In strong oxidizing nitric acid, compared with high alloy steel containing molybdenum, low corrosion resistance. In hydrochloric acid, the use of 904L stainless steel pipe is limited to a lower concentration of 1-2%. In this concentration range.
The corrosion resistance of 904L stainless steel pipe is better than the conventional stainless steel. 904L stainless steel pipe has a high resistance to pitting corrosion. In chloride solution, the corrosion resistance is also very good. 904L stainless steel pipe with high nickel content, reduce the corrosion rate in the pit and crevice. When the ordinary austenitic stainless steel is more than 60 degrees Celsius, it may be sensitive to stress corrosion in a chloride rich environment. Due to the high nickel content, 904L stainless steel pipe in the chloride solution, concentrated hydroxide solution and the rich hydrogen sulfide environment, has a high resistance to stress corrosion cracking capacity. Because the 904L carbon content is very low (maximum 0.020%), there will be no carbide precipitation in the case of general heat treatment and welding. This eliminates the general heat treatment and the risk of intergranular corrosion after welding. As a result of the high chromium nickel molybdenum content, and added a copper element, so the 904L stainless steel pipe even in the reducing environment, such as sulfuric acid and formic acid can also be passive. The high nickel content also has a lower corrosion rate in the active state. In the 0~98% concentration range of pure sulfuric acid, the use of 904L temperature can be as high as 40 degrees celsius. The corrosion resistance of pure phosphoric acid is very good in the range of 0~85% concentration.
In the industrial phosphoric acid produced by the wet process, the impurities have a strong influence on the corrosion resistance. In all kinds of phosphoric acid, the corrosion resistance of 904L stainless steel pipe is better than that of ordinarystainless steel pipe.
Source: Zhejiang Yaang Pipe Industry Co., Limited (www.yaang.com)