Differences Between Stainless Steel Seamless Pipes and Welded Pipes

1. Differences in Production Process

Stainless steel welded pipes are formed by welding rolled steel sheets or strips and then using equipment and molds. The inner walls of these pipes typically have weld seams. In contrast, seamless pipes are made from solid round billets through hot extrusion processes such as drilling, cold rolling, and cold drawing, resulting in pipes without any weld seams.

2. Differences in Appearance

Welded pipes have very small wall thickness tolerances and uniform thickness around the circumference. They have high precision, bright inner and outer surfaces, and can be made to any length. Seamless pipes, however, have lower precision, uneven wall thickness, less bright surfaces, high cost for fixed lengths, and may have interior and exterior defects. Therefore, seamless pipes generally have thicker walls.

3. Differences in Performance and Price

Seamless pipes offer better corrosion resistance, pressure resistance, and high-temperature resistance compared to welded pipes. However, with advancements in welded pipe manufacturing technology, the mechanical properties of welded pipes have gradually approached those of seamless pipes. Seamless pipes are more complex to manufacture and thus are more expensive than welded pipes.

Given the characteristics and differences between stainless steel seamless pipes and welded pipes, selecting the appropriate type for specific applications can achieve economical, aesthetic, and reliable results:

1. For decorative pipes, product pipes, and support pipes, which typically require good surface appearance, stainless steel welded pipes are generally used.

2. For low-pressure fluid transport such as water, oil, gas, air, hot water, or steam, stainless steel welded pipes are usually employed.

3. For applications in power plants, nuclear power boilers, where high temperature, high pressure, and high strength are required, and in industrial engineering and large equipment fluid pipelines, stainless steel seamless pipes should be used.

4. Stainless steel welded pipes are generally used for fluid transport below 0.8MPa, while seamless pipes can withstand fluid transport above 0.8MPa. If the pressure requirement is not high, welded pipes are more economical.