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How are welded steel pipes processed?
time2025/05/28
- The processing of welded steel pipes is a multi-step, multi-process manufacturing process involving key links such as material selection, forming, welding, heat treatment, and finishing.
How are welded steel pipes processed?
The processing of welded steel pipes is a multi-step, multi-process manufacturing process involving key links such as material selection, forming, welding, heat treatment, and finishing. Depending on the production method (such as straight seam welded pipes, spiral welded pipes, high-frequency welded pipes, etc.), the process and applicable scenarios also vary significantly. The following is a comprehensive analysis from the aspects of production process, technical characteristics, and application fields:
1. Main production methods of welded steel pipes
1. Longitudinal Seam Welded Pipe
Process:
Sheet preparation: Cut the steel plate or steel strip into the required width (i.e. the circumference of the steel pipe).
Forming: Bend the sheet into a round tube by JCOE (progressive bending forming) or UOE (U-type pressure forming) process.
Welding: Use submerged arc welding (SAW) or laser welding to weld the straight seam (internal welding + external welding).
Expanding and straightening: Eliminate residual stress and improve dimensional accuracy by mechanical expansion.
Features:
The weld is a straight line, and the welding quality is easy to control.
It is suitable for large-diameter (Φ406mm or above) and high-pressure pipelines (such as oil and natural gas transportation).
2. Spiral Welded Pipe
Process:
Steel strip curling: spirally coil the steel strip into a tube to form a continuous spiral weld.
Welding: submerged arc welding (SAW) or high frequency welding (HFW).
Cutting and testing: cut by length and perform non-destructive testing (such as X-ray, ultrasonic).
Features:
High production efficiency and flexible adjustment of pipe diameter (Φ219~Φ3000mm).
Weld stress distribution is uniform, but the risk of welding defects is slightly higher than that of straight seam pipe.
Commonly used for structural support, pile foundation, and low-pressure fluid transportation.
3. Electric Resistance Welded Pipe (ERW)
Process:
Steel strip forming: The steel strip is rolled into a round tube through multiple rollers.
High frequency heating: High frequency current (100~400kHz) is used to melt the edge of the weld instantly.
Pressure welding: Apply pressure in the molten state to achieve filler-free welding.
Features:
Narrow weld, small heat-affected zone, and smooth surface.
Applicable to small-diameter (Φ20~Φ610mm) and thin-walled pipes (such as water pipes and furniture pipes).
2. Analysis of the core technology of welded steel pipe
JCOE--Large diameter straight seam welded pipe--low equipment cost, high flexibility--low production efficiency
UOE--Large diameter high pressure pipe--High forming accuracy, good strength, high investment, suitable for mass production
Spiral curling--Large diameter spiral welded pipe Continuous production, high material utilization rate, long weld, difficult to detect
Multi-roll rolling--Small diameter ERW pipe high-speed production, low cost--Limited wall thickness (usually ≤20mm)
3. Comparison of welding technologies
Welding method---heat source Applicable scenarios Weld quality
Submerged arc welding (SAW)---arc + flux coverage---straight seam/spiral welded pipe, thick-walled pipe---deep penetration, good impact resistance
High frequency welding (HFW)---resistance heat---thin-walled ERW pipe---no slag, but strict control of parameters is required
Laser welding---laser beam---high-precision thin-walled pipe Narrow weld, small deformation, high cost