DSAW Pipe Manufacturing Process

Double Submerged Arc Welded (DSAW) steel pipes have become increasingly important in various industries, from oil and gas transportation to large-scale construction projects. As a leading manufacturer of high-quality steel pipes, Longma Group is committed to providing our customers with in-depth knowledge about our products. In this comprehensive guide, we'll explore the DSAW pipe manufacturing process, its key steps, and the advantages it offers over other welding techniques.

What are the key steps in DSAW pipe production?

The production of DSAW steel pipes involves several crucial steps, each contributing to the final product's quality and performance. Let's delve into the main stages of the manufacturing process:

1. Raw Material Preparation: The process begins with the selection of high-quality steel plates or coils. These materials undergo rigorous testing to ensure they meet the required chemical composition and mechanical properties.
2. Edge Preparation: The steel plates are carefully edge-milled to create a precise bevel angle, which is crucial for achieving proper weld penetration and strength.
3. Forming: The prepared plates are then formed into a cylindrical shape using either a U-ing and O-ing process or a continuous spiral forming method, depending on the desired pipe specifications.
4. Tack Welding: Once formed, the pipe is temporarily held together with tack welds to maintain its shape during the main welding process.
5. Double Submerged Arc Welding: This is the core of the DSAW process, where both the inside and outside of the pipe are welded simultaneously or in quick succession using the submerged arc welding technique.
6. Heat Treatment: After welding, the pipes may undergo heat treatment to relieve residual stresses and improve their mechanical properties.
7. Non-Destructive Testing: Each pipe is subjected to various non-destructive tests, including ultrasonic testing, radiographic testing, and hydrostatic testing, to ensure weld integrity and overall pipe quality.
8. Final Inspection and Finishing: The pipes undergo a final visual inspection, and any necessary surface treatments or coatings are applied before the pipes are prepared for shipping.

How does the submerged arc welding process work in DSAW pipes?

The submerged arc welding (SAW) process is at the heart of DSAW pipe manufacturing. This technique offers several advantages, including high deposition rates, deep penetration, and excellent weld quality. Here's how it works:

1. Flux Application: A layer of granular flux is deposited along the joint to be welded. This flux plays a crucial role in shielding the weld pool from atmospheric contamination.
2. Arc Initiation: An electric arc is struck between the welding wire (electrode) and the workpiece, hidden beneath the layer of flux.
3. Weld Pool Formation: The intense heat from the arc melts both the welding wire and the edges of the pipe, creating a weld pool. The melted flux forms a protective slag over the weld pool.
4. Continuous Welding: As the welding progresses, the wire is continuously fed into the joint, and the flux is replenished. This allows for uninterrupted welding of long seams.
5. Slag Removal: Once the weld cools, the solidified slag is removed, revealing a smooth, high-quality weld.

In DSAW pipes, this process is performed on both the inside and outside of the pipe, either simultaneously or in quick succession, ensuring complete penetration and superior weld strength.

What are the differences between single and double seam DSAW pipes?

While both single and double seam DSAW pipes utilize the submerged arc welding process, there are significant differences in their manufacturing and performance characteristics:

Single Seam DSAW Pipes:

• Manufacturing Process: Welded from one side only, typically the outside of the pipe.
• Weld Penetration: May have limited penetration, especially in thicker-walled pipes.
• Production Speed: Generally faster to produce than double seam pipes.
• Cost: Usually less expensive due to simpler production process.
• Applications: Suitable for less demanding applications or where cost is a primary concern.

Double Seam DSAW Pipes:

• Manufacturing Process: Welded from both the inside and outside of the pipe.
• Weld Penetration: Offers complete penetration, even in thick-walled pipes.
• Weld Strength: Generally provides superior weld strength and integrity.
• Quality Control: Allows for better inspection of the weld quality from both sides.
• Applications: Ideal for high-pressure applications and critical infrastructure projects.

The choice between single and double seam DSAW pipes depends on factors such as the intended application, required pressure ratings, and project specifications. At Longma Group, we specialize in double seam DSAW pipes, offering our customers the highest level of quality and reliability for their most demanding projects.

Conclusion

The DSAW pipe manufacturing process represents a significant advancement in steel pipe production, offering superior weld quality, strength, and versatility. By understanding the key steps in DSAW pipe production, the intricacies of the submerged arc welding process, and the differences between single and double seam pipes, you can make informed decisions for your projects.

At Longma Group, we stand at the forefront of the global DSAW (Double Submerged Arc Welded) steel pipe manufacturing industry, leveraging over three decades of engineering excellence and technological innovation. Our vertically integrated production facilities, spanning 200,000 square meters in strategic locations across Asia and Europe, are equipped with cutting-edge automated welding systems, precision CNC forming machines, and advanced non-destructive testing (NDT) laboratories. These state-of-the-art assets enable us to produce seamless and longitudinally welded pipes ranging from 114mm to 2,540mm in diameter, with wall thicknesses up to 40mm, ensuring compliance with international standards such as API 5L, ISO 3183, and ASTM A671.

Contact our expert team today at info@longma-group.com. We're here to answer your questions, provide detailed specifications, and help you find the perfect pipe solution for your unique needs. Let's build a stronger future together with Longma Group's premium DSAW pipes.

References

1. American Petroleum Institute. (2018). API Specification 5L: Specification for Line Pipe.
2. American Society for Testing and Materials. (2019). ASTM A370: Standard Test Methods and Definitions for Mechanical Testing of Steel Products.
3. Masubuchi, K. (1980). Analysis of Welded Structures: Residual Stresses, Distortion, and Their Consequences. Pergamon Press.
4. American Welding Society. (2015). AWS D1.1/D1.1M: Structural Welding Code - Steel.
5. Lancaster, J. F. (1999). Metallurgy of Welding. Abington Publishing.
6. ASM International. (2016). ASM Handbook, Volume 4: Heat Treating.
7. American Society for Nondestructive Testing. (2016). Nondestructive Testing Handbook, Fourth Edition: Volume 7, Ultrasonic Testing.