About stainless steel pipe classification

Classification of stainless steel pipes: stainless steel seamless steel pipes and stainless steel welded steel pipes (seamed steel pipes) are basically two categories. According to the outer diameter and shape of steel pipes, they can be divided into round pipes and special-shaped pipes. Round steel pipes are widely used, but there are also some special-shaped steel pipes such as square, rectangular, semicircular, hexagonal, equilateral triangle, and octagonal.
For steel pipes under fluid pressure, hydraulic tests and radiographic flaw detection are required to test their pressure resistance and quality. It is qualified if no leakage, soaking or expansion occurs under the specified pressure.
Seamless stainless steel pipes, also known as stainless steel seamless pipes, are made of steel ingots or solid tube blanks that are perforated into capillary tubes, and then made by hot rolling, cold rolling or cold drawing. The specifications of seamless steel pipes are expressed in millimeters of outer diameter * wall thickness.
The full name of 304 stainless steel pipe is SUS304 stainless steel pipe.
SUS304 stainless steel pipe belongs to the stainless steel pipe of American brand material, and the domestic brand is equivalent to 0Cr19Ni9 stainless steel pipe, which is usually replaced by 0Cr18Ni9.
The anti-rust mechanism of stainless steel is that the alloying elements form a dense oxide film, which isolates oxygen contact and prevents further oxidation. So stainless steel is not "stainless".
There may be several reasons for the rusting of 304 materials:

1. Chloride ions exist in the use environment.

Chloride ions are widely present, such as table salt, sweat stains, sea water, sea breeze, soil and so on. Stainless steel corrodes very quickly in the presence of chloride ions, even more than ordinary low carbon steel.
Therefore, there are requirements for the use environment of stainless steel, and it needs to be wiped frequently to remove dust and keep it clean and dry.
316 and 317 stainless steel (see below for the performance of 317 stainless steel) are types of molybdenum-containing stainless steel. The molybdenum content in 317 stainless steel is slightly higher than that of 316 stainless steel. Due to the molybdenum in the steel, the overall performance of this steel is better than that of 310 and 304 stainless steel. Under high temperature conditions, when the concentration of sulfuric acid is lower than 15% and higher than 85%, 316 stainless steel has a wide range of uses. 316 stainless steel also has good resistance to chloride attack, so it is usually used in marine environments.
With the development of social economy, the application of stainless steel pipes has become more and more popular. It will definitely bring new changes in various fields.
Theoretical weight of stainless steel pipe: W=outer diameter-wall thickness x wall thickness x0.02491.