Working principle of SSAW steel pipe

The working principle of SSAW (Spiral Submerged Arc Welded) steel pipes revolves around a specific manufacturing process that involves bending hot-rolled strip steel into a spiral shape, followed by welding the inner and outer seams using automatic submerged arc welding. Here's a more detailed breakdown of how SSAW steel pipes are produced and their working principle.

1. Raw Material and Preparation

The process begins with hot-rolled steel strips that are continuously fed into a forming machine.

The strip steel is gradually bent into a spiral shape as it moves through the machine. The forming angle is adjustable to produce pipes of various diameters from the same width of steel strip.

2. Spiral Forming

The hot-rolled steel strip is spirally formed by bending it progressively, creating a helical shape as the material moves along the forming section.

The angle at which the strip is bent determines the diameter and wall thickness of the final pipe.

3. Submerged Arc Welding

Once the steel strip is spirally shaped, the two edges of the strip are brought together, and the seams (inner and outer) are welded using submerged arc welding (SAW).

In submerged arc welding, an arc is struck between the welding wire and the base metal (steel), and a flux is used to shield the weld from contamination. This process ensures a high-quality, strong bond between the edges of the steel strip.

The welding is done in a continuous process along the spiral seam, ensuring uniform strength along the entire length of the pipe.

4. Cooling and Inspection

After welding, the pipe is cooled, and the weld seam is typically subjected to a quality inspection, including visual and non-destructive testing (e.g., ultrasonic testing) to ensure the weld is free from defects.

The pipe is then cut to the required length and may undergo additional treatments such as coating, inspection, and pressure testing depending on its intended application.

5. Final Product

The final SSAW steel pipe features a spiral seam running around its circumference. This design provides the pipe with high resistance to external forces and stress, making it suitable for applications like large-diameter pipelines, oil and gas transmission, and structural uses.

Working Principle Summary:

Bending: Hot-rolled steel strips are bent into a spiral shape.

Welding: The strip edges are welded together using submerged arc welding, forming a strong bond along the spiral seam.

Quality Control: The welds and the pipe as a whole are inspected for defects to ensure structural integrity.

This manufacturing process allows for efficient production of large-diameter pipes with uniform strength and durability, especially beneficial in industries requiring robust pipeline systems.