The production process of square welded steel pipes usually includes the following main steps, and the specific process may be adjusted depending on the production equipment and product specifications:

1. Raw Material Preparation
Steel strip selection: Use hot-rolled or cold-rolled steel strip as raw material, and select the appropriate steel strip material (such as carbon steel, alloy steel, etc.) according to the product specifications (such as wall thickness, size).
Uncoiling and leveling: Unroll the coiled steel strip through the uncoiling machine, and use the leveling machine to eliminate the wave shape or bending of the steel strip to ensure the surface flatness.

2. Forming
Pre-bending and rough forming: The steel strip is gradually bent by multiple sets of rollers to form a preliminary rectangular profile. Usually "cold bending forming" technology is used to avoid material hardening.
Fine forming: Use precision molds to further adjust the shape to ensure the dimensional accuracy of the square steel pipe (such as side length, verticality).

3. Welding
High-frequency resistance welding (ERW):
Align the edges of the formed steel strip and heat the edges of the steel strip to a molten state through a high-frequency current.
Apply pressure to fuse the edges to form a continuous weld.
Submerged Arc Welding (SAW):
Applicable to large-diameter or thick-walled steel pipes, flux is covered at the weld, and the welding wire and the base material are melted by the arc to form a weld.

4. Weld Processing
Deburring: Use a milling cutter or grinding wheel to remove burrs on the inner and outer surfaces of the weld to ensure a smooth surface.
Weld flaw detection: Use ultrasound or X-ray to detect internal defects in the weld (such as pores and lack of fusion).

5. Sizing and Straightening
Sizing machine: Adjust the dimensional accuracy of the steel pipe by rolling to ensure that the side length and roundness meet the standards.
Straightening machine: Eliminate the bending deformation of the steel pipe during the forming or welding process.

6. Cooling and Cutting
Cooling: Use water cooling or air cooling to reduce the temperature of the steel pipe to avoid thermal deformation.
Cutting: Use a flying saw or a circular saw to cut the continuous steel pipe into the required length (such as 6 meters, 12 meters).

7. Surface Treatment
Pickling/phosphating: remove surface oxide scale and impurities to prepare for subsequent treatment.
Galvanizing or painting: improve the corrosion resistance of steel pipes by hot-dip galvanizing or spraying anti-rust paint.

8. Quality Inspection
Dimension measurement: check parameters such as side length, wall thickness, length, etc.
Mechanical property testing: tensile test, impact test, etc. to verify material strength and toughness.
Appearance inspection: visually or through automated equipment to detect surface defects (such as scratches, dents).

9. Packaging and Storage
Packaging: bundle, label, or use moisture-proof materials for packaging according to customer needs.
Storage: store in categories to avoid deformation or rust caused by heavy pressure or humid environment.