In the world of steel pipe manufacturing, Electric Resistance Welded (ERW) and Double Submerged Arc Welded (DSAW) pipes are two widely used types of straight seam welded pipes. While both serve structural and fluid transport purposes, their production methods, performance characteristics, and application ranges differ significantly. Understanding the key differences between ERW and DSAW pipes is essential for selecting the right pipe for specific industrial needs.
Process
The manufacturing process for ERW (Electric Resistance Welded) pipes is relatively simple and efficient. It typically involves high-frequency resistance welding, making it ideal for the continuous production of straight seam pipes with uniform specifications. ERW pipes are formed by shaping steel strips into cylindrical shapes and welding the seam using high-frequency currents. This method allows for high production speeds and comparatively lower manufacturing costs.
In contrast, DSAW (Double Submerged Arc Welded) pipes are produced using a more complex process, commonly through the JCOE (J-forming, C-forming, O-forming, and Expanding) technique. This method involves the gradual forming of steel plates into pipe shapes, followed by inner and outer submerged arc welding. Though more labor-intensive and costlier than ERW, the DSAW process provides superior weld quality and thicker wall capabilities, making it suitable for demanding applications requiring high strength and durability.
Length
Both ERW and DSAW pipes are produced in straight lengths with longitudinal welds, but their maximum lengths differ due to their forming processes and material constraints. ERW pipes can typically reach up to 14 meters in length, as they are made from coiled steel strips that allow for continuous welding. In comparison, DSAW pipes, made from steel plates with width limitations, usually reach a maximum length of about 12.8 meters. Additionally, DSAW pipes are more constrained by plate size, generally producing pipes up to 2.2 meters in diameter due to single-width plate limitations.
Detection
Quality control is essential for both ERW and DSAW pipes. They undergo a variety of mechanical and non-destructive tests to ensure safety and structural integrity. These tests typically include:
Chemical composition analysis
Tensile strength testing
Flattening and bending tests
Guided bend tests
Hydrostatic (water pressure) testing
Ultrasonic testing
Specifically, ERW pipes are subject to ultrasonic and eddy current testing, whereas DSAW pipes also include radiographic (X-ray) inspection due to their thicker walls and critical applications. In both types, surface defects such as cracks, laps, delamination, arc burns, or inclusions beyond allowable limits are strictly prohibited. Pipes must have a smooth internal and external surface, ensuring long-term durability and performance.
Uses
ERW pipes are most commonly used in low- to medium-pressure applications, such as transporting water, gas, oil, air, or steam, and are also utilized as structural steel in construction. Their consistent dimensions and efficiency make them suitable for pipelines in residential, commercial, and agricultural sectors.
On the other hand, DSAW pipes are engineered for high-stress, large-diameter, and long-distance applications. Their robust construction makes them ideal for oil and gas transmission pipelines, power plants, bridge structures, large-span grid engineering, and foundation piling. Their superior strength and weld integrity offer greater reliability in harsh environments.
Conclusion
In summary, both ERW and DSAW pipes play essential roles in modern pipeline systems, each with unique manufacturing processes, performance characteristics, and application scopes. ERW pipes offer cost-effective solutions for lower-pressure environments with high production efficiency, while DSAW pipes provide superior strength and weld quality for demanding, large-scale infrastructure projects. Selecting the right type of pipe depends on the specific pressure requirements, project scale, and environmental conditions. A clear understanding of their differences ensures optimal performance, safety, and cost control in practical engineering applications.
