According to the different manufacturing processes, it can be divided into several basic types: hot rolling, extrusion, cold drawing and cold rolling, and according to the cross-sectional shape, it can be divided into round tubes and special-shaped tubes. Round steel pipes are widely used, but there are also some special-shaped stainless steel pipes, such as square, rectangle, semicircle, hexagon, equilateral triangle and octagon.
For steel pipes subjected to fluid pressure, water pressure test should be carried out to test their pressure resistance and quality. If they do not leak, soak or swell under the specified pressure, they will be qualified. According to the standard or the buyer's requirements, some steel pipes shall be subjected to curling test, flaring test and flattening test.
Seamless stainless steel round tube, also known as stainless steel seamless tube, is made of steel ingot or solid tube blank through perforation, and then hot rolling, cold rolling or cold drawing. The specification of seamless steel pipe is expressed by outside diameter * wall thickness mm.
The full name of 304 stainless steel round pipe is SUS304 stainless steel pipe. SUS304 stainless steel round tube belongs to the American brand, and the domestic brand is equivalent to 0Cr 19Ni9 stainless steel tube, which is usually replaced by 0Cr 18Ni9. The mechanism of stainless steel rust prevention is that alloy elements form a dense oxide film to isolate oxygen contact and prevent further oxidation. So stainless steel is not "stainless".