Process of production

The production process of hot-rolled round welded pipe mainly includes the following steps:
1. Raw Material Preparation
Material selection: Low-carbon steel strip or coil (such as Q235, Q345, etc.) is usually used as raw material to ensure that the material thickness and width meet the product specifications.
Uncoiling and leveling: The strip coil is unrolled by the uncoiling machine, and the rolling stress is eliminated by the leveling machine to ensure the flatness of the strip.
2. Forming
Rough forming: The strip is gradually bent into a round tube shape by multiple sets of rollers to form an open "U" or "O" shaped section.
Fine forming: Further adjust the size to ensure the roundness and pipe diameter accuracy, and prepare for subsequent welding.
3. Welding
High-frequency resistance welding (HFIW): High-frequency current is used to generate resistance heat at the joint to melt the edge of the steel strip, and welding is achieved through the pressure of the extrusion roller.
Weld seam treatment: Online flaw detection (such as ultrasonic testing) is performed immediately after welding to ensure that the weld has no defects such as pores and cracks.
4. Sizing and Straightening
Sizing: Adjust the outer diameter of the steel pipe through the sizing machine to ensure dimensional accuracy.
Straightening: Use a straightening machine to eliminate the bending deformation of the steel pipe and make it reach the standard straightness.
5. Cooling and Cutting
Cooling: The welded steel pipe is quickly cooled through the cooling water tank to avoid thermal deformation.
Cutting: Cut the steel pipe into fixed lengths (such as 6 meters, 12 meters) with a flying saw or laser cutting machine according to needs.
6. Surface Treatment and Inspection
Deburring: Remove burrs inside and outside the weld to ensure a smooth surface.
Hydraulic pressure test: Apply a certain pressure to the steel pipe to detect water leakage and ensure sealing.
Appearance inspection: Manually or automatically detect surface defects (such as scratches and dents) and mark unqualified products.
7. Packaging and Warehousing
Oil anti-rust: Apply anti-rust oil to the surface of the steel pipe to prevent corrosion.
Marking and packaging: Mark specifications, batch numbers and other information, and bundle and package according to customer requirements before warehousing.

Key Technical Points
Welding process: High-frequency welding is efficient and low-cost, suitable for small and medium diameter pipes; large diameter pipes may use submerged arc welding (SAW).
Dimension control: The forming and sizing processes require precise control of roller parameters to ensure uniform pipe diameter and wall thickness.
Quality inspection: Online flaw detection and water pressure testing are the core links to ensure weld quality.