The primary difference between SMLS (seamless) and WELDED (ERW or LSAW) pipe is the method of manufacture. SMLS pipe is manufactured by piercing a solid steel billet or bloom, which is then heated and rolled to form a hollow cylindrical shape. Welded pipe, on the other hand, is made by rolling a flat steel strip into a cylindrical shape and welding the edges together.
Here are some of the main differences between SMLS and welded pipe:
Manufacturing process: As mentioned above, SMLS pipe is made from a solid steel billet or bloom, while welded pipe is made from a flat steel strip that is rolled into a cylinder and welded at the seam.
Appearance: SMLS pipe has a smooth, uniform surface finish with no welded seam visible. Welded pipe has a visible welded seam that runs the length of the pipe.
Strength: SMLS pipe is generally considered to be stronger than welded pipe because it has no welded seam that could be a potential point of weakness. The absence of a welded seam also makes SMLS pipe more resistant to cracking under stress.
Size: SMLS pipe is typically available in larger sizes and thicknesses than welded pipe.
Cost: SMLS pipe is generally more expensive than welded pipe because of the more advanced manufacturing process required.
Applications: SMLS pipe is typically used for high-pressure and high-temperature applications such as oil and gas drilling, chemical processing, and power generation. Welded pipe is generally used for low to medium-pressure applications, such as water and gas pipelines, structural and mechanical applications.
Overall, the choice between SMLS and welded pipe will depend on the specific application and requirements. SMLS pipe is generally considered to be of higher quality and strength, but it is more expensive and may not be suitable for all applications. Welded pipe, on the other hand, is more cost-effective and suitable for low to medium-pressure applications.