The steel structure production process involves a series of processing, assembly, and treatments to produce steel structural components that meet design requirements. This involves numerous meticulous steps. The following is a detailed description of the process:

1. Preliminary Preparation Phase

Design and Drawing Review
Based on project requirements (such as building structure and load requirements), the design firm completes the detailed design of the steel structure, including component dimensions, connection methods, and material types (such as Q235 and Q355).
Drawing reviews are organized among the design, production, and construction teams to confirm design rationality, process feasibility, and dimensional accuracy requirements to avoid subsequent production errors.

Material Procurement and Inspection
Steel (such as steel plates, steel sections, steel pipes), welding materials (electrodes, wire, flux), and fasteners (bolts and nuts) are purchased according to the drawing requirements.
Raw materials are quality inspected, including verification of material certificates, visual inspection (for defects such as cracks and rust), mechanical property testing (tensile and bend tests), and chemical composition analysis to ensure compliance with national standards (such as GB/T 700 and GB/T 1591).

II. Processing and Manufacturing Stage

1. Cutting
Purpose: Cut the raw material into the required blanks according to the drawing dimensions.
Common Processes:
Flame Cutting: Suitable for thick steel plates, low cost but lower precision.
Plasma Cutting: Suitable for thin plates, stainless steel, etc., with fast cutting speed and high precision.
CNC Cutting: Computer-controlled cutting paths achieve accuracy of ±1mm and are suitable for complex components.
Precautions: Burrs and slag must be removed after cutting to avoid affecting subsequent processing.

2. Straightening and Forming
Straightening: Steel may be deformed during rolling, transportation, or cutting. This requires mechanical straightening (such as roller straightening) or flame straightening (localized heating followed by cooling) to restore it to a straight line.
Forming: Processing components that require bending or special shaping, such as:
Plate Rolling: Rolls steel plates into round tubes or curved components (such as factory domes).
Press Bending: Bends steel plates into right-angled or acute-angled components such as angles and U-channels.
Presses: Use dies to press complex curved surfaces or special-shaped parts (such as bridge joints).

3. Edge Processing and Hole Forming
Edge Processing: Milling and planing of weld grooves and end faces to ensure weld quality (e.g., groove angles and blunt edge dimensions meet design requirements).
Hole Forming: Bolt and pin holes are machined using a drill press, punch, or CNC drilling equipment. Diameter accuracy (usually H12 grade) and positional accuracy (hole pitch deviation ≤ ±1mm) are required to prevent bolt insertion during installation.

4. Assembly (Assembly)
Assembling multiple parts into components (e.g., beams, columns, trusses) according to the drawing specifications. Common methods include:
Tack Welding: Temporarily securing parts with a small number of welds to ensure assembly dimensions.
Fixtures: Use specialized jigs and fixtures to ensure component verticality and parallelism (e.g., the web and flange of a steel column must be assembled at a 90° angle). Critical dimensions, such as component length and diagonal deviation, should be checked using tools such as tape measures and total stations.

5. Welding
Core process: Permanently joining assembled parts through welding. Common welding methods:
Manual arc welding: Flexible and suitable for complex joints, but inefficient.
Submerged arc welding: Suitable for long straight welds (such as butting steel plates), with a high degree of automation and consistent weld quality.
Gas shielded welding (CO₂ welding, argon arc welding): Suitable for thin plates and stainless steel components, with minimal welding distortion.
Quality Control: Preheating is required before welding (for thick plates or low-alloy steels). Non-destructive testing (UT ultrasonic testing, MT magnetic particle testing) is required after welding to check for defects such as cracks and pores.

6. Welding Straightening
After welding, components may deform (such as bending or twisting) due to thermal stress. Mechanical or flame straightening is required to ensure that component straightness and perpendicularity meet specifications (for example, column perpendicularity deviation ≤ H/1000 and ≤15mm).

III. Post-Processing

Surface Treatment
Rust Removal: Remove scale and rust from the steel surface through sandblasting (high efficiency and thorough rust removal), pickling, or hand polishing to achieve a Sa2.5 (near-white) or St3 (thorough manual rust removal) finish.
Coating: Apply primer (rust prevention), intermediate coat (to increase thickness), and topcoat (decorative and weather-resistant). Coating thickness must meet design requirements (e.g., total thickness ≥ 120μm for outdoor steel structures). For special environments (e.g., chemical and marine environments), anti-corrosion coatings (e.g., epoxy zinc-rich paint) may be used.

Final Inspection
A comprehensive inspection of component dimensions, appearance, welding quality, and coating thickness is conducted, and a quality report is issued.
Critical components (e.g., bridge steel box girders and high-rise steel columns) undergo load testing or load-bearing capacity calculations.

Numbering and Packaging: Components are numbered according to the order of installation to facilitate on-site lifting and assembly.
Protect vulnerable areas (e.g., bolt holes and sharp corners) with protective shields. Secure large components with wire ropes to prevent deformation or damage during transportation.

IV. Transportation and Installation Coordination
During transportation, appropriate vehicles (flatbeds, trailers) must be selected based on component size. Oversized components require an oversize transportation permit.
We will provide installation drawings and component lists, and assist with on-site lifting and positioning to address dimensional deviations during installation.