Steel pipes can be classified by welding methods into arc-welded pipes, high-frequency or low-frequency resistance-welded pipes, gas-welded pipes, furnace-welded pipes, Bundy tubes, etc. According to weld seam shapes, they can be further divided into straight seam welded pipes and spiral welded pipes. Electric welded steel pipes are commonly used in the petroleum drilling and machinery manufacturing industries.
Specifications range from Φ219 to Φ2032 with wall thicknesses of 5-18mm, and materials include Q235, Q345, and grades X42-70.
Spiral welded steel pipes are manufactured by bending steel strips or plates into circular, square, or other shapes and then welding them to form steel pipes with seams on the surface.
Classification of Welded Steel Pipes:
By welding methods: arc-welded pipes, high-frequency or low-frequency resistance-welded pipes, gas-welded pipes, furnace-welded pipes, Bundy tubes, etc.
By weld seam shapes: straight seam welded pipes and spiral welded pipes.
Electric welded steel pipes are applied in oil drilling and machinery manufacturing. Furnace-welded pipes can be used as water and gas pipes, while large-diameter straight seam welded pipes are suitable for high-pressure oil and gas transportation. Spiral welded pipes are used for oil and gas transmission, pipe piles, bridge piers, etc.
Welded steel pipes offer lower costs and higher production efficiency compared to seamless steel pipes. Straight seam welded pipes boast simple production processes, high efficiency, low costs, and rapid development. Generally, spiral welded pipes exhibit higher strength than straight seam welded pipes, enabling the production of larger-diameter pipes from narrower blanks. They also allow for the production of pipes with different diameters from the same width of blanks.
However, compared to straight seam pipes of the same length, spiral welded pipes have a 30-100% longer weld seam, resulting in lower production speeds. Consequently, smaller-diameter pipes tend to be straight seam welded, while larger-diameter pipes are often spiral welded. The spiral submerged arc welded steel pipe is made by spirally bending hot-rolled steel strips and welding the inner and outer seams using submerged arc automatic welding.
Spiral steel pipes are widely used in the production of large-diameter pipes due to the following reasons:
By adjusting the forming angle, various diameters of steel pipes can be produced from the same width of steel strip.
As the forming is continuous, the cut-to-length of steel pipes is not limited.
The spiral weld seam is evenly distributed along the entire circumference of the pipe, leading to high dimensional accuracy and strength.
The ease of size adjustments makes them suitable for the production of small-batch, multi-variety steel pipes.
