Seamless steel pipes are crafted from round steel billets via hot rolling, cold rolling, or cold drawing methods, resulting in a seamless pipe body devoid of any seams.
Welded steel pipes, on the other hand, are made from flat steel plates with a visible welding seam along the pipe body. This category encompasses ERW (Electric Resistance Welded), LSAW (Longitudinal Submerged Arc Welded), and SSAW (Spiral Submerged Arc Welded) pipes.
At CGSteel, we highlight the disparities between seamless and welded pipes, covering aspects such as raw materials, manufacturing processes, performance characteristics, appearances, sizes, applications, and cost considerations.
Seamless steel pipes are crafted using steel ingots or solid tubes as raw materials, which are then perforated and formed through processes such as hot rolling, cold rolling, or cold drawing. Hot rolled seamless pipes are produced through billet forging, perforation, rolling, shaping, and other methods, making them suitable for large diameter and thick-walled pipes. Cold drawn seamless pipes are created using cold drawing technology, resulting in relatively lower material strength but smooth surface appearance and internal control. This method is commonly used for small diameter and thin-walled pipes. These seamless pipes are manufactured from carbon structural steel, low alloy structural steel, alloy structural steel, and stainless steel, and find applications in various industries such as pipelines, thermal services, mechanical industries, and chemicals.
Welded steel pipes, including LSAW (Longitudinally Submerged Arc Welded), SSAW (Spirally Submerged Arc Welded), and ERW (Electric Resistance Welded) pipes, are produced using steel strips or plates. The manufacturing process involves bending the steel plate and then welding it into circular, square, or other shapes. Welded steel pipes boast high production efficiency, cost-effectiveness, and material savings, making them widely utilized in industries such as aviation, aerospace, energy, electronics, automobiles, and light industry. Additionally, they offer strong corrosion resistance, particularly in acidic environments.
Why Choose Seamless Steel Pipes?
Many opt for seamless steel pipes over welded ones due to their ability to withstand extremely high pressure without cracking. Welded pipes, with their seams, are prone to cracking under high pressure, unlike seamless pipes. Moreover, calculating the pressure of seamless pipes is straightforward. They are also thinner, lighter, and possess uniform shapes, thanks to the uniform extrusion of the alloy. For top-notch seamless steel pipes, consider Octal Steel's API 5L and ASTM seamless steel pipes.
Summary of Differences Between Seamless and Welded Steel Pipes:
- Appearance:
- Seamless steel pipes use steel billets as raw material, with outer surface defects that cannot be fully eliminated during the hot rolling process, only polished after finishing.
- Welded steel pipes are made from hot-rolled coils, ensuring high surface quality due to the quality of the coil.
- Molding Process:
- Seamless steel pipes are formed in a single rolling process.
- Welded steel pipes are manufactured from steel strips or plates, utilizing bending and various welding techniques.
- Performance and Usage:
- Seamless steel pipes exhibit better pressure capacity and higher strength compared to ERW welded steel pipes, making them suitable for high-pressure equipment and industries like thermal and boiler applications.
- Welded steel pipes may have weaker points at the welding seam, affecting overall performance, and can generally withstand 20% less working pressure than seamless pipes.
- Available Sizes:
- Seamless steel pipe manufacturers in China typically produce original sizes with a maximum outer diameter of 20 inches (508 mm), as larger sizes require hot expanding machining.
- Welded steel pipes do not face these size limitations, with sizes available from 1-1/2 inches (48.3mm) to 100 inches (2540 mm).
- Cost and Prices:
- Seamless steel pipes generally have higher costs compared to welded pipes due to raw materials, manufacturing equipment, and processes.
- Market pressures may occasionally make welded pipes more expensive. In such cases, opting for seamless steel pipes of the same dimensions is recommended.
