Classification of pipes: steel pipes are divided into seamless pipes and welded pipes (with joints).

According to section shape can be divided into circular tube and profile-shaped tube, widely used is circular steel tube, but also some square, rectangular, semicircle, hexagon, equilateral triangle, octagonal and other profile-shaped tube.

Seamless stainless steel tube, also known as stainless steel seamless tube, is made of steel ingot or solid tube billet perforated into capillary, and then by hot rolling, cold rolling or cold dialing.

The specification of seamless steel tube is expressed in outer diameter * mm wall thickness.

304 stainless steel pipe full name SUS304 stainless steel pipe

SUS304 stainless steel tube belongs to the United States grade stainless steel tube, the domestic grade is equivalent to 0Cr19Ni9 stainless steel tube, usually replaced by 0Cr18Ni9.

Stainless steel rust prevention mechanism is the formation of alloy elements to form a dense oxide film, oxygen contact isolation, prevent continued oxidation.

So stainless steel is not "stainless".