In stainless steel pipes, steel that is resistant to corrosion by weakly corrosive media such as air, steam, and water, and chemically corrosive media such as acid, alkali, and salt, is also called stainless acid-resistant steel. In practical applications, steels resistant to weakly corrosive media are often referred to as stainless steel, and steels resistant to chemical media are referred to as acid-resistant steel. Due to the difference in chemical composition between the two, the former is not necessarily resistant to corrosion by chemical media, while the latter are generally stainless.

Second, the corrosion resistance of stainless steel pipes depends on the alloying elements contained in the steel. Chromium is the basic element for stainless steel to obtain corrosion resistance. When the content of chromium in steel reaches about 1.2%, chromium interacts with corrosion. The effect of oxygen in the substance forms a thin oxide film on the surface of the steel, which can prevent the corrosion of the steel. The substrate is further corroded. In addition to chromium, commonly used alloying elements are nickel, molybdenum, titanium, niobium, copper, nitrogen, etc. to meet the requirements of various applications on the structure and properties of stainless steel.