1.Cutting List
This process involves material inspection, including confirmation of the model and specifications selected for the project, as well as quality checks of the materials.
2.Layout and Marking
① During layout marking, clearly indicate assembly marks, bolt hole markings, the position and direction of stiffening plates, tilt marks, centerlines, reference lines, and inspection lines. Create templates if necessary.
② Consider allowances for welding shrinkage during fabrication and installation; cutting, edge planing, and milling processing allowances; and installation dimensional requirements.
③ Before marking, correct any bending or deformation of the material.
3.Cutting
Steel plates are cut using CNC multi-head cutting machines. Before cutting, remove rust and contaminants from the cutting surface to ensure clean and smooth cuts. After cutting, clear slag and splatter. Operators must be proficient in using mechanical equipment and adjusting device parameters to optimal values.
4.Assembly and Forming
Before assembly, correct any deformation of the steel to ensure it falls within the controlled deviation range. Contact surfaces must be free of burrs, contaminants, and debris to guarantee tight assembly of components and compliance with quality standards. Use appropriate tools and equipment, such as right-angle steel rulers, to ensure sufficient precision after assembly. The equipment used is the Z12 section steel assembly machine.
5.Welding
① Equipment used: Gantry-type fully automatic submerged arc welding machine.
② Welding process:
Gantry automatic submerged arc welding is used for welding steel columns and beams; manual welding is used for connecting plates and stiffeners on columns and beams.
Requirements for gantry automatic welding:
(1) Remove rust, burrs, and contaminants within 30–50 mm of the welding edge to reduce factors that could cause welding defects such as porosity.
(2) The lead plate should be of the same material as the base metal, with the same welding groove form, and its length must meet standard specifications.
Requirements for manual arc welding: Use a welder in good condition with full functionality, and dry the selected electrodes in a drying oven.
6.Hole Making
7.Section Steel Straightening
① Equipment used: Flange straightening machine.
② Process requirements: Operators must be familiar with the process content and proficient in equipment operation procedures. After straightening, self-inspection should be conducted, and allowable deviations must comply with the relevant provisions of the "Steel Structure Construction and Acceptance Code."
8.End Cutting
After welded section steel columns and beams are straightened, their ends must be cut flat using an end milling machine.
9.Rust Removal
Rust removal is performed using specialized equipment. Shot blasting can improve the fatigue strength and corrosion resistance of steel. It also enhances the surface hardness of the steel to varying degrees, which benefits paint adhesion without requiring additional coating thickness. The abrasives used for rust removal must meet quality standards and process requirements. The relative humidity of the construction environment should not exceed 85%. After rust removal, clean the steel surface with tools such as brushes before proceeding to the next step. If the steel surface rusts again before priming, it must undergo rust removal again.
10.Painting
After the rust removal is inspected and approved, apply the first coat of primer. Generally, if the steel is stored indoors after rust removal, the primer should be applied within 24 hours. If stored outdoors, the primer should be applied during the same shift. Paints must be used in combination as required by the design. After the first coat of primer has dried, apply the intermediate and top coats to ensure the coating thickness meets design requirements. The paint should be applied evenly without sagging.
11.Packaging and Transportation
① Before packaging, convert various symbols into the component numbers specified in the design drawings, and mark them with a pen (paint) or stickers on the designated parts of the components for identification during packaging.
② During handling, protect the components and coatings, and provide appropriate protection for vulnerable areas.
③ If components are deformed or damaged during handling, repair them promptly to ensure they are in perfect condition before shipment.
12.Acceptance
Before steel components leave the factory, the following documents must be submitted:
(1) Product certificate
(2) Construction drawings and design documents
(3) Agreement documents addressing technical issues during fabrication
(4) Quality certificates or test reports for steel, connection materials, and coatings
(5) Weld inspection records
(6) Coating inspection records
(7) Main component acceptance records
(8) Component shipment list documents
