Stainless Steel Pipe: How Seamless and Welded Pipes Are Made

What Is Stainless Steel Pipe?

Stainless steel pipe is used across many industries thanks to its durability, high corrosion resistance, and ease of maintenance. Its bright, decorative surface finish also makes it a popular choice for a wide range of visible applications. Stainless steel pipes are installed together with matching fittings and connection components.

Stainless steel pipes fall into two main categories: welded pipes and seamless pipes. The manufacturing method is one of the most important distinctions between them.

Seamless Stainless Steel Pipe

Seamless pipe is generally used in working environments with high pressure levels. It withstands pressure better than welded stainless steel pipe because it is formed from a single solid piece. Production starts with the hot billet, which is pierced and worked in dies to take on a round form. Special tooling is used to bring the pipe to the required inner diameter and give it its final round shape. The pipe is then left to cool. Once cool, it is pickled to remove the marks left on its surface by the rolling equipment. After pickling, the pipes are cleaned and made ready for use.

Welded Stainless Steel Pipe

Welded stainless steel pipe has a lower pressure rating than seamless pipe, because welding is used in its production. All stainless steel pipe used for decorative purposes is welded pipe, and welded pipe is mainly used in low-pressure lines and for architectural and decorative applications. The process begins with slitting stainless steel sheet into strips. These strips pass through a series of forming rolls that gradually shape them into a tube. The formed tube is then welded along the seam by machine to become a pipe. After welding, the pipe goes into an annealing furnace. Annealing makes the stainless steel pipe easier to work and significantly improves its resistance to bending and deformation. The pipes are then cut to the required lengths and dimensions and sent for cleaning. Finally, the burr left by the welding process is removed by grinding, and the pipe is ready for use.