Steel structure plants primarily consist of steel as the main load-bearing components, including steel columns, beams, foundations, and roof trusses. With the advent of larger spans in factories, steel roof trusses and roofs have become predominant. While the walls can also be maintained using brick, the surge in China's steel production has spurred the widespread adoption of steel structure plants, classifiable into light and heavy types. Any industrial or civil construction employing steel is termed as steel structures. Notable features include: 1. Lightweight yet high-strength buildings with large spans. 2. Short construction periods that lower investment costs. 3. High fire resistance and strong corrosion resistance. 4. Easy mobility and pollution-free recycling.
Advanced Construction Technology for Steel Structures
Scope of Application: This technology is tailored for building steel structure processes, encompassing selection of process flow, lofting, marking, cutting, correction, molding, edge processing, tube ball processing, hole making, friction surface treatment, end processing, component assembly, round tube processing, and steel component pre-assembly.
1. Material Requirements
1.1.1 All steel, welding materials, coatings, and fasteners must come with quality certificates and comply with design requirements and current standards.
1.1.2 Raw materials must undergo on-site witness sampling, inspection, and acceptance, overseen by Party A and the supervisor, in line with contract requirements and relevant standards. Records and inspection reports must be provided to Party A and the supervisor.
1.1.3 If defects in raw materials are discovered during processing, they must be assessed and addressed by inspectors and qualified technicians.
1.1.4 Any material substitution requires prior submission of an application (technical approval sheet) with the material certificate, and must be approved by Party A, the supervisor, and confirmed by the design unit.
1.1.5 Electrodes with peeling or rusted cores, damp or caked flux, melted flux, or rusty wire are strictly prohibited. Stud surfaces used for welding must be free from defects like cracks, striations, dents, and burrs.
1.1.6 Welding materials should be centrally managed in a dedicated, dry, and well-ventilated warehouse.
1.1.7 Bolts must be stored in a dry, ventilated room. High-strength bolts must adhere to the national standard JGJ82 for design, construction, and acceptance procedures. Corroded, stained, damp, bruised, or mixed batch bolts are prohibited.
1.1.8 Paint must meet design requirements and be stored in a dedicated warehouse. Expired, deteriorated, caked, or ineffective paint cannot be used.
2. Main Machinery
State-of-the-Art Steel Structure Equipment
Hai Luo Steel Structure
1.2.1 Main Equipment
Long Tools for Steel Structure Production
3. Operating Conditions
1.3.1 Detailed construction drawings must be completed and approved by the original designer.
1.3.2 Necessary technical preparations, including construction organization designs, construction schemes, and operation instructions, must be in place.
1.3.3 All process evaluation tests, process performance tests, and material purchase plans must be completed.
1.3.4 Main materials must have entered the factory.
1.3.5 All kinds of mechanical equipment debugging acceptance.
1.3.6 All production workers have received pre-construction training and obtained the corresponding qualification certificate.
4 Operation process
1.4.1 Process flow
1.4.2 Operation process
1 Lofting, marking material
1) Familiar with the construction drawings, find any questions, should contact the relevant technical departments to solve.
2) Ready to do sample, sample rod materials, generally can be used thin iron sheet and flat steel.
3) Lofting requires steel ruler must be checked and reviewed by the metrological department, and can be used after passing.
4) The material and specifications of the raw materials must be understood before the number of materials, and the quality of the raw materials must be checked. Different specifications, different materials of parts should be divided into different numbers. And according to the principle of first big and then small in turn.
5) The sample rod should be painted to indicate the processing number, component number and specification, and mark the diameter of the upper hole, the working line, the bending line and other processing symbols.
6) Lofting and marking should reserve shrinkage (including on-site welding shrinkage) and machining allowance required by cutting and milling end:
Milling end allowance: generally 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 given by the process according to the structural characteristics of the member.
7) The main force members and members that need to be bent should be taken in the direction specified by the process when marking the material, and there should be no sample impact points and scars on the outside of the bending parts.
8) The marking material should be conducive to cutting and ensuring the quality of parts.
9) The remaining materials after the marking shall be identified, including the number, specification, material and batch number of the remaining materials, so as to facilitate the reuse of the remaining materials.
2 Cutting
The steel after the blanking line must be cut according to its desired shape and size.
1) The following points should be noted when cutting:
(1) When many parts are arranged on a steel plate and there are several intersecting shear lines, a reasonable cutting procedure should be arranged in advance before cutting.
(2) The bending deformation of the material after shearing must be corrected; The shear surface is rough or has burrs, and must be trimmed and polished.
(3) In the shearing process, the metal near the incision is squeezed and bent due to the shearing force, and the interface position of the important structural parts and welds must be milling, planing or grinding wheel.
2) Sawing machinery construction should pay attention to the following construction points:
(1) The section steel should be straightened before sawing.
(2) For single-piece sawing components, first draw the marking line, and then cut the line. The components processed in batches can be pre-installed with positioning baffles for processing.
(3) Important components with high machining accuracy requirements should be considered to reserve appropriate machining allowance for face finishing milling after sawing.
(4) When sawing, attention should be paid to the control of the perpendicularity of the cutting section.
3) In the gas cutting operation should pay attention to the following process points:
(1) Prior to initiating gas cutting, it is paramount to meticulously inspect all equipment and tools within the gas cutting system to ensure optimal operational efficiency and stringent safety compliance.
(2) Selection of the correct process parameters is crucial during gas cutting. Adjust the oxygen jet (wind line) to maintain a well-defined outline, extended wind line, and robust shooting force for superior results.
(3) Pre-gas cutting preparation necessitates the removal of dirt, oil, surface rust, and other contaminants from the steel. Ensure a gap beneath the steel to facilitate effective slag expulsion.
(4) Vigilance against tempering is essential during gas cutting to maintain structural integrity.
(5) To avert deformation during gas cutting, operations should commence from the shorter side. Prioritize cutting smaller parts before larger ones; intricate parts should precede simpler ones.
3 Correction and Molding
1) Correction
(1) Cold correction of finished products typically involves mechanical forces applied via equipment such as flange levelers, straighteners, hydraulic presses, and standard presses.
(2) Flame correction employs various heating methods: point heating, linear heating, and triangular heating.
For low carbon and ordinary low alloy steels, thermal correction heating temperature ranges between 600 ~ 900°C, with 800 ~ 900°C being optimal for thermoplastic deformation. Avoid exceeding 900°C.
Medium carbon steel is prone to cracking under deformation, thus flame correction is generally avoided for this material.
Post-heating correction of ordinary low-alloy steel should involve a slow cooling process.
Process Flow
2) Molding
(1) Hot Processing: Low carbon steel typically undergoes hot processing at 1000 ~ 1100°C, with termination temperatures not falling below 700°C. Avoid hammering or bending below 500 ~ 550ºC due to brittleness.
(2) Cold Processing: Steel is processed at room temperature, predominantly using mechanical equipment and specialized tools.
4 Edge Machining (Including End Milling)
1) Routine edge processing methods include 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, ensure a minimum processing allowance of 2.0mm.
3) The machining depth of the edge must ensure all surface defects are removed, maintaining a depth of no less than 2.0mm. Surface integrity must be preserved with grinding following edge contours.
4) Post-manual cutting of carbon structural steel parts, surfaces must be cleaned to eliminate any roughness exceeding 1.0mm.
5) The planing top tight and section accuracy of member ends necessitate precision, regardless of the cutting method or steel type, requiring planing or milling.
6) Construction drawings with specific welding requirements necessitate planing. General plate or steel shear edges typically do not require planing.
7) Post-mechanical automatic cutting and air arc cutting, the edge flatness of parts should not exceed 1.0mm. Main stress member free edges demand a planing or milling allowance of at least 2mm on each side post-gas cutting, without any burrs or defects.
8) After the column end milling, ensure that the top tight contact surface covers more than 75% when checked with a 0.3mm feeler gauge. The stuffing area should not exceed 25%, and the edge gap should be less than 0.5mm for optimal precision.
9) The selection of milling tools and milling depth must be tailored to the material and specific processing needs of the workpiece. This judicious choice is the cornerstone of superior processing quality.
10) End processing of components should be executed only after confirming that corrections meet the required standards.
11) Appropriate measures must be taken based on the component's form to ensure that the milled end remains perpendicular to the axis for precision and 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 other holes can be produced through drilling, milling, punching, reaming, or countersinking methods.
2) Drilling is the preferred method for component holes, though punching is permissible if it can be demonstrated that the material's quality, thickness, and aperture remain unaffected and do not cause brittleness.
All ordinary structural steels under 5mm thick and minor structures up to 12mm thick are permissible for punching. Post-punching welding is generally not allowed unless proven that the material retains significant toughness. For larger holes to be punched, the hole must be 3mm smaller than the specified diameter.
3) Prior to drilling, it is essential to properly grind the drill and choose an appropriate chip allowance for smooth and efficient drilling.
4) Bolt holes must be cylindrical, perpendicular to the steel surface, and have an inclination of less than 1/20. The hole perimeter should be free of burrs, cracks, flares, or bumps, ensuring clean cutting.
5) Bolt holes created by refining or reaming must match the bolt rod diameter. After drilling or assembly, they should have an H12 accuracy grade, with a hole wall surface roughness of Ra less than 12.5μm.
6 Friction surface processing
1) High-strength bolted friction surfaces can be processed via sandblasting, shot blasting, or grinding. Note: The grinding direction must be perpendicular to the force direction, and the range should be at least four times the bolt diameter.
2) Treated friction surfaces should be protected against oil contamination and damage to maintain integrity.
3) Both the manufacturer and installation unit must conduct anti-slip coefficient tests on steel structure batches. Each treatment process must be inspected separately, with three groups of specimens per batch for consistency.
4) Anti-slip coefficient test specimens should be processed by the manufacturer. They must be made from the same material, batch, and friction surface treatment as the represented steel structural members and stored under identical environmental conditions.
5) The specimen steel plate thickness should correspond to the representative plate thickness in the steel structure engineering. The specimen surface must be smooth, oil-free, and free of flash and burrs around the hole and plate edges.
6) The manufacturer must conduct anti-slip coefficient tests during steel structure manufacturing and issue a detailed report stating test methods and results.
7) Components with the same material and treatment method for retesting anti-slip coefficient should be made according to the requirements of the current national standard 'Design, Construction and Acceptance Procedures for High-Strength Bolted Connection of Steel Structures' JGJ82 or the provisions of the design document. The components should be handed over simultaneously.
7) Tube Ball Processing
1) Rod Production Process: Purchase steel pipe → Inspect material, specifications, and surface quality (anti-corrosion treatment) → Cutting, beveling → Spot welding with cone head or seal plate assembly → Welding → Inspection → Pre-anti-corrosion treatment → Anti-corrosion treatment.
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 its surface → Processing each thread hole and plane → Processing worker number and ball number → Anti-corrosion pretreatment → Anti-corrosion treatment.
3) Cone Head and Sealing Plate Production Process: Finished steel blanking → Die forging → Normalizing → Mechanical processing.
4) Welding Ball Joint Grid Manufacturing Process: Purchase steel pipe → Inspect material, specifications, and surface quality → Lofting → Cutting → Hollow ball production → Assembly → Anti-corrosion treatment.
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.
8) Assembly
1) Before assembly, staff must familiarize themselves with the construction drawings and related technical requirements of the components, and review the quality of the parts to be assembled according to the construction drawings.
2) If raw material size is insufficient, or due to technical requirements, parts generally must be spliced before assembly.
3) The following requirements must be followed when using mold assembly:
(1) The selected site must be smooth and have sufficient strength.
(2) When arranging the assembly mold, consider prerelease welding shrinkage and other various processing allowances according to the characteristics of the steel structure members.
(3) After assembling the first batch of components, it must be comprehensively inspected by the quality inspection department. Assembly can continue after passing the inspection.
(4) Components must be assembled in strict accordance with the process regulations. Hidden welds must be welded first and covered only after passing inspection. For complex assembly parts that are not easy to weld, welding while assembling can be used to complete the assembly work.
(5) To reduce deformation and improve assembly sequence, first assemble into components, then assemble into larger assemblies.
4) The selection of the assembly method for steel structure components must be based on the structural characteristics and technical requirements of the components. Combine this with the processing capacity of the manufacturer and mechanical equipment to choose a method that effectively controls assembly quality and high production efficiency.
5) Typical Structure Assembly
(1) Welding H-Beam Construction Technology
Process Flow
Cutting → Assembly → Welding → Correction → Secondary cutting → Hole making → Welding other parts → Correction and grinding.
(2) Processing Technology of Box Section Components
(3) The Processing Technology of the Rigid Cross Column
(4) General Pipe Rolling Process Flow Chart
1) The number of pre-assemblies shall be according to the design requirements and technical documents.
2) The selection principle of pre-assembled assembly parts encompasses: prioritizing the main stress framework, intricate joint connections, and composite components that are near the tolerance limits. This ensures the utmost precision and representativeness in the assembly.
3) Pre-assembly must be conducted on a robust and stable platform tire frame, ensuring that its bearing point levelness is meticulously maintained:
A≤300 ~ 1000m² Tolerance ≤2mm
A≤1000 to 5000m² Tolerance< 3mm
(1) During pre-assembly, all components should strictly adhere to construction drawings. Each bar's center of gravity line must converge at the node center, remaining completely free of external forces. Each single member, whether column, beam, or support, should be supported on at least two points.
(2) Pre-assembled components must have clearly marked center lines that align with the platform and ground baselines. Control bases should align with design specifications. Any changes to the pre-assembly basis position must receive approval from the process design team.
(3) Components scheduled for pre-assembly must be inspected and accepted by specialized inspectors, ensuring they meet quality standards post-production. Identical single members should be interchangeable without altering the overall geometry.
(4) Throughout the pre-assembly process, components must not be altered or cut using flames or machinery. Additionally, the use of heavy weights for ballast, as well as collision or hammering, is strictly prohibited.
Audited Supplier 
){kind=link}
){kind=link}