How are spiral submerged arc welded pipes formed?
Spiral submerged arc welded pipes are formed by spirally curling the steel strip into a cylindrical shape and welding the seams using a submerged arc welding process. The steel strip is continuously fed into the former at a certain angle to form a stable spiral angle. During welding, the arc burns under the flux layer to prevent air from contaminating the weld. This process allows for continuous production, high efficiency and uniform welds. It is suitable for the manufacture of large-diameter and long-distance pipelines.
What are the advantages of submerged arc welding compared to other welding processes?
Submerged arc welding has a large penetration depth and fast welding speed, which is suitable for the production of thick-walled steel pipes. The flux protects the weld from oxidation and has more stable quality. It has a high degree of automation and reduces human operation errors. The heat input is concentrated, the deformation is small, and the residual stress is low. It is especially suitable for the continuous welding needs of spiral welded pipes.
What is the effect of the spiral forming angle on the performance of the pipe?
The spiral angle is usually 20°–70°. The smaller the angle, the stronger the axial load-bearing capacity, but the difficulty of forming increases. A large angle leads to high production efficiency, but may reduce the hoop strength. The angle design needs to be optimized according to the pipe diameter and purpose. A reasonable angle can balance the forming efficiency and mechanical properties. The common angle is 45°–60°, which takes into account both strength and production economy.
Why are spiral welded pipes often used for oil and gas transportation?
Its continuous forming process can produce ultra-long pipelines and reduce the number of welds on site. The high reliability of submerged arc welding is suitable for high-pressure environments. The spiral structure disperses stress and has strong resistance to external pressure. The cost is lower than that of straight seam welded pipes, especially suitable for large-diameter requirements. In addition, the material can be adjusted to adapt to corrosive media.
How to control the quality of welds during production?
The welding current, voltage and speed parameters need to be precisely controlled. The flux composition and particle size affect the stability of the molten pool. Regularly perform X-ray or ultrasonic non-destructive testing. Use an online monitoring system to adjust the process in real time. After welding, a water pressure test and mechanical property spot check are required.
