Spiral steel pipes for piling—formally known as spiral-welded steel pipes for piling—are a type of welded steel pipe specifically designed for use as foundation piles in civil engineering structures, such as docks, bridges, and buildings. These pipes are manufactured using hot-rolled steel strips, which are formed into a spiral shape at ambient temperature and then joined using a double-sided submerged arc welding (SSAW) process. As a primary material for foundation piles, the spiral configuration of the weld seam effectively reinforces the pipe wall and enhances overall structural stability, making these pipes particularly well-suited for large-diameter, thick-walled piling projects. They are widely utilized in the construction of infrastructure—including buildings, bridges, docks, highways, and railways—serving as critical foundation components that support the loads of the structures above.
Spiral steel pipes for piling are typically fabricated from carbon structural steel or low-alloy, high-strength structural steel to ensure sufficient strength and toughness under complex geological conditions. Common material grades include the Q235 series (e.g., Q235A, Q235B), Q345 (16Mn), and Q355. These materials offer excellent weldability and are capable of withstanding the impact loads encountered during the piling process, as well as long-term stress from the foundation soil.
Structural Advantages
The defining structural feature of these pipes is their unique spiral weld seam. Unlike straight-seam welded pipes, the spiral weld wraps around the pipe body; this design ensures that the weld seam is not aligned with the primary stress direction, thereby increasing the pipe's load-bearing capacity and resistance to buckling. Furthermore, the spiral-welding process allows for the production of large-diameter pipes using narrower steel strips, making it a highly cost-effective solution for manufacturing large-bore, relatively thin-walled piling pipes.
Mechanical Properties
In terms of mechanical performance, the "reinforcing rib" effect created by the spiral weld enhances the overall stability of the steel pipe when subjected to axial compression and lateral bending moments. For a given diameter and wall thickness, spiral-welded pipes demonstrate yield and burst pressure values that meet or exceed design requirements. Furthermore, spiral-welded pipes exhibit superior plastic deformation capacity compared to straight-seam welded pipes; they can accommodate ground deformation and are highly effective at inhibiting crack propagation .
Fields of Application
Due to their excellent structural properties, spiral-welded steel pipes are widely used in the foundation work of various civil engineering projects. In building construction, they frequently serve as foundation piles for high-rise and super-high-rise structures, capable of supporting immense vertical loads. In bridge engineering, they are used for pier foundations, providing stable support. In the construction of docks and ports, they function as pile foundations that withstand the impact of waves and vessels. Additionally, they are employed in the treatment of soft soil foundations for highways and railways—for instance, in the form of CFG piles or pipe piles—effectively enhancing the load-bearing capacity of the roadbed and ensuring the safe operation of transportation infrastructure.
