Traditional carbon steel equipment or other equipment with a protective coating, such as asphalt, has been gradually withdrawn from the beer industry. Most modern fermentation vessels are now made of stainless steel, including from the brewhouse to the fermentation tanks and fermenters, as well as the filling pipes. So when choosing cleaning agents and biocides, there are two things to keep in mind: the nature of the organic dirt, and the characteristics of the equipment being cleaned. Usually, cleaners and disinfectants erode stainless steel and require careful attention especially when chlorides are present. Therefore, in the choice of cleaning agents and disinfectants should also be fully considered chemical properties. For example, peroxyacetic acid will corrode rubber products, but it can be partitioned in alcohol or water. Only trace amounts exist and are not harmful.
The effect of cleaning agents and disinfectants on stainless steel
(1) On the impact of chlorinated substances on stainless steel
To increase the function of cleaning agents and disinfectants, there is usually a small amount of chloride. Because the chloride will corrode stainless steel, in the use of products will corrode stainless steel, the type of tank corrosion and occur at the crystal interface, also not easy to be noticed. For example, thin stainless steel is prone to perforation, almost weld line perforation. After treating the stainless steel interface, a strong passivation film of about 3nm can be formed. But it can not work on chloride and has a strong permeability, easy to corrode the equipment.
(2) The effect of acid on stainless steel.
Stainless steel corrosion prevention has certain limitations, usually austenitic stainless steel to organic acids or some inorganic acids such as HON3 or HPO3 have good corrosion resistance. But for HCL and HSO4, just like carbon steel has no corrosion resistance. Even the stress corrosion results for chlorides are lower than carbon steel.
(3) Effect on seal
The seal is made of elasticity and direct contact with beer. So the material must meet national standards and must not have any components that affect the taste of beer.