covering the selection of process flows, lofting, marking, cutting, correction, molding, edge processing, tube ball processing, hole making, friction surface processing, end processing, component assembly, round tube component processing, and steel component pre-assembly.
1. Material Requirements
1.1.1 All steel, welding materials, coating materials, and fasteners must come with quality certifications, aligning with both design requirements and current standards.
1.1.2 Incoming raw materials should be accompanied by the manufacturer's quality certificate and undergo on-site witness sampling, inspection, and acceptance by Party A and the supervisor, adhering to contract requirements and relevant standards. Inspection records and reports must be provided to Party A and the supervisor.
1.1.3 Any defects discovered in raw materials during processing must be addressed and resolved by inspectors and competent technicians.
1.1.4 Material substitutions require a pre-submitted application form (technical approval sheet) with the material certificate, which needs approval from Party A and the supervisor and confirmation from the design unit.
1.1.5 It is strictly prohibited to use electrodes with peeling or rusted cores, damp or caked flux, melted flux, or rusty wire. The surface of studs used in stud welding must be free from defects like cracks, striations, dents, and burrs.
1.1.6 Welding materials must be centrally managed. A dedicated, dry, and well-ventilated warehouse should be established for storage.
1.1.7 Bolts should be stored in a dry, ventilated room. 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. Use of corroded, stained, damp, bruised, or mixed batch high-strength bolts is strictly prohibited.
1.1.8 Paint must meet design requirements and be stored in a special warehouse. Expired, deteriorated, caked, or ineffective paint 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 Preparations including construction organization design, construction schemes, and operational instructions must be completed.
1.3.3 All process evaluation tests, process performance tests, and material purchase plans must be finalized.
1.3.4 Main materials must be delivered to the factory.
1.3.5 Comprehensive debugging and acceptance of various mechanical equipment.
1.3.6 All production workers have undergone rigorous pre-construction training and have obtained the necessary qualification certificates.
4 Operation Process
1.4.1 Process Flow
1.4.2 Operation Process
1 Lofting, Marking Material
1) Thoroughly familiarize yourself with the construction drawings. Address any questions by consulting the relevant technical departments.
2) Prepare sample materials and sample rods. Generally, thin iron sheets and flat steel are used.
3) Ensure all steel rulers used for lofting are verified and approved by the metrological department before use.
4) Understand the raw materials and specifications prior to counting materials. Check the quality of raw materials. Different specifications and materials should be categorized accordingly, in order of size.
5) Paint the sample rod to indicate the processing number, component number, and specification. Mark the diameter of the upper hole, working line, bending line, and other processing symbols.
6) Reserve shrinkage (including on-site welding shrinkage) and machining allowance required for cutting and milling ends when lofting and marking.
Milling End Allowance: Add 3-4mm per side after cutting, and 4-5mm per side after gas cutting.
Cutting Margin: Automatic gas cutting slit width is 3mm, manual gas cutting slit width is 4mm.
The welding shrinkage is determined by the process according to the structural characteristics of the member.
7) Main force members and bent parts must be marked in the process-specified direction, without impacting or scarring the bending parts.
8) Marking materials should facilitate cutting and ensure the quality of parts.
9) Identify the remaining materials after marking, including number, specification, material, and batch number for easy reuse.
2 Cutting
Cut the steel according to the desired shape and size after the blanking line.
1) Pay attention to the following when cutting:
(1) Arrange a reasonable cutting procedure in advance when multiple parts with intersecting shear lines are arranged on a steel plate.
(2) Correct any bending deformation after shearing. Trim and polish rough or burred shear surfaces.
(3) Due to shearing forces, metal near the incision may bend. Important structural parts and weld interfaces must be milled, planed, or ground.
2) For sawing machinery construction, consider the following:
(1) Straighten section steel before sawing.
(2) For single-piece components, draw the marking line before cutting. Batch processed components can use positioning baffles.
(3) For components with high machining accuracy, reserve an appropriate allowance for face finishing milling after sawing.
(4) Ensure the perpendicularity of the cutting section when sawing.
3) During gas cutting operations, note the following process points:
(1) Before commencing gas cutting operations, it is crucial to thoroughly inspect all equipment and tools within the gas cutting system to ensure they are in optimal working condition and safe for use.
(2) It is essential to select the appropriate process parameters when performing gas cutting. Adjust the oxygen jet (wind line) to maintain a distinct outline, ensuring a long and powerful wind line for effective cutting.
(3) Prior to gas cutting, ensure the steel surface is free from dirt, oil, floating rust, and other debris. Leave sufficient space underneath to facilitate the easy expulsion of slag.
(4) Take necessary precautions to prevent tempering during gas cutting operations.
(5) To mitigate the risk of deformation during gas cutting, initiate the process from the shorter side. Prioritize cutting smaller parts first before moving on to larger components. For intricate designs, cut the more complex sections initially, followed by the simpler ones.
3 Correction and Molding
1) Correction
(1) Cold correction of finished products typically employs mechanical forces such as flange levelers, straighteners, hydraulic presses, and other similar equipment.
(2) Flame correction involves different heating methods, including point heating, linear heating, and triangular heating.
For thermal correction, the heating temperature for low carbon steel and ordinary low alloy steel generally ranges between 600 ~ 900°C. The ideal thermoplastic deformation temperature is 800 ~ 900°C, but it should not exceed 900°C.
Medium carbon steel is prone to cracking due to deformation; hence, it is not advisable to use flame correction for medium carbon steel.
After heating correction, ordinary low-alloy steel should be cooled down slowly.
Process Flow
2) Molding
(1) Hot Processing: For low carbon steel, hot processing typically occurs between 1000 ~ 1100°C. The termination temperature for hot processing should not fall below 700°C. The heating temperature is around 500 ~ 550ºC. Steel becomes brittle under these conditions, so hammering and bending are strictly prohibited to prevent breakage.
(2) Cold Processing: Cold processing of steel is performed at room temperature, primarily using mechanical equipment and specialized tools.
4 Edge Machining (Including End Milling)
1) Common edge processing methods include edge cutting, planing, milling, carbon arc gouging, gas cutting, and bevel machining.
2) For gas-cut parts requiring the elimination of the influence zone during edge processing, the minimum processing allowance is 2.0mm.
3) The machining edge depth must ensure the removal of surface defects, with a minimum depth of 2.0mm. The surface must remain undamaged and free of cracks post-processing, and grinding traces should follow the edge during grinding wheel processing.
4) After manually cutting the edge of carbon structural steel parts, the surface should be cleaned to ensure no roughness exceeds 1.0mm.
5) The supporting side of the member's end requires tight planing with high section accuracy, regardless of the cutting method or steel type used. Planing or milling is necessary.
6) Edges specified or required for welding in construction drawings need planing, whereas shear edges of general plates or steel do not require planing.
7) After mechanical automatic cutting and air arc cutting of a part's edge, the cutting surface flatness should not exceed 1.0mm. The main stress member's free edge requires a processing allowance of at least 2mm on each side post gas cutting, with no burrs or other defects.
8) Upon completing the column end milling, ensure that the top tight contact surface covers more than 75% of the area, with a 0.3mm feeler gauge. The stuffing area should remain under 25%, and the edge gap should not exceed 0.5mm, ensuring impeccable precision and quality.
9) The selection of milling type and milling amount must be tailored to the material of the workpiece and specific processing requirements. This careful selection guarantees superior processing quality.
10) Component end processing should commence only after the correction has been thoroughly verified and deemed qualified.
11) Implement necessary measures based on the component's form to ensure the milling end remains perfectly perpendicular to the axis, maintaining structural integrity.
Five-hole System
1) High-strength bolts (large hexagonal head bolts, torsional shear bolts, etc.), semi-round head rivet self-tapping screws, and similar holes are produced through drilling, milling, punching, reaming, or countersinking to achieve precision and durability.
2) Component drilling is prioritized, but punching is permissible if it is proven that the material's quality, thickness, and aperture remain intact without causing brittleness.
All ordinary structural steels under 5mm thick may be punched, while minor structures under 12mm thick may also be punched. Punching should not be followed by welding unless it is confirmed that the material retains significant toughness post-punching. Typically, for larger holes meant for punching, the initial hole should be 3mm smaller than the final specified diameter.
3) Prior to drilling, ensure the drill is well-ground and the chip allowance is appropriately selected for optimal performance.
4) The resulting bolt hole must be a perfect cylindrical shape, perpendicular to the steel surface. The inclination should not exceed 1/20, and the perimeter should be free of burrs, cracks, flares, or bumps, ensuring clean and smooth cutting.
5) The diameter of the bolt hole refined or reamed must match the diameter of the bolt rod. The hole should meet H12 accuracy after drilling or assembly, with a surface roughness of less than 12.5μm.
6) Friction Surface Processing
1) High-strength bolted friction surfaces can be processed using sandblasting, shot blasting, or grinding. (Note: The grinder's direction should be perpendicular to the component's force direction, and the grinding range should be at least four times the bolt's diameter.)
2) Ensure the processed friction surface is protected against oil and other potential damage to maintain its integrity.
3) Both the manufacturer and the installation unit must conduct anti-slip coefficient tests on steel structure manufacturing batches. These batches can be divided into divisions of specified engineering quantities, with each 2000t batch requiring three groups of specimens for inspection.
4) Specimens for the anti-slip coefficient test should be processed by the manufacturer, using the same material, batch, friction surface treatment process, and surface state as the steel structural members they represent. Ensure the same batch of high-strength bolt connection pairs with identical performance grades are applied and stored under consistent environmental conditions.
5) Determine the specimen steel plate's thickness based on the representative plate thickness in the steel structure engineering. The plate's surface should be smooth and oil-free, with edges and holes free of flash and burrs.
6) The manufacturer must conduct the anti-slip coefficient test during steel structure manufacture and issue a detailed report, specifying the test methods and results for comprehensive analysis.
7) Ensuring maximum safety and reliability, components with identical materials and treatment methods for retesting anti-slip coefficients should strictly adhere to the current national standard "Design, Construction, and Acceptance Procedures for High-Strength Bolted Connection of Steel Structures" JGJ82. Alternatively, guidelines provided in design documents may be followed. It is crucial that these components are handed over simultaneously to ensure cohesive quality control.
7) Precision Tube Ball Processing
1) Rod Production Process: Our meticulous rod production journey starts with the procurement of high-quality steel pipes. Each pipe undergoes rigorous inspection for material consistency, specifications, and surface quality, including anti-corrosion treatment. The process continues with precise cutting and beveling, followed by spot welding with cone heads or seal plate assembly. Post-welding, a thorough inspection is conducted, leading to pre-anti-corrosion and anti-corrosion treatments, ensuring unmatched durability and reliability.
2) Bolt Ball Manufacturing Process: Starting with premium steel bars (or ingots) for pressure processing or round steel for machining, the process involves forging the blank, followed by normalizing treatment. We then meticulously process the positioning thread hole (M20) and its surface, along with each thread hole and plane. Unique worker and ball numbers are assigned before undergoing anti-corrosion pretreatment and comprehensive anti-corrosion treatment to ensure exceptional longevity.
3) Cone Head and Sealing Plate Production Process: Our production begins with finished steel blanking, progressing through die forging, followed by normalizing. The components then undergo precision mechanical processing to meet exacting standards.
4) Welding Ball Joint Grid Manufacturing Process: From the purchase of high-quality steel pipes, each step is meticulously executed. Inspections for material, specifications, and surface quality are followed by precision lofting and cutting. Hollow ball production and assembly are carried out with unparalleled accuracy, culminating in a thorough anti-corrosion treatment for superior durability.
5) Welding Hollow Ball Production Process: Our advanced production process starts with precise blanking (using a copying cutter), followed by pressing and heating molding. Subsequent machine tool or automatic gas cutting grooves lead to welding, with stringent weld non-destructive inspection. The final stages include anti-corrosion treatment and careful packaging to ensure quality and protection.
8) Seamless Assembly
1) Prior to assembly, our highly skilled staff meticulously familiarize themselves with the construction drawings and associated technical requirements. Each part undergoes rigorous quality reviews to ensure conformity with construction specifications, guaranteeing the highest standards of workmanship.
2) In instances where raw material sizes are insufficient or specific technical requirements necessitate splicing, these elements are expertly spliced before assembly to maintain structural integrity and precision.
3) Strict Adherence to Mold Assembly Requirements:
(1) The selected assembly site must be smooth and exhibit sufficient strength to support the process without compromise.
(2) When arranging the assembly mold, it is imperative to consider prerelease welding shrinkage and other processing allowances according to the nuanced characteristics of the steel structure members.
(3) After the first batch of components is assembled, a comprehensive inspection by the quality inspection department is mandatory. Only upon passing this inspection can further assembly proceed, ensuring unwavering quality standards.
(4) Components must be assembled in strict accordance with process regulations. Hidden welds must be welded first and inspected before being concealed. For complex parts that are challenging to weld, the method of welding while assembling is employed to complete the task effectively.
(5) To minimize deformation and optimize assembly sequence, the strategy of assembling smaller components first before integrating them into larger assemblies is adopted, ensuring precision and efficiency.
4) Assembly Method Selection: The choice of assembly method for steel structure components is based on their structural characteristics and technical requirements. It is essential to consider the manufacturer's processing capabilities, available mechanical equipment, and other factors to select a method that guarantees control over assembly quality and promotes high production efficiency.
5) Mastery in Typical Structure Assembly:
(1) Advanced Welding H-beam Construction Technology
Comprehensive Process Flow:
Cutting → Assembly → Welding → Correction → Secondary Cutting → Hole Making → Welding Other Parts → Correction and Grinding.
(2) State-of-the-Art Box Section Components Processing Technology.
(3) Expert Processing Technology for Rigid Cross Columns.
(4) General Pipe Rolling Process Flow Chart.
1) The pre-assembly quantity must adhere strictly to design requirements and accompanying technical documents, ensuring that every component meets precise specifications.
2) Principles for Selecting Pre-Assembly Parts: Prioritize the main stress frame, any joint with a complex connection structure, and components at the tolerance limit that represent composite components.
3) Pre-assembly must be performed on a robust, stable platform tire frame. It is crucial to ensure that the bearing point is perfectly level:
A≤300 ~ 1000m², with a Tolerance of ≤2mm.
A≤1000 to 5000m², adhering to the specified Tolerance.< 3mm
(1) During pre-assembly, all components must be controlled as per construction drawings. The center of gravity line of each bar should converge at the node's center, remaining in a completely free state. No external force should be applied to fix them. Each single member, whether column, beam, or support, must have at least two supporting points.
(2) The control basis for pre-assembled components should be clearly marked and consistent with the baseline of the platform and ground. The control basis should meet design requirements. Any adjustment in the pre-assembly basis position must be approved by the process design team.
(3) All components for pre-assembly must be single components that have been inspected and accepted by special inspectors, meeting quality standards post-production. Single members should be interchangeable without compromising overall geometry.
(4) Throughout the pre-assembly of the tire frame, components must not be modified or cut using flame or machinery. Heavy weights for ballast, collision, or hammering are prohibited.
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