Progress in the Production of Spiral Seam Submerged Arc Welded Steel Pipes

Advantages of Spiral Seam Submerged Arc Welded Steel Pipes

Spiral seam steel pipes offer several benefits that make them a preferred choice for large diameter steel pipe production.

• Versatility in production: By simply altering the forming angle, steel pipes of various calibers can be produced from strips of the same width.
• Unlimited fixed length: The continuous bending process allows for the production of steel pipes of any fixed length.
• High dimensional accuracy and strength: The weld seam is evenly distributed on the entire circumference of the steel pipe, resulting in high dimensional accuracy and strength.
• Cost-effective and adaptable: The equipment cost is low, and it is easy to change the size, making it suitable for the production of small batches and multiple varieties of steel pipes.

However, despite these advantages, the use of spiral welded pipes has been limited due to certain challenges.

Challenges in the Use of Spiral Welded Pipes

The weld seam of the spiral pipe is longer than that of the straight seam pipe. This means that the probability of defect occurrence is high as most steel pipe defects are concentrated in the weld and heat affected zone. This has been a major factor restricting the wider application of spiral welded pipes.

Advancements in Spiral Tube Manufacturing Technology

The development of spiral tube manufacturing technology has led to a better understanding of the issue of long spiral tube welds.

Firstly, the defect of the weld of the spiral tube is an "inclined defect" because it is parallel to the weld. This means that the steel equivalent defect length in the pipe axis direction is shorter than that in the straight seam pipe during use.

Secondly, the pipeline steel is a rolled steel plate, and the impact toughness has a greater anisotropy. The CVN value in the rolling direction can be greater than the CVN value perpendicular to the rolling direction. This is 3 times higher. The main stress on the straight seam pipe is exactly perpendicular to the direction of the lowest impact resistance of the pipe, while the spiral pipe staggers the direction of the lowest impact resistance of the pipe. This turns the disadvantage of the weld length of the spiral pipe into an advantage.

In conclusion, the advancements in spiral tube manufacturing technology have not only addressed the challenges but also leveraged the inherent advantages of spiral seam submerged arc welded steel pipes. This has led to their increased use in the production of large diameter steel pipes.