This kind of steel pipe can be divided into stainless steel seamless steel pipe and stainless steel welded pipe (seam pipe) two categories.  

According to the different manufacturing process can be: hot rolling, extrusion, cold drawing and cold rolling these basic types, according to the shape of the section and can be divided into round pipe and special-shaped pipe, widely used is circular steel pipe, but there are some square, rectangular, semicircular, hexagonal, equilateral triangle, octagonal special-shaped stainless steel pipe.  

For the steel pipe under fluid pressure to carry out hydraulic test to test its pressure capacity and quality, under the specified pressure does not leak, wet or expansion for qualified, some steel pipe according to the standard or the requirements of the side test, flaring test, flattening test.  

Seamless stainless steel round pipe, also known as seamless stainless steel pipe, is made of steel ingot or solid tube blank through perforation of wool tube, and then made by hot rolling, cold rolling or cold dialing.  The specifications of seamless steel pipe are expressed by the number of millimeters of outer diameter * wall thickness.  

304 stainless steel pipe full name SUS304 stainless steel pipe, SUS304 stainless steel pipe belongs to the American brand of stainless steel pipe material, domestic brand is equivalent to 0Cr19Ni9 stainless steel pipe, usually replaced by 0Cr18Ni9.  The mechanism of stainless steel rust prevention is the formation of dense oxide film alloy elements, isolated oxygen contact, prevent continued oxidation. So stainless steel is not "rust".