Large-diameter seamless steel pipes can be traditionally divided into straight-seam electric arc welded steel pipes and straight-seam submerged arc welded steel pipes. Straight-seam welded steel pipes have a simple production process, low cost, rapid development, and high production efficiency. Seamless steel pipes are square, round, or rectangular steel pipes with a hollow cross-section and no joints on all four sides.

First, the steps of manufacturing large-diameter seamless steel pipes:
1. A large-diameter seamless steel pipe is a steel pipe made from a single piece of metal with no seams on its surface. Seamless steel pipes have a hollow cross-section and are suitable for transporting fluids such as oil, water, and some solid materials.
2. Large-diameter seamless steel pipes are widely used in manufacturing structural and mechanical parts, such as oil drill pipes, automobile drive shafts, bicycle frames, and steel scaffolding. Straight-seam steel pipes refer to steel pipes where the weld seam is parallel to the longitudinal direction of the pipe. Under the same pipe diameter and wall thickness, seamless steel pipes have significantly greater pressure resistance and stability than straight-seam steel pipes.
3. Large-diameter seamless steel pipes are steel pipes made by pressing steel plates or strips together. Welded steel pipes are steel pipes made by pressing steel plates or strips together.

Second, a comprehensive guide to large-diameter seamless steel pipe manufacturing methods:
1. Large-diameter seamless steel pipes have significantly higher corrosion resistance, pressure resistance, and high-temperature resistance than welded steel pipes. When the pipe diameter and wall thickness are the same, seamless steel pipes withstand much greater pressure and exhibit greater stability than straight-seam steel pipes.
2. Large-diameter seamless steel pipes have a hollow cross-section, making them suitable for transporting fluids such as oil, water, and some solid materials. Straight-seam welded steel pipes have a simpler production process, lower cost, faster development, and higher production efficiency.
3. Large-diameter seamless steel pipes have significantly higher corrosion resistance, pressure resistance, and high-temperature resistance than welded steel pipes. Welded steel pipes are steel pipes made by pressing steel plates or strips together.