What is the difference between ERW and seamless stainless steel pipes?

In simple terms, stainless steel pipes refer to pipes made from stainless steel materials, while the term "steel pipes" encompasses a broader category. Seamless pipes and ERW (Electric Resistance Welded) pipes are two distinct types of stainless steel pipes, differing in raw materials, manufacturing processes, appearance, mechanical properties, cost-effectiveness, and applications. Here's a closer look at these differences.

Raw Materials
Seamless stainless steel pipes are crafted from solid round steel "billets" that are heated and either pushed or pulled to create a hollow tube. These billets are sourced from reputable manufacturers in China and abroad.
In contrast, ERW stainless steel pipes are made from stainless steel strips or coils that are rolled and then welded.

Manufacturing Process
The ERW process involves rolling steel plates or strips into a cylindrical shape and using resistance welding, where electric current generates heat to melt and fuse the edges. On the other hand, seamless stainless steel pipes are produced using a perforation and stretching method, resulting in a weld-free structure, which makes the process more complex.

Appearance
ERW pipes feature a longitudinal weld seam, a critical aspect of their quality. In contrast, seamless stainless steel pipes, formed through perforation and extrusion, lack welds, leading to a cleaner appearance. Consequently, the cross-section of ERW pipes will show a welded joint, while seamless pipes will not.

Mechanical Properties
ERW stainless steel pipes generally possess better mechanical strength due to the fusion of the parent material during welding. However, seamless pipes demonstrate superior durability, particularly in fluid transmission under varying temperatures and pressures. The pressure distribution along the walls of seamless pipes is more uniform, making them less prone to breaking or leaking.

Cost-Effectiveness
The production of ERW stainless steel pipes is more cost-effective due to the efficient welding process, whereas seamless pipes involve a more complicated manufacturing process, resulting in higher costs.

Applications
ERW stainless steel pipes are widely used in construction, machinery manufacturing, and bridge engineering, among other fields. Their efficiency, low cost, and stable quality make them ideal for various industrial applications, including aviation, energy, electronics, and automotive sectors. ERW pipes typically have a maximum outer diameter of 24 inches and are suited for low to medium pressure applications.

Seamless stainless steel pipes, due to their absence of welds, offer enhanced corrosion resistance, higher mechanical strength, and exceptional pressure resistance. They are particularly suitable for high-pressure applications in industries such as hydrocarbons, oil and gas exploration, and hydraulic systems, making them ideal for demanding applications requiring superior material performance.