Welding process of spiral steel pipe

The most common connection method for SSAW steel pipes is welding, a traditional technique that falls short of current market demands for safety, sealing performance, cost efficiency, and emergency repair effectiveness. Here is an overview of welding process of spiral steel pipe.

Manual Arc Welding:

Due to its flexibility and low equipment requirements, manual arc welding still accounts for 40% to 50% of outdoor pipeline welding workloads.

Cellulose Downhill Welding:

This widely used method is applicable for welding all thin-walled large-diameter pipes, including steels below X70. It offers fast welding speeds, good root welding performance, high weld seam radiographic flaw detection pass rates, and excellent economy.

Low-Hydrogen Vertical Welding:

Compared to cellulose downhill welding, this process has a slower root welding speed. It is mainly used for welding pipes or thick-walled pipes under harsh weather conditions, for transporting acidic gas and high-sulfur oil and gas media, and where high low-temperature toughness is required.

Cellulose Electrode for Root Welding and CO2 Gas Shielded Welding for Filling:

This method, which combines high productivity and low cost, has gained popularity. However, for oil and gas pipeline welding, achieving all-position welding with a small current range and short-circuit transition can lead to defects like incomplete penetration. Thus, one-sided welding is performed with a vertical cellulose electrode as the primer, and the back is formed, followed by filling the surface with high-efficiency CO2 gas shielded welding.

Semi-Automatic Welding with Self-Shielded Flux-Cored Wire:

Ideal for outdoor windy conditions, this method uses the gas protection generated by the flux core instead of CO2, offering good wind resistance and high deposition rates for all-position welding of pipelines. Brands like Lincoln’s NR-207, NR-204-H, and NR-208-H are widely recognized and used for welding pipelines such as X70 and X80. However, the root weld can be prone to unfused defects.

CO2 Gas Shielded Semi-Automatic or Fully Automatic Welding with High-Performance Machines:

Advanced welding power supplies now offer real-time control of welding current and voltage waveforms, enhancing CO2 gas shielded welding efficiency and quality. Technologies like Lincoln's STT (Surface Tension Transfer) welding, which falls under waveform control, significantly improve pipeline welding performance.